Abstract
Research on tight gas reservoirs in the eastern margin of the Ordos Basin, China, has recently become a hot spot. This paper mainly studies the reservoir characteristics of tight sandstone in the north-central area close to the provenance in eastern Linxing. Cast thin section, scanning electron microscopy, high-pressure mercury injection, and X-ray diffraction (XRD) were applied to discriminate the tight sandstone reservoir differences between the Permian Taiyuan and Shanxi formations in the study area. The results show that the deltaic tight sandstones in the Shanxi Formation are dominated by lithic quartz sandstone and lithic sandstone with an average porosity of 2.3% and permeability of 0.083 mD. The epicontinental tight sandstones in the Taiyuan Formation are mainly lithic sandstone and lithic quartz sandstone, with average porosities and permeabilities of 6.9% and 0.12 mD, respectively. The pore type is dominated by secondary dissolution pores, containing a small number of primary pores, and fractures are not developed. The capillary pressure curves of the Taiyuan Formation sandstone are mainly of low displacement pressure, high mercury saturation, and mercury withdrawal efficiency, while the Shanxi Formation sandstone is mainly of high displacement pressure, low mercury saturation, and withdrawal efficiency. The diagenetic evolution of sandstone in the Shanxi Formation is in meso-diagenesis stage A, and the Taiyuan Formation has entered meso-diagenesis stage B. The siliceous cement in the Taiyuan Formation sandstone enhanced the sandstone resistance to compaction and retained some residual intergranular pores. The pore types in the Shanxi Formation sandstone are all secondary pores, while secondary pores in the Taiyuan Formation sandstone account for approximately 90%. The results can be beneficial for tight gas production in the study area and similar basins.
Highlights
Tight sandstones have great development potential within coal measures on the eastern margin of the Ordos Basin [1, 2]
The porosity and permeability of tight sandstone were quantitatively analyzed by an E-HYFZ-00062 Autopore IV 9500 high-pressure mercury injection experiment, and the pore structure characteristics of tight sandstone were inferred by testing the displacement pressure (Pd), maximum pore throat radius, withdrawal efficiency, porosity, and permeability, and other data [22]
Through the microscopic observation of the sandstone samples in the study area, it is found that the pore type of the coal-bearing sandstone reservoir in the study area is dominated by secondary pores and contains a small number of primary pores (Figure 5)
Summary
Tight sandstones have great development potential within coal measures on the eastern margin of the Ordos Basin [1, 2]. Even though all coal-bearing formations show potential tight gas production layers, their sedimentary environments are different [3]. The sandstones have different pore structures influenced by both the sedimentary environment and complex diagenetic processes [6]. The diagenetic evolution process is mainly influenced by the original clastic particle composition, sedimentary environment, geological fluid, stratum temperature, pressure, basin tectonic setting, and sedimentary burial process, which reflects the long geological process of interaction between inorganic minerals and organic matter [13, 14]. Diagenesis mainly includes compaction (mechanical compaction and chemical compaction), cementation, dissolution, metasomatism, recrystallization, and mineral polymorphism, in which compaction, cementation, and dissolution are of great significance in the process of reservoir physical transformation [15,16,17]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
