摘要
在微地震监测过程中,压裂区域的应力状态对于水力压裂的效果有着不可忽视的影响,但是由于压裂区域裂缝形态交错,应力场较为复杂,往往很难有效地获取较为准确的应力状态。本文将探究应力场的复杂程度对于应力反演的影响,通过数值模拟均一应力场条件下和复杂应力场条件下的震源机制解,利用Vavry?uk的迭代联合反演方法进行应力反演,并对反演结果进行误差分析。发现均一应力场作用下震源机制的不确定性对于求解应力模型的影响不大,但是会对滑动方向的误差统计带来一定程度的影响;在复杂应力场的条件下进行应力反演,滑动方向的误差值会随着应力场复杂程度的增加而增大,并且比震源机制的不确定性造成的误差值大得多。此外,当应力场的复杂程度增加到一定水平时,反演得到的单一应力模型将使得相当一部分断层面无法满足摩尔—库伦破裂准则,这种反演结果是不可取的。本文还选择了与数值实验有相似特征的两组实际数据,大庆油田某压裂井和长宁区块的某压裂井监测数据,分别进行应力反演和误差分析,用以验证上述结论。
The regional stress state impacts on the effectiveness of microseismic monitoring of hydrofracturing. But the ideal stress state in the fracturing region is difficult to obtain because of the interlaced distribution form of fractures and complex stress fields. In this paper, the object is to study the impact of complexity of stress field on stress inversion. We first numerically simulate two series of focal mechanisms in a homogeneous stress field and a complex stress field, and then implement stress inversion by utilizing Vavry?uk’s iterative joint inversion method and do the error analysis. The results indicate that the uncertainty of focal mechanisms in homogeneous stress field has a slight influence on acquiring a stress model, but does impact on the error statistics of the slip direction. Also the slip deviation increases as the complexity of the stress field rises and the error is much bigger than that caused by uncertainty of focal mechanisms when stress inversion is in a complex stress field. In addition, part of the fault planes cannot meet the Mohr-Coulomb failure criterion with the condition of a single stress model inverted as the complexity of stress field reaches a high level, which means the inversion result is desirable. Two series of actual field data in the Daqing oil field and the Changning Block are chosen in this paper. These agree well with the numerical simulation and are applied to stress inversion and error analysis to verify the conclusions above.
作者
陈筱青
王润秋
江勇勇
黄炜霖
储仿东
尹陈
CHEN Xiaoqing;WANG Runqiu;JIANG Yongyong;HUANG Weilin;CHU Fangdong;YIN Chen(State Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum-Beijing,Beijing 102249,China;Bureau of Geophysical Prospecting INC.,CNPC,Zhuozhou 072751,China;Chuanqing Drilling Engineering Company Limited,CNPC,Chengdu 610051,China)
出处
《石油科学通报》
2019年第1期27-40,共14页
Petroleum Science Bulletin
基金
国家科技重大专项"水力压裂实时监测与地质工程一体化评估技术"项目(2016ZX05023004)资助
关键词
微地震监测
水力压裂
应力反演
均一应力场
复杂应力场
microseismic monitoring
hydrofracturi ng
stress in version
homoge neous stress field
complex stress field