Oil-based Mud Intrusion Correction And Fluid Property Evaluation Research

With the development of the petroleum industry and the increasing global oil demand,research on low-porosity and low-permeability tight sandstone oil and gas reservoirs has become a key research area in the oil and gas industry.The Cretaceous reservoirs in the Kuche Depression in this paper are precisely low-porosity and low-permeability tight sandstone reservoirs,and individual wells are affected by the infiltration of oil-based mud filtrates,caused inaccurate resistivity measurement and faced greater difficulties in reservoir fluid identification.In order to meet the actual needs of the development and production of the research area,it is necessary to study the correction of oil-based mud invasion and the identification of fluids.This article is based on the above background.The main research content is the correction of oil-base mud intrusion and the identification and evaluation of fluid properties.Comprehensive use of core,logging and test data to develop reservoir quadruple relationship research.It is found that the reservoirs in the working area are mainly fine sandstones with low porosity and permeability and are low porosity and low permeability tight sandstone reservoirs.For the study of oil-base mud intrusion,the physical model of intrusion is firstly analyzed,then the difference method is used for numerical calculation,and the influencing factors of the intrusion are simulated(mainly based on three factors:physical properties,pressure difference,and rock wettability)Finally,the true resistivity of the formation is inverted through numerical simulation,and a correction chart is established to correct the resistivity.After correcting the resistivity of the test section,it is found that the resistivity characteristics are more in line with the test results,laying the foundation for fluid identification.In order to improve the accuracy of fluid identification,the reservoir fluids in the working area were identified by the porosity-resistivity intersection method,Fisher discriminant method and decision tree method based on logging data,and the fluid properties of the three wells in the work area were studied.Comprehensive recognition and evaluation have achieved better recognition results.Through the study of this paper,a practical and feasible method is provided for the correction of the resistivity correction of the oil-base mud intrusion in the Kuqa depression and the identification and evaluation of the fluid properties.