A hydrocarbon detection factor for detecting a coalbed methane enrichment and high permeability area and an application method thereof

Abstract

The invention provides a hydrocarbon detection factor for detecting a coalbed methane enrichment and high permeability area and a method of using the hydrocarbon detection factor to detect the coalbed methane enrichment and high permeability area. The hydrocarbon detection factor AVO (Amplitude versus Offset) is characterized by difference between an intercept A and a gradient B (A-B), wherein (A-B) =2delta mu / (lambda+2mu)+1delta rho / 2rho. The method comprises the steps of calculating intercepts and the gradients of earthquake return wave amplitude changed along with incident angle and the differences between the intercepts and the gradients (A-B) base on earthquake information; drawing hydrocarbon detection factor exception graphs with (A-B) serving as drawing data, the graphs comprising profile maps, planar graphs, horizon flattening graphs, space charts, and amplitude envelop diagrams; and determining the spacing position of the coalbed methane enrichment and high permeability area according to the graphs. The part with high exceptional strength of (A-B) is the part with high methane content and high permeability and can be judged as the coalbed methane enrichment and high permeability area.

Description

technical field [0001] The invention relates to a hydrocarbon detection factor for detecting coalbed methane-enriched and high-permeability areas and a method for detecting coalbed methane-enriched and high-permeability areas using the hydrocarbon detection factor. Specifically, the invention relates to a method for calculating seismic reflections using seismic data. The intercept and gradient of the change of wave amplitude with the incident angle, and the difference between the intercept and gradient as the hydrocarbon detection factor, is a method for detecting coalbed methane enrichment and high permeability areas. Background technique [0002] Coal bed gas is the gas in the coal seam, and its main component is methane, which is the cause of gas outburst and explosion in coal mines. However, before coal is mined, the gas is extracted, which is natural gas, which is clean energy and is called coal bed methane. According to reports, in China, the United States, Canada, Au...

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Problems solved by technology

There have been attempts to transplant the AVO technology suitable for conventional natural gas exploration and development into coalbed methane exploration and development, but there has been no success recognized by the coalbed methane industry (see Ramos, A.C.B., and Davis, T.L., 1997, "3-D AVO analysis and modeling applied to fracture detection in coalbed methane reservoirs", Geophysics, V.62, p.1683-1695)

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