Method for classifying bioclastic limestone reservoir pore structures

Abstract

The invention discloses a method for classifying bioclastic limestone reservoir pore structures. The method comprises the steps as follows: a, nuclear magnetic logging, conventional logging and drilling coring are performed on a target well section in a researched block; b, matched high-pressure mercury injection and nuclear magnetic resonance experiments are performed on a core; c, the pore structures are classified into four types according to the capillary pressure curve shape, the pore throat distribution feature and oil-gas production capacity, and pore throat space bounds at different scales are determined; d, relaxation distribution ranges of different pore components of a nuclear magnetic resonance T2 spectrum are acquired according to the scales of the core; e, the classification standard of the pore structures is established according to the distribution condition of different pore components of the nuclear magnetic resonance T2 spectrum; f, the types of the continuous pore structures of the whole well section are recognized according to the nuclear magnetic logging information. The relation between mercury injection capillary pressure curve fractal features and diagenesis and pore throat distribution is fully mined, the ratio of different pore components is obtained in combination with nuclear magnetic information, the reservoir pore structures are classified more elaborately, and the problem about fine evaluation of the heterogeneous bioclastic limestone reservoir pore structures is solved.

Description

technical field [0001] The invention relates to a new method for classifying the pore structure of bioclastic limestone reservoirs, which belongs to the field of petroleum exploration and development. Background technique [0002] The microscopic pore structure of reservoir rocks directly affects the macroscopic physical properties, electrical properties, industrial types, and oil and gas productivity of the reservoir, and ultimately determines the difference in productivity distribution of oil and gas reservoirs. Evaluation and reservoir exploration and development are of great significance. [0003] At present, the research methods of pore structure mainly include the direct method of observing and describing the pore structure by using scanning electron microscope, cast thin section and CT imaging, and the indirect method of reflecting the pore structure by using capillary pressure test and so on. For reservoirs with strong heterogeneity, the direct method is greatly aff...

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Problems solved by technology

For reservoirs with strong heterogeneity, the direct method is greatly affected by the observation horizon, and the consistency with the macroscopic properties of the reservoir and oil and gas production is not high; currently the most direct and effective data is the analysis of the shape of the capillary force curve Qualitatively characterize the pore structure of the reservoir, but the judgment of the transition type curve by this method is highly subjective, the classification is relatively rough, and the subtle differences in the pore structure cannot be accurately represented, and the cost of this method is high, and continuous coring analysis cannot be performed in actual production. Cannot achieve the purpose of continuous quantitative evaluation of pore structure

[0004] NMR logging technology can provide abundant pore structure information, and can realize continuous evaluation of pore structure, but it is currently impossible to analyze the pore structure from T 2 To obtain accurate results of pore-throat distribution information directly on the spectrum, it is usually necessary to set T 2 Only by combining the spectrum with the capillary force curve and studying the relationship between the two and their mutual transformation can an accurate evaluation of the pore throat size be made

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