Study On Evaluation Technology Of Water Injection Effect In The 350 Meters Transition Area Of Z Oilfield

After nearly 60 years of development,the southern block of Z oilfield has already entered the middle and late period of development,and the water content has become more than 95%.After the 350 meters transition area of the south Z oilfield entered the late stage of high water cut development period,due to the development of faults in the block and the complex strata,the adjustment difficulty of water injection development is increasing year by year,and the effect of the adjustment of the measures and programs is getting worse and worse.Based on the development problems of the above realities,the transition zone blocks are in urgent need of a scientific and effective method to evaluate and guide the development of water injection.In view of the characteristics of poor formation in the transition area,a new method of extended unit analysis is tentatively adopted to separate the single well group from the development well pattern and analyze the injection production relationship within a well group.Under the guidance of the extended element analysis method and Darcy's law,the output splitting model of the extended unit is constructed.The model analysis that takes well group as research platform can avoid the interference of heterogeneity in the transition zone on the analysis result to the large degree.The injection-production ratio in the well group calculated by the model is compared with the theoretical injection-production ratio calculated by the area method to accurately evaluate the current water injection effect.The theoretical injectionproduction ratio can be used as the target value of the model for reverse calculation,which provides the basis for the adjustment of the later plan.After the model is proposed,the model is proved to be scientific by reverse verification through a known example and the calculation results are consistent with the development trend of the example.In the later period,4 well groups were selected to carry out field tests for up to more than 300 days.The test data shows that under the guidance of the model,the injectionproduction relationship of the test well group has been greatly improved,which proves that the model is more practical.The model can accurately evaluate the effect of water injection in the transition area and guide the adjustment of the project.