A three-dimensional in-situ stress determination method based on borehole wall displacement measurement

Abstract

The invention discloses a method for determining the three-dimensional ground stress based on the displacement measurement of the borehole wall. The measuring points are arranged in the hole section in a quincunx-shaped arrangement, and the angle between different test points between the drilling axes; C. The displacement test equipment is approached to the test point in the radial direction and pierces the mud layer of the hole wall, and the core drill bit is used along the Carry out circular cutting around the displacement measuring equipment in the radial direction, and transmit it to the ground in real time through the cable, and the stress relief is completed; D. After the strain relief operation is completed, the drilled core is broken by the core bit and stored on the ground; E. After the test work of all test points is completed, the side wall coring device is recovered and the core is taken out to obtain the three-dimensional ground stress of the test point. The method is easy to operate and easy to operate. The displacement components in different directions are obtained, and the relationship between the displacement of the hole wall and the far field stress is established to obtain the ground stress component at the measuring point.

Description

technical field [0001] The invention belongs to the technical field of rock and soil mechanics measurement, and more specifically relates to a method for determining three-dimensional ground stress in deep underground rock formations, which is suitable for estimating the three-dimensional ground stress state of rock mass from local deformation data of hole walls in deep boreholes. Background technique [0002] Crustal stress state is one of the essential data for dealing with deep rock mass problems in civil engineering, mining energy engineering and other fields. In civil engineering, the high ground stress state of deep rock mass will induce rock mass damage, collapse or burst after being disturbed by engineering. In the nuclear waste treatment project, the rock mass with high ground stress and good integrity is denser and has lower permeability, which helps to block the migration of pollutants. In the exploration and development of unconventional oil and gas resources, i...

AI Technical Summary

Problems solved by technology

Strain rosette measurement is used in the strain relief method. There are often thick mud and rock debris on the hole wall, and it is very difficult to stick the strain rosette. In addition, general electronic components often fail in this environment, and the ground stress parameters cannot be obtained correctly.

[0006] 3. The traditional stress relief method needs to obtain the elastic modulus and Poisson's ratio of the rock mass through supplementary laboratory tests

However, due to the particularity of deep drilling construction, it is generally difficult to obtain the core at the test point, and the rock mass elastic parameters obtained by other indirect methods are often inaccurate

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