Xin Jiang Shinan Low Permeability Reservoir Waterflooding Identification And Residual Oil Distribution Study

The majority of China’s low permeability oilfield mainly adopts the way of water injection to develop, most oil fields have entered secondary oil recovery or tertiary recovery stage, and composite water cut has reached more than 80%. Reservoir flooding situation is increasingly seriously, precise identification of the flooded layer and evaluation and clarify reservoir remaining oil distribution are the currently problems.For solving these problems, this paper takes Xinjiang Shinan low permeability oilfield as an example and do the depth study of its flooding identification method and the remaining oil distribution.This paper based on the extensive literature research,mainly focused on flooding interpretation and the method of the presence of starting pressure gradient in numerical simulation of low permeability reservoir. Then combine the dynamic and static data in the study area to do the study of waterflooding interpretation and use the numerical simulation method and reservoir engineering method to study the residual oil distribution and influencing factors. On the basis of the above proposed suggestions for carring out the potential. This paper mainly obtains the following results:1. Research on waterflooding interpretation methods, according to the actual situation in the study area, and take into account of the differences in resistivity "U" type curve and different lithology of archie parameters for waterflooding explanation, and verify the interpretation of results by using the testing data.On the basis of these,do the study of potential cognition in this area.2. Considering the feature of the low permeability and the predecessors did not carry out the actual large-scale reservoir which considered the start-up pressure gradient of the numerical simulation.Using well testing method to calculate the relationship between the start-up pressure gradient and the permeability in the study area then doing the permeability zoning and using the threshold pressure equivalent simulation method solves the the problem, choosing the considering septal interlayer and starting pressure value model to simulate and forecast, and consider that this method is more in line with the true underground fluid flow;At the same time, using the streamline model simulation in different development stages and different well pattern and well fluid flow characteristics, provided the basis for the injection production well pattern adaptability, injection production structure rationality analysis.3. Using reservoir engineering method and numerical simulation method to recognise the remaining oil distribution and influencing factors of the study area, that plane J₂t₂¹+J₂t₂² strata’s residual oil mainly in the edge of the rectangular well pattern. J2t22 strata’s residual oil mainly in the cornor of the anti nine spot well pattern, the longitudinal remaining oil is mainly distributed in the J₂t₂¹+J₂t₂² layer; the influence factors of remaining oil distribution are the main reservoir heterogeneity, interlayer distribution, well pattern and threshold pressure gradient etc, which the density of well pattern result in injection production structure change is one of the main factors that affect the distribution of remaining oil;4. Combined with the current problems in the main reservoir, and taking into account the current network in the form of wells that should be adjusted on the injection and production structure, and put forward the appropriate corresponding measures for tapping the potential, so the reservoir can be developed more efficiently.