A Research on E₃^l N_l N₂^l Clastic Rock Reservoir in Yuejin Area,Oaidam Basin,Northwest China

Key words: 
• Qaidam Basin /
• Yuejin area /
• diagenesis /
• porosity evoiution /
• pore and throat combination

Abstract: More attention has been paid to the report of hvdrocarhon from E₃¹、N₁、N₂¹ clastic rock reservoir in Yucjin area Qaidam hasin, northcrnwcst China. Based on research of approximate one hundred cast thin sections and mcrcurv intrusion curve from 15 wells, some results on E₃¹、N₁、N₂¹ elastic rock reservoir in Yuejin area have been obtained.as follows:①The elastic rock reservoir was composed of fcldspathic sandstone } lithic arkosc and fcldspathic litharcnitc which is characterized by lower composition and texture maturity②The elastic rock reservoir has undergone compaction, pressure dissolution, authigcnc(fcrroan calcite, dolomite, anhydrite, cuthalitc, fcrroan dolomite pyrite ) ccmcntation and dissolution, which results in the forming of overwhelming relic primary intcrgranular pore.Corrclatahlc beds from eastern Yucjin and western Yucjin have different diagcnctic-porosity evolution because of their different burial depths which results in a more favourable reservoir in western Yucjin than in eastern Yuejin,③E₃¹、N₁、N₂¹ elastic rock reservoir developed under distrihutarv channel sand flat and braided channel microfacics.Reservoir quality was controlled by composition and texture maturity, matrix material and diagcnctic environment}depth especially),④E₃, elastic rock reservoir from western Yucjin characterized by very large, large and medium pore,Ⅱ-grade( high porosity and medium permeability ) in reservoir quality and a combination of large porefine throat while E₃ elastic rock reservoir from eastern Yucjin did large and medium pore,Ⅴ-graded (very low porosity(very low permeability) in reservoir quality and a combination of medium pore-very fine throat. N₁ elastic rock reservoir in Yucjin area characterized by very large large and medium pore,Ⅳ-andⅤ-grade( low porosity and very low permeability) in reservoir quality and a combination of large pore-very fine throat.