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 73 lacustrine shale from the Ordos Basin
郭鹏 1李晓 2李守定 3赫建明 3毛天桥 3郑博3
作者信息
- 1. Institute of Energy,School of Earth and Space Sciences,Peking University,Beijing 100871,China
- 2. 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
- 3. Key Laboratory of Shale Gas and Geoengineering,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China
- 折叠
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73陆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73陆相页岩进行了原位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.
Abstract
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 73 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 73 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Key words
lacustrine shales/mechanical behavior/hydraulic fracture/rock fabric/in-situ stress/fluid viscosity引用本文复制引用
基金项目
国家自然科学基金(42090023)
国家重点研发计划(2020YFA0710504)
出版年
2024
NETL
NSTL
万方数据