Reservoir characteristics and controlling factors of Permian glutenite in Northern Zhongghai uplift, Junggar Basin, China

Abstract

The Permian Sandstone is well preserved in the Junggar Basin, China. It is consisting of fine to medium sandstone with interbedded shale. The present study is focused on to evaluate the reservoir characteristics and controlling factors of the Permian sandstone of Jinlong 51 well, Junggar basin, China. To fulfil the objectives of the current study, geological field, petrographic analysis, SEM, analysis, mercury injection capillary pressure, and progressed geochemical analysis has been used to evaluate the characteristics and diagenetic history of the Permian sandstone to evaluate its potential. Thin section analysis shows that rock comprises of medium to fine-grained lithic sandstone, and glutenite. Pores are primary isolated into intergranular pores, intergranular pores and intra granular pores. The SEM analysis reveals that the major diagenesis types are compaction, cementation, dissolution, and fractures. Rock is moderately compacted, with intermediate cementation as well as feldspar, rock fragment and carbonate cement dissolution. According to core NMR analysis evaluated as low porosity, low permeability of the reservoirs, some of them are low porosity and low permeability reservoirs. The mercury injection capillary pressure shows that pore throat is intermediate pores with moderate pore throat. Permian sandstone consisting of average porosity 17.8% and permeability is from 5.2 to 8 mD, which recommended that the studied formation consisting of moderate reservoir characteristics. Compaction, cementation and fractures fills with clastic material decreases, whereas primary intergranular pores, dissolution pores and fractures increases the reservoir quality. Finally, the impact of diagenesis on the physical properties of the reservoirs under study has been investigated, the compactions and cementation along with other constrains effect the porosity as well as permeability of the glutenite reservoirs.