Method for predicting pore pressure of carbonate rock stratum

Abstract

The invention provides a method for predicting pore pressure of a carbonate rock stratum. The method comprises the following steps of firstly, carrying out a rock physical simulation experiment on a rock sample; then utilizing a Voigt-Reuss-Hill average modulus model for calculating the volume modulus of a rock matrix; calculating the volume modulus of a pore fluid by utilizing a Wood model and aPatch model; and calculating the volume modulus of a rock framework according to a rock physical simulation experiment fitting relational expression, and further calculating the pore pressure of the carbonate rock stratum. The beneficial effects of the invention are that: the technical scheme provided by the invention is based on a fluid-containing rock porous elastic mechanical theory and a generalized fenugreek law; starting from analysis of the carbonate rock stratum stress-strain pore pressure constitutive relation, a porous elastic mechanical pore pressure prediction theoretical model forrepresenting the quantitative relation between the pore pressure and the rock elastic parameter is established, so that the problem that the pore pressure is difficult to predict due to the fact thatthe carbonate rock is compact in lithology and extremely uneven is solved, and the method has industrial application value.

Description

technical field [0001] The invention relates to the field of geological exploration, in particular to a method for predicting pore pressure in carbonate formations. Background technique [0002] Prediction of pore pressure in carbonate rock formation is an unresolved research problem at home and abroad. In the past, the widely used and effective empirical methods for the prediction of abnormally high pressure in clastic rock formations include: the equivalent depth method using porosity and acoustic logging data, the Eaton( 1972) formula method, using the Fillippone (1979) formula method of seismic layer velocity, the Eberhart-Phillips model (1989) and Bowers model (1989) and Bowers model ( 1995) etc. These methods are based on Terzaghi's effective stress theory, and realize the quantitative evaluation of clastic rock formation pore pressure by establishing the empirical relationship between pore pressure and different response parameters. However, these methods are not s...

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Problems solved by technology

[0003] In a word, the lithology and physical properties of the present-day carbonate rock strata are the result of the superimposition of various types of diagenesis and multiple chemical reactions in the process of underground and surface processes, resulting in the heterogeneity of the lithology and physical properties of the carbonate rock strata. Therefore, there is almost no regular change in the vertical direction of the carbonate rock formation, and it is difficult to establish logging and seismic response parameters that reflect the change of Terzaghi effective stress. Therefore, the prediction of carbonate rock overpressure has always been a difficult problem in domestic and foreign research.

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