Study On The Genetic Mechanism And Fluid Identification Method Of Low Resistivity Reservoir

Low resistivity reservoir is one of the important targets of oil and gas exploration and development.Because the mechanism of low resistivity reservoir is complex,and fluid identification is difficult.The study on the genetic mechanism and fluid identification method of low resistivity reservoir has important practical significance for oilfield production.This paper takes Hainan Fushan Oilfield as the study object,and studies the genetic mechanism,formation water distribution and fluid identification method of low resistivity reservoir in Fushan Oilfield.In the study on the genetic mechanism of low resistivity reservoirs,using logging data,core test data,water sample data,and oil test data,it is concluded that there are four main genesis mechanisms of low resistivity reservoirs in Fushan Oilfield,namely:differences in formation water salinity,the additional conductivity of the shale,the difference in formation water salinity and the additional conductivity of the shale,the difference in formation water salinity and poor physical properties.In the study on the distribution of formation water,the vertical and horizontal distribution of the formation water salinity and water type are given.That is,global aspect,the shallow formation water has high salinity and the deep formation water has low salinity.There is little difference in the salinity of the formation water in some areas vertically.The southeastern region has high salinity and northwest region has low salinity.There is a huge difference in formation water salinity between adjacent fault blocks in some areas horizontally.And three main controlling factors for this distribution are identified,namely paleoclimatic change factors,tectonic factors,water-rock interaction and carbondioxide transportation factors.In HC area,standard water layer is far from the target layer,this paper presents a method for calculating the resistivity of formation water using resistivity and sonic log data of adjacent mudstone layer.In the study on the fluid identification of low resistivity reservoirs,sensitive parameters such as?GR/?SP??GR/CNL?R_wa?RT??R_wa?SP?were selected,and the chart method,water spectrum method,R_wa?RT?/R_wa?SP?method,array induction method,high resistive zone method to identify poor reservoir are evolved.Applying these five methods to the fluid identification of Fushan Oilfield in Hainan not only improves the interpretation coincidence rate of oil and gas layers,but also achieves good application results in the identification of poor reservoir and dry layers.