扇三角洲体系沉积微相对成岩的控制作用——以辽河坳陷西部凹陷南段扇三角洲沉积体系为例

Controls of the fan-delta sedimentary microfacies on the diageneses in the south of western Liaohe Depression,Bohai Bay Basin

以辽河坳陷西部凹陷南段扇三角洲沉积体系为例,根据储集层物性、薄片镜下鉴定、铸体薄片,扫描电镜和X-衍射等分析资料,研究扇三角洲沉积体系沉积微相对成岩作用的控制作用。分析表明:从扇三角洲平原到扇三角洲前缘,矿物成分成熟度呈现递增的趋势,河口坝微相的长石砂岩最为发育;在扇三角洲各沉积微相中,河口坝砂体的溶蚀作用和次生孔隙最发育,辫状分流河道、心滩微相以机械压实作用为主,而河口坝、沼泽微相以胶结作用为主;沼泽和前扇三角洲砂体的填隙物主要为碳酸盐矿物,而河口坝、辫状分流河道、心滩砂体的填隙物主要为泥质。认为在储集层成岩作用研究和孔隙度预测中,必须考虑沉积微相的作用。

The controls of the sedimentary microfacies of fan-delta on the diageneses in the south of the western Liaohe Depression, Bohai Bay Basin are discussed by using measured porosity data, thin sections, blue epoxy resin-impregnated thin sections, SEM,and XRD. The results show that the mineral comparative maturity of sandstones increases with the distance from the fan-delta plain to the fan-delta front;of all kinds of sandstones in the fan-delta microfacies, channel mouth bars have undergone the most intensive dissolution, secondary pores are well developed, and diageneses of the braided channel and channel bar sandstones are dominated by compaction and diageneses of the channel mouth bar and marsh sandstones are dominated by cementation. The cementation materials of the sandstones in the marsh and profan-delta are mainly calcites （carbonates）, while the interstitial materials of channel mouth bar, channel bar and braided channel deposits are mainly clay. The sedimentary microfacies of the fan-delta have significant controls on the diageneses and mineral components of clastic reservoirs.