A method for predicting the diffusion coefficient of natural gas in tight sandstone under geological conditions
A diffusion coefficient and tight sandstone technology, applied in the field of petroleum exploration, can solve problems such as the inability to correctly calculate the diffusion amount of natural gas and the inability to determine the diffusion coefficient of natural gas
Active Publication Date: 2019-08-06
PETROCHINA CO LTD
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Problems solved by technology
To at least solve the technical problem of the inability to correctly calculate the natural gas diffusion amount in the historical period caused by the inability to determine the natural gas diffusion coefficient in the case of multiple geological factors changing simultaneously in related technologies
Method used
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Embodiment 1
[0043] In Embodiment 1 of the present invention, a method for predicting the diffusion coefficient of natural gas in tight sandstone under geological conditions is provided, such as figure 1 shown, including the following steps:
[0044] Step S101: collecting rock samples with similar structural background and sedimentary environment in the study area and with wide distribution of physical properties;
[0045] Step S102: Perform porosity, permeability, high-pressure mercury intrusion and X-ray diffraction analysis on the samples, and screen tight sandstone samples with pore-throat median radius and clay mineral content ranging from high to low;
[0046] Step S103: Determine the formation water salinity, natural gas composition, and the highest and lowest historical temperature and pressure experienced by rocks in the study area;
[0047] Step S104: saturate the screened sample with formation water, and measure the diffusion coefficient under the same temperature, pressure fro...
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The invention provides a method for predicting diffusion coefficients of natural gas in tight sandstones under geological conditions. The method comprises the following steps: acquiring rock samples, screening tight sandstone samples and enabling the selected samples to be saturated with formation water; performing experimental determination on the diffusion coefficients of the natural gas under different temperature and pressure conditions according to the temperature and pressure change range of a stratum in a study area and the natural gas composition; establishing a dynamic model for natural gas diffusion coefficient and temperature, and determining the ratio of diffusion activation energy to a gas constant; establishing an index model for natural gas diffusion coefficient and pressure, and determining a diffusion pressure factor; establishing a linear model for the ratio of clay mineral content and diffusion activation energy to the gas constant; establishing a linear model for a pore throat median radius reciprocal and the diffusion pressure factor; establishing a diffusion coefficient multi-factor model; predicting the diffusion coefficients of different rocks under different temperature and pressure conditions in the study area.
Description
technical field [0001] The invention relates to the field of petroleum exploration, in particular to a method for predicting the diffusion coefficient of natural gas in tight sandstone under geological conditions. Background technique [0002] Tight sandstone gas has become a key area of unconventional natural gas exploration in the world. At present, tight sandstone gas has been discovered or speculated to be developed in more than 70 basins around the world, with resources of about 209.6×10 12 m 3 , mainly distributed in North America, Latin America and Asia Pacific. The United States is the earliest area to develop tight sandstone gas, and the tight sandstone gas production in 2011 was about 1690×10 8 m 3 , accounting for 26% of total US natural gas production (EIA, 2012). With the advancement and large-scale application of large-scale fracturing technology in China in recent years, significant progress has been made in the exploration and development of tight sands...
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IPC IPC(8): G01N13/00
CPCG01N13/00G01N2013/003
Inventor 赵忠英卢山
Owner PETROCHINA CO LTD