Comprehensive Logging Evaluation Method of Complex Water Flooded Layers in M Oilfield

Abstract M oilfield has experienced over 20 years of exploitation and currently exhibits a total water content of 73.2%. The coexistence of bottom water encroachment and injected water flooding, along with diverse injection water types, has led to intricate water flooding scenarios. Urgent research is needed to develop identification and assessment techniques for water-swept layers. Firstly, by analyzing the regional water flooding characteristics and integrating sedimentological data, the primary water flooding mechanisms are delineated. Leveraging water flooding experimental results, formation resistivity alteration patterns are categorized into sewage re injection and freshwater flooding types. During sewage re injection and edge/bottom water flooding, resistivity logging exhibits heightened sensitivity to water flooding effects. An automatic logging identification module is thus established using cross-plot techniques, water flooding sensitivity functions, and envelope line approaches to enable semi quantitative identification of water-swept layers. Secondly, the variable multiple injected water material balance simulation technique is introduced to refine the mixed water resistivity calculation model. This allows for precise remaining oil saturation determination and the establishment of a mercury injection permeability data-based water production rate calculation method. Thirdly, the high resistivity of certain freshwater-flooded layers in some wells may lead to misinterpretation. The underlying causes are explored by examining near-well water injection-production characteristics and the horizontal/vertical layer distribution features of such wells. Ultimately, tailored evaluation standards for diverse water injection types in M oilfield are formulated, yielding an 87.1% interpretation compliance rate. These achievements offer guidance for optimizing perforation layer selection in oilfields and hold significant promise for residual oil assessment in overseas clastic rock reservoirs.