Diagenesis Of Upper Es₄ In Wangjiagang Area Of Dongying Depression

The beach bar reservoir of Upper Es4 in Wangjiagang Area is low porosity and low permeability reservoir. Because of the strong heterogeneity and the complexity of oil distribution, the exploration and development is very difficult. To find out the rule of the oil and gas distribution, basic geology study should be carried out firstly and detailed reservoir characterization is needed.Based on core analysis, ordinary sheet, cast sheet, scanning electron microscopy and clay minerals analysis, lithologic characteristics, pore characteristics and diagenesis characteristics were studied with the integration of geochemical marks, well logging, testing, production test and so on. And then, preliminary reservoir evaluation was made.In the study area, the main rock types are syrosem-feldspar find sandstone containing coarse silty, feldspar packsand-coarse-silty sandstone and argillaceous-fine silty sandstone. The main diagenesis types are compaction, carbonate cementation and dissolution of feldspar and carbonate. The reservoir has experienced diagenetic evolution sequence of acidic and alkaline environments alternation. The diagenetic stage is early diagenetic phase B and middle diagenetic subphase A1. Based on above analysis, five types of diagenetic facies are recognized in this area, including moderate compaction-feeble cementation-powerful dissolution face, powerful compaction-feeble cementation-moderate dissolution face, powerful cementation face-powerful compaction-feeble cementation face.The main storage space types are fracture and secondary porosity. The secondary porosity developed from the dissolution of feldspar and carbonate. Based on the sedimentary facies, physical property and diagenesis, preliminary reservoir evaluation is made and the reservoir is divided into three categories. Typeâ…¡is the most widely distributed reservoir type in the three..