Wushenqi Gas Field Of Ordos Basin Sub In Box 8 Of The Shihezi Formation Permian Sandstone Sedimentary Facies And Reservoir Research

According investigate-research and cores observation and analysis of 18 wells in research area, research for the sedimentary characters of the surrounding of research area, we think the bottom of Shihezi Formation (bottom of the lower part of Member 8) with Shanxi Formation are non-sequence. We also think the facie of the "Luo Tuobo" sandstones in the middle and underside is bank-bar, the upside is swamp or swamp nipped with little river through the characters of lithologic character, profiles, sedimentary structures and bore logs and distribution of sandstones. In the basic of these, we detailedly research the unfolding rules of the sandstones in the longitudinal and transverse direction, and come up with rational mode of deposition.These are main a kind of quartzarenite sandstones and partly are thin bedded lithic sandstones. Reservoir is main quartz sandstone with silicon, lithic quartz-sandstone or with kaolin and silicon which are with high compositional and textural maturity. The reservoir with bad physical property is always low-porosity and low-permeability, individual is middle-porosity and low-permeability. The types of pores are mixed pore with remnants primary pore and secondary pore. So the reservoir pore texture is less. The CP curve is divided into I, II, III, IV types according to its form, SK, selecting, throat size, R50, Pc, Pc₅₀ and Smin. The reservoir is divided into four types and transition types according to parameters of physical property and characters of mercury penetration. Wu Shenqi gas field main are middle reservoirs that are II -III and III types, occasional develops good reservoirs.The sandstones of researches are low-porosity and low-permeability, exceptional is middle-porosity and low-permeability because of multiphase and intense diagenesis according to many thin sections and SEM analysis. The diagenesis all destroy the pores except feldspar corrosion increasing 0.3～0.5% porosity. The main diagenesis take turns as follow: compaction-secondary growth of early clastic quartz (the first silicon cementation) -chlorite rim cementation (the first chlorite cementation)-the quartz and kaolin after feldspars corrosion insufficiently fill into moldic pores of feldspars and remnants primary pores-"gelatinous" chlorites filling or insufficient filling in residual pores (the secondary chlorite cementation). In the basic of these researches we divide the diagenesis.We analyze the factors of reservoir develop on the basis of primeval sediments, deposition, diagenesis. According to expert marking we classify and appraise the sandstones reservoir based on sandstone thickness, effective thickness, porosity, permeability, gas saturation and absolute open flow of gas during reservoir testing. The most favorable areas (the I type ) of reservoir development are Shaan 232 well-Shaan 240 well-Shaan 191 well, Shaan 145 well-G6-9 well -G7-11 well, G7-3 well, Shaan 147 well and G23-4 well-Shaan 2 well, the II, III type reservoirs basically surround the I type reservoirs.