Genesis Analysis And Logging Identification Of Chang 6 Low Resistivity Reservoir In Luohe Area,Zhidan Oilfield,Ordos Basin

With the deepening of oil and gas exploration,the low resistivity reservoir is paid more and more attention.In recent years,low-resistivity oil reservoirs have been discovered continuously in Ordos Basin.Due to the complex formation of low-resistivity oil reservoirs and the variable logging response characteristics,it is difficult to distinguish low-resistivity oil reservoirs,which reduces the overall exploration and development benefit.Therefore,it is very important to systematically study the formation and identification methods of low-resistivity oil reservoirs.This paper takes the Chang 6 oil reservoirs in the Zhidan Luohe oil area of the Ordos Basin as the research object,combined with the geological background,based on the logging data and conventional physical properties,rock thin sections,scanning electron microscopy,mercury injection,phase permeability,nuclear magnetic resonance and lubrication Wet and other core experimental analysis results,finely analyze and summarize the lithology,physical properties and oil-bearing characteristics of the reservoir in the study area,and establish an interpretation model for the physical properties of the reservoir in the study area.Based on Archie’s formula,according to the actual formation water system in the study area and the treatment of rock electricity experiment,the formation water resistivity（R_W）and rock electrical parameter a,b,m,n were determined,and a quantitative interpretation model of oil content was established.Based on the reservoir characteristics and the four-property relationship,the genesis mechanism of the low resistivity oil reservoirs is analyzed.The comprehensive analysis shows that the genesis of the low resistivity oil reservoir in the study area is closely related to bound water saturation and high natural gamma ray sandstone,among which the complex pore structure and rock hydrophilicity are the factors leading to the increase of bound water saturation.Secondly,The salinity of formation water and the intrusion of drilling fluid also have certain influence on the low resistance oil reservoirs in the study area.Based on the genesis mechanism of low resistivity oil reservoirs,sensitive logging parameters were extracted respectively for controlling factors of low resistivity oil reservoirs,and the differences between oil and water reservoirs were amplified.AC-R_ILDand SP-PSP overlapping maps were established by analyzing various parameters.AC-R_ILD,GR-R_ILD,GR*GR*△SP-R_ILD,intrusion faction-R_ILDcross plot,array induction logging,movable water analysis and other identification methods are mutually constrained and verified to form a gradual identification mode,and the comprehensive identification rate of oil and water reservoir is more than 90%.Combined with the production data,the result is good,and the goal of accurately identifying the Chang 6 low resistivity reservoir in Zhidan Luohe area is realized.