准噶尔盆地深层—超深层致密碎屑岩储层特征及有效储层成因

Characteristics and effective reservoir genesis of deep to ultra-deeptight clastic reservoir of Junggar basin,NW China

为明确准噶尔盆地深层—超深层致密碎屑岩储层特征及有效储层成因,利用60余口关键探井岩芯、录测井、薄片及化验等各项分析、鉴定数据和资料,对其储层基本特征和物性特征研究和分析,明确储层类型、特征、质量及有效储层成因。结果表明:储层以三角洲分流河道砂体为主,分为砾岩和砂岩两大类,为典型低—特低孔、低—特低渗致密碎屑岩储层;砾岩以中砾岩为主,砾石成分主要为凝灰岩,砂岩岩屑含量高,岩性以细粒、中—细粒岩屑类砂岩为主,岩屑主要为凝灰岩,成分成熟度较低;胶结物以碳酸盐和硅质为主,局部富集浊沸石和钠长石;成岩作用主要包括破坏型的压实、压溶和胶结作用及建设型的溶蚀作用。孔隙垂向变化可分为南部原生孔隙型和北部次生孔隙型两类,次生孔隙型又分为长石类溶蚀型和沸石类溶蚀型两种,二者在不同区块和埋深范围分别发育数目不同的次生孔隙带。有利相带、溶蚀作用和异常高压共同形成了有效储层。

In order to clarify the characteristics and effective reservoir genesis of deep to ultra-deep tight clastic reservoir in Junggar basin,the basic characteristics and physical properties of reservoir are studied using the analysis and identification data of core,logging,thin section and laboratory tests of more than 60 key exploration wells,so as to determine the reservoir type,characteristics,quality and effective reservoir genesis.The results show that the reservoir is mainly delta distributary channel sandbody,which can be divided into conglomerate and sandstone.It is the typical low ultra-low porosity and permeability tight clastic reservoir.The conglomerates are mainly medium conglomerates,and the gravel is mainly tuff.The content of sandstone cuttings is high.The lithology is mainly fine-grained,medium fine-grained lithic sandstone,and the cuttings are mainly tuff with low maturity.The cement is mainly carbonate and siliceous,locally enriched in laumontite and albite.Diagenesis mainly includes destructive compaction,pressure solution and cementation,and constructive dissolution.The vertical variation of pores can be divided into two types:primary pore type in the south and secondary pore type in the north.The secondary pore type can further be divided into two types i.e.,formed by feldspar dissolution and zeolite dissolution.The two types have different numbers of secondary pore zones in different blocks and buried depths.Favorable facies,dissolution and abnormal high pressure formed effective reservoirs.