A calculation method of shale formation pore pressure based on double correction

Abstract

A method for calculating pore pressure of mud shale formations based on double correction, (1) preparing data such as cores; (2) drilling, drying, measuring density, resistivity and acoustic time difference of rock samples; (3) soaking in drilling fluid, Measure and obtain the change of three parameters; obtain the change of resistivity through double lateral resistivity logging; (4) obtain the relationship between the acoustic time difference and the content of organic carbon of different contents of organic carbon rock samples, and obtain the organic carbon content The limit value of the sonic time difference when the content tends to 0; the difference between the rock sample sonic time difference and the limit value is obtained, and the relationship between the difference and the organic carbon content is obtained; the sonic time difference after hydration correction and organic matter correction is obtained, (5 ) Construct the compaction trend curve based on the corrected acoustic time difference, obtain the compaction correction coefficient c of different pressure test points, and establish its relationship with the depth. The formation pore pressure calculated by the invention is closer to the original formation state, and the prediction accuracy is improved.

Description

technical field [0001] The invention belongs to the technical field of oil drilling, and in particular relates to a method for calculating the pore pressure of mud shale formations based on double correction. Background technique [0002] Reservoir geomechanics refers to various geomechanical problems encountered in reservoir development, generally involving parameters such as rock mechanics, pore pressure, and in-situ stress, among which pore pressure has an important impact on wellbore stability and fracturing stimulation. In terms of reservoir pore pressure prediction, it can be mainly divided into three categories: equivalent depth method and Eaton method based on undercompaction theory, Bowers and effective stress method based on effective stress theory, and comprehensive interpretation method. There is a certain degree of adaptability in stress prediction. With the increase in energy demand, unconventional shale oil and gas reservoirs have received more and more atten...

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Problems solved by technology

[0003] Therefore, during the drilling process of shale oil and gas reservoirs, it will be affected by organic matter and hydration, and the conventional porosity calculation method cannot be directly applied.

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