With the research and application of the geology-engineering integration technologies, North America has won the victory of shale revolution, and the United States has realized energy independence, playing a dominant role in the global energy market. Its history and experience in shale revolution are the references of great value to the exploration and production of hydrocarbon resources in China. With abundant oil and gas in the exploration areas of Sinopec and various types of favorable targets, accelerating exploration and production is of great significance to improve China's energy structure and ensure national energy security. The application of geology-engineering integration has brought benefit development for the marine shale gas in the Sichuan Basin. In terms of realizing efficient exploration and production of the ultra-deep marine carbonate, tight sandstone and shale, five key studies are suggested to be strengthened: ①fine reservoir description and adaptive fracturing technology of exploration and production for complicated reservoirs, ②ultra-deep carbonate reservoir prediction and optimal drilling technology system, ③application of big data in realizing efficient adjustment and optimize completion program for tight sandstone gas reservoirs, ④development of multi-layer and three-dimensional production technology for marine shale oil and gas, ⑤research on the key problems in the deep, normal-pressure and continental shale oil and gas. To achieve high quality exploration and efficient production of oil and gas, Sinopec will keep strengthening the basic geological research and engineering technology innovation, upgrading technical equipment and following the idea of geology-engineering integration. And then, Sinopec will establish integrated operation coordination mechanism and emphasize integrated management of whole process in order to cut costs and increase efficiency.

Shale oil reservoir bears heterogeneous pore structure with multi-scale pore sizes. Nano-scale organic intra-granular pore, nano-micro scale inorganic inter-granular pore and micro-fracture coexist in shale oil reservoir. The ultra-low porosity and ultra-low permeability characteristics make the laboratory core flow experiment unavailable for shale oil core sample. As a consequence, shale oil flow parameters in different scale of porous medium can not be measured and it is difficult to accurately evaluate the shale oil flow ability in different scale of porous medium. To solve this problem, a calculation method for pore structure characterization and flow ability of shale oil reservoir is proposed based on digital cores. The nanopore shale oil flow model is first established considering nano-micro scale transport mechanisms and occurrence state, and the influences of shale pore surface physicochemical property and pore size on shale oil flow are analyzed. Then, the nanopore shale oil flow model is further extended to 3D porous media by establishing pore network shale oil flow model. The digital cores in different medium and its pore network are constructed based on the multi-scale shale core imaging data in shale oil reservoir. The multi scale pore structure characteristic and shale oil flow ability are studied in detail on this basis. The analysis results indicate that when the pore radii are less than 5 nm, the shale oil permeability is dependent on adsorbed phase permeability. Inter-granular pore dominates shale oil flow ability. The micro-scale effect on shale oil permeability is very small which can be neglected. The micro scale effect and oil slippage are more obvious in organic pores. However, the contribution of organic pore permeability on total shale oil permeability relies on the connectivity of organic pore structure.

The machine learning is not only an important tool for oil and gas big data analysis, but also a general data-driven analysis method. As an important field with a long history and a large data base, oil and gas exploration and development has a great potential for data mining. The use of big data analysis technology for oil and gas field can help decision makers to conduct investment analysis, risk assessment and production optimization, which brings significant economic benefits. The machine learning method has been tried by the researchers applying to the researches on oil and gas. Nowadays, many application scenarios have been proposed with the development of machine learning algorithms, but general solutions for specific scenario are still divided. So that, we introduces the procedure of a machine learning modeling upon the most basic principles, and summarizes the development history of the main three kinds of machine learning methods that can be applied to oil and gas big data analysis. And then based on the characteristics of oil and gas field big data, the core contents, goals and advantages of oil and gas field big data analysis and utilization are discussed, the main application scenarios of machine learning in oil and gas field are analyzed, and the existing problems and countermeasures in typical oil and gas production prediction are summarized.

Climate change centering on carbon dioxide（CO₂） emissions and energy security centering on the shortage of oil resources are two major problems restricting the sustainable development of China's social economy. In order to solve the bottleneck of both the CO₂ capture and the great improvement of recovery factor of low permeability reservoir, the related technology researches have been carried out in Shengli Oilfield, forming the supporting technologies such as CO₂ capture, safe long-distance transmission, reservoir engineering optimization design, the injection-production process design, design of surface gathering and oil displacement and environmental monitoring, and building an industrial-scale demonstration project for flue gas CO₂ capture, oil displacement and underground storage of coal-fired power plants. The industrial tests show that the cost of the new MSA technology is 35 % lower than that of the traditional MEA technology. Over 31×10⁴ t of CO₂ have successfully been injected into the reservoir, with the cumulative oil increment of 8.6×10⁴ t, and 28×10⁴ t of CO₂ storaged in G89-1 block. The central well area has increased the recovery rate by 9.5 %, and the recovery rate is expected to reach 17.2 %.

Efficient development of Zhongjiang gas reservoir is faced with four difficulties: the meticulous channel depiction, the establishment of high-yield enrichment mode, the formulation with development technology policy, and corresponding engineering fracturing technology. For the narrow channel sand bodies, the multi-domain and multi-attribute fine description and accurate reservoir prediction technology are used, and the spatial distribution characteristics of multi-stage and overlapping channel sand bodies are well described. It can depict the channel sand bodies of the thinnest 8 m and the narrowest 50 m, and the sedimentary time sequence of each channel sand body is also very clear. An improved three-parameter pre-stack inversion technique based on ray parameter domain is used to realize the high-precision quantitative prediction of thin-layer, the predicted error of reservoir thickness and porosity is less than 10 %. By establishing an effective combination model of source rock fault and channel sand, with high ancient and modern structures or high ancient and low modern structures, and good reservoir physical properties, it is expected to obtain high and stable production of gas wells in these areas. By using the techniques of 3D deployment of well groups, well pattern optimization and horizontal well optimization design, the production degree of tight sandstone gas reservoir in narrow channel is greatly enhanced, and the investment cast is saved. By using the integrated horizontal well fracturing technology, the single well test gas production is steadily increased, and the transformation effect is increased to 10.6 times before implementation. High-efficiency development technology of tight sandstone gas reservoir formed by narrow channel enables efficient exploration and development of the Zhongjiang Gas Field, the largest gas field of Sinopec in western Sichuan, with an annual gas production of more than 1 billion cubic meters.

Nanchuan Shale Gas Field is China's first commercially developed shale gas field dominated by normal pressure shale gas. In order to evaluate the exploration and development prospects of this type of shale gas, the exploration and development history of this area has been reviewed, the geological characteristics of the gas field are analyzed from the aspects such as structure, deposition, reservoir, preservation, in-situ stress, gas reservoir and production characteristics, and finally, the key technologies of exploration and development are summarized. The results show that: ①Nanchuan Shale Gas Field has experienced multi-stage tectonic movement. Its shale gas geological conditions are complex, and there are three structural belts: Pingqiao, Dongsheng and Yangchungou. The characteristics of deposition, reservoir, preservation and in-situ stress are quite different in different tectonic zones, but the shale gas reservoirs are generally with the type of elastic gas drive, mid-deep to deep layer, normal temperature, high pressure to normal pressure and dry gas. ②As for the production, its has the characteristics of high initial test output, high liquid volume, fast decline, medium elastic yield and relatively low single well's EUR. ③Six key technologies of exploration and development have been formed, which are, “sweet spot” target evaluation, reservoir characterization, in-situ stress field prediction, geology-engineering integration design of horizontal wells, development technology policy and low-cost engineering technology. ④The discovery of Nanchuan shale gas field brings four inspiration: firstly, firming exploration confidence is the foundation of exploration breakthrough; secondly, deepening basic geological research is the core of breakthrough; thirdly, innovative technological practice is the key to benefit development; fourthly, the implementation of the integration model is the guarantee of improving quality and efficiency.

