Research and progress on factors affecting the flow capacity in unsupported fracture network area of shale reservoir

doi:10.3969/j.issn.1006-6535.2025.01.003

Abstract

Abstract: To address of issue of the unclear understanding of the gas-liquid flow characteristics and the influence on development patterns within the unsupported fracture network in shale volume fracturing,the research progress on the volume of unsupported fracture networks,water-rock interaction,fracture conductivity,and gas-liquid two-phase flow both domestically and internationally are summarized.Meanwhile,the influencing factors of unsupported fracture conductivity and its impact on the water production and gas production capabilities of the reservoir are analyzed.The study indicates that the unsupported fracture network area (including unsupported artificial fractures,induced fractures, and connected natural fractures) is the major body that connects supported fractures with the matrix and significantly increases the gas leakage area.The conductivity and gas-liquid two-phase flow patterns of unsupported fractures are more complex due to factors such as support conditions,water-rock interaction,and overburden stress,and they are more sensitive to changes in overlying stress.The permeability of water-bearing fractures can decrease by 2 to 4 orders of magnitude with increasing stress.The conductivity and evolution patterns of the unsupported fracture network area during shale gas development are key to the design of the wellbore flowback system and the optimization of production systems,providing a scientific basis for maintaining long-term high and stable production of gas wells.The next key research directions mainly include the mechanism of gas-liquid-solid interaction and micromechanics in unsupported fractures,the main controlling factors of long-term fracture conductivity and gas-liquid two-phase flow models,as well as the evolution patterns of fracture networks throughout the entire life cycle.This research results can provide a scientific basis for the optimal design of wellbore flowback systems and production systems in shale gas development,ensuring long-term high and stable production of gas wells.

Key words: shale, fractures, water-rock interaction, unsupported fractures, flow capacity, fracture network evolution

CLC Number:

TE377

DUAN Xianggang, HU Zhiming, CHANG Jin, SHI Yuxin, WU Zhenkai, XU Yingying. Research and progress on factors affecting the flow capacity in unsupported fracture network area of shale reservoir[J]. Special Oil & Gas Reservoirs, 2025, 32(1): 22-31.

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