Pore-Throat Combination Types and Gas-Water Relative Permeability Responses of Tight Gas Sandstone Reservoirs in the Zizhou Area of East Ordos Basin, China

论文摘要

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 <15%）. Primary intergranular pores and secondary intergranular pores are mainly found in type-Ⅲ samples, which are connected by various throats. The throat size distribution curves of type-Ⅲ sandstones show a nearly normal distribution with low kurtosis（peak ratio <10%）, and the micro-scale throat radii（>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.

论文目录

• 1 Introduction
• 2 Geological Setting
• 3 Samples and Experimental Methods
•   3.1 Samples
•   3.2 Experimental methods
• 4 Results
•   4.1 Detrital mineralogy
•   4.2 Reservoir quality
•   4.3 Pore-throat combination types
•   4.4 Pore-throat size and distribution
•   4.5 The gas-water relative permeability
• 5 Discussions
•   5.1 Effects of pore-throat combination types on the gas-water relative permeability
•   5.2 Diagenetic control on the pore-throat combination types
• 6 Conclusions

文章来源

类型: 期刊论文

作者: LI Mi,GUO Yinghai,LI Zhuangfu,WANG Huaichang,ZHANG Jingxia

来源: Acta Geologica Sinica(English Edition) 2019年03期

年度: 2019

分类: 基础科学,工程科技Ⅰ辑

专业: 地质学,石油天然气工业

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 Company,PetroChina

基金: supported by the Natural Science Foundation of China (grant No. 41772130)

分类号: P618.13

页码: 622-636

总页数: 15

文件大小: 1427K

下载量: 23