Geophysical quantitative prediction method for gas content of shale reservoir

Abstract

The invention discloses a geophysical quantitative prediction method for the gas content of a shale reservoir, comprising the following steps: (1) acquiring geological parameters of a shale reservoirin a target work area, the geological parameters comprising porosity and total organic carbon content; (2) acquiring rock physical parameters of a to-be-measured shale reservoir, the rock physical parameters comprising longitudinal wave impedance and density; (3) establishing a shale reservoir gas content prediction model according to the acquired geological parameters and rock physical parametersof the shale reservoir in the target work area; (4) based on seismic pre-stack simultaneous inversion, acquiring a longitudinal wave impedance data volume and a density data volume through professional software; and (5) substituting the longitudinal wave impedance Ip data volume and the density rho data volume obtained into the prediction model to obtain a total gas content prediction value of the to-be-measured shale reservoir. The prediction result conforms to geological facts. The method has the advantages of being accurate and reliable in gas content quantitative prediction result, has awide range of applications, and can be directly used in shale gas exploration and development decisions.

Description

technical field [0001] The invention relates to natural gas exploration technology, in particular to a geophysical quantitative prediction method for gas content in mud shale reservoirs. Background technique [0002] Shale gas is an unconventional natural gas resource that has attracted widespread attention in recent years. It mainly occurs in dark organic matter shale in free and adsorbed states. Free shale gas is mainly distributed in the pores or fractures of shale reservoirs, while adsorbed shale gas is mainly attached to organic matter. The gas content of shale reservoirs is an important parameter for shale gas area selection evaluation and shale gas productivity evaluation, and has important practical significance for shale gas exploration and development. [0003] The methods for predicting the gas content of shale reservoirs mainly include in-situ analytical test method, isothermal adsorption test method, logging interpretation method, earthquake prediction method a...

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Problems solved by technology

Moreover, the existing seismic prediction methods for shale gas content generally do not distinguish free gas from adsorbed gas. Only a patent with application number 201610796174.2 under substantive examination has published a method for the free gas content of shale gas. method of prediction

Therefore, the shale gas content obtained by existing methods generally faces problems such as small calculated values, large errors, or insufficient regional coverage, which brings a certain degree of uncertainty to objectively guide the practice of shale gas exploration and development.

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