塔中地区新近纪构造作用下寒武系应力场模拟与裂缝预测

根据塔中地区地震资料解释的断裂体系、上下寒武统顶底界面构造图和6 口钻井裂缝特征等资料, 在对塔中地区寒武系岩石力学进行测试的基础上, 考虑断裂对裂缝形成的影响, 采用三维有限元法对新近纪构造作用下塔中地区寒武系的构造应力场进行模拟, 并将模拟结果与塔中地区钻井统计的构造裂缝面密度进行匹配, 得到塔里木盆地寒武系的构造裂缝发育分布情况。结果显示: 断裂对裂缝的影响明显, 靠近断层或位于断层交汇处的构造裂缝发育, 裂缝在断层的一盘发育, 在另一盘则相对不发育; 膏岩层对构造应力的传播有一定程度的阻碍作用, 盐上的寒武系上统较盐下的寒武系下统构造裂缝发育, 盐间的中寒武统构造裂缝则相对不发育。

Structural Stress Field Simulation for Upper-Middle-Lower Cambrian in Tazhong Area and Forecast of the Fracture

Based on the fracture systems interpreted from seismic data, tectonic map of bottom and top surface of upper-lower Cambrian and cores fracture parameters statistics from 6 wells, the Cambrian dolomite reservoirs in Tazhong area were studied from analysis of rock mechanics parameters test. Considering the influence of faults on the fracture forming, 3D finite element method was applied to simulate structural stress field of the Cambrian in Tazhong area, and then match the simulation results with the fractures density of the 6 wells, the distribution of the fractures in the upper-middle-lower Cambrian is obtained. The results show that the effect of faults on fractures is obvious, for example, fractures which sit near faults or at the junction of the faults are relative development, and also that fractures in a dish of fault development, while in another dish less development. Paste layers hinder the spread of the tectonic stress, for example, fractures in the upper Cambrian (over salt) are more development than in the lower Cambrian (below slat) while in the middle Cambrian (between salt) are less development.