Research On Sedimentary Facies And Reservoir Of Benxi Formation In The Eastern Region Of Yanchang Gas Field

After extended exploration area of Benxi Formation sedimentary characteristics in a comprehensive study of the identified beach barrier sedimentary system and shelf depositional system, and further divided into sand flat, mixed flat, mud flat, marl flat, lagoon mud, muddy continental shelf seven sedimentary microfacies. Barrier sand bar of the main sand dam was North East South Distribution and small sand dam is scattered; sand flat is NNW-SSE distribution.To support is basically similar to the study area 2 period and the period of the sandstone type, mainly quartz sandstone, followed by lithic quartz sandstone also showed a small amount of lithic sandstone. Sandstone detrital quartz, lithic feldspar content is extremely low, the interstitial cements, impurity content is low, the cements to kaolinite, followed by calcite and silica. Tight sandstone, compositional maturity and structural maturity are higher, the separation medium, rounded sub angular time circle. Between the particles bump contact or mosaic contact, particle cement pore cementation and regeneration of pore cementation. The barrier island and sand flat quartz sandstone property is good.In the study area, the main development zone and type III reservoir are developed, and the high permeability zone and the high porosity zone are combined with the characteristics of high permeability zone and the well logging data.