The Research On Reservoir Characteristics And Its Preliminary Geochemical Geneses Of The Shan₂～3 And He₈ Member In Upper Paleozoic Of Zizhou-Qingjian

Ordos Basin is a polycyclic superposition basin that is formed in an earlier geological history and has experienced a longer evolution. It possesses abundant oil and gas resources and has bright prospects in oil and gas exploration. It has been becoming one of the important tactical areas in oil and gas exploration in China. The amount of oil-gas resources and the degree which is proven up will directly influence the Chinese petroleum industry.According to theory of multidisciplines, the reservoir characteristics and its preliminary geochemical geneses of the Shan₂³ and He₈ Member in Upper Paleozoic of Zizhou-Qingjian have been studied by means of the combination macroexamination with microexamination and regional with well data as well as the investigation in the field with research indoors. The research as follows that Shan₂³ Member is meandering stream delta facies, Heg and Heg are both braided stream delta facies. Main reservoir bodies include the subaqueous distributary channel sandbodies of the meandering stream delta, braided stream delta front and beach sandstones.The research shows that Shan₂³, main reservoir rock type is quartzose standstone, that of He₈¹, is lithic sandstone and Heg₈², rock type is nearly single lithic sandstone. What's more, the maturation of composition and texture in Shan₂³ is much better than that of in Heg. Those rocks have experienced diagenesis of mechanical compaction, cementation, metasomasis and dissolution. Based on synthesis analyses of autogenous minerals associations and clay minerals transform and pore types as well as evolution of organic matter etc, the Shan₂³ and Heg Member have already entered into the latediagenesis A subage and most have reached the late diagenesis B subage.Geochemical variation strongly controls the Shan23 and Heg Member' lithogenesis and pore evolution in Zizhou-Qingjian. Carbonate and siliceous and authigenic clay cementation, carbonate authigenic clay metasomatism, feldspthic and carbonate corrosion are typical and major diagenesis which is great influenced by geochemical variation. The mechanical compaction and cementation are major factors to make reservoir to lose porosity. The dissolution playing an important role to improve reservoir quality is favorable for secondary pores.The formation of secondary pore contributes to feldspthic and carbonate corrosion as well as dehydration reaction of clay mineral, resulting of CO2 and organic acid, providing by inorganic diagenesis and organic thermal mature evolution, corroding soluble components. The dissolution of aluminosilicate and carbonate cement result in organic acid contributed by kerogen before or during it's mature stage in the source rocks and coal seams nearby, and that of silica is straightly related with alkali water in the pores. Secondary pore in Shan23 are much more than those in Heg and Heg1 is more than Heg2.In another hand, high value of porosity and permeability in Shan23 having rough pore and tunnels is usually closed to the paleochannel sandbodies, high value of porosity with low value of permeability in Heg having slim pore and tunnels represents tight reservoir.On the studying basis of depositional facies belt and sandstone body distribution with the reservoir quality as well as logging, porosity, permeability and so on, the most gas-producting favorable blocks include Yu30-Drill^Yu55-Drill, Yu29-Drill, Yu69-Drill and the more gas-producting favorable blocks include Yu68-Drill Yu48-Drill, Yu40-Drill, Pu2-Drill^Yu69-Drill.