Method for obtaining logging saturation of low porosity permeability reservoir

Abstract

The invention provides a method for obtaining a logging saturation of a low porosity permeability reservoir, belonging to the technical field of exploration and development of oil and gas fields. The method comprises the following steps: firstly, determining bond indexes m in the reservoir, which are corresponding to different resistivities, then building functional relationships between the resistivities and the bond indexes m, and finally obtaining an approximate solution of the gas saturation of the reservoir to further obtain a correct judgement on the type of the reservoir. The invention solves the current situation that the m variable calculated by the rock electrical experiment is difficult to guide the production application, and logging recognition problems of the air layer, the air and water layer and the water layer in the low porosity permeability reservoir. The method disclosed in the invention has a strong operability and research conclusion thereof is accurate and reliable. The method also raises the accordance rate of logging interpretation for the volcanic reservoir, and has excellent application values on the tight sand rock, the carbonate rock and the igneous rock reservoirs.

Description

technical field [0001] The invention belongs to the field of exploration and development of oil and gas fields, and in particular relates to a method for obtaining logging saturation of low porosity and permeability reservoirs. Background technique [0002] In oil and gas field exploration and development, using Archie's formula to calculate reservoir water saturation is a key technology for judging reservoir fluid properties and accurately identifying gas layers, gas-water layers, water layers, and dry layers. Archie's formula is: [0003] [0004] In the formula, a and b are coefficients related to formation factors and resistivity increase rate; [0005] m is the cementation index; [0006] n is the saturation index; [0007] Rw is formation water resistivity; [0008] φ is the log porosity; [0009] Rt is the true resistivity of formation; [0010] Sw is the water saturation. [0011] Archie's formula contains m, a, n, and b to be determined interpretation para...

AI Technical Summary

Problems solved by technology

The study of Archie's formula with variable m value is technically reasonable for logging interpretation of volcanic rocks with variable lithology or material composition, but the difficulty of obtaining m value affects the implementation of this method

Even if the same lithology is analyzed by experiment, the m value may vary greatly due to the difference in pore structure. Therefore, the method of calibrating multiple cores to obtain the m value is not only costly, but also not necessarily effective.

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