As a new field of unconventional natural gas exploration and development, deep coalbed methane（CBM） has great resource potential, but its benefit development faces great challenges. How to carry out efficient development is a problem needed to be solved at present. In order to achieve stable production and steadily promote the expansion of the gas field, focusing on how to realize the problem of “long fracture and far support” in reservoir reconstruction, Yanchuannan gas field has achieved good results through fracturing optimization and tackling key problems of deep coalbed methane geology-engineering integration. The research shows that: ①Deep CBM has great resource potential with a high gas content of 13~20 m ³/t, but it is difficult to develop and transform the reservoir and the daily production of single well is low, only of 0~500 m³/d; ②According to the underground observation, in the existing active hydraulic fracturing technology, the effective supporting seams mainly distributes within eight meters of the wellbore, and the main fracture extension is generally less than 30 m; ③Deep coal seam fracturing should take the large-scale artificial fracture with long-distance support and high conductivity as the main target to improve the sand adding strength with large displacement, and at the same time develope “low density and long migration” proppant. The average daily gas production of single well is 1 800 m ³. It provides a new idea for the deep CBM development.

In order to explore the characteristics of rich accumulation and the exploration potential of transitional shale gas, the lower Carboniferous shale in southern Guizhou is taken as the research object. Based on the data of two investigation wells and two exploration wells, the analysis is conducted from the aspects of stratigraphic sequence and sedimentary facies, occurrence characteristics of shale, accumulation conditions and favorable area evaluation. The research result shows that: ① The lower Carboniferous shale deposits in western Guizhou are controlled by the NW-SE Shuicheng-Ziyun synsedimentary fault and the Shuicheng-Liuzhi uplift partition, which can be divided into weining shuicheng tidal flat lagoon-transition sedimentary facies and Shuicheng-Ziyun shallow-water shelf marine sedimentary facies, forming Weining and Ziyun depositional central areas with deposition thickness ranging from 30 m to 200 m. The sedimentary thickness of Weining-Shuicheng is 119 m, and the embedded depth of floor is between 1 500 m and 3 000 m, which is a favorable area for exploration. ② Influenced by multi-stage structure and controlled by syndeposition, the gas accumulation type controlled by the combination of folds and faults is relatively developed in this area, which is a typical gas accumulation mode controlled by the structure of anticlinal combination blocked by reverse fault. ③ On the plane, the accumulation zone of Weishui anticline and Shuicheng-Ziyun fault structure is a favorable exploration area for shale gas research in Weining-Shuicheng, the sedimentary center of Jiusi Formation, with an area of about 944 km². There are at least three sets of organic-rich shale gas bearing beds vertically in the shale, which have good exploration potential

Staged fracturing for horizontal wells is one of the key technologies for shale gas development. As the shale gas development in China extends to normal pressure fields, it is urgent to enhance the speed and efficiency of fracturing technology. The existing plug and perf operation technology has many limitations, including long duration of pumping, easiness to stuck tools, limited number of fracturing stages for ball-actuated sliding sleeves, and limited fracturing scale for packers dragged by coiled tubing. For the new infinite stage and full-bore sliding sleeve fracturing technology, the structure principle of the sliding sleeve as well as its technological characteristics are explained, and a pilot test has been carried out in 16 fracturing stages of two wells in Nanchuan Shale Gas Field. This technology replaces perforation and coiled tubing drilling plugs by preset sliding sleeves. All the sliding sleeves are opened successfully. The number of fracturing stages is unlimited and the operation is continuous. The average time of single stage fracturing is 3.5 h and it can finish seven fracturing stages per day. As a fast, safe and efficient staged fracturing technology, it provides a new technical means for enhancing speed and efficiency of fracturing technology for shale gas wells in China.

Cluster deployment is the only way to realize the decarbonization industry development for the carbon capture, utilization and storage （CCUS） technology. The innovation and development for the engineered full flowsheet technology of CCUS is the key and urgent need to complete the scale deployment of CCUS decarbonization industry cluster, serving great significance to China’s energy security and carbon neutrality. In this study, the scientific connotations are clarified. The concept is proposed. The basic mode, application mode and key combination mode are firstly summarized, then the technologically scientific process is analyzed. The key techniques are summarized. The formation mechanisms are investigated. The representative project cases both at home and abroad are summarized. The current challenges and outlook are discussed and analyzed. Current works have shown that the efficient CO₂ capture technology, CO₂ chemical and bio-utilization, CO₂ mineralization, efficient CO₂ geological utilization and storage are the core connotation, with CCUS system optimization, source-sink matching and technology matching as the configuration mechanisms. The full flowsheet technology of CCUS is complex and diverse, with five main steps composing in its technical and scientific process. The framework of this technology has been established, and a lot of progress has been made in the field of scientific research and engineering applications. However, there is still a gap between China and developed countries in Europe and America in this field. The main direction of tackling challenges in China includes: accelerating the engineering demonstration of CCUS cluster scale deployment, strengthening the formation mechanism of the engineered full flowsheet technology of CCUS cluster scale deployment technology and scientific research, focusing on the breakthrough of CO₂ capture, geological storage, and other key technical links among the engineered full flowsheet CCUS technology.

In China, shales are widely distributed, continuous in time and complex in space. In this paper, the distribution of shales in the North China, South China and Tarim Plates are systematically sorted out and discussed. The Middle and Upper Proterozoic shales are dominated by marine facies with some continental facies, of which the littoral-neritic to neritic shelf, marine and continental moraine shales are developed, and the field shale sections are characterized by the distribution on the edges of different paleoplates. The Lower Paleozoic shales are dominated by marine facies, with the development of open shelf to neritic shelf shales, which are mainly distributed in the South China Plate and the Tarim Plate. The Upper Paleozoic shales which are dominated by marine-continental transitional facies and locally by marine and continental facies have the largest development and distribution in China. The Mesozoic and Cenozoic shale types are diverse but dominated by continental facies. The Mesozoic shales are mainly developed longitudinally along Yunnan, Sichuan and Shanxi and latitudinally from Xinjiang to Heilongjiang via Shanxi, while the Cenozoic shales are primarily developed in the eastern and western sides of the North China Plate. The plate margins, fold belts and complex tectonic activity areas exert an important impact on the distribution of shales. The ancient trough has a significant influence on the shale deposition, so do the depositional environment on the shale components, and the components on the weathering resistance of field shale sections. The development of field shale sections in different epochs and regions are affected by multi-factors, and each has specific geological characteristics. Shale in sections can be divided as manganese, siliceous, calcite or dolomite, silty, carbonaceous, coal and mixed types, in which carbonaceous shale can occur in various sections. Manganese shale is primarily developed in the strata before Middle Permian in South China Plate, while siliceous shale is mainly found in the open shelf facies, coal-type shale is developed later and mainly deposited in the marine-continental transitional facies and continental facies, The silty, calcite or dolomite shales are widely distributed. Each type of shale has specific epochal and regional distribution characteristics, so a systematic review of the shale strata in China could be helpful for the discovery for more shale gas in new strata or new areas.

The geological sequestration of greenhouse gas, CO₂, is an important means to cope with carbon peaking and carbon neutralization. However, the depleted gas reservoirs are the significant targets for the storage of CO₂. Due to the different forms of CO₂ in gas reservoirs, the effective CO₂ storage calculation method of gas reservoirs is established based on the theoretical CO₂ storage calculation method, which can be used to estimate the CO₂ storage potential of the depleted gas reservoirs. Meanwhile, the model of low permeability gas reservoir is established for the CO₂ storage in the later stage of the development. Considering the dissolution of CO₂ in formation water and the mineralization reaction of CO₂ between water and rock, the error of supercritical buried stock, dissolved buried stock and mineralized buried stock is 2.81 %, 7.37 % and 6.25 %, respectively, and the error of effective buried stock is only 3.06 % by comparing the calculated results with the numerical and analog results.

