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Numerical Simulation Study on the Mechanical Integrity of Caprock in CO 2 Geological Sequestration
Bin LIU, Tiantian HUANG
Abstract62)   HTML4)    PDF (3022KB)(13)      

CO2 geological storage is one of the most important means to mitigate the greenhouse effect.The safety of CO2 securely stored in underground reservoirs largely depends on the mechanical integrity of the caprock.This paper establishes a coupled fluid-solid model for CO2 geological storage to study the changes in pore pressure,vertical displacement,and effective stress in the caprock during the CO2 injection process.It analyzes the effects of CO2 injection rate,caprock elastic parameters,and geostress factors on the occurrence of tensile and shear failures in the caprock.The results indicate that,at the initial stage of CO2 injection, changes in pore pressure,vertical displacement,and effective stress at the bottom of the cap near the injection well are significant but gradually stabilize thereafter.The area near the injection well is considered the most critical part of the caprock,where the risk of mechanical failure is greatest.During the CO2 injection process,the injection rate and geostress factors have the most significant impact on the occurrence of mechanical failures in the caprock.The findings of this study provide a theoretical basis for assessing the long-term stability and safety of CO2 geological storage systems.

2025, 38 (1): 33-41. DOI: 10.12422/j.issn.1006-396X.2025.01.005
Experimental Study on Influence Factors for High PV Water Flooding Efficiency in LD Heavy Oil Reservoir
Jinyi Li, Xianbo Luo, Yingxian Liu, Zongbin Liu, Haichao Feng, Ke Chen
Abstract821)   HTML    PDF (2281KB)(494)      

In order to explore the water displacement efficiency and its influencing factors of high porosity and high permeability unconsolidated sandstone heavy oil reservoir through the thermal production boundary in the mode of large volume liquid extraction and cold production,taking LD oilfield in Liaodong mining area of Bohai Sea as an example, the systematically study on oil displacement efficiency of 2 000 PV high multiple water was carried out with flow rates were 1.0,7.5,15.0 mL/min.At the same time,combined with mercury injection,X?ray diffraction,whole rock and gas permeability measurement,the liquid extraction system can be optimized,and the influence of various factors on the water oil displacement efficiency of this type of heavy oil reservoir after liquid extraction was analyzed as well.The experimental results show that the differences of reservoir geological characteristics such as micro pore?throat structure,interstitial content and permeability have a great influence on the displacement characteristics after liquid extraction. The worse micro pore?throat structure would induce a higher the interstitial content, inferior permeability and lower high PV water flooding efficiency.Compared with the direct liquid extraction method, the step?by?step liquid extraction method can achieve higher water flooding efficiency.For this type of heavy oil reservoir,it has the best liquid extraction range.If the amplitude is too large, it is easy to cause the front edge to burst, and reduce the micro sweep. It should be controlled at 7.5 times. The experimental results can effectively guide the exploitation of residual oil by using horizontal well extraction in heavy oil reservoirs.

2021, 34 (6): 42-49. DOI: 10.3969/j.issn.1006-396X.2021.06.007
Based on the Reservoir Architecture of the Remaining Oil Reservoir Fine Characterization and Potentialities: A Case of the Oil Layer of the Lower ED2 of Dongying Formation in Bohai L Oilfield
Bin Zheng, Xinwu Liao, Zongbin Liu, Yujuan Liu, Jing Zhang, Zhiming Yan
Abstract599)   HTML    PDF (3590KB)(541)      

Bohai L oilfield has undergone multiple adjustments since it was exploited, such as well pattern internal infilling, changing well patterns, and reversing lines. The scattered distribution of remaining oil on the flat and extremely complicated vertical flooding law resulted in difficulty for tapping the remaining oil. Based on the data of core, well logging, seismic, production dynamic and other results, the thick reservoir can be comprehensively characterized, so as to guide the remaining oil fine characterization and potential development. The results show that the plane contact styles of single sand body is mainly in butt type, and the vertical overlap mainly in cut type. The remaining oil of the southern vertical accretion type leaf body is mainly concentrated near the vicinity of the fault, the buried hill area and the sand?body deposition margin, which can be tapped using directional wells. The remaining oil of the central prophase frond is mainly concentrated in the top of the thick sand body and the lower part of the thin interbe, which can be tapped using horizontal wells.

2021, 34 (5): 36-42. DOI: 10.3969/j.issn.1006-396X.2021.05.006