Study On Refined Logging Evaluation Method Of Water Flooded Reservoir In D Oilfield

In most oilfields in China,water injection development methods are widely used.During the oilfield water injection process,the pore structure of the reservoir,the nature of the formation water,the physical and chemical properties of the rock,and the distribution of remaining oil will all change to some extent.Based on the analysis of the characteristics of the freshwater flooded reservoir in the target area,this paper studies a set of key techniques and methods for logging interpretation of the waterflooded reservoir in the block.The research results provide certain theoretical and technical support for guiding oilfield development.In this paper,the geological and geophysical characteristics of the water-flooded reservoir in the block are studied firstly,and the characteristics of electrical,physical properties,oil-bearing properties,wettability and rock-electric parameters before and after flooding are comprehensively analyzed for qualitative identification of subsequent flooded reservoir.Then based on the water flooding experiment,it is analyzed that the oil layer will have complex rock-electric relations such as “L” type,“U” type and “S”type under different flooding conditions.The technical difficulty of the evaluation lies in how to solve the multi-solution and complexity of the logging data.For this reason,the micro-element dynamic material balance method for accurately calculating the resistivity of the formation mixture is proposed,which can accurately simulate the dynamic process of the water flooding.The change process provides a theoretical basis for the subsequent quantitative interpretation of water-flooded reservoir.Based on the study of geology and geophysical characteristics of water-flooded reservoir,qualitative identification of water-flooded layers was established by using spontaneous potential baseline migration method,spontaneous potential amplitude method,spontaneous potential and resistivity correspondence analysis method and probabilistic neural network method.Finally,the core locating is carried out according to the target area data,and then combined with the target area logging interpretation model and the micro-element dynamic material balance model,the logging interpretation method and data processing software for solving the key parameters of the water-flooding reservoir are established under the reservoir geological constraints.The calculated key parameters of the water-flooded reservoir,such as the mixed liquid resistivity,the remaining oil saturation and the water productivity are in good agreement with the sealed coring experimental data and the test oil conclusion,and the coincidence rate of comprehensive logging interpretation has reached 87%.It provides a scientific basis for oilfield development program and has important reference value and guidance for the interpretation and evaluation of the water flooded reservoir logging of other oilfields.