Accurate information of in-situ stresses is critical to all deep underground engineering. Unlike the vertical stress and minimum horizontal stress, the maximum horizontal stress cannot be directly measured, instead it must be inferred from other measurements. One widely used method is to inversely compute the maximum horizontal stress from borehole breakout angle revealed by caliper log or borehole televiewer. However, theoretical derivation and numerical modeling indicate that the accuracy of the existing equation computing the maximum horizontal stress from borehole breakout needs to be improved for both impermeable and permeable boreholes and formations. The refined equations are proposed and verified in this technical note.

准确的现场应力信息对于所有深层地下工程至关重要。与垂直应力和最小水平应力不同，最大水平应力不能直接测量，而必须从其他测量值中推断出来。一种广泛使用的方法是根据井径测井仪或井眼望远镜所显示的井眼破裂角反算最大水平应力。但是，理论推导和数值模型表明，对于不渗透性和可渗透性的井眼和地层，计算来自井眼破裂的最大水平应力的现有方程式的精度都需要提高。在本技术说明中提出并验证了改进的方程式。