Characteristics Of The Yan’an Formation Reservoir In The Northern Zhiluo Oil Field

On the basis of the theories of petroleum geology, sedimentary petrology, geochemistry and other theories and methodologies, applied with geological outcrop, well boring, logging, production dynamic data and core analysis data as a resort to analysis subsurface picture reservoir petrologic character, microscopic reservoir pore structure characteristics, diagenesis, law of spread of sand body and sedimentary parfacies, we can evaluate the reservoir of study area.Comprehensive studies suggest that the sources direction of Yan’an formation is the NNE. The same as the direction of the river channel, this page study sedimentary features of delta front deposits, describe the character of sediment microfacies about underwater distributary channel and interdistributary in detail. Sandstone body of Yan9member is developing very well and a main oil reservoir. Sandstone body of Yan9and Yan10members are poor. Sedimentary cycle of Yan’an formation is apparent.Sandstone classification of Yan’an formation is gray, gray-green feldspar lithic quartz sandstone and lithic arkose and debris is mainly composed of quartz, feldspar, lithic, mica, low matrix contents and cement higher levels. Sandstone compositional maturity is high and medium textural maturity. Sorting and roundness is good. It main develops the Remnant intergranular porosity, intergranular dissolution porosity, interiorgranular dissolution porosity, and casting pore, of which the intergranular dissolution porosity was most common. The pore structure characteristics of Yan7-Yan8is similar with the Yan9, is a middle hole in middle larynx and holes, small holes and medium-si zed throat primarily. The average values of porosity of Yan7-Yan8is16.58%, and average values of reservoir permeability is40.16×10-3μm2; The average values of porosity of Yan9is17,18%, and average values of reservoir permeability is47.35×10-3μm2, belong to the middle porosiy, low permeability resevir. The Because of bigger granulanrity, the physical of Yan10is best among Yan10-Yan7, and physical property of Yan8is worst. The study area development of main Ⅱ、Ⅲ resrrvoir, distributed in channel sang body, the general for effective reservoir. Reservoid only in the local area in the development. Reservoir Ⅲ is mainly distributed in channel sand body of edge. Reservoir Ⅳ is mainly distributed in interdistributary.