气候变化领域集成服务门户(CCPortal): Breakthrough pressure and permeability in partially water-saturated shales using methane-carbon dioxide gas mixtures: An experimental study of Carboniferous shales from the eastern Qaidam Basin; China

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DOI	10.1306/07111818018
	Breakthrough pressure and permeability in partially water-saturated shales using methane-carbon dioxide gas mixtures: An experimental study of Carboniferous shales from the eastern Qaidam Basin; China
	Zhang C.; Yu Q.
发表日期	2019
ISSN	0149-1423
起始页码	273
结束页码	301
卷号	103 期号:2
英文摘要	As an important unconventional and alternative resource, shale gas has attracted worldwide attention. The breakthrough pressure is amajor factor in the generation and migration of shale gas as well as in the evaluation of the caprock sealing capacity. Carboniferous shales are considered to have great potential for the exploitation of shale gas; thus, investigations of the breakthrough pressure and gas effective permeability are significant. Two shale samples taken from the Carboniferous Hurleg Formation in the eastern Qaidam Basin, China, were chosen to conduct breakthrough experiments to investigate the effects ofwater saturation andCO 2 -CH 4 mixed mole fractions on the breakthrough pressure and gas effective permeability. Prior to the experiments, various relevant parameters (e.g., the porosity, mineral composition, and organic geochemistry; the total organic content, thermal maturity and kerogen type; and microstructure) of these samples were also measured. The results of our breakthrough experiments show that the breakthrough pressure increases with the water saturation and decreases with the CO 2 mole fraction in the gas mixture. The situation for the gas effective permeability is just the opposite. Pore-size distribution measurements indicate that there are many nanoscale micropores that can easily be blocked by water molecules. This results in the reduced connectivity of gas pathways; thus, the breakthrough pressure increases and the gas effectivepermeability decreases with increasing water saturation. The breakthrough pressure decreases with the CO 2 mole fraction because the interfacial tension of the CO 2 -water system is smaller than that of the CH 4 -water system. The viscosity of the CO 2 -CH 4 mixture was found to increase with the CO 2 mole fraction by fitting a series of values under the same temperature and pressure conditions, leading to an increase in the gas effective permeability. Furthermore, CO 2 molecules are smaller than CH 4 molecules, making it easier for CO 2 to move across pathways. After each breakthrough experiment, the CO 2 mole fraction in the effluent was less than that in the injected gas, and it increased over time until reaching the initial injected gas composition. This is because the adsorption and solubility of CO 2 inwater are greater than those of CH 4 . This study provides practical information for further investigations of shale gas migration and extraction and the sealing capacities of caprocks. © 2019. The American Association of Petroleum Geologists.
语种	英语
scopus关键词	Carbon dioxide; Effluents; Gas mixtures; Gas permeability; Geochemistry; Molecules; Petroleum reservoir evaluation; Pore size; Shale gas; Waterworks; Breakthrough experiment; Breakthrough pressures; Effective permeability; Mineral composition; Organic geochemistry; Temperature and pressures; Total organic contents; Water saturations; Gases; adsorption; breakthrough curve; cap rock; carbon dioxide; Carboniferous; experimental study; hydrocarbon migration; kerogen; permeability; shale; shale gas; thermal maturity; China; Qaidam Basin; Qinghai
来源期刊	AAPG Bulletin
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/143779
作者单位	Ministry of Education (MOE), Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences (Beijing), Beijing, China
推荐引用方式 GB/T 7714	Zhang C.,Yu Q.. Breakthrough pressure and permeability in partially water-saturated shales using methane-carbon dioxide gas mixtures: An experimental study of Carboniferous shales from the eastern Qaidam Basin; China[J],2019,103(2).
APA	Zhang C.,&Yu Q..(2019).Breakthrough pressure and permeability in partially water-saturated shales using methane-carbon dioxide gas mixtures: An experimental study of Carboniferous shales from the eastern Qaidam Basin; China.AAPG Bulletin,103(2).
MLA	Zhang C.,et al."Breakthrough pressure and permeability in partially water-saturated shales using methane-carbon dioxide gas mixtures: An experimental study of Carboniferous shales from the eastern Qaidam Basin; China".AAPG Bulletin 103.2(2019).