The Researches On Reservoir Diagenetic Characters And Controlling Factors Of Petrophysical Property In Mesozoic At Hongshanzui Area

Hongshanzui area in western Junggar Basin has a long prospective history, but the basically geological work is less and there are still questions in geological reservoir, such as, reservoir lithology features, pore texture and petrophysical property; the type, stage as well as the sequences of the diagenesis is not systemically enough; and the controlling factors of petrophysical property is not rather clear. Under the guidance of sedimentology and reservoir geology theories, taking advantage of slice, mercury injection and others geochemistry data and combining outcrop observation, drilling core and logging resources, this paper deeply researched the sedimentary facies, diagenesis,reservoir characteristics and controlling factors. At the end, it predicts the favorable perspective target areas.By means of outcrop, drilling core, slice, cathodoluminescence, SEM and vitrinite reflectance, reservoir lithology features and diagenesis is researched in detail. In this area, the componential and textural maturity is lower and the lithological types are mostly Arkoses, lithic arkoses and feldspar litharenite.Diagenesis types: compaction, cementation, silty filling, dissolution and metasomatism. The former two functions are the main reasons of decreasing reservoir quality.The diagenetic sequence as follows:mechanic compaction→authigenic chlorite clay rim→the dissolve of felspar→quartz overgrowths-latter calcite cementation→calcite Metasomatism→feldspar overgrowths→Hydrocarbon Emplacement(eg.Qigu Formation). According to the stage of the diagenesis, the sand reservoir in lower and upper Ke Formation in Jurassic and the Ba daowan and Qigu Formation in Cretaceous are at late phrase A. Less Jurassic reservoir is early phase B (especially, the Qigu Formation).Base on research results of fore two items, refer to data of porosity, permeability and mercury penetration and so on. Study on features of physical property and pore texture in the areas, and apply the evaluation scheme of reservoir classification that is adapting for these areas, classify and evaluate the reservoir in the areas. The physical property of Mesozoic's reservoirs are preferable generally which belong to Hongshanzui areas, the origin intergranular porosity and intergranular corroded hollow develop considerably in sands, intragranular corroded hollow is common too, considering conditions of reservoir are best which are in series of Qigu of Jurassic in the areas, I and II types are main reservoir types.Through studying features of reservoir and diagenism systematically, according to profiting facies belt distribution of sediment microfacies, porosity's distribution on the plane and discoveried oil area of region of interest which used evaluating and predicting, predicted beneficial target area in series of Kexia and Keshang of Triassic, series of Badaowan of Jurassic each one, and there are three beneficial target areas in series of Qigu, which are major block of exploration disposition in next step.