Analysis On Controlling Factors And Characteristics Of Chang6Reservoir Of Yanchang Formation In Triassic Of Yong152Well Block Of Zhidan

Yongning of southern Zhidan oil field located in central-southern North Shaanxi slope in Ordos basin, formation is a pour sloping in the west as a whole, develop some low amplitude nose fold structures. The paper aim at Chang6reservoir group of Yanchang formation in Triassic, used theory of sedimentology, oil geology, and reservoir geology and logging, with drill, and logging, rock logging, and well test and producing test data, and combination with multiple test method and the analysis means, researched formation, structure, characteristic of reservoir with type and distribution of micro-facies. The research shows that Chang6is Delta front deposition that divided into facies of distributary channel, shunt Bay, mouth bar and distal bar.The research indicates that lithology of Chang6reservoirs are mainly powder to fine grain, fine grain arcose sandstone with low compositional maturity and higher textural maturity. Chang6reservoirs experience strong diagenesis that included machinery compaction pressure solution, cementation, filling, and dissolution, metasomatosis and deposition of authigenic clay mineral, reached into "A" stage of late diagenesis period at least, are typica reservoir with low-porosity and ultra low permeability. Pore type main with residua intergranular pore, secondary intergranular dissolved pore, secondary intragranular dissolvec pore, moldic pore and dissolved pore within the interstitial matter. Pore size is main middle and small pore, pore throat with fine and micro-throat mainly. Chang6reservoirs are classified and evaluated by the above data. hydrocarbon accumulation is controlled by sandstone body, porosity and microstructural of reservoir in Yongning area.