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26 February 2024, Volume 14 Issue 1
  • China's CCUS technology challenges and countermeasures under “double carbon” target
    YE Xiaodong,CHEN Jun,CHEN Xi,WANG Haimei,WANG Huij...
    2024, 14(1):  1-9.  doi:10.13809/j.cnki.cn32-1825/te.2024.01.001
    Abstract ( 14 )   HTML( 0 )   PDF (2009KB) ( 0 )   Save

    Carbon Capture, Utilization, and Storage(CCUS) technology is pivotal for global carbon emissions reduction and plays a crucial role in ensuring China's energy security and fostering the concurrent growth of its economy. It also supports China's path towards sustainable development and ecological advancement. While significant strides have been made in CCUS technology within China, challenges persist that hinder its widespread adoption. Based on literature research and work accumulation, the current status of CCUS technology both domestically and internationally is described, and the current technical challenges and research directions that CCUS technology are pointed out. The existing research efforts have provided countermeasures to address the challenges of high energy consumption and cost of capture technologies, the need for further research on oil recovery and storage technologies, the high energy consumption and low conversion efficiency of chemical utilization technologies, and the lack of a technical system for monitoring and evaluating the safety of storage. These countermeasures are as follows: ①Diversified integration of different carbon capture methods to achieve cost reduction at the source based on the characteristics of different emission sources; ②Tackling multi-objective optimization techniques, coordinating and optimizing oil recovery efficiency and CO2 storage rate; ③Continuously developing new catalysts to accelerate the conversion reaction of CO2 and improve conversion efficiency; ④Fully draw on the carbon tax policies of countries such as the United States and Australia, explore fiscal and tax incentive policies suitable for China's CCUS industry, increase economic benefits, and enhance enterprise enthusiasm; ⑤Establish a series of standard specifications covering all aspects of the CCUS entire chain, guide the implementation of engineering construction, and reduce enterprise risks from a standardized perspective. Through the implementation of these measures, the rapid development of CCUS technology in China will be promoted, and greater contribution will be made to achieving the goal of carbon neutrality.

    Key engineering technologies of one-million-ton CCUS transportation-injection-extraction in Shengli Oilfield
    SHU Huawen
    2024, 14(1):  10-17.  doi:10.13809/j.cnki.cn32-1825/te.2024.01.002
    Abstract ( 9 )   HTML( 1 )   PDF (2004KB) ( 1 )   Save

    CCUS technology is a crucial technology for achieving the goal of “dual carbon”, involving process such as capture, transportation, injection, extraction and re-injection. Shengli Oilfield has developed essential engineering technologies for transportation and injection through years of exploration. To manage the phase changes of CO2 and the risks of long-distance leakage due to pressure loss and temperature variations, a safety transportation technology for long-distance CO2 pipelines was established. This technology is based on phase state control, ensuring efficient and cost-effective transportation. developed China’s first casing pipeline transport pump; and built China’s longest long-distance supercritical pressure CO2 pipeline, which makes up for the shortcomings of the long-distance CO2 transport in China. In order to meet the needs of high-pressure injection of large-displacement CO2 in the demonstration project, China’s first high-pressure dense-phase injection pump has been developed, realizing high-pressure dense-phase injection of 40 MPa. In view of the problems of high injection pressure, high gas-to-liquid ratio, low pumping efficiency, and corrosion of CO2, the engineering process technology of injection and extraction supporting such as safe injection of gas pipeline columns for pressure-free wells, multi-functional oil recovery pipeline columns, and corrosion prevention of CO2 repulsion has been formed to realize high-efficiency, safe injection and extraction and long-lasting corrosion protection. China's first multi-field, multi-node, one-million-ton CCUS demonstration project integrating pipeline transport engineering, injection equipment, flooding and sequestration, injection-extraction process, and gathering-transmission and re-injection, has been operating well and realizing “smooth, safe, efficient and green” operation in all aspects. This summary of the one-million-ton CCUS transportation-injection-extraction process and supporting equipment in Shengli Oilfield is intended to provide reference and guidance for the construction of subsequent CCUS project.

