Sedimentary Facies And Favorable Reservoir Distribution Of 1 Oil Group Of Sha 3’s Upper Member In The Dawangzhuang Oilfield

Dawangzhuang oilfield belongs to the Dawangzhuang-Lioxi fault structural belt in Raoyang Sag,Jizhong Depression.It is a large monoclinal structure with northwest dip,southeast lift and northeastward strike,and the dip Angle is large at the bottom but small at the top.The Paleogene 1 oil group of Sha 3’s upper member in Dawangzhuang Oilfield is the target interval of this study.The formation is a set of sedimentary rocks mixed with sand,mudstone and carbonate rocks.The results of oil test and production show that the carbonate beach bar reservoir is a favorable reservoir with high productivity in this area.The clastic sandstone reservoir is poor in physical property,mostly water layer or dry layer.It is difficult to distinguish sandstone from carbonate rock and the distribution range of favorable carbonate beach bar reservoir is not clear.In addition,the reservoir is controlled by lithology and structure,so the resistivity of oil-water reservoir varies greatly,and the phenomenon of high water and low oil exists.The law of oil-water accumulation also needs to be re-recognized.In this study,data such as rock composition,physical property analysis,logging,logging and oil test and production were collected,and core observation and description,sedimentary facies,lithology identification,reservoir physical property interpretation,favorable reservoir distribution and oil-water distribution law were carried out,providing a basis for finding favorable reservoirs and improving the effect of oil exploration and development.The results show that:(1)the provenings come from the Xinhe uplift in the southwest direction,which is a braided river delta-shore-shallow lake sedimentary system.There are three subfacies: braided river delta front,shore-shallow lake and semi-deep lake.The microfacies include underwater distributary channel,estuary bar,sheet sand,carbonate beach bar and distributary stream bay.(2)The bioclastic limestone carbonate beach bar developed in the shallow lake area is the favorable reservoir,which has the characteristics of high porosity,high permeability and high productivity;The pure clastic reservoirs are mostly low porosity and low permeability reservoirs,and a few well point sandstones can store oil and gas.The mixed rock deposited by cloud mud,stucco and clastic sandstone has poor reservoir property and is an unfavorable reservoir.The mixed rocks deposited by bioclastic and clastic sandstones have medium to low porosity and permeability,and have a certain ability to store oil and gas.(3)The reservoir is controlled by both structural and lithology factors.The structure is the main control factor of the reservoir,and the lithology control factor also plays an important role.The hydrocarbon accumulation generally conforms to the law of high oil and low water.(4)The resistivity of oil-water layer varies greatly,and there are high-resistance oil layer and low-resistance water layer.The high resistance water layer above the oil-water interface controlled by lithology can only be identified according to the results of logging and oil test.