Method for obtaining tight sandstone permeability by utilizing nuclear magnetic resonance T2 spectrum form

Abstract

The invention discloses a method for obtaining tight sandstone permeability by utilizing a nuclear magnetic resonance T2 spectrum form. The method comprises the steps of 1) collecting core analysis permeability and nuclear magnetic resonance T2 spectrum well-log data of multiple groups of well sections, and performing depth alignment to serve as sample data; 2) performing normalization on the collected core analysis permeability and nuclear magnetic resonance T2 spectrum well-log data to enable a sample data range to be a range [0,1]; 3) establishing a nonlinear mapping relationship between anuclear magnetic resonance T2 spectrum and the core analysis permeability; and 4) obtaining tight sandstone permeability values of to-be-calculated well sections by utilizing the trained nonlinear mapping relationship between the nuclear magnetic resonance T2 spectrum and the core analysis permeability.

Description

technical field [0001] The invention relates to a method for obtaining the permeability of tight sandstone by using the form of nuclear magnetic resonance T2 spectrum, and belongs to the field of petroleum exploitation. Background technique [0002] With my country's increasingly serious environmental problems and the background of green and low-carbon energy transformation, natural gas, as the cleanest fossil energy, has reached an unprecedented level of importance in energy strategies, and the demand for natural gas continues to increase, of which unconventional dense Sandstone gas is an important future source. [0003] In the exploration and development of tight sandstone natural gas, accurate estimation of reservoir permeability plays an important role in productivity evaluation. The methods to obtain reservoir permeability mainly include core analysis method and logging calculation method. Among them, core analysis permeability is the most accurate, but the cost of dri...

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Problems solved by technology

However, these models using nuclear magnetic resonance T2 spectrum to calculate permeability are not very effective in tight sandstone reservoirs. The heterogeneity is serious, so it is difficult to accurately obtain the constantly changing NMR T2 spectrum cut-off value, and the calculation results of permeability have large errors; in addition, the above methods cannot make full use of all the rock pore structure information reflected by the NMR T2 spectrum

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