柴达木盆地跃进地区E3^1、N1、N2^1碎屑岩储层特征

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

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、N2 1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 。

More attention has been paid to the report of hydrocarbon from E 3 1、N 1、N 2 1 clastic rock reservoir in Yuejin area, Qaidam basin, northernwest China. Based on research of approximate one hundred cast thin sections and mercury intrusion curve from 15 wells, some results on E 3 1,N 1,N 2 1 clastic rock reservoir in Yuejin area have been obtained as follows:① The clastic rock reservoir was composed of feldspathic sandstone,lithic arkose and feldspathic litharenite which is characterized by lower composition and texture maturity, ② The clastic rock reservoir has undergone compaction,pressure dissolution,authigene (ferroan calcite,dolomite,anhydrite,euthalite,ferroan dolomite pyrite) cementation and dissolution, which results in the forming of overwhelming relic primary intergranular pore. Correlatable beds from eastern Yuejin and western Yuejin have different diagenetic porosity evolution because of their different burial depths, which results in a more favourable reservoir in western Yuejin than in eastern Yuejin,③ E 3 1,N 1,N 2 1 clastic rock reservoir developed under distributary channel,sand flat and braided channel microfacies. Reservoir quality was controlled by composition and texture maturity, matrix material and diagenetic environment(depth especially),④ E 3 1 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 combination of large pore fine throat, while E 3 1 clastic rock reservoir from eastern Yuejin did large and medium pore, Ⅴ grade(very low porosity ( very low permeability) in reservoir quality and a combination of medium pore very fine throat. N 1 clastic rock reservoir in Yuejin 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.