Well wall stability simulation method and device based on joint surface roughness

Abstract

The invention discloses a well wall stability simulation method and device based on joint surface roughness, and the method comprises the steps: carrying out the three-dimensional contour scanning of a joint surface, obtaining the parameters of the joint surface, and calculating the roughness of the joint surface; the joint surface is obtained by cutting the rock sample according to a preset fluctuation angle; calculating rock mechanical parameters of the rock sample according to the normal stress and the tangential stress of the rock sample obtained by the shear test; calculating rock physical property parameters of the rock sample according to the axial stress, the axial strain and the radial strain of the rock sample obtained by the rock mechanics triaxial experiment; according to the roughness of the joint surface, the rock mechanical parameters, the rock physical property parameters and fluid parameters obtained through a fluid experiment, a borehole wall stability model is established; cutting the rock sample for multiple times by changing the number of fluctuating angles and / or joint surfaces to obtain a plurality of well wall roughness; and inputting the plurality of well wall roughness into a well wall stability model to obtain a plurality of well wall rock displacements, and judging whether the well wall stability model is stable or not, so that the accuracy of well wall stability judgment can be improved.

Description

technical field [0001] The invention relates to the technical field of unconventional drilling engineering, in particular to a well wall stability simulation method and device based on joint surface roughness. Background technique [0002] This section is intended to provide a background or context to embodiments of the invention that are recited in the claims. The descriptions herein are not admitted to be prior art by inclusion in this section. [0003] Wellbore stability is a key issue to be considered in the drilling and completion process. Due to the existence of natural joint surfaces in shale gas reservoirs, slippage is prone to occur during drilling, and drilling accidents such as stuck pipe are caused by falling blocks. Deal with stuck pipe accidents Increase drilling cycle, reduce drilling efficiency and increase drilling cost. Through pre-drilling simulation analysis, it is possible to calculate the amount of rock slippage at the borehole wall, determine whether...

AI Technical Summary

Problems solved by technology

Among them, the laboratory simulation method uses large-scale equipment in the laboratory to create complex downhole conditions, and then simulates the downhole stress field to obtain the change in the wellbore radius during the drilling process. This method is relatively expensive, and laboratory simulation can only be done to part close to site conditions and are for reference only

The finite element prediction method is to obtain the rock mechanics parameters through the previous rock mechanics experiments, and bring the rock mechanics parameters into the established model, but it cannot simulate the instability of the borehole wall containing the joint surface

Images