Study On Permeability Logging Evaluation Method Of Block A In Eastern South China Sea

Rock permeability refers to the ability of rock to allow fluid flow in its pores under pressure.It is an important parameter to measure the ability of porous media to allow fluid flow and output,reflecting the difficulty of oil,gas and water being produced.The size depends on the pore volume,pore distribution and connectivity of the rock.It is a decisive factor in controlling reservoir quality and oil and gas well productivity,and is one of the important parameters for determining the lower limit of effective reservoir properties.Its accuracy is directly related to reservoir heterogeneity analysis,capacity determination and development plan design and adjustment.Reasonable reservoir evaluation must be based on permeability.The interpretation accuracy of permeability directly affects a series of subsequent development studies such as reservoir interpretation and numerical simulation,and is the key to quantitative interpretation of logging data.The eastern part of the South China Sea is one of the important oil and gas producing areas in China's offshore areas.With the deepening of exploration and the increasing difficulty of exploration,how to continue to maintain high and stable production of oil and gas has become an urgent task for exploration in the region.Taking the A block in the eastern South China Sea as an example,this paper uses the conventional permeability model and the NMR permeability model to conduct an in-depth study on the calculation method and evaluation method of the permeability in the eastern South China Sea,and has achieved the following results:(1)A statistical analysis method is used to study the multiple regression analysis between absolute permeability and well logging data and parameters calculated from well logging data(eg,irreducible water saturation).(2)In view of the serious reservoir heterogeneity and the existence of the same porosity for multiple permeabilities in the study area,it is indicated that there are differences in reservoir flow units.When the relationship between porosity and permeability of samples is relatively discrete,the method of dividing flow units by FZI is used,and the corresponding relationship between permeability and porosity of flow units is determined.On the basis of reservoir classification of flow unit,intersection diagram method and supervised pattern recognition method are still used to establish reservoir classification method or algorithm model.(3)Through the feature selection and extraction,preferably used for the sensitive parameters of permeability calculation,a supervised pattern recognition method,such as Bayesian,neural network,etc.,is used to establish an absolute permeability calculation model.(4)Nuclear magnetic resonance technology can obtain the distribution characteristics of pore throat structure,so in the case of nuclear magnetic resonance spectrum,it is often used to obtain permeability.In this paper,the microscopic pore structure parameters are combined with the NMR spectrum curve morphology to estimate the permeability.(5)The equivalent rock unit theory is combined with the pressure sampling and test data to estimate the permeability.The established permeability model was applied in the A block of the eastern South China Sea,and the prediction of the permeability of the actual block achieved good results.