Reservoir characteristics and physical property controlling factors of Kexia Formation in WEH Oilfield, Junggar Basin

Abstract

The Kexia Formation reservoir in WEH oilfield is located at the bottom of the Triassic, which is mainly characterized as delta plain and front margin deposits. Through a comprehensive analysis of rock flake identification, scanning electron microscopy and physical properties, the petrological characteristics and the physical properties and physical property control factors of the reservoir were studied in detail. The results showed that the reservoir rock of Kexia Formation is consisted of medium-fine-grained lithic sandstone, glutenite and conglomerate, and the reservoir pore types of the reservoir space are mainly divided into intergranular pores, intergranular dissolved pores and intra-granular dissolved pores. The mercury intrusion data indicated that the reservoir throat of the Kexia Formation is featured as a medium-small pore thin throat, and the average porosity of the reservoir physical property is 17.78%, and the average permeability is 5.2mD, which suggested that it is a medium deviation reservoir with medium-low porosity and low permeability. The physical properties of the reservoir are essentially subject to the actions of sedimentation and diagenesis. The reservoir development is benefited by the distributary channel, river mouth bar and subaquatic distributary channel sedimentary environment in the delta plain and front. And the actions of compaction and cementation works as the major causes for the low permeability of reservoir, while the action of alteration serves as the basic sources of clay minerals.