Two-dimensional nuclear magnetic resonance D-T<2> spectrum inversion method and device

Abstract

The invention discloses a two-dimensional nuclear magnetic resonance D-T<2> spectrum inversion method and device. The two-dimensional nuclear magnetic resonance D-T<2> spectrum inversion method comprises the following steps: collecting multiple sets of nuclear magnetic resonance echo string data of different echo intervals; constructing an elastic network objective function for inversion; determining a ratio c of a ridge regression regularization parameter [Alpha] and a Lasso regression regularization parameter [Beta] in the elastic network objective function; determining the optimal regularization parameter [Alpha]<2> of the ridge regression and the optimal regularization parameter [Beta]<2> of the Lasso regression in the elastic network objective function; and substituting the obtained parameters into the elastic network objective function to perform solving, so as to obtain the two-dimensional nuclear magnetic resonance D-T<2> spectrum. The invention inverts the two-dimensional nuclear magnetic resonance D-T<2> spectrum based on the elastic network, so that the inverted two-dimensional nuclear magnetic resonance D-T2 spectrum balances the smoothness and sparsity; therefore, theproblem that the inversion result is too smooth under low signal-to-noise ratio data is avoided, and a high-precision two-dimensional nuclear magnetic resonance D-T<2> spectrum can be obtained; and the invention benefits oil and gas identification and quantitative calculation.

Description

technical field [0001] The invention relates to the technical field of geophysical inversion in oil and gas exploration, more specifically, to a two-dimensional nuclear magnetic resonance D-T 2 Spectral inversion method and device. Background technique [0002] NMR logging is widely used to calculate formation porosity, permeability, saturation, pore size distribution, bound fluid volume and movable fluid volume, and to identify and quantitatively evaluate oil and gas. At present, domestic research is mainly focused on one-dimensional nuclear magnetic resonance logging, which measures fluid T 2 Signal. However, the T of oil, gas and water 2 The distributions usually overlap partially or completely, and it is sometimes very difficult or impossible to identify fluid properties and determine fluid volume using 1D NMR logging. Compared with one-dimensional nuclear magnetic resonance logging, two-dimensional nuclear magnetic resonance logging collects multiple sets of echo tr...

AI Technical Summary

Problems solved by technology

Under the condition of low signal-to-noise ratio, the 2D NMR D-T 2 The spectrum is usually too smooth, causing the oil and gas spectra to partially overlap or completely overlap with the water spectrum, which affects the identification effect of oil and gas

Since the above method cannot take into account the smoothness and sparseness of the solution at the same time, the oil, gas and water spectra partially overlap or completely overlap, which affects the two-dimensional nuclear magnetic resonance D-T 2 Accuracy of spectral inversion

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