Investigation Of The Asphaltene Deposition Distribution In CO₂ Flooding Of Low Permeability Reservoir

CO₂ flooding is a effective measure to improve the recovery of low permeability reservoirs,which has been widely confirmed.But in the process of CO2 flooding asphaltene component has risk of deposition.Asphaltene deposition in low permeability reservoir will affect the reservoir porosity,permeability and wettability,and also affects the development effect of CO₂ flooding.According to the problem of asphaltene deposition in CO₂ flooding,firstly ensure a method to study asphaltene deposition.Through solid detection system research tests asphaltene deposition conditions,including asphaltene precipitation critical pressure of CO₂-oil system,the influence of pressure and temperature on asphaltene precipitation amount.By designing a one-dimensional core displacement experiment,study the influence of asphaltene deposition under different pressure and temperature on porosity,permeability and oil displacement efficiency.Build one dimensional numerical model,through the fitting model and the experimental results to ensure the accuracy of the model.Asphaltene model parameters are applied to build models of different reservoir characteristics and well types,predicting asphaltene distribution under the condition of different pressure and influence on the reservoir and recovery.The research result also uses to predict the asphaltene deposition distribution in the process of gas flooding in Changqing Oilfield.Through the experiment results and numerical model find that asphaltene deposition easily occurs in low permeability reservoirs in CO₂ flooding.Study has found that during the CO₂ flooding asphaltene deposition is affected by the components,pressure and temperature conditions.These three conditions are the main factors influencing the distribution of asphaltene.Asphaltene deposition affects porosity,permeability,also oil recovery.By using a numerical model to predict the asphaltene deposition distribution in the process of CO₂ flooding of a special block of Changqing oilfield,put forward some proposals about reducing the influentce of aspaltene deposition damage and oil recovery.