Pore-Throat Combination Types and Gas-Water Relative Permeability Responses of Tight Gas Sandstone Reservoirs in the Zizhou Area of East Ordos Basin, China 机翻标题: 暂无翻译,请尝试点击翻译按钮。

来源
Acta Geologica Sinica(English Edition)
年/卷/期
2019 / 93 / 03
页码
622-636
作者单位
Key Laboratory of Coalbed Methane Resource and Reservoir Formation Process, Ministry of Education;School of Resources and Geosciences, China University of Mining & Technology;Research Institute of Petroleum Exploration & Development of Changqing Oilfield ;
作者
LI Mi;GUO Yinghai;LI Zhuangfu;WANG Huaichang;ZHANG Jingxia;
摘要
With the aim of better understanding the tight gas reservoirs in the Zizhou area of east Ordos Basin, a total of222 samples were collected from 50 wells for a series of experiments. In this study, three pore-throat combination types in sandstones were revealed and confirmed to play a controlling role in the distribution of throat size and the characteristics of gas-water relative permeability. The type-Ⅰ sandstones are dominated by intercrystalline micropores connected by cluster throats, of which the distribution curves of throat size are narrow and have a strong single peak(peak ratio >30%). The pores in the type-Ⅱ sandstones dominantly consist of secondary dissolution pores and intercrystalline micropores, and throats mainly occur as slice-shaped throats along cleavages between rigid grain margins and cluster throats in clay cement.The distribution curves of throat size for the type-Ⅱ sandstones show a bimodal distribution with a substantial low-value region between the peaks(peak ratio 0.5 μm) constitute a large proportion. From type-Ⅰ to type-Ⅲ sandstones, the irreducible water saturation(Swo) decreased; furthermore, the slope of the curves of Krw/Krg in two-phase saturation zone decreased and the two-phase saturation zone increased,indicating that the gas relative flow ability increased. Variations of the permeability exist in sandstones with different porethroat combination types, which indicate the type-Ⅲ sandstones are better reservoirs, followed by type-Ⅱ sandstones and type-Ⅰ sandstones. As an important factor affecting the reservoir quality, the pore-throat combination type in sandstones is the cumulative expression of lithology and diagenetic modifications with strong heterogeneity.
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关键词/主题词
tight gas sandstone;pore-throat combination type;throat characteristic;gas-water relative permeability;Zizhou area;Ordos Basin;
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