Nuclear magnetic resonance T2 geometric mean correction method and system for low-porosity water layer invaded by oil-based mud

Abstract

The invention provides a nuclear magnetic resonance T2 geometric mean correction method and system for a low-porosity water layer invaded by oil-based mud. The method comprises the following steps of acquiring a nuclear magnetic resonance T2 geometric mean value of a low-porosity water layer invaded by target oil-receiving base mud and a nuclear magnetic resonance T2 geometric mean value of invaded oil base mud, obtaining a calculation model of the formation nuclear magnetic resonance T2 geometric mean value about the nuclear magnetic resonance T2 geometric mean value after the formation intrudes into the oil-based mud and the nuclear magnetic resonance T2 geometric mean value of the formation intruded oil-based mud, on the basis of the nuclear magnetic resonance T2 geometric mean value of the target oil-receiving base mud invaded into the low-porosity water layer and the nuclear magnetic resonance T2 geometric mean value of the target oil-receiving base mud invaded into the low-porosity water layer, determining the nuclear magnetic resonance T2 geometric mean value of the target oil-receiving base mud invaded into the 100% saturated water state of the stratum of the target oil-receiving base mud invaded into the low-porosity water layer by utilizing the calculation model, and thus, completing correction of the nuclear magnetic resonance T2 geometric mean value of the target oil-receiving base mud invaded low-porosity water layer.

Description

technical field [0001] The invention belongs to the field of reservoir evaluation, in particular to a nuclear magnetic resonance T 2 Geometric mean correction method and system. Background technique [0002] T 2 The geometric mean is a very important parameter in the interpretation of nuclear magnetic resonance logging data, and its value intuitively and qualitatively reflects the rock nuclear magnetic resonance T 2 The width of the spectrum and the relative position of the main peak. It can be used to qualitatively reflect the rock pore structure and quantitatively calculate the rock permeability. In general, for a unimodal NMR T 2 Spectrum, its T 2 Geometric mean and NMR T 2 T corresponding to the position of the main peak of the spectrum 2 The relaxation times coincide, while for non-unimodal NMR T 2 Spectrum, T 2 The wider the distribution, the further to the right the position of the main peak, and the corresponding T 2 The larger the geometric mean, it reflec...

AI Technical Summary

Problems solved by technology

[0003] Aiming at the deficiencies of the prior art, the object of the present invention is to provide a nuclear magnetic resonance T 2 The geometric mean method effectively solves the problem of low-porosity water layers affected by oil-based mud invasion, and the NMR T obtained based on NMR logging 2 The problem that the geometric mean cannot reflect the real situation of the formation

Images