CO₂ flooding has the dual purpose of enhancing oil recovery（EOR） and carbon dioxide storage, and has a large development prospect. In particular, the need of carbon emission reduction gives a large space for the development of large-scale application of this technology. For Sinopec, the development history of CO₂ flooding can be divided into three stages: single well stimulation, pilot test and comprehensive application. After more than 50 years of development, CO₂ flooding mechanism and supporting technology have been relatively mature. According to the reservoir characteristics of Sinopec and three types of CO₂ flooding, which are miscible drive, near miscible drive and immiscible drive, the screening standard of CO₂ drive reservoir are established to clarify the mechanism of CO₂ flooding in low permeability reservoir, tight reservoir, medium and high permeability reservoir. Taking three reservoirs of Subei Basin, Fu-3 member of Caoshe Oilfield, Fu-3 member in Hua-26 fault block, and Duo-1 member of Zhoucheng Oilfield, and Gao-89-1 block of Zhengli Zhuanggao Block in Bohai Bay Basin as examples, the actual development effect of typical blocks are summarized, showing that CO₂ flooding is an important way to improve oil recovery efficiency. In order to solve the technical bottleneck of large-scale application of CO₂ flooding in low permeability reservoirs and medium-high permeability reservoirs, the researches on oil displacement mechanism and gas injection effect should be further strengthened to promote the development of CCUS. It is of great significance to achieve “carbon peak” and “carbon neutral” and ensure national energy security.

In order to solve the problem that water flooding is difficult to effectively develop low-ultra-low permeability reservoirs, Sinopec has carried out more than 30 field tests of CO₂ flooding, and achieves preliminary results and understanding. In this paper, firstly, the field test progress of CO₂ flooding and typical reservoir effects of SINOPEC are systematically described. Then, the change characteristics of technical policies and key indicators are analyzed. Finally, the problems faced by the development of CO₂ flooding in Sinopec are pointed out, and the development suggestions are put forward. The analysis reveals that the CO₂ flooding is an effective method to supplement energy for the low and ultra-low permeability reservoir. In order to produce more oil, WAG （water alternating gas） flooding are performed after continuous gas flooding. The oil well take effects about 6 months after the program is implemented. The average oil production by single well is increased by more than one-time and the oil change rate is 0.15~0.40 t/t. But the economic benefit through CO₂ flooding is limited by two problems. The first one is that the minimum miscible pressure for CO₂ is usually higher than 25 MPa in the low and ultra-low permeability reservoir and it is difficult to achieve fully miscible condition. The second one is that the lack of low-cost gas sources limits the economic benefits of CO₂. In order to improve the oil displacement efficiency and achieve high economic benefit, not only the national subsidy policy is required, but also the optimization for CCUS is needed. The CO₂ flooding can also be performed with chemical agents, flue gas or nitrogen to improve oil displacement effect and enhance economic benefit.

Based on the concept of geology-engineering integration, a systematic research, including theoretical study and field investigation, has been performed on design optimization, implement control and post-frac management of the whole lifecycle of volumetric fracturing technology in unconventional reservoir. The key technologies include: ①the series of pre-frac evaluation technologies regarding geology-engineering double “sweet spots”, double sweetness and comprehensive fracability; ②big data and AI algorithm based “well pattern-fracture-fracturing technique” multi-parameter collaborative optimization technology; ③fracturing control technology based on formation geological properties obtained from inversion study of on-site fracturing operation data; optimization on fracturing fluid flowback scenarios with consideration of imbibition effect; ④comprehensive post-frac evaluation technology; ⑤progressive production management optimization and adjustment technology in effective period of fracturing treatment. Field applications demonstrate that the geology-engineering integration volumetric fracturing technology with consideration of whole lifecycle development can maximize the potential to increase production, stabilize production and improve single well EUR, which has enormous guidance and reference significance towards the achievement of the “Four Improvements” and “Cost Reducing” goals in unconventional reservoir development.

The distributed optical fiber temperature monitoring technology is gradually being used to monitor the downhole production of fractured horizontal wells. However, it is still a huge problem to interpret the production profile of fractured horizontal wells quantitatively based on DTS data in low permeability gas reservoirs. In view of this, this study established the method, first, the temperature data preprocessing, and then, on the basis of the principle of conservation of mass and energy conservation of horizontal wells in low permeability gas reservoir fracturing coupling temperature forward model, finally using a variety of traffic data of mathematical methods of inversion layers, forming a set of monitoring based on distributed optical fiber temperature measurement technology of horizontal wells in low permeability gas reservoir fracturing of output profile processing and interpretation methods.The actual data processing of fractured horizontal well 5 was carried out by using the established method.The results show that the forward temperature fitting curve is basically consistent with the original temperature curve, which indicates the rationality and accuracy of the forward model.In addition, the calculated absolute errors of daily gas production of the five wells were between 100 m³ and 1 712 m³, and the absolute errors of daily water production are between 0.7 m³ and 1.8 m³. The errors are small and meet the production requirements. All these provided technical support for the development of low permeability gas reservoirs.

Aiming at the problems that the structural reservoir of the 3rd member of Funing Formation in the shallow layer of the western slope of Qintong depression is not developed and the benefit development of the deep low permeability reservoir is difficult, the sedimentary modeling technology and waveform inversion technology are adopted to deepen the study on the accumulation rule and evaluate the favorable area of the structural lithologic oil reservoir of the 3rsd member of the shallow Funing Formation. The spontaneous potential-waveform inversion technology can clearly describe the sand body of about five meters. Based on the established sedimentation and reservoir forming mode of shallow lake beach bar in the 3rd member of Funing Formation in the western slope of Qintong, Nanhua-Cangji ten-million-ton high quality reserve position has been found by the integrated research, deployment and implementation of exploration and development, and the exploration well success rate is 70 %. The construction and production mode of “decision-making and deployment, geological engineering, organization and operation integration” has been implemented to promote the structure-lithologic reservoir evaluation of the 3rd member of Funing Formation in the western slope of Qintong, and realize the available reserves of 1 003×10⁴ t and the built the production capacity of 17.5×10⁴ t. The break-even point for crude oil has been reduced from $81/bb1 to $46/bb1, enabling efficient exploration and development of concealed reservoirs.

Shale gas resource evaluation includes resource calculation, favorable distribution area and economic effectiveness based on geological and exploration process analysis. Its core is evaluation method selection, parameter processing and result analysis in line with geological process evolution characteristics and data mastery degree. The intelligent evaluation of shale gas resources can overcome the limitations of real resource evaluation, and can realize the whole process simulation and evaluation from qualitative to quantitative. It has obvious characteristics of development stages. The main feature of resource evaluation at this stage is to use modern means such as machine learning and inference engine. Method selection, parameter quality and evaluation effect are the keys to shale gas resource evaluation. Knowledge base establishment based on geological characteristics and exploration level, data collection, parameter analysis, data mining, geological reasoning, method selection, intelligent calculation, and reliability of results analysis, spatial expression of results and continuous execution throughout the process are the basic ideas and methods for intelligent evaluation of shale gas resources. Intelligent evaluation with powerful functions and continuous implementation throughout the whole process is the basic direction of the development of shale gas resource evaluation, which requires continuous accumulation and practice on the basis of existing technologies to promote the development of shale gas resource evaluation methods and technologies in a wider range.

