To address the difficult problem of poor understanding of the reservoir mobilization law of water-bearing sandstone gas reservoirs, a multi-point piezometric physical simulation experiment method and apparatus were used for long cores. Six natural matrix cores with permeability levels of 0.047,0.064,0.154,0.175,0.602, and 1.74×10-3 μm2 were selected, and a series of physical simulation experiments of depletion extraction were conducted under the conditions of water content saturation of about 0%,30%,40%,50%,60%, and 70%, respectively. The effects of reservoir matrix permeability and water saturation on the instantaneous gas production, pressure drop curve and characteristics of the reservoir, as well as the degree of reserve utilization (R) at different development stages (end of steady production, abandonment conditions and ultimate conditions) were investigated. The results show that: (1) the gas production capacity of reservoir matrix and the degree of reservoir utilization are controlled by both reservoir matrix permeability and water content saturation, but the sensitive threshold value is different in different stages of gas reservoir development. (2) Based on the characteristic diagram of the degree of utilization under the abandoned condition, a set of reserve utilization classification evaluation boundary map is constructed with the reservoir permeability and water content saturation corresponding to 60% and 80% of the reservoir utilization degree respectively as the indexes, and three levels of priority utilization, conditional utilization and potential utilization are divided, and the reservoir parameters corresponding to each level are clearly defined, which can provide prospective guidance for prioritizing and determining the sequence of reservoir utilization for high-quality reservoirs in the field.
Keywords:Water-bearing sandstone gas reservoir
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Reservoir mobilization
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Graded evaluation
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Experimental study
;
Physical simulation
JIANG Liangji, WANG Guofeng, HU Yong, WANG Jiping, LI Zhongcheng, JIAO Chunyan, GUO Shichao, GUO Changmin, CHEN Luyao. Experiment on production classification evaluation of water-bearing sandstone gas reservoirs. Natural Gas Geoscience[J], 2023, 34(7): 1137-1145 doi:10.11764/j.issn.1672-1926.2023.03.003
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