Research On Sedimentary Facies And Reservoir Of Shanxi Formation In The Western Region Of Yanchang Gas Field

The western region of Yanchang exploration area is located in mid-western the Shanbei slope of the Ordos Basin. The exploration in recent years shows that the upper paleoioic of area is of great exploration potential. On the basis of previous studies.according to the available area data,Based on the sedimentology,sequence stratigraphy.reservoir geology and other theories.This paper researches in the sedimentary fades analysis and reservoir study which provided scientific basis for later exploration and well spacing.exploration. The conclusions are as follows:Shanxi Formation rock types in the study area mainly in clastic rocks, there are sandstone, siltstone, mudstone, carbonaceous mudstone and coal.Sedimentary facies in the study area mainly developed delta facies, Especially the front delta deposition is the most important which is the main reservoir of reservoir group. Local area development is lake.The study area of Shanxi formation is mainly ithic quartz sandstone and lithic. less content quartz sandstone. The composition and structure maturity are higher. Sandstone cementation very density, porosity is not developed. Debris dissolution pore and micro fracture is the main. In the area of porosity distribution in the 0,69% to 15.49% range, the average value is 5.40%,the permeability distribution in 0.004 ?56.415x10°|irr T in the range of 0.401 x?Cr3|im2?average value, sandstone gas reservoir is of low porosity?low permeability.The study area of shanxi formation sandstone reservoir performance is p o o r. M a i n l y f o r I I I, T V r e s e r v o i r a n d I I I c l a s s e s m o r e I V r e s e r v o i r i n h i g h f r e q u e n c y, I. I I reservoir with low frequency.