Study On Well Logging Evaluation Of The Cretaceous Oil Sands Reservoirs In Fengcheng Area,Junggar Basin

Around the world,the resource of oil sands is considerably abundant,which can be used as a substitute for conventional oil & gas resources.Currently,the research on well logging evaluation of the oil sands reservoir is not much at home.The burial depth of the oil sands reservoirs are commonly shallow,the study on the "four-property relationship" and well logging evaluation is the first time.The complex geological environment in Fengcheng area also increases the difficulty for well logging evaluation.In the paper,we have been aiming at studying Qingshuihe Formation of Crataceous,Junggar Bsin.At the beginning,we studied the basic geological Characteristics,including the stratum,sedimentation,structure.Firstly,we applied to the technology of sequence stratigraphy dividing the stratum subtly into 3 parts;secondly,according to the tectonic history,we came up with the features of faults combining the seismic data.Advanced study showed that 3 ores were all the structural-lithologic oil reservoirs that inherited paleotopography feature;thirdly,based on the core data,Fengcheng area could be divided into 3 sedimentary facies,including braided river delta facies.braided fluvial facies and alluvialfan facies.Qingshuihe Formation is a monocline structure plunging towards southeast,and overlap to the piedmont.Based on pre-processing and core normalization of the well logging data,combining well test,production test,analysis and assay data,we researched the four properties respectively,including lithology,physical,oiliness and electrical property,then we established the relationship between each other.The lithology chart shows that the resistivity of the mudstone is lower than 10?·m,the resistivity of the sandstone is larger than 18?·m and the density is lower than 2.3 g/cm~3;the reservoir porosity is not less than 26% and the penetration is not less than 90mD;the reservoir saturationis not less than 50%.The thesis had carried on the elaborate analysis on the high resistance of water layer in the study area,a lot of possibilities may cause abnormal resistivity of oil and water layer,the reason that lead Qingshuihe Formation to the phenomenon mainly fell into three aspects: firstly,the Cretaceous strata is commonly rich in clay film;secondly,the high content of oil sand's oil without flow ability in the water yield formation;lastly,the moisture content of Qingshuihe Formation is higher,which led to the lower resistivity of the oil reservoir.On the basis of research on "four properties ",combining practical production data and well logging experience formula,The Cretaceous reservoir interpretation model in Fengcheng was established,oil and water layer were distinguished successfully,and the planar distribution characteristics of effective thickness were concluded.