重复压裂转向机制流-固耦合分析  

Fluid-solid coupling analysis of reorientation mechanism of refracturing

作　　者：岳迎春[1,2] 郭建春[1] 

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,成都610500 [2]中石化西南石油局井下作业公司,四川德阳618000

出　　处：《岩土力学》2012年第10期3189-3193,共5页Rock and Soil Mechanics

摘　　要：重复压裂已成为油田老井挖潜、稳产增产的重要技术手段,而地应力转向机制与压裂时机选择一直是制约该技术增产效果的关键问题。对ABAQUS有限元软件平台进行了二次开发,考虑储层孔隙度和渗透性随岩石体积应变的动态演化,实现了流体压力变化与岩石物性参数的全面耦合,并分析了重复压裂转向机制。结果表明,地应力转向现象普遍存在,人工裂缝对地应力的影响范围有限,而孔隙压力变化是造成地应力转向的主要因素;随着生产的持续进行,地层压力下降变缓,岩石体积应变变化趋缓,导致渗透率下降趋于平稳,应力转向距离逐渐增大并最终趋稳;应力差越大、应力转向距离越小,越难形成重复压裂转向裂缝。其研究结果实现了流-固耦合作用下地应力转向的可视化描述,直观地模拟结果有利于指导重复压裂的应用实施。The refracturing technology has become an important means to develop the potential of old wells and stabilize or increase the production in oil field,while the reorientation mechanism and fracturing time are the key issues of restraining the stimulation effects of refracturing.This article makes the secondary development of ABAQUS finite element software platform,considers the dynamic evolution of rock porosity and permeability with the volumetric strain,achieves the overall coupling of fluid pressure change and physical property parameters,and makes the fluid-solid coupling analysis of reorientation mechanism of refracturing.The results show that stress reorientation phenomenon is common;the impact range of artificial fracture on the stress is limited which is not enough to form reorientation fracture;and the change of pore pressure is the major factor affecting stress direction;with the continuing progress of production,formation pressure and pore volume decrease,the change of volumetric strain of rock becomes slow,which makes the permeability decreases to a stable value;and the distance of stress reorientation increases and eventually turns to be stable finally;the greater stress differences,the more difficult the reorientation fracture forms because of little stress reorientation distance.This article realizes the visual depiction of stress reorientation in the condition of fluid-solid coupling;and the visual simulation is benefit for guiding the application and implementation of refracturing.

关 键 词：重复压裂 应力转向 流-固耦合 有限元 

分 类 号：TE357.1[石油与天然气工程—油气田开发工程]