Lithologic Scanning Logging Of Complex Lithologic Formations Research On Fluid Identification Method

The complex lithologic strata are mainly carbonate rocks and igneous rocks,and the mineral composition and reservoir space are complex and changeable,with strong heterogeneity.Conventional logging technology has no obvious logging response characteristics to the fluid in its pores and it is difficult to identify the fluid.The lithologic scanning logging can accurately measure the formation mineral content,Cl content,skeleton density,macro capture cross section,C content,C/O value and other parameters without the influence of pore fluid,providing a new way for the identification of complex lithologic formation fluid.Therefore,it is necessary to develop the method of fluid identification from lithologic scanning logging.This thesis presents a fluid recognition method based on Σ.Firstly,the mineral components in the multi-mineral interpretation model were corrected by core analysis data,and then the Σwith 50% gas saturation was calculated by mineral volume model.The influence of hole diameter and drilling fluid salinity on Σ was analyzed and the corresponding correction formula was obtained.The calibration ΣSg=50% was compared with the measured lithology scanning logging Σ to identify the fluid properties,and the results in the treatment of carbonate and igneous rock sections proved the applicability of the method.In addition,fluid identification methods using YCl and C/O,Σ and C/O,and YCl and Σcross plots are also proposed.The influence of the factors affecting each layer on the crossplot was analyzed,and the applicability of crossplot in complex lithology and formation was judged.The wellbore calibration was carried out on the actual well data,and the crossplot method was used to study the fluid identification of complex reservoir.The application effect of crossplot method was good in the actual carbonate and igneous well sections.The results show that the calculated results of the corrected mineral model in the actual well section are closer to the real situation of the reservoir.The sigma-based fluid identification method and the three crossplots can better indicate the gas and water supply zones in complex lithologic formations than conventional logging techniques,and meet the actual production requirements in the field.