Reservoir Evaluation of Sand-conglomerate Reservoir Based on Peteophysical Facies: A case study on Bai 2 reservoir in the Ma131 region, Junggar Basin

Key words: 
• petrophysical facies /
• diagenetic facies /
• sedimentary facies /
• reservoir evaluation /
• Junggar Basin /
• Triassic Baikouquan Formation

Abstract: The petroleum exploration of Junggar Basin shows that there exist serious heterogeneity in Bai 2 reservoir of Mabei region, and it is necessary to identify the types of reservoir in consideration of a mass of geological factors that influence reservoir quality. Using core observation, thin section, logging and drilling data, physical property data, CT data, etc., the sedimentary facies, diagenetic facies and fracture facies of the Upper Triassic Baikouquan Formation Member 2 (Bai 2) reservoir in the Ma 131 region were studied. On this basis, the petrophysical faices of Bai 2 layers were examined to evaluate the pore structure by classification and predict zones with high porosity and permeability. The petrophysical facies were divided according to the superposition and combination of sedimentary facies, diagenetic facies. A number of petrophysical facies of Bai 2 layers such as underwater distributary channel, dissolution of unstable components, were identified in this way. Three main categories of petrophysical facies were summed up according to the constructive and destructive impact of sedimentary facies, diagenetic facies on the reservoir property and pore structure of Bai 2 layers. According to three petrophysical facies, the reservoir of Bai 2 can be divided into three categories. Based on mercury injection data, casting thin section, CT data and oil capacity data, reservoir of each categories was characterized and evaluated. At last, the horizontal distribution of different petrophysical facies were mapped, and it can be used to predict the beneficial zones.