Experimental Study On Micro Residual Oil Of Water Flooding In Triassic Reservoir In 9 Area Of TH

The TH reservoir is located in the Tarim basin with rich bottom water,so it can be exploited by the bottom water energy for early mining,and at the same time,it is associated with low amplitude and low back slope and good reservoir property,which belongs to medium pore and medium high permeability sandstone reservoir,and is unsaturated in normal pressure and atmospheric pressure.Since the middle and late development of the development,the micro structure of the reservoir is difficult to identify,and the heterogeneity is strong.And because of the different pore structure,the position and the residual form of the micro residual oil in the formation are different,so the mining method is not the same.Therefore,the microscopic pore structure and the distribution characteristics of remaining oil need to be studied.It provides theoretical and technical basis for the two oil recovery and enhanced oil recovery,and has guiding significance for the development of such bottom water reservoirs.In view of this reservoir,we carry out real core displacement experiments and X-CT long core displacement experiments on TH oil field,sum up the remaining oil on the micro scale,and analyze the distribution of residual oil in the stratum after displacement.Through the above research,we get the following understandings and conclusions:(1)The Triassic reservoir in the 9 area of TH oilfield belongs to a medium pore and medium high permeability sandstone reservoir.The permeability plane changes greatly,the penetration coefficient is 3.1,the coefficient of variation is 0.72,and the heterogeneity is strong.On the macro level,the remaining oil is generally distributed in the wells,fault sealing,well control unused,edge and so on.Vertically,the oil layer is distributed in the top of the oil layer,the horizontal section and the sand top,and the interlayer occlusion,but on the micro scale,the residual oil is insufficient because of the serious heterogeneity.Therefore,this paper designs a new real microcosmic core displacement experiment process.Through the micro visualization water flooding experiment of four different pore structure cores,the core is transformed from two dimensional observation to three-dimensional visualization,and the remaining oil is converted from qualitative analysis to quantitative analysis.(2)By using long core X-CT scanning experiment,high permeability,low permeability,high and low permeability combination long core displacement experiment and double tube parallel experiment are carried out respectively.It is clear that the remaining oil is mainly in the hypotonic rock.The distribution of residual oil and the characteristics of water flooding in the core scale are obtained.At the same time,through the parallel long core,it is found that the remaining oil is mainly low permeability core under the condition of non stratification,and it is judged that in the later period of development,it is necessary to dig potential for low permeability reservoirs.(3)To compare the remaining oil status and distribution position at different microscopic scales,the remaining oil is more accurately classified and summed up.For the TH oilfield,the micro distribution characteristics of the remaining oil are channel,membrane,pore center precipitate,spot shape,particle adsorption and so on.Through cross scale research,we know the remaining oil.Based on the mechanism and characteristics of the formation,suggestions for later mining and three development are made to reduce residual oil in the strata.Through the above research,the distribution pattern and position of the residual oil in the micro scale in the heart of the rock are clarified,which provides technical support for the implementation of the project in the middle and late development of TH field.