准噶尔盆地阜东斜坡区侏罗系石树沟群储层主控因素

Main Controlling Factors of Reservoirs of Jurassic Shishugou Formation in Fudong Slope,Junggar Basin

综合岩心观察、薄片鉴定、测井、录井、分析化验等资料,查明了准噶尔盆地阜东斜坡区侏罗系石树沟群储层的主要特征:以较低成熟度的细粒—细中粒长石岩屑砂岩为主,岩屑砂岩为辅,方解石胶结物较发育,存在5种成岩相;不同层段、不同区块储层的物性不同,其中齐古组主要为中孔中渗型储层,头屯河组以中孔低渗型储层为主,局部发育中孔中渗型以及低孔低渗型储层。在此基础上,总结了储层主控因素:压实作用造成了储层物性明显的不可逆性降低;沉积相带是相对优质储层的主要控制因素;不同成岩相储层的物性差异较大,其中弱压实—弱胶结成岩相的储层物性最好,自生高岭石胶结成岩相的储层物性次之,含铁方解石中等—强胶结成岩相的储层物性随方解石的含量不同存在较大的变化,另外2类成岩相的储层物性最差。

Combined with materials of ore observation,thin section identification,well logging,analysis and test,we figure out the main characteristics of the Jurassic reservoirs of Shishugou Formation in Fudong slope,Junggar Basin.Fine-grained or medium-grained feldspar lithic sandstone which is a little low-maturity is primary,rock-fragment sandstone is secondary.Calcite cement develops slightly better and there are5 diagenetic facies.The properties in different members and reservoir areas are various.Qigu Formation is dominated medium-porosity and medium-permeability reservoirs;Toutunhe Formation is primarily characterized by medium-porosity and low-permeability reservoirs.There are also medium-porosity and mediumpermeability,low-porosity and low-permeability reservoirs in some place.On this basis,we concluded the main controlling factors of reservoirs.Compaction causes obvious and irreversible reduction of reservoir.Sedimentary facies are the main controlling factor of relative fine reservoirs.The reservoir properties of different diagenetic facies are various.For example,the reservoir property of weak compaction-weak cement digenesis facies is the finest,the reservoir property of authigenic kaolinite cement diagenetic facies is secondary.The reservoir property of medium-strong cement diagenetic facies including ferrocalcite varies with the proportion of ferrocalcite,and the reservoir properties of the two other diagenetic facies are the worst.