Study on Identification Methods of Shallow Low-contrast Reservoir in Nanpu Oilfield

Due to the combined influence of many factors in the reservoir, such as complex sedimentary environment, low amplitude structure, high irreducible water saturation and additional conductivity of clay mineral, there are a lot of low-contrast oil layers and oil-water layers in shallow reservoirs of Nanpu Oilfield. Based on the systematic study of the sensitive parameters of 36 typical low-contrast oil layers and water layers, 5 typical identification methods for low-contrast oil layers have been proposed:(1)R_wa(R_t)/R_wa(△SP)-V_sh intersection pattern method; (2)logging curve sensitivity diagram method; (3)amplitude difference recognition method of natural potential; (4)carbon-oxygen ratio logging method based on calcareous content correction; (5)comprehensive identification method of conventional dynamic and static data. Through the practice of the field, a large number of low-contrast oil layers in Nanpu Oilfield have been identified and obtained industrial oil flow, and good application results have been achieved in the interpretation of low-contrast oil layers.