岩屑分形特征对PDC齿破岩性能影响规律研究  

Influence of Fractal Characteristics of Cuttings on the Rock Breaking Performance of PDC Cutter

作　　者：赫文豪 陈振良 史怀忠[3] 黄中伟[3] 熊超 李欣龙 史明豪 He Wenhao;Chen Zhenliang;Shi Huaizhong;Huang Zhongwei;Xiong Chao;Li Xinlong;Shi Minghao(Beijing Key Laboratory of Optical Detection Technology for Oil and Gas,China University of Petroleum(Beijing);Basic Research Center for Energy Interdisciplinary,College of Science,China University of Petroleum(Beijing);State Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum(Beijing))

机构地区：[1]中国石油大学(北京)油气光学探测技术北京市重点实验室 [2]中国石油大学(北京)理学院能源交叉学科基础研究中心 [3]中国石油大学(北京)油气资源与探测国家重点实验室

出　　处：《石油机械》2023年第8期1-10,共10页China Petroleum Machinery

基　　金：国家重点研发计划项目“复杂油气智能钻井理论与方法——复杂地层智能化破岩机理与导向控制方法”(2019YFA0708302);国家自然科学基金项目“三轴应力条件下奔驰形PDC齿压剪耦合破岩机理研究”(52004296)、“轴扭耦合冲击辅助钻头破碎高温花岗岩机理研究”(52274016);中国石油大学(北京)科研基金“能源交叉学科基础研究中心建设与发展规划”(2462022YXZZ007)、“高温作用下深层硬岩力学特性与渗流机制演化机理研究”(2462022BJRC012);油气资源与探测国家重点实验室定向课题“考虑摩擦功耗的PDC齿破岩比功评估模型研究”(PRP/DX-2206)。

摘　　要：随着油气井钻井工程研究的不断深入,岩屑形貌特征已成为评测岩石可钻性级值与钻头破岩效率的关键考量因素之一。为探究岩屑形貌分形特征对钻头破岩效率的影响规律,结合理论建模和室内试验等研究方法,围绕岩屑粒径分形维数、岩屑最大粒径、地层岩性系数等关键岩屑形貌描述参数,建立了基于岩屑粒径分形特征的PDC齿破岩比功评估模型,并针对常规齿和锥形齿等PDC齿开展破碎硬质花岗岩试验研究,验证该模型评估PDC齿破岩性能的预测精度。利用该理论模型和试验规律,进一步揭示常规齿和锥形齿等类型PDC齿不同出刃高度、布齿角度等破岩工艺参数下岩屑形貌生成特征及破岩能耗变化规律。研究结果发现:切削深度对PDC齿破岩性能影响效果远大于切削角度,随着地层埋深的增大,PDC齿吃入深度减小,PDC齿生成岩屑分形维数逐渐增大,最大岩屑粒径显著减小,且锥形齿生成岩屑平均粒径大于常规齿;同等钻压或破岩能量条件下,锥形齿脆性破碎能力强于常规齿,生成岩屑分形维数和最大粒径均大于常规齿。研究结果可为深层硬岩钻进过程中岩屑录井形貌数据和PDC钻头混合布齿工艺提供理论依据。Along with the deepening research on oil and gas well drilling engineering,the morphology of cuttings has become one of the key considerations for evaluating the drillability level of rocks and the rock breaking efficiency of bits.In order to explore the impact of fractal characteristics of cuttings morphology on the rock breaking efficiency of the bit,combined with theoretical modeling and laboratory tests,centered on the key cuttings morphology description parameters such as fractal dimension of cutting size,maximum cutting size and formation lithology coefficient,a rock breaking specific energy evaluation model of PDC cutter based on the fractal characteristics of cutting size was built,and experimental research on breaking hard granite by conventional and conical PDC cutters was carried out to verify the predictive accuracy of the model in evaluating the rock breaking performance of PDC cutter.The theoretical model and experimental rules were used to further reveal the generation characteristics of cuttings morphology and the variation law of rock breaking energy consumption under different rock breaking process parameters such as exposure height and cutter arrangement angle of conventional and conical PDC cutters.The results show that the influence of cutting depth on rock breaking performance of PDC cutter is far greater than that of cutting angle;as the buried depth of the formation increases,the penetration depth of PDC cutter decreases,the fractal dimension of cuttings generated by PDC cutter gradually increases,the maximum cutting size significantly decreases,and the average particle size of cuttings generated by conical cutter is larger than that by conventional cutter;under the same weight on bit(WOB)or rock breaking energy conditions,the brittle breaking capacity of conical cutter is stronger than that of conventional cutter,and the fractal dimension and maximum particle size of generated cuttings are all larger than those of conventional cutter.The research results provide a theoretical basis for th

关 键 词：PDC齿 岩屑 分形维数 最大岩屑粒径 破岩比功 

分 类 号：TE21[石油与天然气工程—油气井工程]