Method and device for determining oil-gas saturation

Abstract

The present invention provides a method and device for determining oil and gas saturation, wherein the method includes: obtaining long echo interval measurement echo strings and short echo interval measurement echo strings; according to actual formation information, in the set experiment Under the temperature and experimental pressure, the formation water diffusion coefficient is determined; according to the formation water diffusion coefficient, the water diffusion relaxation time is obtained; the water diffusion relaxation time under the long echo interval and the water diffusion relaxation time under the short echo interval The time is added to the short echo interval T2 spectrum to obtain the constructed echo string, and the fluid properties of the reservoir are determined according to the long echo interval measured echo string and the constructed echo string, and the oil and gas saturation of the reservoir is calculated. The invention solves the problem that the existing nuclear magnetic resonance shifting method requires strong regional experience, and widens the application range of the nuclear magnetic resonance logging fluid identification method.

Description

technical field [0001] The invention relates to the technical field of petroleum logging, in particular to a method and device for determining oil-gas saturation. Background technique [0002] In the field of petroleum exploration and well logging technology, nuclear magnetic resonance is an important reservoir fluid identification method, especially when there are "low-resistivity" oil layers with high irreducible water content, it is difficult to accurately obtain reservoir fluid identification methods with conventional resistivity fluid. Fluid information, NMR fluid identification technology is not affected by bound water, etc., can accurately identify fluids, and has a good application prospect. However, the distribution of the lateral relaxation time T2 of NMR logging will be affected by the fluid properties and pore structure. The NMR T2 of oil and water in the reservoir overlaps to a certain extent, which increases the difficulty of identifying the properties of oil a...

AI Technical Summary

Problems solved by technology

Due to the complex pore structure, it is often encountered that the short waiting time cannot fully polarize the water signal in the pore. At this time, the phenomenon of difference spectrum signals in the water layer will appear, which will lead to misinterpretation of the oil layer by the water layer and reduce the coincidence rate of NMR logging.

[0005] 2) For the spectral shift method, it mainly relies on experience, which is still quite far-fetched in theory, and it is difficult to realize the quantitative identification of oil, gas and water in practical applications

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