Shale gas reservoir stratum minimum closing pressure evaluation method based on logging and seismic data

Abstract

The invention relates to a shale gas reservoir stratum minimum closing pressure evaluation method based on logging and seismic data. According to the method, a rock physical model of a shale gas reservoir stratum is built, the Lame coefficient of rocks when different mineral constituents are included is predicted, and then the parameter of minimum stress needed by rupture of the rocks is computed and obtained; on the basis of the parameter, an interpretation chart capable of visually reflecting the relation among the parameter, the Lame coefficient representing the different mineral constituents, and a minimum closing pressure coefficient of the mineral constituents can be obtained, measured logging data or the flexible seismic data obtained through prestack inversion are led into the interpretation chart, the minimum closing pressure of the shale gas reservoir stratum is evaluated quantitatively, and the position with the small value of the minimum closing pressure coefficient serves as a high-quality shale gas reservoir stratum suitable for project fracture. The minimum closing pressure of the reservoir stratum can be evaluated through the logging data or the seismic data without obtaining structure coefficients and pore pressure parameters, and the high-quality shale gas reservoir stratum is selected according to the minimum closing pressure.

Description

technical field [0001] The invention relates to a method for evaluating the minimum closure pressure of a shale gas reservoir, in particular to a method for evaluating the minimum closure pressure of a shale gas reservoir based on well logging and seismic data. Background technique [0002] For shale gas reservoirs, since fracturing directly affects gas production, the prediction and evaluation of underground stress parameters determine whether fracturing can be successful. These parameters specifically refer to the maximum horizontal principal stress, the minimum horizontal principal stress, and the minimum closure Pressure, among which the minimum closure pressure is particularly important, which represents the minimum force required for formation cracking. Therefore, it is very important to evaluate reservoir stress by logging and seismic methods in the development of shale gas reservoirs. In well logging, some stress evaluation models, such as the Huang Rongzun model, c...

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Problems solved by technology

However, to use these methods, some underground reservoir parameters must be known, such as the structural items (or called structural coefficients) that must reflect the structural effects in the stress method, and pore pressure, due to cost constraints or technical limitations , these parameters are often unavailable or cannot be accurately obtained, resulting in the inability to obtain the in-situ stress parameters

Moreover, due to the heterogeneity of the formation itself, this method can only be used for single well evaluation, and cannot be realized in seismic data.

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