Study On Logging Response Characteristics And Identification Methods Of Low Resistivity Reservoirs In An Oil Field In The Middle East

Over the past ten years,with the continuous growing of the global oil and gas exploration level,the proportion of oil and gas exploration in the actual process has gradually increased with finding of reserves and production of low resistivity reservoirs.The reasons of low resistivity formation is complex and varied,which conclude the change of formation water salinity,clay additional conductivity,etc.The genesis of low resistivity reservoir is often complex and difficult to explain directly.At present,the researches on low resistivity reservoirs in China are mainly focused on sandstone reservoirs,while the researches on carbonate low resistivity reservoirs are few.In the thesis,the logging response of low resistivity carbonate reservoir was analysed by comparing with the conventional reservoir and combining with the study of the regional geological structure environment to determine the reasons of low resistivity reservoir.The crossplot method was used to establish the identification criteria of low resistivity reservoir in the research area.The pore throat distribution in the low oil resistance zone is uneven and the pore structure is complex.Low resistance due to drilling fluid intrusion or other engineering reasons has been excluded.The main controlling factors of low resistivity are formation water salinity and reservoir pore structure.Due to the uneven pore structure of low resistivity reservoirs,the differences in oil and gas filling at different layers lead to high irreducible water saturation of low resistivity reservoirs.A large amount of bound water in the reservoir would form a conductive network and reduce the reservoir resistivity.High irreducible water saturation is also the main cause of low resistivity in the study area.Through the combination of MDT data and well logging data,the identification chart for identifying low-resistivity oil reservoirs in the study area is drawn,and the identification effect is good.The accuracy and effectiveness of the identification chart can be greatly improved by the use of multiple crossplots.