柴达木盆地跃进地区E31、N1、N21碎屑岩储层特征

通过 15口井近百个铸体片的鉴定及压汞数据的分析,对跃进地区E₃1、N₁、N₂1碎屑岩储层取得如下认识 :①长石砂岩、岩屑长石砂岩、长石岩屑砂岩为主,成分成熟度和结构成熟度均较低;②储层经历压实压溶作用、成岩自生矿物胶结和溶解作用,剩余原生粒间孔占绝对优势,相同层位地层在跃东和跃西因埋藏深度不同导致成岩-孔隙演化史也不同,西区储层物性明显优于东区;③储层主要发育于水上分流河道、砂坪和辫状河道微相,碎屑的成份和结构成熟度、填隙物含量、成岩环境对储层性质有重要影响;④西区E₃1储层属高孔中渗的Ⅱ类储层,大孔细喉道组合特征,储集物性较佳,东区E₃1储层属特低孔特低渗的Ⅴ类储层,中孔微细喉道组合特征,储层物性不理想,N₁储层属低孔特低渗的Ⅳ-Ⅴ类储层,大孔小喉道组合特征,渗透率不佳.

A Research on E31 N1 N21 Clastic Rock Reservoir in Yuejin Area, Qaidam Basin, Northwest China

More attention has been paid to the report of hydrocarbon from E31、N1、N 21 clastic rock reservoir in Yuejin area, Qaidam basin, northernwest China. Based on res earch of approximate one hundred cast thin sections and mercury intrusion curve from 15 wells, some results on E31,N1,N21 clastic rock reservoir in Yuejin are a have been obtained as follows:① The clastic rock reservoir was composed of f el dspathic sandstone,lithic arkose and feldspathic litharenite which is characte riz ed by lower composition and texture maturity， ② The clastic rock reservoir has unde rgone compaction,pressure dissolution,authigene (ferroan calcite,dolomite,anhydr ite,euthalite,ferroan dolomite pyrite) cementation and dissolution, which re sults in the forming of overwhelming relic primary intergranular pore. Correlata ble beds from eastern Yuejin and western Yuejin have different diagenetic-por osity evolution because of their different burial depths, which results in a more fav ourable reservoir in western Yuejin than in eastern Yuejin，③ E31,N1, N21 clasti c rock reservoir developed under distributary channel,sand flat and braided ch annel microfacies. Reservoir quality was controlled by composition and texture matu rity, matrix material and diagenetic environment(depth especially)，④　E31 clastic rock reservoir from western Yuejin characterized by very large,large and medium pore, Ⅱ-grade(high porosity and medium permeability) in reservoir quality and a c ombination of large pore-fine throat, while E31 clastic rock reservoir fro m east ern Yuejin did large and medium pore, Ⅴ-grade(very low porosity ( very low pe rmea bility) in reservoir quality and a combination of medium pore-very fine throat . N1 clastic rock reservoir in Yuejin area characterized by very large,large and medium pore, Ⅳ- andⅤ-grade(low porosity and very low permeability) in reservo ir quality and a combination of large pore-very fine throat.