辫状河三角洲水下分流河道储层特征

以海安南地区堡1断块泰州组一段为例，在岩石薄片和压汞资料分析的基础上，从砂体的内部结构入手对水下分流河道储层特征进行了研究，将泰一段储层的孔隙结构划分为三种类型。经研究表明：泰一段辫状河三角洲前缘水下分流河道砂体内部结构单元为典型的中一低孔、中一低渗储层，碎屑组份成分成熟度和结构成熟度均较低，储层孔隙类型以次生孔隙为主，原生孔隙较不发育；填隙物为泥质杂基和碳酸盐矿物胶结物，属长石岩屑质砂岩和岩屑长石质砂岩；成岩作用主要发育压实作用、胶结交代作用和溶解溶蚀作用等，塑性颗粒的变形、碎屑颗粒的破裂甚至错断、石英次生加大、方解石及铁白云石交代碎屑组份、溶蚀现象等均较普遍。对各结构单元孔隙结构类型参数分析表明，水下分流河道内部结构单元河道主体砂岩储集性能好于河道侧缘，认为岩相类型和沉积环境是影响储层物性的原生因素。

Sandstone reservoir characteristics of braided river delta underwater distributary channel

On the basis of analysis of rock sections and mercury injection curves, etc. A study is given on the reservoir characteristics of underwater distributary channel in member 1 of Taizhou, formation from internal structure of sand body in baol fault block of the south of Haian area, and three types of the reservoir pore structures are presented. The studies show that the architecture element of underwater distributary channel sandstone of braided delta front in baol fault block is reser- voir with middle--low porosity and permeability The compositional maturity and the textural maturity are low in this area. the pores of the reservoir are mostly secondary pores and few primary pores. Interstitial materials are mudstone matrix and carbonate cements, and the lithology is feldspathic lithic arenite and litharenite. The main diagenesis types are compaction, cementation and replacement, corrosion and dissolution. The deformation of ductile grain, detrital grainfracture even fault, secondary origin quartz, ankerite and calcite cementation and corrosion are the common appearances, the analyses of pore structure characteristic parameter of each architecture element show that the reservoir properties of underwater distributary channel main body is better than those of channel side body. lithofacies and sedimentary environment are major primary fac- tors that affect reservoir quality.