摘要
页岩自支撑裂缝闭合过程对于页岩气井产量有着重要影响,而现有自支撑裂缝闭合数值模拟方法未考虑真实粗糙裂缝形态和岩石塑性变形特征。本文提出了一种基于激光扫描的粗糙裂缝形态三维仿真方法,建立了考虑塑性特征的真实裂缝面接触变形模型,模型平均误差9.4%;在此基础上分析了页岩自支撑裂缝闭合过程中的应力状态、流动通道和残余宽度变化,探究了表面粗糙度、滑移量、力学性质对自支撑裂缝闭合过程的影响规律。结果表明,具备高粗糙度、大滑移量、高杨氏模量特征的自支撑裂缝通常具有较高的残余宽度;针对四川盆地龙马溪组页岩储层,自支撑裂缝在60MPa闭合应力作用下的残余宽度仍保持在0.7mm以上,能够提供一定程度的流动通道和导流能力。
The closure process of unpropped fracture in shale under in situ stress has a significant effect on the eventual well production,but the existing numerical simulation methods of unpropped fracture closure do not consider the real rough surface and plastic deformation of rock.In this paper,a 3 D simulation method based on laser scanning was established to construct the unpropped fracture surface numerically.A contact and deformation model of unpropped fracture was built with the consideration of rough surface and plastic characteristics,and its average error is 9.4%.On this basis,the changes of stress state,flow channel and residual width in the closure process of unpropped fracture are analyzed,and the effects of surface roughness,slippage degree and mechanical properties on the closure process are explored.The results show that unpropped fractures with high roughness,large slippage degree and high Young’s modulus usually possess high residual width.For shale of deep Longmaxi formation in south Sichuan,China,simulation results show that the unpropped fracture retains a residual width higher than 0.7 mm under 60 MPa closure stress,which should serve as considerable flow passages for oil and gas in shale.
作者
卢聪
罗扬
郭建春
黄楚淏
周广清
王建东
刘彦辉
单昕
Lu Cong;Luo Yang;Guo Jianchun;Huang Chuhao;Zhou Guangqing;Wang Jiandong;Liu Yanhui;Shan Xin(State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Southwest Petroleum University,Chengdu 610500;State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Chengdu University of Technology,Chengdu 610059;Oil and Gas Exploration Management Center,Sinopec Shengli Oilfield Company,Dongying 257001)
出处
《中国科学基金》
CSSCI
CSCD
北大核心
2022年第1期137-144,共8页
Bulletin of National Natural Science Foundation of China
基金
国家自然科学基金项目(52022087)的资助。
关键词
页岩
自支撑裂缝
三维仿真
闭合过程
shale
unpropped fracture
3D simulation
closure process