Traditionally, laboratory testing and measurement are considered to be the most reliable characterization methods. However, in many cases, due to the unclear understanding of the sensitivity to the range of reservoir properties and local changes of heterogeneous reservoir properties, and based on the oversimplified assumptions, the feature prediction obtained by this deterministic strategy is highly uncertain. In recent years, molecular dynamics （MD） simulation has received extensive attention in the study of reservoir rock, fluid properties and their interactions, as well as at the atomic level. In MD simulation, interesting properties are extracted from the time evolution analysis of atomic position and velocity through the numerical solution of Newton's equations for all atomic motions in the system. This technology can help to carry out the computer experiments which can be used to do the experiments that may not be able to complete, with high cost or very dangerous. In this paper, we review the MD simulation technology and its application in the study of oil displacement mechanism and properties of oil displacement agent, and expounds the theoretical concept and program of MD, especially in the analysis of polymer flooding. It will provide useful guidelines to characterize reservoir rocks and fluids and their behaviors in various reservoirs, help to better optimize the operation of design and production plan, and provide a theoretical basis for the development of polymer flooding technology in oilfields.

The design of shale gas well spacing is the key to the technical policy of gas field development, which is related to the maximum utilization of resources. Well spacing design is closely related to geological characteristics and fracturing technology. The well spacing of Weirong Shale Gas Field designed at the initial development stage is 400 m. With the transformation of the fracturing technology of the main body of productivity construction from “controlling the fracture propagation and making longer hydraulic fractures” to “intensive perforating”, microseismic monitoring, fracturing simulation and dynamic analysis all reflect that the reserves between production and construction wells are still not fully utilized, and the existing well spacing needs to be further optimized. In order to further improve the reserve production and recovery degree of the gas field, and realize the beneficial development of gas reservoirs, the integrated technical method of geological modeling and numerical simulation is adopted to carry out the studies on single well numerical simulation with different fracturing technology. It is clear that the difference in the production status of single well reserves is caused by the fracturing process. On the basis of the researches of the single wells, the numerical simulation model of well groups under “intensive perforating” technology is established, and the development well spacing is optimized by combining technical and economic indexes. The study shows that under the current technological and economic conditions, it is recommended that the optimal well spacing in Weirong Gas Field could be adjusted from 400 m to 300 m, and the recovery degree can be increased from 22 % to 28 % at the end of 20 years.

Oil & gas exploration and development is a combination of innovative thinking and practice. Firstly, a geologist should have the concept of oil and gas in his mind. The geologists should constantly emancipate their minds and be full of passion for oil exploration. They should look at the problems in a sight of development, re-recognize themselves, re-recognize the underground, re-recognize the potential of geological-engineering integration, and study the geological situation of oil and gas reservoirs with the continuous development of the understanding. On the basis of re-understanding the exploration discovery of Well-Yan1, the theory of fault-fracture body reservoir is formed by summarizing the exploration and development practice and the field geological investigation of oil and gas reservoirs in Ordos Basin. The continuous innovation of exploration and development theory has realized the continuous breakthrough of exploration and development in Ordos Basin. As the annual oil and gas equivalent has exceeded 80 million tons, Ordos Basin become the first oil and gas bearing basin in China. By summarizing the experiences of Sinopec North China Oil and Gas Company in oil and gas exploration and development in Ordos Basin, it is found that seeking truth from facts is the key to deepen the understanding of oil reservoirs for the breakthrough of oil and gas exploration, the philosophical method of dialectical thinking can obtain new understanding of oil and gas geology at different stages, the fine description of oil and gas reservoirs is the basis for the preparation of development plans, and the integration of geological engineering realize the benefit development of tight oil and gas reservoirs. The object of oil and gas exploration and development will be more complex in Ordos Basin. As a result, the oil and gas exploration should focus on the whole basin to re-recognize the oil and gas reservoirs, and find different types of oil and gas reservoirs by the breakthrough of exploration and development theory.

The exploration and development practice in Shunbei area of Tarim Basin shows that oil and gas resource there is rich. However, the reservoir is deeply buried, the degree of oil and gas enrichment varies greatly, the reservoir type is very complex, and the overlying strata has the engineering problems such as easy leakage and collapse. All these problems above bring great challenges to the efficient development in this region. In order to expand the scale of oil and gas and realize the efficient development, the exploration in organizational management and work model has been carried out. The main practices and corresponding technologies of key links such as management mode, well position demonstration, well type design, safe drilling and effective well completion have been initially formed. The research will give reference for development of the ultra-deep fault- karst reservoirs in this area and similar reservoirs.

With the continuous and further development in Sinopec shale oil exploitation, a series of characteristic technologies such as drilling, logging cementing and fracturing have been preliminarily formed. By the summary and analysis of the progress and achievements made by Sinopec in shale oil engineering technology during the "14th Five-Year Plan" period, the problems and challenges currently existing in shale oil development engineering technology are reviewed, and the technical countermeasures and development suggestions in the aspects of geological and drilling engineering integration, speed-up of drilling and completion, three-dimensional well development, and ultra-long horizontal wells are pointed out. Therefore, it promotes the development of shale oil engineering technology in China, realizes the low-cost, large-scale and cost-effective development of shale oil resources, and provides useful reference.

The lower Cambrian Qiongzhusi Formation in southern Sichuan is one of the important strata for marine shale gas exploration. In the early stage, the exploration of black shale in Qiongzhusi Formation has achieved certain results, but the thin thickness of black shale restricts the breakthrough of commercial productivity. Silt-shale of Qiongzhusi Formation's gas logging shows high. Therefore, it is necessary to strengthen the systematic research of this new type of shale reservoir and widen the exploration field of unconventional shale gas. Based on the experimental data such asTOC, X-ray diffraction, thin section, SEM, Helium porosity, pulse permeability, Nitrogen adsorption, and mercury intrusion porosimetry, the studies of the geochemical characteristics, petrological characteristics, reservoir space types, physical properties and pore structure of this new type of reservoir have been carried out. The study shows that the new type of shale reservoir is mainly composed of silty shale, which has the property of low TOC, high brittleness, high porosity, good pore connectivity and high gas bearing. The main types of reservoir space are brittle mineral intergranular pores, carbonate minerals and feldspar dissolution intrapores, with only a small amount of organic pores. The support of silty brittle minerals is the key factor for pore preservation. It is generally considered that the new strata of shale reservoirs in Qiongzhusi Formation of southern Sichuan have good reservoir conditions for shale gas exploration.

The machine learning method is the main technical means of carbonate lithofacies log identification. Selecting the appropriate machine learning method according to the different geological conditions and data is one of the key factors for high-precision identification of lithofacies. However, there are few researches on the applicability of machine learning identification methods. In this paper, four most commonly used machine learning methods for identifying lithofacies are studied, including Self Organizing Maps（SOM）, Multi-Resolution Graph-based Clustering（MRGC）, K Nearest Neighbor（KNN）, and Artificial Neural Network（ANN）. By comparing the principle and practical application effects of these methods, the advantages, disadvantages and applicability of the four machine learning methods have been summarized. When there are few core samples, MRGC is preferred, while when there are more core data, KNN is preferred as well as MRGC. Their application of lithofacies identification in the Longwangmiao Formation in the MX area in Sichuan Basin shows that MRGC and KNN are the best, SOM is the second, and ANN is the worst. This study of the application effects of machine learning methods provides a guidance for the identification of carbonate rock facies in other layers and regions, and has strong practical value.

