The Study On Logging Evaluation Method For Water Fooded Layer In Y Oilfield

The Y block is located in the offshore oilfield.Since it was put into production,it has been developed by artificial water injection for a long time.The water content of the oilfield continues to rise,and the comprehensive water content is 65%-70%.It has been in the middle and high water moisture content stage,and the heterogeneity leads to uneven flooding,part of the interval is heavily flooded.After the oil layer is flooded,the parameters such as lithology,physical properties,oil content and electrical properties will change accordingly,which further leads to more complicated logging response.Therefore,the qualitative and quantitative evaluation of the water-flooded layer brings great challenges.In this paper,a set of methods suitable for the evaluation of water-flooded layers in the block is obtained through the study of the water-flooded layer in the Y block.The application effect is remarkable,which lays a scientific foundation for potential oil tapping and enhanced oil recovery.This paper first sorts out the regional geological profile of the target area.Based on a deep understanding of the geological structure background and exploration and development status of the research block,the basic characteristics of the reservoir are comprehensively analyzed,which provides strong support for the subsequent comprehensive evaluation of the waterflooded layer.Through the analysis of petrophysical experiments,the changes of lithology(non-clay mineral composition and clay mineral content),physical properties,electrical properties and residual oil distribution after reservoir flooding were studied,and the mechanism was analyzed.Based on the comparative analysis of logging response characteristics before and after flooding,the conventional well logging intersection method,original resistivity curve inversion method and probabilistic neural network prediction method are used to comprehensively judge the water-flooded layer.Based on the homing of the core depth,the logging parameter interpretation model of the study oilfield is established.The variable multiple material balance method was applied in conjunction with the Indonesian equation to accurately evaluate the key parameters of the water-flood layer such as resistivity,water saturation and water production rate of the formation mixture.Finally,the flooding level standard is divided according to the actual flooding situation of the study oilfield.Applying the above research results,the second well-precision interpretation of the wells in the study block and the old well was carried out,and the interpretation rate reached 86.5%.The application effect was significant,indicating that the theory and method proposed in this paper have higher application value.