Pressure Transient Analysis Of CO₂ Flooding And Application In Low Permeability Reservoirs

CO₂ flooding has become one of promising techniques to develop low-permeability reservoir.Pressure transient analysis,a main method to know reservoirs and wells,is of great importance in production and reaserches of mechanism of carbon dioxide flooding.However,there are limited researches of well-pressure response charateristics in carbon dioxide flooding,making it necessary to study well-pressure response pattern of CO₂ flooding.In this paper a well-pressure response model CO₂ flooding in low permeability reservoirs based on composite models is built and the numerical solution is presented.The model can simulate changes of fuild properties caused by carbon dioxide injection.Then the model considering components and phase change is built and numerically solved.Combing well-pressure response models,pressure transient interpretation software and SPSA algorithm,an interpretation method of pressure transient of carbon dioxide flooding in low-permeability reservoir is formed.The results show that the curve of pressure derivative will have a depression with a high-compressiblity flooding front.The derivatives of pressure transient exhibit 5 flow regimes which share similar charateristers of flow regimes of composite models.According to the sensitivity analysis,flooding front;reservoir permeability,storage effect,skin factor and the reservoir fluid with different compositon will afffect the shape of pressure-derivative curves.The results of automatic match processing show that the consideration of low-permeablity reservoir characteristics will have a major impact on the permeability interpretion while the consideration of changes in compressibility coeffient will mainly influence the interpretion of fluid diffusivity ratio.The research provides necessary theories and technique support for field application...