In China, the South China Sea Block has great potential of natural gas hydrate resources. At present, the pilot production of natural gas hydrate has been successfully conducted in the Shenhu area, the northern part of the South China Sea, indicating a major breakthrough in hydrate exploration. However, the geological conditions, accumulation factors and hydrate distribution are still unclear, so it is necessary to further study the formation conditions and distribution of natural gas hydrate. Based on the oil and gas exploration data and the achievements of oil, gas and natural gas hydrate in the South China Sea, the accumulation conditions and distribution of natural gas hydrate in the South China Sea have been discussed in the aspects of sedimentation, structure, oil and gas conditions and hydrate enrichment factors. The results show that: ① The thin crustal thickness and high heat flow value of the South China Sea Block are conducive to the thermal evolution of organic matter; ② The sedimentary facies of delta, alluvial fan, turbidite fan and slump fan are developed in the meso-Cenozoic, and the sand and mud are interbedded, which provides favourable conditions for gas hydrate accumulation; ③ The diverse and complex structure elements such as tensional or transtensional fault system can form migration channel for natural gas hydrate; ④ Four types of gas resources such as biogas, shallow-layer pyrolysis gas, middle-deep pyrolysis gas and gas field gas are developed, which provide a good material basis for gas hydrate accumulation; ⑤ Uplifts and depressions are favorable locations for gas hydrate accumulation. The results not only provide the guidance for the natural gas hydrate exploration and development, but also provide scientific evidence for the natural gas hydrate exploration in other sea areas.

In the early stage of shale oil development, the investment is large and the recovery factor is low, bringing great risk of economic loss. Therefore, it is necessary to combine different development methods to study its economic decision. To this end, based on the idea of the integration of numerical simulation method and reservoir development and management, firstly, the economic decision-making system and oil price index prediction are established, and then a series of new methods for the selection of development mode at different stages and different oil prices are improved through the combination and optimization of various numerical simulation schemes. Taking the shale oil of Kong-2 Member in Cangdong Sag of Dagang Oilfield as an example, different overall development program indexes are predicted. Finally, based on the idea of reservoir development and management integration, the suitable development programs for different international oil prices are selected. By comparing the changes of the cumulative net present value of the single production plan and the combined production plan, it is found that the single production method with higher recovery factor is not necessarily the economic optimal plan. Finally, the most economical development plan with different oil price ranges is obtained, and a set of optimal method for the economic and efficient development plan of shale reservoir is formed.

At present, the research at home and abroad of self-suspension proppant, a new type of proppant, is mainly focus on indoor preparation and field application, but the study of its stimulation mechanism is less. In this paper, the solubility and swelling of self suspension proppant have been evaluated by the theoretical analysis of its suspension performance. Based on the physical simulation and numerical simulation, the dynamic flow mechanism of fluid mixed with sand has been studied, its flow conductivity has been evaluated and the influencing factors have been analyzed. The results show that the density of aggregate, multiple of swelling and viscosity of liquid after hydration are the main factors that affect the settling speed and the realization of self-suspension. Compared with the ordinary proppant, it has longer laying distance and more balanced longitudinal laying mode, and is beneficial to improve the conductivity of fracturing fractures. It has been applied in Qintong sag in Subei Basin twice. Compared with that of conventional guar gum fracturing, the daily production of single well can be increased by more than two times, which shows that the self suspension proppant in sand-carrying fracturing by water can effectively improve the productivity of the fractured wells.

Nanchuan Block is rich in shale gas resources, and the proven reserves of Pingqiao and Dongsheng structural belts are nearly 2 000×10⁸ m³, mainly in normal pressure shale gas reservoir, with complex structure and stress, and relatively poor resource quality. Affected by the preservation conditions, burial depth, in-situ stress, complex structure, uneven fracture development and fracturing effect, the productivity of single wells on the same platform is quite different, and the test production, productivity and single well EUR of some wells have not been able to meet the expectation, all these above greatly limit the scale production and benefit development. By the comparative analysis of production effects of typical wells in geology, development and engineering, it is considered that formation pressure coefficient, development degree of natural fracture network, local complex structure and in-situ stress are the main factors affecting normal pressure shale gas development in resource implementation area. The pressure coefficient represents the driving energy of the formation, and a certain degree of natural fracture network can effectively improve the development effects. The local complex structure leads to a low drilling rate of high-quality shale, and the stress increase caused by extrusion deformation, deepening burial depth and excessive angle between horizontal section azimuth and minimum principal stress azimuth will limit the complexity of artificial fracture network to a certain extent. According to the plane difference distribution characteristics of main controlling factors, the basis of improving the development effects of normal pressure shale gas is to select the best from sweet spot and adjust the local optimization.

With the expansion of domestic shale gas development demand and production capacity, the all-electric fracturing equipment and technology has become the recommended application technology for normal pressure shale gas fracturing engineering due to the low efficiency of conventional fracturing equipment, large environmental pollution and insufficient water power guarantee in the domestic market. This paper focuses on analyzing the demonstration application effect of all-electric fracturing technology in atmospheric shale gas resource block, demonstrating its advantages in shale gas benefit development and green and low-carbon development. Results show that the all-electric fracturing all-electric case can achieve stable high load, high reliable and continuous construction of the large displacement, high construction efficiency, The comprehensive costs of construction equipment, power, labor and maintenance, etc., fell by more than 40 %, pollution emissions by 70 %, the effective control of noise at boundary of atmospheric pressure shale gas can effectively help realize benefit the development and construction of green mining enterprises of the forehead.

The southern Yanchuan Block is a deep, high-rank coal-bed methane reservoir with large buried depth at 800~1 500 m, meagre coal or anthracite, and good gas content at 12 m³/t. The resource conditions are relatively favorable, but the single well productivity level of the gas field varies greatly. Based on the comprehensive study of gas field geological conditions, and by the analysis of the influence of structure on reservoir hydrocarbon generation, porosity and permeability, hydrogeological conditions, coal body structure, and CBM storage, the researches on the control mechanism of structure on CBM reservoir formation are carried out to find out the main controlling factors of coal seam formation and its changing rules. Combined with the CBM development dynamic data, the relation between block structure and CBM well productivity is analyzed, and a structural gas control mode for CBM well productivity is established. The research results show that the buried depth of the coal seam controls the gas-bearing and permeability of the reservoir. The deeper the buried, the better the gas-bearing and the worse the permeability. The control effect of tectonic activities on the formation of coal-bed methane has two sides, the local folds and the development of faults has a significant effect on improving permeability, which is conducive to the enrichment of gas reservoirs, but the excessive tectonic activity on the other hand will also lead to the enhanced hydrodynamic conditions and the escape of coalbed methane. The structure has an obvious control effect on the gas well productivity. The high-yield wells are mainly distributed in the coalbed methane enrichment and the permeability improvement areas at the wing of the local micro-uplift belt with a buried depth of 830~1 280 m. The middle-production wells are mainly distributed in the low-permeability areas with a buried depth of more than 1 280 m, whose structure is gentle and the faults are not developed. The low-yield wells are mainly distributed in local depression areas with severe structural damage and CBM escape areas near fault development belts.

In order to solve the problems existing in the development of Nanchuan Shale Gas Field, such as complex geological conditions, drilling leakage collapse, unsatisfactory fracturing effect and lack of effective artificial lifting, the optimization, integration and improvement of development technologies have been completed through in-depth research on drilling and completion technology, fracturing technology and gas production technology, and integration development technologies such as high-efficiency drilling and completion technology, high-efficiency fracturing technology and shale gas well drainage and gas production technology have been formed. Among them, the high-efficiency drilling and completion technology of normal-pressure shale gas mainly includes wellbore structure optimization, bit and screw integrated speed-up technology, limit parameter drilling technology and high-efficiency completion technology; high-efficiency fracturing technology mainly includes integrated all-electric pump fracturing technology, integrated sliding sleeve completion fracturing technology, combined temporary plugging steering technology, etc.; the applicable drainage and gas recovery technology of normal pressure shale gas well mainly includes two processes: single pipe jet pumping and mechanical pumping. Through the popularization and application of the above technologies, Nanchuan Block has formed a complete series of high-efficiency development technologies for normal-pressure shale gas fields in different areas and different well depths has been formed in Nanchuan Block, which has promoted the development of normal-pressure shale gas fields with reduced costs and increased efficiency.

