塔里木盆地塔中地区上奥陶统古构造应力场模拟与裂缝分布预测

塔里木盆地塔中地区上奥陶统良里塔格组碳酸盐岩构造裂缝是区内油气显示十分活跃的有效储集空间，其发育和分布主要受古构造应力场的控制。依据塔中地区上奥陶统地震资料的断裂构造解释和钻井、测井裂缝特征分析等成果，在声发射地应力测量、岩石力学参数和单轴抗拉强度测试的基础上，考虑断裂对裂缝形成的影响，采用三维有限元法对塔中地区上奥陶统加里东中期Ⅱ幕裂缝形成期的古构造应力场进行了数值模拟，预测了裂缝的分布。结果表明，裂缝形成期地应力最大主应力有效值为47.9～58.3MPa,平均值为51.97MPa，抗张强度为5.13～6.91MPa，平均值为5.81MPa。有效张应力的高值区是构造裂缝发育的有利地区，主要分布在塔中东部大的断裂带交会处和断裂带的部分区段内，与实际钻井统计的上奥陶统高裂缝线密度和油气井分布区基本吻合，可以为研究区的油气勘探提供新的地质依据。

Upper Ordovician paleo tectonic stress field simulating and fracture distribution forecasting in Tazhong area of Tarim Basin,Xinjiang, China

The structural fractures in the Upper Ordovician Lianglitage Formation in Tazhong area, which has active hydrocarbon show, is effective reservoir space for hydrocarbon accumulation. Fracture reservoir is controlled by paleo structural stress field. Based on the faults systems interpreted from seismic data, fractures characteristics from drilling and logging data, carbonate reservoirs are studied from acoustic emission, stress measurement, rock mechanics parameters and uniaxial tensile test. Considering the influence of faults on the fracture forming, 3-D finite element method is applied to simulate the period II Middle Caledonian paleo structural stress field in the Tazhong area and predict the distribution of fractures. The simulation result shows that during fracturing the maximum major stress effective value range from 47.9 to 58.3MPa, with average 51.97 MPa, tensile strength ranging from 5.13～6.91MPa, with average 5.81MPa. High value area of effective tensile stress is the favorable area for structural fractured reservoirs development, most distributed in the interchange area of fracturing belts and part section of fractured zone in the east of Tazhong area, coinciding with the Ordovician fracture-developed zone defined by fracture linear density statistic date from actual drilling, which provides new geological evidences for the Lower-Middle Ordovician carbonate rock prospecting and exploitation.