Earthquake prediction method for porosity and shale content of sand shale reservoir

Abstract

The invention discloses an earthquake prediction method for porosity and shale content of a sand shale reservoir. The method comprises steps as follows: measuring test data of a core sample; calculating a matrix elastic parameter according to a rock physical theory; acquiring a longitudinal and transverse wave speed-porosity-shale content theoretical relation of the sand shale reservoir according to the matrix elastic parameter of the sand shale and the test data of the core sample; calculating logging porosity and logging shale content according to acquired actual logging data; on the basis of the longitudinal and transverse wave speed-porosity-shale content theoretical relation, performing parameter cross analysis, and calibrating and correcting the logging speed, the logging porosity and the logging shale content; establishing a quantitative prediction model about logging longitudinal and transverse wave impedance-porosity-shale content; acquiring an earthquake longitudinal wave impedance data cube, a transverse wave impedance data cube and a density data cube through earthquake pre-stack inversion; performing earthquake porosity and shale content data inversion to acquire an earthquake-predicted porosity data cube and an earthquake-predicted shale content data cube.

Description

technical field [0001] The invention relates to the technical field of oil and natural gas exploration, in particular to a seismic prediction method for the porosity and shale content of sand-shale reservoirs. Background technique [0002] Continental sandstone and mudstone reservoirs are the main targets of oil and gas exploration in my country. Sandstone and mudstone reservoirs have the characteristics of wide distribution, rich oil and gas resources, well-developed oil and gas reservoirs and great difficulty in exploration. Sandstone and mudstone reservoirs are generally formed in a certain depositional environment, and their vertical sequences often show some periodicity, showing a sand and mudstone interbedded structure, and clay minerals are often distributed between sandstone particles. Whether sandstone and mudstone reservoirs can become oil and gas reservoirs with industrial value is mainly limited by petrophysical and lithological conditions, among which rock poros...

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Problems solved by technology

In addition, there is no clear physical meaning between the seismic waveform attributes and the petrophysical properties of the reservoir, so it is difficult to explain the characteristics of reservoir porosity changes

[0009] 3. Conventional post-stack inversion data can only obtain P-wave impedance information, and the use of P-wave impedance single information to predict reservoir physical parameters must have multiple solutions in calculation results

Generally speaking, the formation porosity of sand-shale reservoirs is inseparable from parameters such as shale content. Therefore, a single post-stack wave impedance inversion method cannot theoretically obtain accurate reservoir porosity and other reservoir information.

[0010] In the process of practical research, the above-mentioned technical deficiencies limit the calculation accuracy of the existing prediction technology on a theoretical basis, and cannot accurately predict the porosity and lithology changes of continental sand-mudstone reservoirs

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