岩石组构、地应力与流体黏度对鄂尔多斯盆地长73陆相页岩水力裂缝扩展的影响规律  

Combined effect of rock fabric,in-situ stress,and fluid viscosity on hydraulic fracture propagation in Chang 7_(3) lacustrine shale from the Ordos Basin

作　　者：郭鹏 李晓 李守定 赫建明 毛天桥 郑博 GUO Peng;LI Xiao;LI Shou-ding;HE Jian-ming;MAO Tian-qiao;ZHENG Bo(Institute of Energy,School of Earth and Space Sciences,Peking University,Beijing 100871,China;Key Laboratory of Shale Gas and Geoengineering,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China)

机构地区：[1]Institute of Energy,School of Earth and Space Sciences,Peking University,Beijing 100871,China [2]Key Laboratory of Shale Gas and Geoengineering,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China

出　　处：《Journal of Central South University》2024年第5期1646-1658,共13页中南大学学报（英文版）

基　　金：Project(42090023) supported by the National Natural Science Foundation of China;Project(2020YFA0710504) supported by the National Key R&D Program of China。

摘　　要：页岩油是原油增储上产的重要领域。由于储层结构致密、超低渗透,页岩油工业开发需要对储层进行大规模压裂改造。与海相页岩储层相比,鄂尔多斯盆地长7_(3)陆相页岩油储层矿物成分与岩石组构差异较大,力学非均质性较强。陆相页岩油靶层选取和高效压裂改造需要明确页岩力学行为和水力裂缝扩展规律。对长7_(3)陆相页岩进行了原位X-ray CT力学试验和三轴水力压裂试验。分析了岩石组构、地应力差和流体黏度对水力裂缝垂向扩展的影响规律。结果表明,岩石组构对陆相页岩的力学行为和破坏过程有显著影响。陆相页岩水力裂缝的垂向扩展受垂向应力差和流体黏度的共同控制。当垂向应力差较小时,黑色页岩中原生弱面显著抑制了水力裂缝的垂向扩展。随着垂向应力差的增大,黑色页岩裂缝体积呈线性增加趋势,而纹层型页岩裂缝体积呈先增大后减小趋势。增大压裂液黏度可减弱层面的阻碍作用,促进水力裂缝垂向扩展。Shale oil is an important area for the increasing of crude oil reserves and production.Due to the tight structure and ultra-low permeability of shale oil reservoir,the industrial exploitation needs large-scale hydraulic fracturing.However,compared with marine shale reservoirs,the Chang 7_(3) lacustrine shales of the Ordos Basin present large differences in mineral composition and rock fabric,resulting in strong mechanical heterogeneity.The target interval selection and effective hydraulic fracturing of lacustrine shale oil reservoir requires a thorough understanding of the mechanical behavior and hydraulic fracture propagation in shale rocks.In-situ X-ray CT mechanical tests and triaxial hydraulic fracturing tests on Chang 7_(3) lacustrine shales were conducted.The effects of rock fabric,in-situ stress difference and fluid viscosity on hydraulic fracture vertical propagation were analyzed.The results show that the rock fabric significantly influences the mechanical behavior and failure process of lacustrine shales.The vertical growth of the hydraulic fracture in lacustrine shales is dictated by vertical stress difference and fluid viscosity.When the vertical stress difference is small,the intrinsic weak interfaces in black shale significantly inhibit the vertical growth of hydraulic fracture.With the increase of vertical stress difference,the fracture network volume of black shale increases linearly,however,the fracture volume of laminar shale first increases and then decreases.Increasing the fracturing fluid viscosity could weaken the obstruction effect of weak bedding interfaces and promote the vertical propagation of hydraulic fracture.

关 键 词：陆相页岩 力学行为 水力裂缝 岩石组构 地应力 流体黏度 

分 类 号：TE357.1[石油与天然气工程—油气田开发工程]