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Early Edition
Table of Content
26 August 2018, Volume 8 Issue 4
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  • Reservoir Geology
    Uncertainty analysis of reserves of fluvial reservoir calculated by geological model
    Xue Yanxia,Liao Xinwu,Huo Chunliang,Hu Yong,Zhang Rucai
    2018, 8(4):  1-5. 
    Abstract ( 258 )   HTML( 153 )   PDF (1879KB) ( 153 )   Save
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    The reserves of the geological model in the offshore fluvial reservoirs are influenced by the uncertain parameters, such as the structure, plane variogram, correlation between reservoir properties and seismic attributes, irreducible water saturation, lower limiting value of effective reservoir, volume coefficient, and oil-water interface. The root that causes these uncertain parameters is analyzed. Meanwhile, taking oilfield-Q in Bohai bay as an example, and by the integrated application of the Monte-Carlo method and stochastic modeling, the effects of the uncertainty parameters on the reserves are estimated quantitatively. The probability cumulative distribution curves of reserves and 3 probability reserve value which are the pessimistic reserves(P90), expected reserves(P50) and optimistic reserves(P10) are obtained to predict the risk and potential of the reserves.

    Study on the fine fault interpretation in Nanchuan district
    Jin Xiaobo
    2018, 8(4):  6-10. 
    Abstract ( 272 )   HTML( 263 )   PDF (3705KB) ( 263 )   Save
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    In order to further determine the distribution characteristics of the faults in Nanchuan district, we adopted the "three stories" structure for the fine structure interpretation, and combined with the technology such as the frequency division fusion, inclination of coherent, curvature, structure entropy, AFE and dip angle of curvature to predict the distribution of the fault. The application of the multiple attributes for the fault interpretation and the quality control of the fault section interpretation in 3D space improved the accuracy of the fault interpretation. There were 96 faults interpreted and closed in the district. It provides theoretical basis for oil and gas exploration and development.

    Reservoir Evaluation
    Application of discrete fracture network modeling technology in mudstone fractured reservoir in Daqing oil region
    Wei Xu,Zhang Yongping,Bo Yunhe,Guo Hao,Guo Yuhang,Wu Senhao
    2018, 8(4):  11-16. 
    Abstract ( 268 )   HTML( 83 )   PDF (3537KB) ( 83 )   Save
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    :The mudstone fractured oil and gas reservoir is a kind of special unconventional reservoirs and its hydrocarbon mainly exists in fractures. This kind of reservoirs has industrial exploitation value due to the large reserves, but the complex geological condition leads to its poor develop effects. In order to reconstruct the geological condition and analyze the production capacity of the mudstone fractured oil and gas reservoir before fracturing, the core characteristics, downhole microseismic and dynamic information of production are fully considered. According to the characteristics and production of the development layer with mudstone fractures in Daqing area, and combined with the seismic and other structural research results, we established the fracture network model, which was constrained by the crack strength attribute. Based on the network model, the coupling model of the artificial fracture and natural fracture is established, so that to analyze the effect before and after fracturing. The results show that the fractured model can accurately describe the numbers and direction of the natural fractures, and estimate the oil and gas production before and after fracturing. The study is used as a method for evaluating the productivity of mudstone fractured oil and gas reservoirs in area A of Daqing, and to provide the basis for the fracturing construction of other wells in this zone.

    Study on the speed of oil recovery and influence factors in extra-high water content period
    Chen Jun,Yang Junyi,Liu Qiguo
    2018, 8(4):  17-21. 
    Abstract ( 230 )   HTML( 369 )   PDF (1379KB) ( 369 )   Save
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    The oil recovery rate has great impact on the development effects of the water drive reservoir in the period of extra-high water cut. During this period, the water saturation is further increased. The reservoir is subjected to the flooding, scour and erosion of the long-term water injection. Along the main line of the injection and mining, and under the long-term effect of the large pressure gradient, the loose particles of the reservoir will gradually peel off and move with the oil and water flow to the well. The pore structure of the reservoir is well remodeled in the wellbore near the well area. All these lead to the profound change of the microscopic pore structure of the reservoir. What's more serious is that a secondary dominant channel will form, which causes the abrupt change of the characteristics of the oil and water seepage. So there arises a non-linear characteristic of the oil-water infiltration ratio curve. Based on this feature, we established the relation between the oil recovery rate, and the reservoir characteristics, water cut, water saturation and the water cut increasing rate by using the water diversion equation to show the inner links between the oil recovery rate and the factors above. We also analyzed the influence of the various factors on the oil recovery rate. Compared with the previous methods, this new method has obvious advantages in the application of the reservoirs with the high water cut.

