A three dimensional visualized physical simulation for natural gas charging in the micro-nano pore system
A three dimensional visualized physical simulation for natural gas charging in the micro-nano pore system作者机构：State Key Laboratory of Petroleum Resources and ProspectingChina University of PetroleumBeijing 102249.China College of GeosciencesChina University of PetroleumBeijing 102249China Institute of Geophysics and GeomaticsChina University of GeosciencesWuhan 430074China Key Laboratory of Tectonics and Petroleum Resources of Ministry of EducationChina University of GeosciencesWuhan 430074China Dagang Oilfield CompanyPetroChinaTianjin 300280China Sinopec Petroleum Exploration and Production Research InstituteBeijing 102206China CNPC Engineering Technology R&D Company LimitedBeijing 102206China
出 版 物：《Petroleum Exploration and Development》 (石油勘探与开发（英文版）)
年 卷 期：2022年第49卷第2期
页 面：349-362页
核心收录：
学科分类：0820[工学-石油与天然气工程] 08[工学] 0708[理学-地球物理学] 082002[工学-油气田开发工程]
基 金：Supported by the National Natural Science Foundation of China (41330319 and 42072174) Foundation of China University of Petroleum Beijing (2462020XKBH016) Fellowship of China Postdoctoral Science Foundation (2020M680030)。
主 题：low permeability(tight)sandstone gas charging three-dimensional visualization physical simulation micro-nanometer pore network gas and water flow and distribution
摘 要：A micro-nano pore three-dimensional visualized real-time physical simulation of natural gas charging, in-situ pore-scale computation, pore network modelling, and apparent permeability evaluation theory were used to investigate laws of gas and water flow and their distribution, and controlling factors during the gas charging process in low-permeability(tight) sandstone reservoir. By describing features of gas-water flow and distribution and their variations in the micro-nano pore system, it is found that the gas charging in the low permeability(tight) sandstone can be divided into two stages, expansion stage and stable stage. In the expansion stage, the gas flows continuously first into large-sized pores then small-sized pores, and first into centers of the pores then edges of pores;pore-throats greater than 20 μm in radius make up the major pathway for gas charging. With the increase of charging pressure, movable water in the edges of large-sized pores and in the centers of small pores is displaced out successively. Pore-throats of 20-50 μm in radius and pore-throats less than 20 μm in radius dominate the expansion of gas charging channels at different stages of charging in turn, leading to reductions in pore-throat radius, throat length and coordination number of the pathway, which is the main increase stage of gas permeability and gas saturation. Among which, pore-throats 30-50 μm in radius control the increase pattern of gas saturation. In the stable stage, gas charging pathways have expanded to the maximum, so the pathways keep stable in pore-throat radius, throat length, and coordination number, and irreducible water remains in the pore system, the gas phase is in concentrated clusters, while the water phase is in the form of dispersed thin film, and the gas saturation and gas permeability tend stable. Connected pore-throats less than 20 μm in radius control the expansion limit of the charging pathways, the formation of stable gas-water distribution, and the maximum gas saturation. The heterogeneity of connected pore-throats affects the dynamic variations of gas phase charging and gas-water distribution. It can be concluded that the pore-throat configuration and heterogeneity of the micro-nanometer pore system control the dynamic variations of the low-permeability(tight) sandstone gas charging process and gas-water distribution features.
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