As a typical unconventional gas reservoir with low pressure, permeability and water cut, deep coalbed methane needs effective support fracturing to achieve good development effects, leading to large difference of liquid production in the whole life cycle of gas wells. Based on the comparison of coalbed methane recovery effect of different well types in Yanchuan South coalbed methane exploration and development block, it is considered that although the L-shaped horizontal well has the construction cost similar to that of three directional wells, but its production is higher and post-operation and maintenance cost is lower. It is more suitable for coalbed methane development in mountainous areas. By comparing the characteristics of different lifting processes, the combination of pumping unit and forced closed spring inclined well pump is optimized, and the drainage and gas recovery in the whole life cycle of L-shaped horizontal well is realized. In the gas wells with low liquid production, the technology of water drainage gas recovery has achieved good stimulation effects in the gas wells with small deviation, and high influence of liquid accumulation and pulverized coal. The existing mechanical production equipments can realize the efficient utilization of assets, save the cost of purchased materials, reduce the energy consumption index, and provide referential significance for the further drainage gas production in low liquid production wells.

K oil reservoir, in Oilfield-A, Iraq, is a typical porous carbonate reservoir. It is characterized by complex pore structure, wide range of resistivity and complex oil-water contact（OWC）. In order to establish the reliable criteria for fluid typing and ascertain the OWC, firstly, the study of pore structure has been taken as a starting point, and the relationship between resistivity and elevation has been taken an insight into. Then a new criteria for fluid typing and OWC for each sub zone have been established by incorporating well testing and production dynamics. Lastly, the lateral variation of OWC and its genesis is analyzed based on structural evolution and hydrocarbon accumulation history. The results are as follows. ①Pore structure of the K oil reservoir shows strong longitudinal stratification characteristics, and the amount of mold pores and interparticle pores as well as effective pore-throat radius increases upwards. ②Vertical variation in pore structure is the main controlling factor of the identification criteria for oil and water layers and OWC variations for each sub layer. The layers dominated by micropores have small pore-throats radius, high displacement pressure, high OWC and low reservoir resistivity threshold, while the layers dominated by interparticle pores and mold pores are the opposite. ③The OWC is curved laterally, and slopes eastward along the long axis of the structure in the same small layer. Along the short axis of the structure, the contact is arched, that is the north and south margin is lower than the structure crest, and the lowest contact is in the northeast margin. ④The determination of the curved OWC has been verified by the reservoir interpretation of 85 vertical wells and the production dynamics of more than 260 horizontal wells. This study provides not only an effective solution for water control and stabilizing oil production but also a guideline for further optimization of field development plan and trajectory adjustment of horizontal wells.

In recent years, extensive attention has been paid to the decarbonization of petroleum and gas exploration and related technologies at home and broad. The structural transformation of the energy industry of the oil and gas is one of the inevitable ways for China to achieve the “carbon peak and neutrality” targets. Under the prerequisite of energy reform to accelerate the achievement of the targets, the energy reform direction and pathway for the oil and gas technology have been analyzed. Taking the project of the electricity substitution technology in the PetroChina Southwest Oil and Gasfield Company as an example, the changes in terms of environmental pollution and energy consumption before and after the implementation of the project are compared. Then, it focuses on the necessity of the drilling and completion electrification transformation and the advantages of the drilling and completion are emphasized. Based on the analyses and summary of the key and difficulties in the practice process, the key technologies that restrict the development of electricity substitution technology and the breakthrough points of the future researches are put forward, which provides reference for the application of “electricity substitution” technology in oil and gas exploration and development under the “dual-carbon” targets.

In order to clarify the main principal factors that affect the initial productivity during the development of shale oil reservoirs, a comprehensive data analysis method involved both the hierarchical cluster analysis and the principal component analysis in data statistics is presented; and then the deta of the static formation parameters, fracturing operation parameters and the oil productivity of 51 wells in Block Li-151 are analyzed quantitatively. At first, the wells in the block are divided automatically into two types, Type A and Type B, by the hierarchical cluster analysis method. Then, a principal component analysis method is used to analyze the principal productivity factors for different types of wells. Analysis results show that, when the well shut-in time is less than 125 days, the oil production decline rate can be reduced effectively by the well shut-in measures; however, when it is greater than 125 days, the effect of well shut-in measures on oil production decline rate becomes negative. The production decline rate of Type A wells is highly negative with the amount of injected fracturing water; the main principal factors for the production decline rate of Type B wells are the moving liquid level and the porosity of shale matrix. The principal factors for the production rate of Type B wells are the number of fracturing sections. All in all, for the production optimization of shale oil development in Block Li-151, the differences of principal production factors between Type A wells and Type B wells should be considered and the different analysis results of the principal factors that affect the initial shale oil productivity under different well types should be fully utilized. Some guidance can be provided specifically for the formulation of a reasonable shale oil efficient development plan.

It is generally known that shale layers are the source rock layers of hydrocarbons. The shale gas is a kind of methane gas which is adsorbed on the surface of shale particles. The weight-volumetric method is used to estimate the geological resources of shale gas. Due to the extremely low permeability of the shale, it is represented by the nano Darcy levels （1 nD=10^-9 D=10^-6 mD）, and the adsorbed gas is in a saturated adsorption state. Therefore, the development of shale adsorbed gas requires horizontal well drilling, multi-stage fracturing, depressurization and desorption before putting into production. Since the horizontal well is an independent closed production unit for the shale gas fields, it is necessary to estimate the well-controlled recoverable reserves firstly, and then to estimate the recoverable reserves of the shale gas field. Based on the normalized production decline curve shifting method proposed by Baihly, the well-controlled recoverable reserves and the reserves of the estimation areas from the three large shale gas fields （Barnett, Woodfort, and Haynesville） in the United States have been effectively predicted using the generic exponential production decline（GEPD） model proposed by Chen Yuanqian in recent years. Furthermore, the production decline rate of shale gas wells is theoretically analyzed, and the results completely accord with the actual production decline characteristics of shale gas wells. It shows that the production of a gas well decreases rapidly in the initial stage, and gradually slows down after another 20 months of production. At the same time, five kinds of decline models are studied and estimated in this paper.

In the tight reservoir like mahu with strong heterogeneity, large differences in the productivity of oil wells and obvious differences in the decline characteristics, the production decline analysis and prediction have important guiding significance to the management of oil well production system and the preparation and optimization of oil field development plan, and are also an important part of reservoir performance analysis. However, the traditional empirical decline models used today, such as the Arps production decline model, power law exponential decline model, Valkó extended exponential decline model, and Duong decline model, have different applicability. When using these methods to fit the production data of the fractured horizontal wells in the Mahu tight reservoir, the accuracy of the fitted results is low. Therefore, a new method of combination that uses different models for fitting in stages based on the model fitting results of Mahu oil wells in different stages is explored, and the examples are applied to verify it in this block. The research results show that this new method has lower error rate and higher degree of agreement than the traditional ones. In addition, by using this method, the prediction results of Estimated Ultimate Recovery（EUR） for the tight oil wells in Mahu reservoir are more accurate, and the method is highly feasible, which can be used as a reference for the research on the production decline law and the productivity prediction of other similar tight oil reservoirs.

