Abstract:

Based on the data of cast slice, SEM, X-ray and normal physical properties, this paper studied the reservoir rock types, diageneses characteristics and reservoir space types of Xujiahe Formation in Woxinshuang area, and analyzed the impact of different diagenese on the reservoir. The result shows that the reservoir lithology is mainly feldspathic litharenite and lithic sandstone with the characteristics of low compositional maturity and medium-high textural maturity, and the provenance is proximal and rapidly accumulated. The sandstone in the study area experienced six diageneses: compaction-pressure solution, cementation, dissolution, replacement, fracturing and authigenic mineral filling. The intensely compaction-pressure solution, calcite cementation and authigenic mineral filling are the main reasons for the degradation of reservoir porosity and permeability and densification. The chlorite rim cementation is the main cause for the preservation of some primary intergranular pores. Dissolution to a certain extent, improves the reservoir performance. Fracturing is more effective for communicating the primary pores and secondary pores, and greatly improves the reservoir permeability. Xujiahe Formation in Woxinshuang area mainly developed fractured-porous type and extra-low porosity and ultra-low permeability reservoir. The reservoir porosity and permeability is poorly correlated in whole, but with the porosity getting higher, the correlation between porosity and permeability is gradually getting better. The Woxinshuang area has favorable conditions for oil and gas accumulation and has a certain exploration and development potential.

Key words: shale gas, total organic carbon, BP neural network, natural gamma ray spectrum, kerogen