Research On Logging Evaluation And Remaining Oil Distribution Of Water-flooded Zones In The Main Area Of ??West Karabulak Oilfield

The M-? reservoir in the West Karabulak oilfield is a layered edge and bottom water reservoir controlled by tectonic process,which belongs to medium porosity and medium permeability reservoirs.After adopting water injection development technology in 2016,oilfield production has accelerated and production increased,and it has entered the middle and high water cut stage,with the ubiquity phenomenon of the edge water,bottom water and injection water.Therefore,in order to ensure the stable production and clarify the distribution of the remaining oil of the oilfield,the log evaluation of water-flooded zone and the distribution of the remaining oil of the West Karabulak oilfield are carried out in view of the current production situation.Using the core analysis data of 4 coring wells in the study area,the basic characteristics of the reservoir are analyzed in this paper.Based on the pre-processing of logging data,the characteristics of log response after water-flooding are systematically analyzed by the comparison between the logging data in early stage and in the later stage.According to the characteristics of water-flooding in the study area,the identification methods of water-flooded layer,such as cross plot method,radial resistivity method,curve overlap method and Fisher discrimination method,are put forward.A logging interpretation model of watered-out zones are established,including porosity model,permeability model,irreducible water saturation model and water saturation model.According to the development characteristics of the middle and high water cut stage in the study area,based on the formula of producing water ratio and the oil-water relative permeability,the relation chart of water production and water saturation under different irreducible water saturation is drawn.Then the classification standard of flooded grades has been established,and through the verification of actual data,the judgment of water-flooding level is accurate and the application effect is better.It is clear that the water-flooding pattern of the study area is dominated by the positive rhythm,the homogeneous rhythm and the complex positive rhythm water-flooding pattern.Combined with the results of the new wells logging interpretation and production performance analysis of adjacent wells,the distribution of remaining oil is studied macroscopically by drawing four sections of connecting wells in four areas:eastern,western,central and southern,and then the enrichment of remaining oil is summarized.The research of this paper provides a basis for the later development and adjustment of the West Karabulak oilfield,and ensures the stable production and sustainable development of the oilfield.