致密油藏多轮次注水吞吐动态应力场及裂缝扩展规律研究  

Study on dynamic in-situ stress and fracture propagation of multi-cycle water huff-and-puff in tight oil reservoirs

作　　者：周晋冲 曹仁义[1] 蒲保彪 王继伟[2] 吕柄辰 易琪 ZHOU Jinchong;CAO Renyi;PU Baobiao;WANG Jiwei;LYU Bingchen;YI Qi(School of Petroleum Engineering,China University of Petroleum,Beijing 102249,China;Research Institute of Exploration and Development,PetroChina Changqing Oilfield Company,Xi'an,Shaanxi 710018,China;State Key Laboratory of Geotechnical Mechanics and Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Wuhan,Hubei 430071,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国石油大学(北京)石油工程学院,北京102249 [2]中国石油长庆油田分公司勘探开发研究院,陕西西安710018 [3]中国科学院武汉岩土力学研究所岩土力学与工程国家重点实验室,湖北武汉430071 [4]中国科学院大学,北京100049

出　　处：《岩石力学与工程学报》2024年第12期3005-3017,共13页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家自然科学基金资助项目(52174038);中国石油科技重大专项资助项目(ZLZX2020-02-04-03);中国石油大学(北京)科学基金资助项目(2462018YJRC015)。

摘　　要：多轮次注水吞吐是致密油藏补充地层能量,提高单井产能的有效措施。现有流固耦合数学模型中未考虑非线性渗流参数,多轮次注水吞吐动态应力场及裂缝形态变化规律亟待研究。建立考虑非线性渗流的致密油藏渗流-应力-裂缝扩展耦合数学模型,形成多轮次注水吞吐数值模拟方法。以鄂尔多斯盆地长庆油田CP1水平井为例,开展多轮次注水吞吐动态应力场演化及裂缝扩展规律研究。研究结果表明:(1)水平井长期衰竭开发后,近井水平主应力均减小,主应力差增大;(2)第1轮次吞吐注水阶段结束时水平主应力增大,主应力差减小,随着吞吐轮次的增加,注水阶段结束时水平主应力逐渐减小,主应力差逐渐增大,主应力方向最大偏转10°~30°;(3)吞吐注水阶段使裂缝扩展延伸,并产生分支缝,随着吞吐轮次增加裂缝扩展幅度逐渐变小,3个轮次后裂缝形态基本不变。研究结果对致密油藏注水吞吐方案优化及转变开发方式设计具有一定指导意义。Multi-cycle water huff-and-puff is an effective technique for replenishing formation energy and enhancing single-well productivity in tight oil reservoirs.Existing hydro-mechanical coupling mathematical models overlook the nonlinear flow parameters,and the dynamic changes in in-situ stress and fracture morphology throughout multicycle water huff-and-puff processes demand urgent investigation.This study has established a mathematical model of coupled flow,geomechanics and fracture propagation,which considers nonlinear flow in tight oil reservoirs,has developed a numerical simulation methodology for multi-cycle water huff-and-puff.The CP1 horizontal well in the Changqing Oilfield,located in the Ordos Basin,is used as a case study to explore the evolution of dynamic in-situ stress and fracture propagation during multi-cycle water huff-and-puff.The research findings indicate that:(1)Prolonged depletion development of horizontal well results in a reduction of principal horizontal stresses near the wellbore and an increase in principal stress difference;(2)By the end of the water injection period in the first cycle,the principal horizontal stresses increase and the principal stress difference decreases.As the number of cycles increases,the principal horizontal stresses decrease at the end of each water injection period,while the principal stress difference increases,with a maximum directional deviation of 10°to 30°of principal stresses;(3)The water injection period extends the fractures and generates branch fractures,and the extent of fracture propagation decreases with each cycle,stabilizing in morphology after three cycles.These results provide valuable guidance for optimizing water huff-and-puff schemes and transforming development strategies in tight oil reservoirs.

关 键 词：岩石力学 致密油藏 多轮次注水吞吐 非线性渗流 渗流-应力-裂缝扩展耦合 地应力演化 复杂裂缝扩展 

分 类 号：TU45[建筑科学—岩土工程]