Tight sandstone pore size and NMR t 2 Method and system for determining value conversion relationship

Abstract

The embodiment of the invention discloses a method and a system for determining a transformation relationship between a tight sandstone aperture and a nuclear magnetic resonance T2 value, and relatesto the technical field of oil and gas reservoir stratum geological evaluation. The method comprises the following steps that: carrying out CT (Computed Tomography) on an obtained tight sandstone sample to obtain a three-dimensional digital core; through the three-dimensional digital core, obtaining aperture radius and volume data, and further obtaining a digital core aperture radius distribution diagram; carrying out saturated salt water nuclear magnetic resonance measurement on the tight sandstone sample to obtain a nuclear magnetic resonance T2 spectrogram; and on the basis of the digital core aperture radius distribution diagram and the nuclear magnetic resonance T2 spectrogram, according to an equal porosity principle, establishing a crossplot of the aperture radius rc and the nuclearmagnetic resonance T2 spectrogram, and carrying out fitting to obtain a relational expression of rc and T2. By use of the embodiment of the invention, the quantitative calculation of the transformation relationship between the tight sandstone aperture radius and the nuclear magnetic resonance T2 value is realized. Compared with the transformation relationship obtained through mercury penetration pore throat distribution and the nuclear magnetic resonance T2 spectrogram in the prior art, the transformation relationship obtained by the method is more reliable, and therefore, the tight sandstonereservoir stratum full-scale aperture structure is further accurately represented.

Description

technical field [0001] The embodiment of the present invention relates to the technical field of geological evaluation of oil and gas reservoirs, in particular to a tight sandstone pore size and nuclear magnetic resonance T 2 A method and system for determining a value conversion relationship. Background technique [0002] Tight sandstone gas is currently the unconventional natural gas with the highest yield and the most practical significance in my country. The pore structure of tight sandstone reservoirs has the characteristics of fine pores and throats or fine pores and microthroats. The size of pores and throats determines the reservoir fluid. Storage space and seepage capacity have a significant control effect on reserves and recovery, so the identification of full-scale pore radius distribution has very important practical significance for the evaluation and development of tight sandstone gas reservoirs. [0003] At present, the commonly used technologies for pore stru...

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Problems solved by technology

[0015] For this reason, the embodiment of the present invention provides a tight sandstone pore size and nuclear magnetic resonance T 2 A method and system for determining the value conversion relationship, to solve the problem in the prior art due to the distribution of mercury injection pore throats and nuclear magnetic T 2 The problem of low reliability caused by the conversion relationship obtained by comparing the spectra

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