EARTH CRUST STRESS MEASUREMENT METHOD

摘要

PROBLEM TO BE SOLVED: To exactly measure a three-dimensional stress element acting on a ground which constitutes an earth crust.;SOLUTION: An earth crust stress measurement method measures: a length of a diameter (D _max) in which deformation under a standard circle diameter of a virtual measurement cross section is the largest and the length of the diameter (D _min) in which the deformation under the standard circuit diameter is the shortest from the shape of the measurement cross-section set in a direction orthogonal to a longitudinal direction of a boring core BC 1 acquired by cutting out an earth crust in a drilling direction of a wellbore 1. A length of a diameter (D1|φ₌₀)in a vertical direction of the measurement cross-section and a length of a diameter (D1|_φ=90)in the horizontal direction are measured from the shape of the measurement cross-section set in a direction orthogonal to a longitudinal direction of a side wall core SC 1 acquired by cutting out the earth curst from an inner side surface of the wellbore 1 in a direction different from a wellbore 1. The maximum horizontal stress and the minimum horizontal stress among three-dimensional elements are obtained from a formula representing difference stress between the maximum horizontal stress and the minimum horizontal stress acting on the earth crust and the formula representing the difference stress between the horizontal stress orthogonal to the longitudinal direction of the side wall core SC 1 and vertical stress.;SELECTED DRAWING: Figure 4;COPYRIGHT: (C)2018,JPO&INPIT