Southeastern Chongqing is the first area to realize commercial development of shale gas in China. According to the main development progress of drilling and completion technologies in this area, 10 key technologies are summarized, which are, casing program optimization, severe loss control in shallow layers, low-cost managed pressure drilling, well trajectory control based on geology-engineering integration, bit selection, oil-based drilling fluid with low oil-water ratio, ROP enhancement through drilling parameter optimization, cementing technology for leakage wells, completion technology for preventing trapped pressure in annulus, and factory-like drilling technology. In order to make up for the deficiency in drilling and completion technologies, six directions of further research are proposed, which are, drilling equipment automation, drilling parameter enhancement, water-based drilling fluid, complex situation treatment, small hole drilling and completion, and shale gas drilling with long horizontal section, which aim to improve the drilling and completion technologies and the exploration and development profits in southeastern Chongqing.

Influenced by the underwater paleouplift and multi-stage structural extrusion of Leshan-Longnyusi, Yuxi Block gradually deepens from north to south, and has the characteristics of large thickness change of type I reservoir and low porosity（less than 4.5 %）, it is very important to study the pore structure of high quality shale. Traditional shale pore analysis technology has weak identification ability for different types and sizes of micro nano pores. Through an optimized analysis method based on maps image, it can reduce the space-time complexity of the algorithm and improve the applicability on the premise of effectively identifying and statistics the organic and inorganic pore fractures of shale. Characterization of organic pore fractures in Longmaxi formation is about 300 μm, inorganic pore seam with a visual field of view length of 500 μm. The diameter or opening range of organic pore gap detected by maps image is mostly between 0~100 nm. The organic matter content and organic matter porosity are different, and the abundance of organic matter is not the only control factor for the development of organic matter pores.

Poor reserve quality, high water-cut and high investment cost have become the bottleneck of developing Dongsheng Gas Field located in Ordos Basin. In this way, the star evaluation management model is put forward to enhance its production performance. It is aiming at maximizing reserve value and investment benefits through geology-engineering integration. In the process of its implementation, the well locations, well patterns, drilling, fracturing and production technologies are optimized comprehensively, then the optimizedinformation is employed to improve and instruct future planning, thus the iterative improvement is achieved from single well to the whole gas field. Finally, the internal rate of return is calculated to determine the implementation sequence for each well. On the base of intelligent gas field construction, the above achievements are reinforced by organically combining downhole management with ground coping facilities, then the higher level of integrated development of geological engineering is realized. The following main results have been achieved: ①The detailed reservoir description and evaluation methods are formed for complicated high water-cut reservoir, and the gas layer penetrating rate raises by 20.8 %. ②Hierarchical constraints system for well network optimization is established, and the reserve production rate increases by 28 %. ③The drilling technology with both borehole stability and leakage prevention being considered is innovated through the combination of logging and seismic technology, and a completion string with slim hole and narrow gap is optimized to cater its demand. After optimization, the drilling cycle is shorten by 51 %, and investment cut by 31 %. ④The “large displacement, short time and high sand ratio” fracturing method is implemented, with the vertical well output increased by 56 %, and horizontal well 39 %. ⑤The “multi-parameter quantitative identification, coupling of nozzle and pipe flow, foam drainage and gas recovery system and production and injection technology in the same well” is combined together to lower the utilization limit of gas saturation to 45 %. Ever since the 13th Five-Year Plan, the production indicators of Dongsheng Gas Field are continuously improved. Moreover, a quantitative, operative and evaluable geology-engineering integration development model, with actual value of promotion, is formed.

Taking the source rock of Chang 7 Member in Ansai area of Ordos Basin as the research object, the differentiation characteristics of shale oil in the process of migration and accumulation are discussed in depth through a series of testing methods, such as TOC test, rock pyrolysis and chromatography-mass spectrometry. The results show that the hydrocarbon generation potential of different source rocks in the study area is quite different. The shale has the strongest hydrocarbon generation capacity, while that of the interaction layer of sandstone and mudstone is the weakest. The high content of free hydrocarbon in interaction layer of sandstone and mudstone results from the receipt of external free hydrocarbon. The distribution of geochemical parameters of shale oil in different lithology is different. Among them, the sand mud interaction layer is rich in saturated hydrocarbon but relatively poor in nonhydrocarbon and asphaltene, while the shale and the mudstone are rich in nonhydrocarbon and asphaltene but relatively poor in saturated hydrocarbon. The properties of crude oil, thickness of source reservoir and physical properties have effects on shale oil migration and accumulation. Shale oil in thin-layer source rocks and small molecular hydrocarbon components are easy to migrate. Shale oil in thick-layer source rocks and macromolecular hydrocarbon components tend to remain in the source rocks.

In order to further clarify the mechanism of steam flooding assisted by CO₂ in the heavy oil reservoir, its visualization experiments are carried out by the acrylic plate model and natural cores, and their synergy is analyzed. After the mechanism of synergistic displacement is clarified, the core flow experiments are carried out to further analyze the influence of the synergistic effect and the injection mode on the actual displacement efficiency. The results show that CO₂ assisted steam flooding has the effects of the synergistic viscosity reduction, the expansion of steam sweep efficiency, the availability of residual oil at the blind end, and the demulsification. Among them, the comprehensive viscosity reduction rate of the crude oil is 59.8 %, and the steam sweep area is increased by 37.44 %. Compared to the flooding by steam alone, after the assitant of CO₂, the recovery rate increased significantly. The alternate injection of steam and CO₂ can get a recovery rate of 65.7 %, 7.9 % more than that of mixed injection, and observe the stable foam oil flow at the outlet.

Qintong Sag of Subei Basin has high abundance of oil and gas resources and great exploration potential, but the geological target has the complex characteristics of “thin, broken, small, scattered and hidden”. Since 1989, there is a series of seismic technical breakthroughs in this area. From conventional 3D to high-precision 3D for secondary acquisition, the acquisition method of “single point broadband receiving with digital geophone, medium surface element grid and high coverage times” is established, a series of processing technologies have been formed, such as sequential processing, improved SNR processing, improved resolution processing, structural-constrained mesh tomographic velocity modeling and reverse-time prestack depth migration imaging, etc., as well as the thin-bedded sandstone prediction technology with the waveform indication inversion of SP sensitive curves. Technological progress has promoted the transformation from simple structural reservoir to complex small fault block reservoir, and then to complex structure-lithology subtle reservoir exploration in Qintong Sag. The analysis shows that the high SNR, high resolution and amplitude-preserving processing effect are limited by the large difference of multi-phase data collection, narrow frequency band of original data and low sampling density of wave field. In order to solve the further problems of the complex subtle reservoir seismic exploration, wireless single-point receiving, single-point broadband excitation, small surface element, high coverage density, wide azimuth seismic acquisition, amplitude quantization quality control, broadband omni-directional processing and five-dimensional interpretation should be explored.

At present, taking a single well as an evaluation unit is a common and accurate method to estimate SEC reserves of shale gas. With the further development of the gas fields, the single well production fluctuates greatly, which can not better reflect the development performance of the gas reservoir. In order to further improve the accuracy of the estimation, Pingqiao South Block of Nanchuan Gas Field is divided into four zones, namely Zone Ⅰ, Zone Ⅱ, Zone Ⅲ and Zone Ⅳ, by the study of regional production rules and combining with geological characteristics based on the single well estimation. The yield normalization method is used to establish the typical curve of each zone, and then the theoretical yield model of this block is established by the dual medium model, so as to meet the harmonic decline. Finally, the evaluation models of different zones are established. Zone Ⅰ directly enters into the harmonic decline with an initial decline rate of 56.5 %; Zone Ⅱ enters into the harmonic decline after 23 months of stable production with an initial decline rate of 52.2 %; Zone Ⅲ enters into the harmonic decline after 13 months of stable production with an initial decline rate of 60.7 %; Zone Ⅳ directly entered into the harmonic decline with an initial decline rate of 59.5 %. The final estimation results are compared with those of foreign countries, and the error is within 6 %, which shows that the estimation of the SEC reserves for each unit of shale gas in Pingqiao South Block in the middle and later period of development has certain adaptability.

