Three-factor estimation method for rock internal magnetic field gradient weighted geometric mean value

Abstract

The invention discloses a three-factor estimation method for a rock internal magnetic field gradient weighted geometric mean value, and particularly relates to the field of oil and gas field exploration and development. The method comprises the following steps: collecting coring data to obtain a rock sample; constructing a rock internal pore structure model by adopting CT scanning and an equivalent deposition method in combination with Avizo software; calculating rock internal magnetic field gradient distribution based on a voxel finite element method; by simulating rock internal magnetic field gradient distribution under different external magnetic field intensities, rock component magnetic susceptibility and pore structure conditions, establishing relational expressions between three factors and the geometric mean value of rock internal magnetic field gradient distribution respectively; and determining a three-factor estimation formula of the rock internal magnetic field gradient weighted geometric mean value, and verifying the accuracy of the three-factor estimation formula. According to the method, the problem that the rock internal magnetic field gradient values are difficultto obtain rapidly in batches is solved, estimation of the rock internal magnetic field gradient weighted geometric mean value is achieved, and an important basis is provided for rapidly knowing the rock physical characteristics of an oil and gas reservoir.

Description

technical field [0001] The invention relates to the field of exploration and development of oil and gas fields, in particular to a method for estimating the three-factor weighted geometric mean value of the magnetic field gradient inside a rock. Background technique [0002] As my country's dependence on foreign crude oil increases year by year, the sustainable development of domestic oil and gas has become a key issue that directly affects my country's energy security. As the only logging technology that directly detects fluid signals, nuclear magnetic resonance logging has achieved good results in the parameter calculation of conventional sandstone reservoirs. However, for oil and gas reservoirs containing high content of paramagnetic substances such as clay minerals or pyrite, the magnetic field gradient inside the rock is too high, and the NMR T 2 The spectrum shifted, which made it impossible to directly apply the reservoir evaluation model based on the NMR response to...

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Problems solved by technology

[0004] The invention aims to solve the problem that there are differences in the measurement results of nuclear magnetic resonance equipment with different field strengths, and it is difficult to obtain large quantities of magnetic field gradient values ​​inside rocks within a limited time, and provides a three-factor estimation method for the weighted geometric mean value of magnetic field gradients inside rocks

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