陆相页岩储层横观各向同性地应力测井预测——以新疆MH凹陷F组陆相页岩油储层为例

Research on in-situ stress logging prediction of transversely isotropic continental shale reservoir:Case study of the F Formation continental shale oil reservoir in MH Sag,Xinjiang

以新疆MH凹陷F组陆相页岩油储层为研究对象,开展了不同角度岩样声波波速测试以及单三轴压缩测试,分析并计算了研究区页岩油储层地层压力及构造应变系数,对比了使用均质体地应力模型(黄氏模型及组合弹簧模型)与横观各向同性地应力模型计算水平地应力效果。结果表明:0°、45°及90°方向岩样声波波速差异明显,体现出较强的各向异性特征;岩样破坏形态以脆性破坏为主,90°方向岩样抗压强度、弹性模量以及泊松比明显大于0°方向岩样力学参数值;横观各向同性地应力模型计算水平最小、最大地应力结果与实测地应力相对误差仅为1.79%、5.00%,相对于均质地层的组合弹簧模型和黄氏模型而言精度更高。因此,使用横观各向同性地应力模型计算陆相页岩油储层地应力有更好的效果,对于压裂层段优选、钻井安全钻进等均具有重要意义。

Taking the F formation continental shale oil reservoir in MH Sag,Xinjiang as the research object,acoustic wave velocity test and triaxial compression test of rock samples from different angles were carried out.The formation pressure and structural strain coefficient of shale oil reservoir in the study area were analyzed and calculated,and the effect of using homogeneous in-situ stress model(Huang’s model and combined spring model) and transverse isotropic in-situ stress model to calculate horizontal geostress was compared. The results showed that the acoustic wave velocity of the rock samples in the direction of 0°,45° and 90° was obviously different,showing strong anisotropy. The main failure mode of rock sample was brittle failure,and the compressive strength,Young’s modulus and Poisson’s ratio of rock samples in the direction of 90° were significantly greater than the mechanical parameters of rock samples in the direction of 0°. The relative errors of the minimum and maximum horizontal stress calculated by the transverse isotropic model was only 1.79% and 5.00%,respectively,which were more accurate than the combined spring model and Huang’s model. Therefore,using the transverse isotropic in-situ stress model to calculate the in-situ stress of continental shale oil reservoir had a better effect.