Characteristics And Genetic Analysis Of Low Resistivity Oil Layer Of The Upper Es_3s In Shanghe Area

Characteristics and Genetic of Low-Resistivity Oil Layer of the upper Es3in ShangheArea are lacking of clear understanding，this paper conduct a comprehensive system ofresearch based on the preliminary work of the research, combined with well logging，mudlogging and geological data.The definition of low resistivity oil layer contains two aspects：the absolute value ofresistivity is less than4Ω.m (major) or water saturation is greater than50%and the increasingrate of resistance is less than3. Sequence is devided into Quasi sequence group Ⅰ、Quasisequence group Ⅱ、Quasi sequence group Ⅲ.Sedimentary facies mainly developed deltafront facies and lake facies,including the margin of underwater distributary channel， thedistributary mouth bar, far sand dam microfacies. Low resistivity oil layer mainly developedin the calcareous sandstone and silty sand rock of the delta front underwater distributarychannel in Quasi sequence group Ⅰ and sandstones of distributary mouth bar in Quasisequence group Ⅱ and Quasi sequence group Ⅲ.In addition， low resistivity oil layerobviously distributed along the fault zone, low resistivity reservoir is developed in the threearea of ShangHe.From lithology，physical properties,pore structure characteristics and fluid properties，etc，the low resistivity oil layer formation mechanism is analyzed by means of comparativeanalysis in reservoir and the low resistance reservoir.According to the comparative study ofreservoir petrology，analysis data，physical properties, formation water and so on，it wasfound that the formation mechanism of low-resistivity oil reservoirs of Upper Es3inShanghe area mainly include: fine lithology mainly composed of siltstone，high content ofmud，especially mixed-layer of illite and smectite，low permeability, poor physical properties，development of micro-pores and high salinity of formation water. The main types oflow-resistivity oil reservoirs are the type of high saturation of bound water，the type of conductive mineral，the type of high salinity water.Combining with the analysis method of logging curve and chart，low resistivity loggingresponse characteristics suggested that SP curve which show negative anomaly is close to thebaseline，AC and RT curve show reverse subtle features in low-resistivity oil reservoirs byhigh shale content，acoustic time range is above254μs/m in the area.This paper establishedthe logging parameter model about shale content，water saturation，porosity，permeability inthe area.