    Effect of CO2 foam on water absorption profile improvement
    Wang Jian,Wu Songyun,Yu Heng,Zhang Zuowei,Xu Peng
    2018, 8(4):  22-25. 
    Abstract ( 214 )   HTML( 282 )   PDF (1267KB) ( 282 )   Save
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    In order to solve the problems of the uneven plane water flooding, great differences between the of vertical water absorption, and low recovery of the waterflooding during the high water cut exploitation period of the oilfield, a series of indoor evaluation experiments were conducted to improve the water absorption profile of CO2 foam flooding. Then we established the flooding model by multiple core combination with the high and low permeability with the differential of 3, 6 and 9. We used the CO2 foam to displace the core to study the effect of the differential permeability and oil saturation difference on the improvement of water absorption profile during CO2 foam flooding, and the CO2 foam displacement efficiency. The results show that the effects of CO2 foam improving the injection profile become better when the permeability reduces. And taking into account the displacement efficiency of CO2 under different permeability ratio, the permeability of the same layer should be controlled within 6. Meanwhile, the effects of CO2 foam on profile improvement gets better when the oil saturation increased. In the practical application, the range of oil saturation level should be 4 ~ 6. At present, the research results have been applied in the test of CO2 foam flooding in Block A of Jilin Oilfield.

    Well test interpretation model about interporosity flow outside casing around vertical well in dual layer reservoir
    Su Zezhong,Li Xiaona,Li Mengmeng,Liu Rui,Lin Jiaen
    2018, 8(4):  26-32. 
    Abstract ( 239 )   HTML( 280 )   PDF (1702KB) ( 280 )   Save
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    In order to monitor and prevent the channeling outside the casing, we established a well-testing interpretive mathematical model of the vertical wells in dual layer reservoir considering the semi-permeability of the interlaminar and the bore hole storage effect. Then we solved and drew the typical well test curves by the Laplace transformation. According to the test curves, there are four flow sections: intermediate flow period, transition section, interporosity flow section and systematic radial flow period. By the analysis of the influence factors of the type curve, we conclude that: ①Well testing curves are influenced by many parameters, for example, the well storage coefficient affects the early curves, while the skin factors, permeability, fluid viscosity, oil layer thickness, and cross flow coefficient affect its transition stage and interporosity flow stage. ②The parameters of the test layer and neighbor layer have an opposite effect on the well test curves. ③The main controlling factors of the strength of the interporosity flow outside the casing include the interporosity flow coefficient, the permeability of neighbor layer and the skin factors of test layer. ④The reason of the interporosity flow outside the casing is the damage degree of the cement sheath outside the casing, and the corresponding monitoring method is put forward.

    Study on production decline factors based on gray correlation
    Huang Shuai,Peng Caizhen
    2018, 8(4):  33-35. 
    Abstract ( 134 )   HTML( 180 )   PDF (1195KB) ( 180 )   Save
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    The production decline rate is an important indicator in evaluating the oil field development. It is of great significance for the development of oil fields to make the corresponding adjustment measures by analyzing the main factors that affect the production decline. The relation between the decline rate and the influencing factors for the development units of JS oilfield was studied by the grey correlation analysis method and based on the static and dynamic data. The weight of each factor was determined and the influence factors were sorted. According to the degree of influence for different factors, it can provide the reference for the development measures and development techniques.

    Petroleum Engineering
    Multifactorial experiment of acid's fingering phenomenon in the multi-stage alternating injection of acid fracturing
    Luo Zhifeng,Yu Yang,Zhao Liqiang,Li Xiaogang,Zhao Xingdong
    2018, 8(4):  36-41. 
    Abstract ( 208 )   HTML( 114 )   PDF (1871KB) ( 114 )   Save
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    The evolution characteristics and the final shape of acid viscosity fingering are influenced by many engineering and geological factors. So that, we used the visual experimental device to explore the change rules under the multifactor. Six factors were considered, those are the concentration of acid, the injection series, the temperature, the construction displacement, the viscosity ratio of the liquid, and the inclination of crack. The fractal dimension and multifractal spectrum width were used to describe the morphological of fingering. It is concluded that the influence degree of each factor on fractal dimension from high to low is in the order of: viscosity ratio, injection series, temperature, acid concentration, construction displacement, and crack inclination. The influence degree of each factor on the multifractal spectrum width from high to low is in the order of: viscosity ratio, crack inclination, construction displacement, acid concentration, injection series, and temperature. In order to achieve the viscosity fingering of acid fracturing, the viscosity ratio should be increased to the value between 100∶1 and 150∶1, the controlled injection series are at level 2 to level 3, and the designed acid dosage is about 0.3. Meanwhile, a large number of pre-liquid was injected to reduce the crack wall's temperature before the acid injection.