    CO2 flooding technology and its application in Jiangsu Oilfield in Subei Basin
    TANG Jiandong,WANG Zhilin,GE Zhengjun
    2024, 14(1):  18-25.  doi:10.13809/j.cnki.cn32-1825/te.2024.01.003
    Abstract ( 10 )   HTML( 0 )   PDF (7106KB) ( 0 )   Save

    CCUS(Carbon capture, Utilization and Storage) technology is of great significance to the green and low-carbon transformation and the realization of the “dual carbon” goal, It includes important strategies like CO2 enhanced oil recovery(EOR) and sequestration. Jiangsu Oilfield has been focusing on CO2 EOR to improve recovery rates in the challenging fault block reservoirs of the Subei Basin. The company has developed four unique CO2 EOR models suitable for these complex reservoirs, featuring techniques like gravity-stable displacement. A notable achievement is the successful pilot of the methods such as “simulated horizontal well” GAGD technology in Hua-26 fault block, which led to the one hundred thousand CCUS project tailored for such reservoirs. According to statistics, Jiangsu Oilfield has injected a total of 30.34×104 t of liquid CO2, with a cumulative oil increase of 9.83×104 t, realizing a better production increase and economic benefits. These technical researches and tests can provide valuable insights for applying CO2 EOR in similar complex reservoirs.

    Molecular dynamics simulation on interaction mechanisms of crude oil and CO2
    LI Jianshan,GAO Hao,YAN Changhao,WANG Shitou,WANG ...
    2024, 14(1):  26-34.  doi:10.13809/j.cnki.cn32-1825/te.2024.01.004
    Abstract ( 6 )   HTML( 0 )   PDF (21910KB) ( 0 )   Save

    Numerous oil displacing mechanisms of CO2 have been widely recognized, but due to reservoir factors, the effectiveness of CO2 flooding varies significantly under different reservoir conditions. It is necessary to further deepen the research on the micro-interaction mechanisms between CO2 and crude oil, clarify the CO2 flooding mode under different reservoir conditions, and maximize the potential of CO2 flooding. Molecular dynamics simulation methods have been used to study the effects of components, temperature, and pressure on the interaction between oil droplets and CO2. The kinetic parameters were obtained to quantitatively characterize the oil droplets-CO2 interaction, clarifying the micro-interaction patterns under different conditions. The simulation results show that the dispersion force is the the main driving force of the interaction between CO2 and alkane molecules, which mainly includes two aspects: one is the dissolution and diffusion of CO2 molecules into the oil droplets by overcoming the steric hindrance between alkane molecules, and the other is the extraction attraction of CO2 molecules to the outer layer molecules of the oil droplets. As the chain length of alkane molecules decreases, the temperature decreases and the pressure increases, the solubility parameter of the oil droplets and the coordination number of CO2 increase, the curvature of the molecules in the outer layer of the oil droplets decreases, and the interaction between the two is enhanced. It is concluded that CO2 miscible and near-miscible flooding should be realised as much as possible in light and medium-light reservoirs with lower temperatures and higher pressures, while in medium and heavy reservoirs with higher temperatures and lower pressures, the advantages of CO2 non-miscible flooding in terms of dissolution viscosity reduction, crude oil volume expansion and energy replenishment should be fully exploited. The study results can provide theoretical guidance for laboratorial research and field application of CO2 flooding.

    Optimal prediction method for CO2 solubility in saline aquifers
    DONG Lifei,DONG Wenzhuo,ZHANG Qi,ZHONG Pinzhi,WANG...
    2024, 14(1):  35-41.  doi:10.13809/j.cnki.cn32-1825/te.2024.01.005
    Abstract ( 6 )   HTML( 0 )   PDF (1809KB) ( 0 )   Save

    CO2 solubility in saline aquifer is an important parameter for estimating the volume of CO2 that can be dissolved and stored underground. To rapidly and economically evaluate and analyze the solubility of CO2 in saline aquifers, a study was conducted using grey GM(1,1) modeling based on existing data of CO2 solubility in water under various temperatures, pressures, and salinities. By using Markov theory, the state interval was divided, the state transition probability matrix was constructed, and the prediction results were revised. A prediction model of CO2 solubility in saline aquifer based on grey Markov theory was proposed. The results showed that the average relative errors between the predicted values of the grey Markov theory and the measured values were 1.52%、17.73%、0.21% and 3.97%, respectively. The average relative errors between the prediction results of the gray GM(1,1) model were 2.37%、19.29%、3.62% and 3.94%, respectively. The predicted values of the grey Markov model were more consistent with the measured data, and the prediction performance of the model was better, so as to provide a new method for predicting the solubility of CO2 in underground salt water.

