Research On Logging Evaluation Method For Low Permeability Reservoir

The low permeability reservoirs have become one of the main objects of petroleum exploration and development in China.The pore structure connectivity of low permeability reservoir is poor,the degree of the pore bending and section changes is large,and the logging data for the reservoir fluid information is not sensitive,the subsequent four property relationship analysis,reservoir parameter calculation and fluid identification are affected.In order to more accurately evaluate the reservoir,the low permeability reservoir of research work area is taken as an example by this paper,the data pretreatment,"four property" relationship analysis,reservoir parameter calculation and low permeability reservoir fluid identification method have been studied respectively.The data preprocessing is to ensure the accuracy of the subsequent reservoir parameter calculation and fluid identification.First,the key wells are selected,the logging data are standardized,and the rock core depth is put in place.Second,the reservoir parameters are calculated by using the thinking of "core scale logging" technology,the shale content,porosity,permeability,saturation and other reservoir parameters are respectively modeled by the application of mathematical statistics method,and the shale content,porosity,permeability model calculation accuracy have been verified by use of the core experimental measurement results,the mercury injection data palmer searle method for the saturation is used to gain the oil saturation to verify its accuracy.This paper has applied five methods to identify the low permeability reservoir fluids:(1)the sensitive parameters are selected,and the crossplot is drawn,the impermeable layer,water layer,oil,gas and water same layer,poor oil and gas layer,and oil and gas layer are distinguished;(2)The Hingle crossplot method,the oil,gas and water layers are visually distinguished by use of the resistivity and porosity crossplot of Sw scale;(3)The water spectrum method,the oil,gas and water layer is judged according to the shape of the water spectrum;(4)the reservoir fluid is identified by the ratio of Rwa(RT)/Rwa(SP);(5)The curve superposition technology,aftert the overlapping of the calculated spontaneous potential and actually measured spontaneous potential,inductive resistivity and acoustic time difference in the water layer or dry layer,the oil and gas layer is identified by use of the deviation appeared in other reservoirs.The well logging data in the study area have been processed by using the established reservoir parameter calculation model and fluid identification methods,and the better effects have been obtained.