    Analysis of influence factor of minimum miscible pressure of CO2
    Tang Yong,Zhao Xuemei,Wang Yang
    2018, 8(4):  42-45. 
    Abstract ( 374 )   HTML( 957 )   PDF (1835KB) ( 957 )   Save
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    CO2 flooding is a promising way to improve the crude oil recovery ratio. CO2 could not only dissolve in crude oil, but also replace some light hydrocarbons or intermediate hydrocarbons in crude oil. So the composition has great influence on the component mass transfer and minimum miscible pressure of the CO2 miscible flooding. Therefore, the influence of the quantitative characterization of crude oil composition on the minimum miscible pressure of the CO2 miscible flooding has engineering significance for the reservoir screening. Taking the original formation fluid of a certain oilfield in China as the research object, we analyzed the multistage contact miscibility mechanism. Meanwhile, we used the Winprop module in CMG to carried out the phase simulation of experimental data. The results show that the minimum miscible pressure between CO2 and crude oil is proportional to the molar composition of N2, C1 and C11+, and inversely proportional to that of C2~C10. While the mixing of the CO2 and reservoir fluids needs higher reservoir pressure than minimum miscible pressure. It requires that when screening reservoirs with CO2 flooding, we should try to consider the reservoir with high mole content of C2 ~ C10 and low mole content of C24. It has great guiding significance for miscible displacement design and miscible phase prediction.

    Study on oil increasing effect and mechanism of comprehensive treatment measures after polymer flooding: Taking LD10-1 oilfield in Bohai Oilfield as an example
    Liu Yigang,Xiao Lihua,Zou Jian,Lu Xiangguo,Yan Dong,Cao Weijia
    2018, 8(4):  46-51. 
    Abstract ( 163 )   HTML( 393 )   PDF (2297KB) ( 393 )   Save
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    LD10-1 oilfield in Bohai reservoir is a thick reservoir with high average permeability, serious heterogeneity, low cementing strength of rock and high single well injection-production strength. For this reason, during the development of the profile control and oil displacement technology of polymer gel in the early stages, the contradiction between and within layers caused by the polymer retention and scour are obvious. Then we test the development of the comprehensive treatment of the effect screening and performance evaluation, profile control, plug release of modifying and flooding agent, alternative injection of the profile control and oil displacement agent and water after polymer flooding. The results showed that, with the same dosage of the polymer gel, and compared with the whole slug injection method, the gel and water alternating injection method can slow down the speed of the entry profile reversal, and extend the sweep coefficient of the medium and low permeability layer. When they are used together, the utilization level of the medium and low permeability layers is further enhanced, and the effect of oil increasing and precipitation is obvious.

    Polymer displacing modeling experiment of conglomerate reservoir with different interlayer heterogeneous
    Tan Xin,Pu Wanfen,Wang Ning,Wang Li,Sun Boshuai
    2018, 8(4):  52-57. 
    Abstract ( 182 )   HTML( 230 )   PDF (1851KB) ( 230 )   Save
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    Because of the strong heterogeneity and complex modal pore structure, the develop dynamic of the conglomerate reservoirs are more complex than those of the sandstone reservoirs. At present, the conglomerate reservoirs in Xingjiang have been in high water cut stage. It faces the problems such as the serious water channeling, low recovery rate, and great production difficulty,so it is necessary to carry out the polymer flooding evaluation experiment of the conglomerate reservoirs to provide references for designing the later development in maturing field. Taking the lower Karamay formation in No. 7 reservoir in east district of Karamay Oilfield as an example, we choose different heterogeneous models for the displacement experiments to analyse the effects of interlayer heterogeneity on the recovery and polymer channeling. The results prove that the producing reserves in the medium-low permeability cores of the strong heterogeneity model are very low, and the oil recovery in the experiment is mostly from the extraction of the high permeability core. There is still a large amount of oil remaining in the core. During the displacement, the serious polymer channeling exists in all test groups, which greatly reduced the sweep efficiency. It is a challenge of dealing with polymer channeling in the future development of the conglomerate reservoir.

