Study On Low Contrast Tight Sandstone Reservoir Logging Evaluation Method In W Oilfield

In the process of global exploration and development of oil and gas,the focus of oil field development has shifted from high porosity and high permeability reservoirs with good geological conditions to low porosity and low permeability reservoirs with poor geological conditions.Tight oil has become an important energy source for continuous stimulation of each oil field,and the demand for production capacity is urgent.The lowcontrast reservoirs have been identified in several fields during the exploration process,which are of great significance to the increase of oil reserves.the complex genesis of the low-contrast reservoirs and the small difference in logging response between the oil and water reservoirs make the fluid identification work more difficult.The southern R area of the W oilfield has typical tight reservoir characteristics,with poor reservoir properties,complex pore structure,complex oil-water relationship and the presence of low contrast reservoirs.In this thesis,the study area is the Quan 4 member reservoir in the R area of the W oilfield,research on low contrast tight sandstone reservoir logging and evaluation methods.After the pre-processing of the log data,completed the study on the "four characteristics" of the reservoir,clear that the causes of formation of low contrast oil layers mainly include poor physical properties,high shale content,additional electrical conductivity of clay minerals and difference of formation water salinity.The interpretation models of reservoir parameters such as porosity,permeability and saturation are established according to the available data and reservoir logging response characteristics,its application is effective in the research area.In this thesis,displacement pressure inflection point method,cumulative frequency statistics method and oil testing conclusion method are used to evaluate the effective physical property lower limit of reservoir.The fluid identification is accomplished by using sensitive parameter rendezvous diagram method,and the curves overlap method,the "non-intrusive line" method,Stratigraphic water resistivity spectrum method,and array induction logging and NMR logging methods,the feasibility of the methods was verified in conjunction with oil test data,and a combination of the six methods was applied to the fluid identification work in the study area to improve the logging interpretation compliance rate.The results of this thesis provide applicable research methods and ideas for similar low contrast reservoir logging evaluation work.