芦草沟组页岩油储层地质力学特性与水力压裂数值模拟  

INVESTIGATION ON THE GEOMECHANICAL CHARACTERISTICS AND THE HYDRAULIC FRACTURING PROCESSES OF THE LUCAOGOU SHALE OIL RESERVOIRS

作　　者：宋斯宇 徐东升[1] 李映艳[1] 余娟[1] 胡彦智 郑博[2] 李晓[2] 李守定[2] SONG Siyu;XU Dongsheng;LI Yingyan;YU Juan;HU Yanzhi;ZHENG Bo;LI Xiao;LI Shouding(Exploration and Development Research Institute,PetroChina Xinjiang Oilfield Company,Karamay 834000,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]中国石油新疆油田分公司勘探开发研究院,克拉玛依834000 [2]中国科学院地质与地球物理研究所,中国科学院页岩气与地质工程重点实验室,北京100029

出　　处：《工程地质学报》2023年第3期1038-1048,共11页Journal of Engineering Geology

基　　金：中国石油天然气集团有限公司重大科技专项《吉木萨尔页岩油国家级示范区水平井效益开发关键工程技术集成与试验》(资助号:2020F-50)。

摘　　要：吉木萨尔凹陷芦草沟组页岩油储层是我国典型的陆相咸化湖盆页岩油藏,甜点体呈现典型的薄互层特征,岩性组合变化迅速,非均质性强烈,储层改造难度较大。其中:芦草沟组储层地质力学参数垂向分布特征及对水力裂缝拓展的影响亟需进一步研究。本文针对芦草沟组页岩油储层下甜点段,对钻井岩芯样品进行高密度取样和力学测试,揭示了芦草沟下甜点段地质力学参数在垂向上的非均匀分布特征,基于数值模拟研究了非均匀分布的力学参数对水力裂缝拓展过程的影响规律。结果表明:(1)芦草沟组地层地质力学参数在垂向上变化剧烈,呈现明显的薄互层特征;(2)芦草沟组地应力和破裂压力变化剧烈,对水力裂缝穿层拓展具有较大的潜在影响;(3)储层非均匀分布的地质力学参数对裂缝垂向拓展影响显著,提高压裂液排量和黏度均可有效促进裂缝穿层。本文研究内容为芦草沟组页岩油有效开发提供了地质力学参数基础,可为储层压裂改造提供重要的理论支撑和设计依据。The Lucaogou shale oil reservoir in the Jimusar Depression is a typical continental shale oil reservoir in China.The reservoir presents a typical thin interlayer feature with rapid changes in lithofacies and strong heterogeneities,resulting in difficult reservoir stimulations.In particular,the heterogeneities of mechanical parameters of the Lucaogou Formation reservoir and its impact on hydraulic fractures should be further studied.In this paper,high-density sampling and mechanical testing on drilling core samples of the Lucaogou Formation are conducted.The heterogeneities of mechanical parameters are revealed,and the heterogeneities of the mechanical parameters on the evolution processes of hydraulic fractures are investigated.The results show that:(1)the mechanical parameters of the Lucaogou Formation are vertically highly heterogeneous,presenting obvious thin interlayers;(2)the variation of the in-situ stress and the breakdown pressure of the Lucaogou Formation are dramatic,which may affects the cross-layer propagation of hydraulic fractures;and(3)the heterogeneities of mechanical parameters greatly influences the vertical expansion of hydraulic fractures.Increasing the injection rate and the viscosity of fracturing fluids can effectively promote the cross-layer expansion of hydraulic fractures.This study provides an important theoretical basis for the effective development of the Lucaogou shale oil reservoir,and the results can help optimize the fracturing technologies of the Lucaogou formation.

关 键 词：页岩油 芦草沟组 水力压裂 非均匀性 

分 类 号：TU458[建筑科学—岩土工程]