Shale formation pore pressure calculation method based on double correction

Abstract

The invention discloses a shale formation pore pressure calculation method based on double correction. The method comprises the steps of (1) preparing data such as a rock core; (2) drilling and drying a rock sample, and measuring density, resistivity and interval transit time; (3) soaking in the drilling fluid, measuring, and solving the change quantity of the three parameters; obtaining the resistivity variation through dual lateral resistivity logging; (4) obtaining a relational expression between the interval transit time and the organic carbon content of the organic carbon rock samples with different contents, and solving an interval transit time limit value when the organic carbon content tends to 0; obtaining a difference value between the interval transit time of the rock sample and a limit value, and obtaining a relational expression between the difference value and the organic carbon content; obtaining the interval transit time after hydration correction and organic matter correction; and (5) constructing a compaction trend curve based on the corrected interval transit time, solving compaction correction coefficients c of different pressure test points, and establishing a relationship between the compaction correction coefficients c and the depth. The formation pore pressure calculated by the method is closer to the original formation state, and the prediction precision is improved.

Description

technical field [0001] The invention belongs to the technical field of petroleum 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 terms of pressure prediction. With the increase of energy demand, unconventional shale oil and gas reservoirs have received mo...

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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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