    Characteristics of pore dynamics in shale reservoirs by CO2 flooding
    ZHANG Zhichao,BAI Mingxing,DU Siyu
    2024, 14(1):  42-47.  doi:10.13809/j.cnki.cn32-1825/te.2024.01.006
    Abstract ( 6 )   HTML( 1 )   PDF (1710KB) ( 1 )   Save

    The pore utilization characteristics of CO2 during shale oil displacement are a crucial indicator for evaluating its effectiveness in enhancing shale oil reservoir recovery rates. Therefore, experiments on supercritical CO2 displacing shale cores were conducted in the laboratory, and nuclear magnetic resonance(NMR) online core scanning technology was used to study the pore utilization characteristics and patterns of CO2 displacement in shale oil reservoirs. The results indicate that immiscible flooding by supercritical CO2 mainly develops the oil in shale pores with radius of 0.1~3.0 μm, but the oil content in pore radius less than 0.008 μm actually increases. The analysis shows that CO2 brings shale oil from large pores into small pores through pressure difference and diffusion effect in the shale layer and makes oil undergo adsorption and retention. After a displacement time of five hours, the recovery rate of shale oil by CO2 displacement reached 35.7%, indicating a relatively effective oil displacement result.

    Suitable conditions for CO2 artificial gas cap flooding-sequestration in high water cut reservoir
    WANG Jun,QIU Weisheng
    2024, 14(1):  48-54.  doi:10.13809/j.cnki.cn32-1825/te.2024.01.007
    Abstract ( 7 )   HTML( 0 )   PDF (2160KB) ( 0 )   Save

    In the development of water-flooded oil fields entering the high water-cut stage, the remaining oil often accumulates at the top of structural high positions or thick oil layers, areas not effectively covered by the existing well network. Utilizing the intrinsic characteristics of the reservoir to inject CO2 and form a gas cap drive can effectively improve development outcomes and achieve CO2 sequestration. However, the suitability of specific reservoirs for gas cap drive development requires further study. This study delves into the effectiveness of CO2 gas cap drive in high water-cut reservoirs by examining the movement of the oil-gas interface during the gas cap drive process, using both numerical and physical simulations. Key evaluation metrics include enhanced oil recovery rate, oil displacement efficiency, time to reach the critical gas-oil ratio, and gas retention rate. The research assesses how various reservoir characteristics, such as formation dip angle, crude oil density, viscosity, reservoir confinement, permeability, and the strength of water drive, influence the efficiency of CO2 gas cap drive for both oil displacement and sequestration. Focusing on these main evaluation criteria, the study identifies that the suitability of CO2 gas cap drive in reservoirs during the high water-cut phase is significantly influenced by factors such as reservoir confinement, formation dip angle, crude oil viscosity, permeability, and reservoir thickness. These findings aim to provide a foundation for broadening the application of CO2 flooding techniques. crude oil viscosity, reservoir permeability, and thickness, to provide a basis for expanding the application range of CO2 flooding.

    Mechanism of CO2 injection to improve the water injection capacity of low permeability reservoir in Shuanghe Oilfield in Henan
    SUN Yili
    2024, 14(1):  55-63.  doi:10.13809/j.cnki.cn32-1825/te.2024.01.008
    Abstract ( 5 )   HTML( 0 )   PDF (5013KB) ( 0 )   Save

    Addressing issues such as poor water injection capacity, substandard water quality and wax deposition of high pour point crude oil in low permeability reservoirs of Shuanghe Oilfield in Henan, an independently designed water-CO2 reservoir injection capability evaluation device was utilized to conduct flowability experiments and CO2 displacement tests. Combined with core scanning electron microscopy and other testing methods, the main mechanism of poor water injection capacity of Shuanghe low permeability reservoirs was clarified, and the main mechanism of CO2 improving the injection capacity of low permeability reservoirs was explored. The results show that the deposition of suspended particles in the produced water and wax crystals in the oil can lead to pore blockage, thereby reducing the water injection capacity of the reservoir. CO2 has a significant dissolving effect on inorganic suspended particles in produced water and on alkaline minerals and carbonate minerals in rocks, which is the main mechanism for significantly enhancing the reservoir's water injection capacity. CO2 can dissolve paraffin deposits on the rock surface, effectively improving the reservoir's water injection capability. At the same time, the effect of CO2 flooding is obvious, the recovery rate is increased by 13.01% ~ 21.51%, and the subsequent water flooding is further increased by 5.40% ~ 6.04%. This study shows that CO2 injection can significantly improve the injection capacity of low permeability reservoirs in Shuanghe Oilfield, and provides theoretical support for the field application of CO2 injection and oil displacement technology.

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