Apparatus and method for testing shale anisotropy under true triaxial conditions

Abstract

The invention discloses a testing device for the anisotropism of shale in a true-triaxial condition and a testing method of the testing device, and aims at solving the problems that the conventional testing method for the anisotropism of shale needs at least 3 times of coring, and the anisotropism of the shale at true crustal stress state cannot be really reflected. The testing device comprises a pressurization mechanism, an acoustoelectric testing mechanism and a data processing mechanism, wherein the pressurization mechanism can apply different pressures to X, Y and Z directions, so that the stress state of the shale in a formation condition can be more really simulated. The acoustoelectric testing mechanism can measure the sound wave and the specific resistance of the shale when the mechansim forms 0 degrees, 45 degrees and 90 degrees with shale bedding. The acoustic and electrical anisotropisms of the shale can be obtained through measured sound wave and specific resistance information. The testing device has the advantages that rock samples are easy to obtain, the success ratio is high, the measurement result is real and reliable, and a reference base can be provided for the accurate evaluation of the thickness of a container rock, the accurate evaluation of water saturation and the design of a fracturing operation scheme.

Description

Technical field [0001] The invention belongs to the technical field of petroleum exploration, and in particular relates to a shale anisotropy test device and a test method used under true triaxial conditions. Background technique [0002] Shale is a kind of clay rock. Due to the compaction, dehydration, and recrystallization of the clay, it is composed of tiny minerals. The particle size is less than 1 / 256mm. It has a sheet or lamellar shape, strong brittleness, and water permeability. Sex is very poor. Complicated geological structure, deep burial, complex in-situ stress and different maturity are the reasons that make shale strong anisotropy. Accurately evaluating the anisotropy of shale is essential for understanding the thickness and water saturation of shale gas reservoirs, formulating appropriate closing pressures during fracturing operations, forming criss-crossing fracture networks, and determining appropriate safety density windows to ensure that The stability of the w...

AI Technical Summary

Problems solved by technology

However, there are certain deficiencies in the traditional method. First of all, for the first method, at least three samples need to be prepared for the experiment, and the shale is highly brittle, and the clay mineral content is high and easy to hydrate and expand. Water must be used in the coring process, which is easy to cause The shale fractures along the bedding plane, and it is difficult to obtain rock samples that are 45° from the shale bedding, making it difficult to carry out experiments

Shale has strong heterogeneity, and the three samples will have certain differences in mineral composition and rock mechanical properties, resulting in the obtained shale anisotropy that cannot truly reflect the properties of the rock

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