Prediction method of brittle mineral index based on compressional and shear wave velocity

Abstract

An embodiment of the invention discloses a brittle mineral index prediction method based on longitudinal and transverse wave velocities. The method comprises steps as follows: a Wyllie longitudinal wave velocity solution equation expressed with a two-term equation is changed into a longitudinal wave velocity solution equation expressed with three terms; the fluid transmission part of the Wyllie equation expressed with three terms is removed, and the Wyllie equation expressed with three terms is simplified into a Wyllie equation of the transverse wave part; a brittle mineral index prediction equation based on the longitudinal and transverse wave velocities is obtained according to obtained physical elastic parameters of rock; basic data required for an application are acquired, the acquired data are substituted into the brittle mineral index prediction equation based on the longitudinal and transverse wave velocities, and brittle mineral index data of a single well or volume data are obtained. The brittle mineral index prediction method based on the longitudinal and transverse wave velocities can be applied to earthquake data with higher longitudinal and transverse resolutions, the distribution condition of longitudinal and transverse mineral indexes of the underground shale gas reservoir is obtained, the prediction accuracy of the brittle mineral indexes of the reservoir is improved, and the effects of reducing the exploration and development risk and reducing the exploration and development cost are achieved.

Description

technical field [0001] The invention relates to the technical field of shale gas exploitation, in particular to a brittle mineral index prediction method based on the velocity of compressional and shear waves. Background technique [0002] Shale gas is a kind of natural gas that occurs mainly in free and adsorbed forms in organic-rich shale intervals, and is an unconventional resource. China has abundant reserves of shale gas, and its technically recoverable resources are estimated to reach 30 trillion cubic meters, far exceeding the 18.83 trillion cubic meters of the United States. Although China's technologically exploited resources far exceed that of the United States, the current shale gas production in China is far behind that of the United States. In 2015, the shale gas production in the United States exceeded 4200×10 8 cubic meters, accounting for about 50% of the total natural gas production in the United States, while China's shale gas production is only 44.6×10 8...

AI Technical Summary

Problems solved by technology

[0008] In the existing technology, due to the lack of reliable basis for the application of mineral index method and fitting method, it is difficult to eliminate users' doubts about the results, and the scope of promotion is limited. Seismic data with high vertical and horizontal resolution are used; only qualitative guidance can be provided for areas without wells, with low prediction error and high risk; and the elastic parameter method is a method that can use seismic data with high resolution to conduct large-scale However, the current elastic parameters also have certain deficiencies, which are mainly manifested in two points: ① The formation of the prediction method is also formed through experience or fitting methods, which lacks geological significance; ② The prediction accuracy of the method is often not high in practical applications

These deficiencies will bring greater risks to exploration and development

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