Research On Logging Evaluation Methods Of Bioclastic Limestone Reservoir In XX Oil Field

The typical reservoir of Mishrif group in XX oil field is Pore-type bioclastic limestone reservoir,whose lithology is pure but don’t develop crack.Secondary solution effect leads pores and holes are abundant,and the heterogeneity of reservoir is strong,which cause problems of reservoir has large changes of horizontal and vertical,and low precision of parameter calculation,and so on.This thesis based on MICP and NMR data to establish a pore structure classification method,then reservoir parameter calculation model.Making use of the logging,well log,formation testing data to identify fluid types,and eventually build a logging evaluation method applies to pore-type bioclastic limestone reservoir.Contrasting and analyzing the MICP,MICP’s fractal curve,MICP’s pore diameter distribution,and the pore diameter distribution of NMR,then combined porosity and permeability test result of cores,the pore structure is divided into five categories,and cross-plot,Fisher discriminance are used to pore structure identification by logging data.Based on the pore structure classification results,porosity calculation model is established.We adopte a dual-stage constraint method which united pore structure and flow units to establish permeability calculation model used convertional logging data.In addition,we improve Timur-Coates formula to create a new permeability calculation model.When NMR logging data is available,two permeability calculation models are established basing on contribution of permeability with different size of pore ratio and porosity.Based on pore structure classification results and pore components,two-component saturation model is bring in to calculate water saturation with Archie’s formulas.Put forward a method that use porosity,permeability and pore structure proportion to gain Lorenz curve and heterogeneity degree coefficient,combined reservoir heterogeneity quantitatively evaluation standard to implement the target of quantitative characterization of reservoir plane,layer and interlayer heterogeneity degree.According to the laws of the reservoir fluid distribution characteristics and logging response,identify the fluid property by cross-plot plate and logging,well log and formation testing data.Finally,core data,pore structure classification results and NMR data are used to determine the lower limit of effective reservoir parameters,the classification standard of reservoir is established,and using the function criterion implementation logging identification of reservoir types.Logging evaluation result has a good correspondence with production logging data,this thesis verifies the pore type bioclastic limestone reservoir logging evaluation method of the accuracy and applicability.