塔里木盆地巴楚—麦盖提地区泥盆系储层特征及影响因素

Reservoir characteristics and influencing factors Devonian in Bachu--Maigaiti area,Tarim Basin

通过钻井岩芯、岩石薄片及铸体薄片观察,结合压汞分析等手段,分析了塔里木盆地巴楚—麦盖提地区泥盆系储层岩石学特征及物性演化特征。研究结果表明:泥盆系储层岩性以石英砂岩、岩屑石英砂岩为主。泥盆系东河塘组沉积环境为滨岸沉积,前滨滩砂物性最好,原生孔隙发育,属于特低孔特低渗储层;克孜尔塔格组为三角洲--潮坪沉积,以水上分流河道砂体物性最好,次生孔隙发育,属于特低孔特低渗--低孔低渗储层。储层砂体中压实作用、硅质胶结作用十分普遍,硅质胶结多以加大边形式存在;碳酸盐胶结在储层中相对发育,充填于岩石孔隙或交代其他碎屑颗粒,降低储层孔隙度与渗透率,表现为破坏性成岩作用;溶解作用对储层影响较大,有助于提高储层物性,表现为建设性成岩作用。

Based on the observation of drilling cores,petrographic slides,cast slides and measurement of mercury intrusion porosimetry,the petrological characteristics and physical property evolution of the Devonian reservoirs in Bachu-Maigaiti area of Tarim Basin have been studied.The results show that the reservoir rocks mainly consist of quartz sandstones and lithic quartz sandstones.The Devonian Donghetang Formation was deposited in a littoral sedimenrary environment.The foreshore sands,developed in primary porosity,have the best reservoir physical properties with the ultra-low porosity and ultra-low permeability.The Devonian Kerziertag Formation was deposited in a deltaic-tidal flat sedimenrary environment.The distributary channel sands are shown as ultra-low porosity and ultra-low permeability,or low porosity and low permeability reservoirs because of well-developed secondary porosity.Compaction and siliceous cementation are ubiquitous in reservoir sands,and the latter one is often shown as overgrowth quartzes.Carbonate cementation is relatively common in the reservoirs,filling pore spaces or experiencing metasomatism with other clastic grains.Such cementation serves to decrease the reservoir porosity and permeability,therefore shown as destructive diagenesis.Dissolution significantly impacts reservoirs by improving their physical properties,shown as constructive diagenesis.