Analysis Of The Controlling Factors Of Reservoir Forming Of Chang-9& Chang-10 Reservoir In Wuqi-ansai Area

The oil-bearing formations of Chang-9&Chang-10 belong to the typical low permeability sandstone lithologic oil reservior. With the increasing investment of exploration and exploitation,a certain amont of controlled reserves and recoverable reserves have been discovered.For the controlling factors and regularity of oil enrichment are still not clear enough,it leads to the serious impact for further exploration and exploitation in Wuqi-Ansai oil field.Therefore,the research of the controlling factors of reservoir forming should be systematically promoted.Based on the result of pre-author research and made full use of logging, core observation, casting lamella, mercury penetration, nuclear magnetic resonance, carbon and oxygen isotopes, nitrogen compounds, fluid inclusion and a series of well test materials, this paper systematically analyzes the controlling factors of Chang-9 and Chang-10 reservoirs. The study concludes that the Chang-91 reservoir belongs to delta front subfacies,the Chang-92 and Chang-101 reservoirs develop delta plain subfacies, and the most favorable reservoirs of the study area are Chang-91 and Chang-101. Chang-91 belongs to small pore with fine throat and high porosity-low permeability reservoir, and Chang-101 belongs to small pore with microthroat and low porosity- high permeability reservoir.The hydrocarbons of Chang-91 come from contiguous "Lijiapan shale",which depends on the divert fracture and pore system.The hydrocarbons of Chang-101 stem from high resistance mudstone in southwestward of the study area, oil-source migrate along the synsedimentary and deposit faults and sand body, and gathered in structure-lithological trap and diagenetic traps.Chang-9 belongs to tight oil reservoir, and Chang-10 belongs to structural and lithological reservoir.The mainly controlling factors of reservoir forming of Chang-91 is hydrocarbon generating potential and reservoir property, and the favorable reservoirs of Chang-91 located in the midwest of the study area.The mainly controlling factors of reservoir forming of Chang-101 is hydrocarbon properties, sand body properties and connectivity, nose structure and the distribution of diagenetic traps, and the favorable reservoirs of Chang-101 located in the northwest of the study area, which is developed diagenetic traps.