Research On The Interlayers Of 4-6 Sand Sets Of The Upper Guantao Formation In The Block 9 Of Gudong Oilfield

The upper Guantao Formation in the block 9 of Gudong oilfield are the main oil bearing development series of Gudong oilfield.It has entered into a period of high-through put and high-water cut and low oil and gas recovery.The remaining oil is widely distributed in the block.The heterogeneity is the main controlling of the remaining oil.Interlayers is a major reason to lead reservoir heterogeneity.Therefore,it is necessary to have research about it.Based on the geology,logging,testing and production data,studies the lithological and electrical,identification standerds.Genetic mechanism,distribution and it is influence to the oil distribution.The main conclusions and achievements are as follows:(1)The 4-6 sand sets of the upper Guantao formation developed a set of fluvial sediments,among which Ng54-Ng6 sand sets developed a set of braided river sediments,Ng4-Ng52 sand sets developed a set of meandering river sediments.The channel sands development is widely distribute at 42?52?55?61 small layers.(2)It mainly developed two kinds of interlayers:muddy interlayers ? physical interlayers,the calcareous interlayers is rare.Through the research on the physical characteristics of the coring,establishment of a electric properties of the interlayers.The genetic mechanism of the interlayers include:at the stage when the flood is dropping?river migration?the weakening of hydrodynamic and the fluctuations of the water which form the muddy and physical interlayers and inorganic or biological origin which form the calcareous interlayers.(3)Take the main oil-bearing layer as an example,analysis the characteristics of the interlayer and its relationship with the sedimentary microfacies.Hold that in vertical direction the the interlayer of the braided river is widely spread in the block but have low stability.The interlayers of the meandering river is limited distribution but have high stability.In the plane,the interlayers of the channel sediment is thin but in the channel margin sediment and flood plain sediment are thicker.(4)Through the method of stochastic modeling,establish the interlayer of the spatial distribution of the 55-61 sand layers.Divided the interlayer into stablility type ?transitional type and random type and summarizes the characteristics of different interlayer.(5)The interlayer is mainly through the capillary pressure to block the migration of the oil and gas.The better stability?in the upper of the reservoir?the water injection wells drilled the interlayer will have the higher oil saturation.