Experimental Study On Conductance Mechanism And Evaluation Methods Of Water Flooded Layers In XX Oilfield

The target layers of 404 wellblock in XX Oilfield,located in Putaohua oil layers of the Upper Cretaceous Yaojia Formation,possess abundant oil and gas resources,yet with great extraction difficulties.Such reservoirs are classified as low permeability fractured sandstone reservoirs,of which the characteristics are as follows: poor lithology development,complex internal structures as well as poor well efficiency,etc.Therefore,in order to establish a safe environment for development and provide basis for well pattern infilling and injection-production system adjustment,we have conducted an experiment on conductance mechanism of water flooded layers and investigated evaluation methods of the water flooded layers.To start with the conductance mechanism of water flooded layers,the changes of resistivity and petrophysical parameters of different types of reservoirs are analyzed systematically and the interpretation plate and evaluation standard of water flooded layer are established based on the analysis of reservoir classification.The changes of fluid pressure and permeability in low permeability reservoirs were studied.It is concluded that by dividing the petrophysical facies of the reservoirs,the oil field of the oilfield in the XX oilfield can be divided into four types,and the model of porosity-permeability of different reservoirs is improved to deal with the emergence of heterogeneity phenomenon.Through the experimental study of flooding mechanism,the changes of resistivity of different reservoir rocks under flooding condition is mastered.At the same time,by using the multiple linear regression method in mathematical knowledge and applying the rendezvous means,four different reservoir evaluation systems are constructed to deal with the problem of water flooding in low permeability reservoir,and then the water flooding layer is fully explained.The use of advanced water injection,to a certain extent,greatly increases the reservoir pressure,thereby reducing the permeability,so that the rock is further stabilized.With the increasing net stress,the pore fluid pressure gradually decreases,the oil displacement efficiency gradually decreases.On the contrary,with the decreasing net pressure,the pore fluid pressure gradually increases,the oil displacement efficiency gradually increases.It is the same as the changing tendency in susceptibility test.The oil displacement efficiency increases with the early increasing of the pore fluid pressure,and the oil displacement efficiency decreases with the further increase of the pore fluid pressure.