Nuclear magnetism capillary pressure curve construction method based on reservoir stratum classification

Abstract

The invention discloses a nuclear magnetism capillary pressure curve construction method based on reservoir stratum classification. The method includes the steps: according to nuclear magnetic resonance logging data and limited capillary pressure data, obtaining the porosity, the permeability and an T2 geometric mean value curve for the reservoir stratum by means of inversion of the nuclear magnetic resonance logging data; calculating a flow zone index FZI which can reflect the difference of the reservoir stratum by means of the porosity and permeability curve, and utilizing the FZI to classify the reservoir stratum into three types; for every type of reservoir stratum, respectively establishing a function relationship among the wetting phase saturation, the nuclear magnetic resonance porosity Phi and the T2 geometric mean value T2LM under different mercury intrusion pressures; according to the obtained function relationship, calculating the wetting phase saturation under different mercury intrusion pressures, and converting the wetting phase saturation into the mercury intrusion saturation; according to the calculated mercury intrusion saturation and the corresponding mercury intrusion pressure, constructing a nuclear magnetism capillary pressure curve; and according to the nuclear magnetism capillary pressure curve, acquiring pore throat radius distribution, and achieving the aim for continuous quantitative evaluation of the pore structure of the reservoir stratum.

Description

technical field [0001] The invention belongs to the field of reservoir evaluation, in particular to a method for constructing nuclear magnetic capillary pressure curves based on reservoir classification. Background technique [0002] The exploration and development process of low-permeability-tight reservoirs is actually a process of “finding the best from the poor”, that is, looking for relatively high-quality reservoirs with oil and gas development potential in generally poor formations. The difference between high-quality reservoirs and non-reservoirs is mainly reflected in the pore structure. High-quality reservoirs tend to have better pore structure and pore connectivity, while non-reservoirs tend to have poor pore structure and pore connectivity. If the pore structure of the reservoir can be quantitatively evaluated, on this basis, the classification of reservoir types and the determination of high-quality reservoirs will be of great significance for improving the exp...

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Problems solved by technology

[0009] In order to overcome the problem of insufficient theoretical basis of existing methods, the present invention provides a method for constructing nuclear magnetic capillary pressure curves based on reservoir classification on the basis of in-depth derivation of the classic J function theory and SDR model, and realizes The purpose of constructing NMR capillary pressure curve accurately

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