Fractal dimension measuring and calculating method for effective pores of hydrate-containing sediments

Abstract

The invention belongs to the field of basic physical property testing of unconventional oil and gas reservoir engineering and geotechnical engineering and particularly relates to a fractal dimension measuring and calculating method for effective pores of hydrate-containing sediments. Firstly, X-CT gray images of the hydrate-containing sediments are acquired and the porosity is measured; then, thegray images are colored again, X-CT colored images of the hydrate-containing sediments are acquired from two groups with gray values of soil particles, hydrate particles, gas and moisture in obvious comparison, then, X-CT colored images with set thresholds are subjected to binarization processing, black and white images are obtained, the effective porosity of the acquired black and white images isthe same as that of the X-CT gray images, and white and black represent a framework material and a pore fluid respectively. The fractal dimensions of black areas in the black and white images, namely, the fractal dimensions of effective porosity of the hydrate-containing sediments, are solved. The problems that solid framework space and pore fluid space cannot be segmented effectively with existing methods are solved, and the fractal dimensions of effective porosity of the hydrate-containing sediments can be measured and calculated accurately.

Description

Technical field [0001] The invention belongs to the field of basic physical property testing of unconventional oil and gas reservoir engineering and geotechnical engineering, and specifically relates to a method for measuring and calculating the fractal dimension of effective pores of hydrate deposits. Background technique [0002] Natural gas hydrate is a clathrate crystalline compound formed by natural gas and water at lower temperature and higher pressure. It is known as one of the most important potential alternative energy sources in the 21st century because of its abundant natural gas. . From May to July 2017, my country successfully tested natural gas hydrate for the first time in the Shenhu area of ​​the South China Sea. At present, the gas production efficiency of hydrate trial mining that has been carried out in the world is far from enough to meet the demand of commercial mining, and higher requirements are put forward for the research of hydrate mining technology. [...

AI Technical Summary

Problems solved by technology

[0004] Aiming at the problem that the binarized image obtained by the existing image processing method is difficult to accurately reflect the microstructure of the effective pores of hydrate sediments, resulting in a large error in the fractal dimension of the effective pores of hydrate-containing sediments calculated based on this, The present invention provides a fractal dimension calculation method for the effective pores of hydrate-containing sediments. By resetting the gray value of each component of hydrate-containing sediments, the pore fluid and the skeleton solid can be accurately distinguished, and then by setting the binary value threshold, to obtain a black-and-white image that can reflect the effective pore distribution of hydrate-containing sediments, and based on the black-and-white image to solve the box counting dimension of the black area, that is, the fractal dimension of hydrate-containing sediment pores

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