Based on the interactions between CO₂ and crude oil, CO₂ and conglomerate, the enhanced oil recovery（EOR） mechanism of CO₂ huff-n-puff has been revealed in Huanmahu tight conglomerate reservoir. Meanwhile, a high temperature and high pressure nuclear magnetic system was applied to monitor the change of oil saturation during experimental processes at pore scale in cores of substrates. Core fracturing and displacement system were used to investigate the effects of fractures on EOR during CO₂ huff-n-puff. The experimental results indicated that CO₂ could effectively dissolve in crude oil to replenish formation energy, reduce oil viscosity and improve wettability. Moreover, the crude oil produced in depletion development was in large pores, while that in medium pores and small pores could be effectively activated by CO₂ huff-n-puff. After depletion development, three cycles of huff-n-puff could enhance oil recovery by 23.1 %, among which the first cycle contributed most with factor of 15.1 %. The existence of fractures could increase the contact area between crude oil and CO₂ and decrease the flow resistance of crude oil, and finally the EOR is up to 27.1 %. All the results reveal the feasibility of CO₂ huff-n-puff to improve oil recovery in tight conglomerate reservoirs from pore scale.

Normal pressure shale gas plays such as the Ohio Formation Shale and Marcellus Formation Shale in the Appalachian Basin in the U.S. have been developed commercially. Although Wufeng-Longmaxi Shale in southeast Sichuan Basin in China has been initially developed, its production efficiency is not obvious and its cost is high due to the large burial depth and poor reservoir properties physical properties. In the normal pressure shale gas formation, the absolute pressure changes at different depths, which influences the gas occurrence state, and then has a significant influence on gas content and mobility. Therefore, it is urgent to carry out quantitative research on the differences of normal pressure shale gas reservoir conditions, gas occurrence state, gas content and mobility between China and the US. In this study, the Wufeng-Longmaxi shales of Well-LY1 in Pengshui of China and the Marcellus shale and Ohio Shale of Appalachian Basin in the United States are selected as the research objects under normal pressure. Based on the volume method, and with the considering of the influence of the temperature, pressure, maturity, water and oil on the adsorption capability and maximum adsorption capacity, and the temperature and pressure, porosity and water saturation on the determination of free gas volume, the gas content of three groups of shale reservoirs is evaluated. The reservoir pressures are considered as the initial pressures and the simulation are conducted based on a pressure drop of 5 MPa. On the basis of clarifying the desorption process of adsorption and free gas in the depressurized production respectively, the fundamental cause of the difference in normal pressure shale gas production between China and the U.S. is revealed. Compared to the Marcellus Shale in Appalachian Basin, the lower adsorption capacity, porosity and free gas of the Wufeng-Longmaxi shales result in low production of adsorbed gas and free gas. However, compared to the shale of the Ohio Formation, the deeper burial, higher temperature and higher pressure in the Wufeng-Longmaxi shales result in the extremely low recovery rate of adsorbed gas. Its lower porosity also contributes to the lower free gas production.

The Permian Lucaogou Formation in Jimsar is rich in continental shale oil reserves. There are two “sweet spot” developed in the vertical direction. As the development progresses advances, the lower “sweet spot” becomes the main development layer. It has the characteristics of large depth and strong heterogeneity, which makes the development difficult. With the impact of market environmental pressure, it is urgent to optimize the stimulation technology to realize the low-cost development of shale oil. Based on the geological characteristics, the methods of numerical simulation, experiments, and fracture monitoring are used to study the cluster spacing, sand-carrying performance of slick water, conductivity of proppant and so on. Then, a series of low-cost tests such as intensive stage, temporary plugging fracturing, quartz sand replacement, and slick water sand injection have been carried out. The application effect showed that the comprehensively use of low-cost stimulation technology can reduce the cost by at least 30 %, meanwhile, maintain the output. It provides a reference for the subsequent development for Jimsar shale oil.

In recent years, Sinopec has used the unconventional natural gas idea to strengthen the Permian natural gas exploration in eastern Sichuan and obtained industrial gas flow in the first member of Maokou Formation of several wells in Jiaoshiba of Fuling and its adjacent area, revealing a good prospect for natural gas exploration. In this paper, the sequence stratigraphy, sedimentary characteristics, hydrocarbon generation conditions, micro pore structure characteristics and gas bearing property of Mao-1 Member in Jiaoshiba area are systematically analyzed. The results show that: ① Mao-1 member can be divided into two fourth-order sedimentary cycles and eight small layers, which mainly develops four kinds of lithology such as Limestone, micritic limestone, nodular limestone and nodular micritic limestone. ② The average TOC of the Mao-1 Member ranges from 0.75 % to 0.87 %, which on the whole, belongs to carbonate source rock with medium organic matter abundance. The organic matter abundance of micritic limestone and nodular micritic limestone is relatively low, while the organic matter abundance of limestone and nodular limestone is relatively high. The type of organic matter is mainly type I and supplemented by type Ⅱ. R_o ranges from 1.71 % to 2.18 %, with an average of 1.97 %. ③ The Mao-1 Member is an ultra-low porosity and permeability reservoir, and the local layers show the characteristics of fractured reservoir. The reservoir space is mainly composed of organic pores, diagenetic contraction fissures of clay minerals, and grain margin fractures of mineral particles, followed by dissolution pores of carbonate minerals. Moreover, the pore size distribution is mainly mesoporous and macroporous. ④ The natural gas of Mao-1 member is mainly composed of methane with low heavy hydrocarbon content, which is typical dry gas; δ ¹³C₁ ranged from -31.25 ‰ to -31.12‰, δ¹³C₂ is between -35.28 ‰ and -31.23 ‰, δ¹³C₃ is between -34.87 ‰ and -34.66 ‰, which is a typical oil type gas. The carbon isotope of alkane series is reversed, showing a trend of change δ¹³C₁>δ¹³C₂>δ¹³C_3. According to the characteristics, the natural gas from Mao-1 Member is the mixture of kerogen cracking gas and liquid hydrocarbon cracking gas. ⑤ Mao-1 Member has the characteristics of self-generated and self-reservoired, which is a set of special carbonate reservoir between shale reservoir and fractured reservoir. It is necessary to learn from shale gas exploration experience, strengthen sweet spot interval evaluation and adaptive engineering technology research, and promote the large scale production and benefit development of natural gas.

There are many nodes in the comprehensive research process of exploration and development, which are highly professional. In order to solve the problems that the research process is not explicit, and lack of data service support and visualization means, a standardized comprehensive research process of exploration and development has been formed, and a digital platform for comprehensive research of oil and gas exploration and development has been developed, so as to achieve rapid acquisition of research data and automatic archiving of research results. Integrating the professional software data service and visual analysis support means, and calling the required professional software with one click can realize multi-disciplinary online collaboration of different research posts. Through the standardized comprehensive research process, the new staff can be able to enter into the spirit of the role as soon as possible, and the valuable experience of the old staff can be inherited through the continuous improvement of the process. The platform has been widely applied in the main research office of Shengli Oilfield Exploration and Development Research Institute, supporting the exploration comprehensive research of seven seismic work areas, and the scheme preparation and optimization of 15 new and old areas, greatly improving the efficiency and quality of comprehensive research work, and providing support for efficient exploration and beneficial development of the oilfield.