    Study on linear analytical model for suspended particle filtration
    Yu Xiaowei,Li Hongjian,Lyu Yunze,Tang Hanlin
    2018, 8(4):  58-62. 
    Abstract ( 150 )   HTML( 138 )   PDF (1798KB) ( 138 )   Save
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    In order to study the influence of suspended particles and emulsified oil droplets on the water absorbing capacity in produced water reinjection process, we analyzed the suspended particles filtration model by the depth filtration and formation of the external filter cake, and optimized the solution of the model parameters(the filtration coefficient λ and the formation damage coefficient β). Based on the solution curves fitted by the core flooding experiment data, and by the numerical solution of the transcendental equation, we obtained the variation rule of filtration coefficient(λ), formation damage coefficient(β) and impedance slope(m) under the influence of different phase suspended particles. Then we got the impedance of the depth filtration and filter cake formation with piecewise fitting and calculated the particle concentration distribution of the core.

    Optimization of horizontal well refracturing technology in tight reservoirs
    Song Liyang,Wang Jiwei,Li Fengxia,Liu Changyin,Su Jianzheng,Zhang Rusheng
    2018, 8(4):  63-67. 
    Abstract ( 263 )   HTML( 506 )   PDF (1367KB) ( 506 )   Save
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    In order to improve the refracturing effects of the tight reservoirs and the economic benefits, we provided the optimization methods for the well and layer selection and fracturing design in the refracturing process of the tight wells: the multi-level fuzzy comprehensive evaluation method and artificial neural network method were applied to study the influence of the geological and engineering factors on the refracturing effect, so that the well and layer selection criteria of refracturing for the horizontal wells in tight reservoirs could be determined. The stress field variation and fracture extension rule were studied, and the fracturing material for tight reservoirs was provided. Based on the field production data, 3D fracturing simulation software was used to optimize the refracturing parameters of 3 target horizontal wells. The studying results can scientifically guide the application of refracturing technology in tight reservoir wells.

    Non-conventional Reservoir
    Geological features of Guanyinqiao member and its influence on the shale gas production: A case study of Nanchuan district
    Li Jiaxin
    2018, 8(4):  68-72. 
    Abstract ( 305 )   HTML( 337 )   PDF (2404KB) ( 337 )   Save
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    The guanyinqiao member in Southeast of Chongqing is a suit of argillaceous limestone formation formed in the Nantes period. The sea level and the control of ancient landform are the main factors affecting the strata. The strata overlying and underlying layer are both black shale formed in deep-water sedimentary environment. On the plane, Guanyinqiao member is distributed uniformly and missing in some parts. By analyzing the characteristics of Guanyinqiao member in Nanchuan area, and combined with the static evaluation indexes and single well productivity of the shale gas wells in this area, we analyzed that whether there was the relationship between the productivity of shale gas well and the existence of the member, thus affecting the shale gas production. The conclusion has geological guidance to the selected areas of shale gas in the Southeast of Chongqing, and great guiding significance on exploration strategy of shale gas.

    Formulation of production plan in overpressure shale gas reservoir
    Zhang Lina,Liu Xin,Zhang Yaozu
    2018, 8(4):  73-76. 
    Abstract ( 200 )   HTML( 146 )   PDF (2166KB) ( 146 )   Save
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    By the adjustment of the global energy consumption structure, the progress of shale gas exploration technology and the clean feature of shale gas, the rational development of shale gas reservoir has been the popular research direction. Therefore, how to make efficient and stable development plan of gas reservoir is very important. Taking the shale gas reservoir in Pingqiao as the research target, we established the horizontal fracturing well models with duel media by the software CMG to simulate the influence of the production allocation and recovery time after shut in on the development effect. The analysis suggests that different fracturing effects need different rational production allocation. The worse the fracturing reconstruction effect is, the lower the rational production will be, along with that are lower final recovery ratio and shorter stable production time. After the stable production period, the wells could be shut in for 20 ~ 30 days in order to recover the pressure and daily production. It is concluded that the allocation system and fracture effects affect mostly on the overpressure shale gas development. The key of the high and stable production is to improve the seepage capacity and reasonable distribution in the fracturing reconstruction region.

    Comprehensive Information
    Effect of SSL VPN of Fortinet on telecommuting of enterprise
    Zhang Wei
    2018, 8(4):  77-80. 
    Abstract ( 248 )   HTML( 452 )   PDF (5032KB) ( 452 )   Save
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    With the rapid development of the network, during the information construction of the enterprises with multiple branches in different places, great mobile office capabilities are needed. The employees of the enterprises can access the Intranet of an enterprise at any time from another place under the Internet or 4G network to do the work efficiently. SSL VPN is the fastest, safest and most efficient technology for remote users to access the internal enterprise data. Through it, the quick and safe telecommuting for the users work remotely can help the enterprises to improve the productivity and enhance the network security. It can also reduce the management and operation cost of the enterprises. Aiming at the Fortinet, which has high market share, the telecommuting system suitable for the enterprise's needs is established by its SSL VPN virtual private network technology.