摘要
明确复杂地应力状态下煤层气水平井井眼破坏失稳机理是合理制定煤层气储层钻井方案的关键前提。利用自主研发的煤层气井围岩形变可视化真三轴物理模拟实验装置,考虑水平地应力差异影响,研究增加垂向应力条件下煤层气储层水平井围岩变形破坏机制。结果表明:1)井眼变形可分为3个阶段:缓慢缩小变形阶段、稳定缩小变形阶段和加速缩小直至闭合阶段。2)在井眼变形后两个阶段,试件3个方向的变形主要受井眼变形破坏控制。3)随着最大或最小水平主应力增加,井眼稳定缩小变形阶段的垂向主应力-变形曲线斜率显著增大,单位应力增量下3个方向应变先减小后增大;同时,井眼破坏时的截面积增大,对应的临界垂向主应力增大而垂向应变减小。4)当两向水平主应力同步增大时,上述变化趋势更为显著,更有利于维持井眼稳定。研究结果可为煤层气水平井钻井设计提供指导。
Understanding wellbore instability mechanisms in coalbed methane(CBM)horizontal wells under complex stress conditions is crucial for optimizing CBM reservoir drilling.Using a self-developed true triaxial device to simulate surrounding rock deformation,this study examines how differential horizontal stresses and vertical stress variations affect deformation and failure in CBM horizontal wellbores,and obtains the following results:1)Wellbore deformation can be divided into three stages:slow shrinkage deformation stage,stable shrinkage deformation stage,and accelerated shrinkage until closure stage.2)In the latter two stages of wellbore deformation,the deformation of the specimen in three directions is mainly controlled by wellbore deformation and failure.3)As the maximum or minimum horizontal principal stress increases,the slope of the vertical principal stress-deformation curve during the stable shrinkage deformation stage of the wellbore significantly increases,and the strain in all three directions per unit stress increment decreases;simultaneously,the cross-sectional area at wellbore failure increases,with a corresponding increase in critical vertical principal stress and a decrease in vertical strain.4)When the two horizontal principal stresses increase simultaneously,the aforementioned trends become more pronounced,which is more conducive to maintaining wellbore stability.The findings of this study can provide guidance for the drilling design of CBM horizontal wells.
作者
张千贵
邓健
范翔宇
贾利春
郭小炜
ZHANG Qiangui;DENG Jian;FAN Xiangyu;JIA Lichun;GUO Xiaowei(Petroleum Engineering School,Southwest Petroleum University,Chengdu,Sichuan 610500,China;School of Geoscience and Technology,Southwest Petroleum University,Chengdu,Sichuan 610500,China;Drilling&Production Technology Research Institute of CNPC Chuanqing Drilling Engineering Company Limited,Guanghan,Sichuan 618300,China;School of Robot Engineering,Yangtze Normal University,Fuling,Chongqing 408100,China)
出处
《西南石油大学学报(自然科学版)》
北大核心
2025年第6期107-118,共12页
Journal of Southwest Petroleum University(Science & Technology Edition)
基金
国家自然科学基金(42172313)
四川省自然科学基金(2024NSFSC0203)
重庆市教委基金(KJQN202101438)。
关键词
煤层气
水平地应力差异
井眼变形
井壁稳定性
物理模型
coalbed methane
horizontal in-situ stresses difference
wellbore deformation
wellbore stability
physical model
