鄂尔多斯临兴西区深煤层地应力场特征及应力变化分析

大小及方向对深部煤层气开发影响显著。以鄂尔多斯东缘临兴西区为对象， 基于实 验测试、井壁崩落法和断层摩擦系数地应力法，分析了三向主应力方向与大小，阐释了基本特征及其空间发育规律。结果显示：8号煤层垂向应力介于44.94 ~ 50.46 MPa，平均48.47MPa；水平最大主应力介于35.16 ~ 44.53 MPa，平均40.62MPa；水平最小主应力介于28.79~39.45 MPa，平均33.02MPa。9号煤层垂向应力介于45.03~ 50.46 MPa，平均48.57MPa；水平最大主应力介于35.33~44.53 MPa，平均40.69MPa；水平最小主应力介于29.01 ~ 39.45 MPa，平均33.11MPa。误差分析显示此地应力计算结果可靠。三向地应力大小与埋深呈正相关关系。在垂向上，三向地应力相对大小表现出明显分带性，即埋深＜1000m左右为Sh＜Sv＜SH为特征的剪切型地应力带、埋深介于1000~1800m 表现为Sh＜SH＜Sv过渡带、埋深>1800m左右表现为Sh＜SH＜Sv为特征的正断型地应力带。在平面上，地应力在平面上总体呈西北部低、中部与南部高、其余地区适中，主要在T-23-2井和T-19井区存在应力低值带。最大水平主应力地应力方向主要以EW-NEE向为主。地应力场的阐释将为研究区深煤层储层物性评价、勘探选区及钻完井工程设计提供地质参考。

Characteristics of the in-situ stress field and stress change of deep coal seams in the western Linxing area, Ordos

The magnitude and direction of crustal stress have a significant impact on the development of deep coalbed methane. This work measured these two parameters in the western Linxing area, Ordos. It was based on experimental tests, the borehole caving method and the fault friction coefficient method. The direction and size of the three principal stresses were analyzed, and the basic characteristics and spatial development laws were explained. The results show that the vertical stress of No.8 coal seam is between 44.94 to 50.46 MPa, with an average of 48.47 MPa; the maximum horizontal principal stress is between 35.16 to 44.53 MPa, with an average of 40.62 MPa; and the minimum horizontal principal stress is between 28.79 to 39.45 MPa, with an average of 33.02 MPa. The vertical stress of No.9 coal seam is between 45.03 ~ 50.46 MPa, with an average of 48.57 MPa; its maximum horizontal principal stress is between 35.33 ~ 44.53 MPa, with an average of 40.69 MPa; and the minimum horizontal principal stress is between 29.01 ~ 39.45 MPa, with an average of 33.11 MPa. The error analysis shows that the stress calculation results are reliable. The magnitude of the crustal stress is positively correlated with the buried depth. In the vertical direction, the relative magnitude of the three principal stresses shows obvious zoning, that is, the shear-type stress zone characterized by Sh1800 m represent a normal fault stress zone characterized by Sh