考虑井筒变形的深层射孔井岩石破裂压力计算模型  

Calculation model of breakdown pressure in deep perforated wells considering wellbore deformation

作　　者：任岚[1] 蒋豪 赵金洲[1] 吴建军 林然[1] 李洋 REN Lan;JIANG Hao;ZHAO Jinzhou;WU Jianjun;LIN Ran;LI Yang(State Key Laboratory of Oil&Gas Reservoir Geology and Exploitation of Southwest Petroleum University,Chengdu 610500,China;PetroChina Coalbed Methane Company Limited.,Beijing 100020,China)

机构地区：[1]西南石油大学油气藏地质及开发工程国家重点实验室,四川成都610500 [2]中国石油煤层气有限责任公司,北京100020

出　　处：《大庆石油地质与开发》2022年第6期64-73,共10页Petroleum Geology & Oilfield Development in Daqing

基　　金：国家自然科学基金青年科学基金项目“基于DEM-LBM流固耦合的深层页岩气水力裂缝长效支撑理论与方法研究”(52104039);国家自然科学基金项目“四川深层页岩气水平井缝网压裂填砂暂堵物理机制研究”(U19A2043);中国石油西南石油大学创新联合体科技合作项目“多层叠置页岩储层地质力学参数场预测及缝网创建理论与优化技术”(2020CX030201)。

摘　　要：为了准确预测井筒变形下岩石破裂压力和研究水力射孔参数对其的影响,基于保角变换方法和断裂力学理论,推导了射孔孔眼尖端应力强度因子,建立了射孔椭圆井筒岩石破裂压力计算模型。通过理论计算与实验结果对比,验证了模型的可靠性,并基于该模型分析了井筒变形程度、射孔参数对岩石破裂压力的影响。结果表明:非变形井筒状态下所预测的破裂压力偏高,随着井筒变形程度的增加,岩石破裂压力降低;射孔方位角控制在20°以内,有利于裂缝起裂和减小近井裂缝弯曲度;随着射孔深度的增加,裂缝起裂角增加,岩石破裂压力降低且幅度逐渐减小。综合考虑降低破裂压力和避免近井裂缝弯曲率过大这两方面因素,推荐最优射孔深度为井筒尺寸的1.5~2.0倍。该模型为射孔椭圆井筒岩石破裂压力计算提供了新的手段。In order to accurately predict breakdown pressure under wellbore deformation and study influence of hydraulic perforation parameters on it,on the basis of conformal transformation method and fracture mechanics theory,stress intensity factor at the tip of perforated hole is derived,and rock breakdown pressure calculation model of perforated elliptical wellbore is established.Model reliability is verified through comparison between theoretical calculation and experimental results.Based on this model,influences of wellbore deformation and perforation param‑eters on rock breakdown pressure are analyzed.The results show that predicted breakdown pressure without well‑bore deformation is overestimated,and breakdown pressure decreases with wellbore deformation increase.Control‑ling perforation azimuth less than 20°is conducive to rock fracture initiation and near-wellbore fracture curvature reduction.With perforated depth increase,fracture initiation angle increases,and breakdown pressure decreases with gradually small range.Comprehensively considering fracture pressure reduction and avoiding excessive frac‑ture curvature near wellbore,optimal perforated depth is about 1.5~2 times of wellbore size.This model provides a new method for calculating rock breakdown pressure of perforated elliptical wellbore.

关 键 词：水力压裂 定向射孔 井筒变形 椭圆井筒 破裂压力 

分 类 号：TE357.1[石油与天然气工程—油气田开发工程]