动载作用下页岩动态破碎力学特性及能耗规律  

Mechanical characteristics and energy consumption of shale dynamic crushing under dynamic loading

作　　者：董广建 白璟 曹权 李兆丰 付建红[1,2] 彭炽 陈平 DONG Guangjian;BAI Jing;CAO Quan;LI Zhaofeng;FU Jianhong;PENG Chi;CHEN Ping(State Key Laboratory of Oil&Gas Reservoir Geology and Exploitation//Southwest Petroleum University,Chengdu,Sichuan 610500,China;School of Petroleum Engineering,Southwest Petroleum University,Chengdu,Sichuan 610500,China;Drilling&Production Technology Research Institute,CNPC Chuanqing Drilling Engineering Co.,Ltd.,Guanghan,Sichuan 618300,China;Engineering Technology Research Institute,PetroChina Southwest Oil&Gasfield Company,Chengdu,Sichuan 610051,China;PetroChina Zhejiang Oilfield Company,Hangzhou,Zhejiang 311100,China)

机构地区：[1]“油气藏地质及开发工程”国家重点实验室·西南石油大学 [2]西南石油大学石油与天然气工程学院 [3]中国石油川庆钻探工程有限公司钻采工程技术研究院 [4]中国石油西南油气田公司工程技术研究院 [5]中国石油浙江油田公司

出　　处：《天然气工业》2023年第4期157-164,共8页Natural Gas Industry

基　　金：中国石油—西南石油大学创新联合体科技合作项目“提高钻遇率的页岩气长位移水平井一趟钻钻井技术研究”(编号:2020CX040202);四川省自然科学基金项目“热裂解—谐振激励联合钻井作用下干热岩多尺度破碎机理研究”(编号:2022NSFSC0975)。

摘　　要：四川盆地页岩气已成为规模效益开发的重要领域和对象,其中四川盆地南部地区(以下简称川南地区)已成为我国页岩气勘探开发的主战场,2022年产量达223.23×10^(8)m^(3),展示了川南地区页岩气良好的勘探开发潜力。但川南地区页岩气长水平井面临机械钻速慢、钻井周期长等严峻挑战。为了解决页岩气水平井钻井破岩过程中页岩动态破碎特征和能耗规律不清的难题,基于霍普金森压杆测试技术测试了动态破岩的应力波传播过程;采用应力波平衡法,评价了动载荷作用下页岩动力学强度演化特征、破碎能耗响应规律、岩石裂纹动态扩展特性。研究结果表明:①页岩破碎过程中,动态强度和能耗直接影响破碎和提速效果,不同加载应变率和加载模式下页岩强度是动态变化的,动态加载会激活页岩内部更多的微裂纹和穿透裂纹;②随着加载应变率增加,页岩压缩强度和拉伸强度均是先缓慢增加,超过临界应变率时,强度快速增长;③页岩压缩破碎能耗存在临界应变率区间,随着应变率增加,破岩能耗增长缓慢,当超过临界区间,能耗快速增长,页岩拉伸破碎能耗呈对数型增加规律,也存在临界应变率区间;④钻头—岩石互作用过程中过高载荷直接增大接触应变率,造成钻头损伤和接触强度增加,降低破岩效率;⑤高效破岩综合考量指标应包括静态单轴压缩强度、岩石动态强度和能耗。结论认为,研究成果对页岩气水平井提速优化提供了理论支撑,对提高深层页岩地层破岩效率具有重要的指导意义,有助于页岩气的规模效益开发。Shale gas in the Sichuan Basin has become an important field and object of large-scale benefit development.The southern Sichuan Basin has become the main battlefield of shale gas exploration and development in China,and its annual shale gas production in 2022 is 223.23×10^(8) m^(3),revealing great exploration and development potential of shale gas in this area.In the southern Sichuan Basin,however,shale gas long horizontal wells face severe challenges of low rate of penetration(ROP)and long drilling cycle.In order to clarify the shale dynamic crushing behaviors and energy consumption laws in the rock breaking process of shale-gas horizontal well drilling,this paper tests the stress wave propagation process of dynamic rock breaking by virtue of the Hopkinson pressure bar test technology.In addition,the evolution characteristics of shale dynamic strength,the response laws of crushing energy consumption and the dynamic propagation behaviors of rock cracks under dynamic loading are evaluated by using the stress wave balance method.And the following research results are obtained.First,in the process of shale crushing,dynamic strength and energy consumption directly influence the crushing and ROP improvement effect.Shale strength changes dynamically under different loading rates and loading modes.Dynamic loading can activate more microcracks inside the shale and penetrating cracks.Second,as the loading rate increases,the compressive strength and tensile strength of shale increase slowly at first and then rapidly when the critical strain rate is exceeded.Third,there is a critical strain rate interval corresponding to the energy consumption of shale compression crushing.As the strain rate increases,rock breaking energy consumption increases slowly.When it exceeds the critical interval,energy consumption increases rapidly.The energy consumption of shale tensile crushing increases logarithmically,and it also has a critical strain rate interval.Fourth,in the process of bit-rock interaction,excessively high loads can direct

关 键 词：钻井工程 长水平井 动态载荷 页岩 破岩效率 动态强度 动态能耗 钻井速度和周期 

分 类 号：TE37[石油与天然气工程—油气田开发工程]