Study On Flow Field Evaluation And Adjustment Limits Of Extra-high Water Cut Stage Reservoir

At present,most onshore oilfields in China have entered high water-cut period or even extra-high water-cut period.According to the characteristics of reservoir flow field,it can be divided into controlling parameter field that characterize the controlling ability of injection and production system and displacement parameter field that characterize the displacement of oil reservoirs.From the point of flow field matching,the matching degree of controlling parameter field and displacement parameter field can reflect the development effect of the current injection and production system in the reservoir.Therefore,establishing a set of reservoir flow field matching evaluation system has important guiding significance for the development and adjustment of reservoirs in the extra-high water cut period.In this paper,flow field indicators are divided into two categories: instantaneous indicators and cumulative indicators.The controlling parameter field and displacing parameter field index set are established respectively.On this basis,a combination of principal component analysis and logical analysis were used to select the final indicators of controlling parameter field,oil phase displacement parameter field and the water phase displacement parameter field from the index set.The flow field characterization is achieved by the membership function normalization and analytic hierarchy process to determine the weight vector.Based on the similarity between flow field matching and image retrieval,the controlling parameter field and displacement parameter field were studied from the overall and distribution perspectives for the five-point standard well pattern and the actual reservoir model respectively.According to the retlationship between flow field matching degree and water cut,flow field matching standard is established and flow field adjustment boundary is divided.Through the study,it is considered that flow field overall matching evaluation method can quickly compare the flow field matching degree of each small layer and filter out the small layers that need to be adjusted,and the distributed matching evaluation method can start from the locality to evaluate the flow field adaptability in each area of the reservoir which makes flow field adjustment more targeted.In a word,this evaluation system enriches the evaluation methods for well pattern adaptability and injection and production system adaptability in extra-high water cut period,and has great significance for the exploitation of remaining oil in extra-high water cut period.