基于断裂过程区的压裂驱油水力裂缝扩展模型及应用  

A hydraulic fracture extension model for fracturing and enhanced oil recovery considering the influence of the fracture process zone and its application

作　　者：曹虎 张广清[1,2] 李世远[1,2] 汪文瑞 谢彭旭 孙伟 李帅[1] CAO Hu;ZHANG Guang-qing;LI Shi-yuan;WANG Wen-rui;XIE Peng-xu;SUN Wei;LI Shuai(College of Petroleum Engineering,China University of Petroleum(Beijing),Beijing 102249,China;State Key Laboratory of Petroleum Resources and Engineering,China University of Petroleum(Beijing),Beijing 102249,China)

机构地区：[1]中国石油大学(北京)石油工程学院,北京102249 [2]中国石油大学(北京)油气资源与工程全国重点实验室,北京102249

出　　处：《岩土力学》2025年第3期798-810,共13页Rock and Soil Mechanics

基　　金：国家杰出青年科学基金(No.51925405);国家自然科学基金面上项目(No.52174011)。

摘　　要：压驱技术被用于解决低渗透油藏能量补充困难的工程问题,其中压驱施工压力是影响储层注水能力的关键参数。为确定合适的压驱施工压力,开展了基于过程区的压驱水力裂缝扩展临界压力研究。首先,结合弹性力学和弹塑性断裂力学,建立水力裂缝扩展稳定性判定模型,该模型考虑了过程区和井筒应力集中对裂缝尖端应力强度因子的影响。其次,设计可视化压驱试验研究压驱裂缝演化规律并验证模型的可靠性。最后,基于理论模型和试验压力曲线,确定压驱施工压力的上下限。结果表明,裂缝扩展有稳态扩展和非稳态扩展两种模式,受裂缝扩展的动力和阻力控制。破裂点前,压驱裂缝经历多个稳态和非稳态扩展阶段。压驱施工压力的下限为注入压力曲线斜率变小的拐点,该点是裂缝第1个稳态扩展阶段的起点,也是注入能力由降转升的起点;压驱施工压力上限对应的裂缝尖端应力强度因子等于0.05 MPa·m^(0.5),该点略高于破裂前最后一个裂缝稳定扩展阶段的终点,是注入能力的极大值点。该研究可为压驱施工参数优化提供理论支持。Pressure-driven fracturing technology has been applied to address the challenge of energy replenishment in low-permeability reservoirs.The operating pressure during fracturing-enhanced flooding is a key parameter that influences the water injection capacity of the reservoir.To determine the appropriate operating pressure,a study on the critical pressure for hydraulic fracture extension based on the fracture process zone(FPZ)was conducted.Firstly,a model for assessing the stability of hydraulic fracture extension was established using elastic mechanics and elastic-plastic fracture mechanics,taking into account the influence of the FPZ and wellbore stress concentration on the stress intensity factor at the fracture tip.Secondly,visual experiments on fracturing-enhanced flooding were designed to investigate the evolution of fractures and validate the reliability of the model.Finally,based on the theoretical model and the injection pressure curve,the upper and lower limits of the operating pressure for fracturing-enhanced flooding were determined.The results indicate that there are two modes of fracture extension:steady-state and non-steady-state,which are governed by the driving and resisting forces of fracture extension.Before the breakdown point,the fractures undergo multiple stages of steady-state and non-steady-state extension.The lower limit of the operating pressure is the turning point where the slope of the injection pressure curve decreases,marking the onset of an increase in injection capacity after a period of decline.The upper limit of the operating pressure corresponds to a stress intensity factor at the fracture tip of 0.05 MPa·m^(0.5),which is slightly higher than the endpoint of the last stable fracture extension stage before breakdown and represents the maximum injection capacity.This study provides theoretical support for optimizing the operating parameters of fracturing-enhanced flooding.

关 键 词：压裂驱油 裂缝扩展的稳定性分析 数字图像法 断裂过程区 

分 类 号：TE348[石油与天然气工程—油气田开发工程]