Fully Implicit Reservoir Simulation For Chemical Flooding

The major oilfields in China have come into the late developing period with high water cut of over 90%,and chemical flooding is selected as an effective technique to improve oil recovery and ensure stable oil production.Today,large-scale chemical flooding applications have been performed in China’s major oilfields.Associated with various physicochemical phenomena,the flow mechanisms of chemical fooding is very complicated.Today,various researches were performed to understand the chemical flooding mechanisms by different means including laboratory experiments,numerical simulation and field test.Numerical simulation,as an important tool for the successful design and evaluation of chemical flooding projects,is gaining extensive attention.This dissertation focuses on the numerical simulation for chemical flooding,in which the mathematical model,numerical scheme for chemical fooding simulation is discussed.Also,the numerical well testing methodology for chemical flooding is investigated to improve the reliability well testing interpretation and make full use of the pressure transient data from field tests.The main works of this dissertation are as follows:1.A multi-phase multi-component mathematical model for chemical flooding is given incorporation the major physicochemical mechanisms.Basing on PEBI gridding,a fully implicit scheme is established for numerical solveing.A numerical simulator for chemical flooding is developed using C++ code.Finally,the correctance of the simulator is validated against the UTCHEM simulator.2.The substitution of variable method is applied to treating the phase behavior calculation in the simulation for surfactant flooding.By deriving separate forms of linearized equations according to oil phase disappearance or appearance,the method reduces the number of primary variables,and improves the simulation speed.3.A new permeability reduction model for polymer flooding is proposed which incorporates the variation of residual oil saturation and polymer/oil relative permeability with polymer concentration.Numerical study is conducted to investigate the impact of relative permeability variation on the prediction of transient pressure and water cut.The results support using variable polymer/oil relative permeability curves in numerical well testing for polymer flooding.Finally,a new approach is proposed to evaluate the formation damage in polymer flooding by means of well testing analysis.4.By employing the proposed numerical simulator,the pressure transient response of chemical flooding wells is studied,and parametric studies are perfomed to investigate the influence of relavant factors on pressure transient curves.The influence of non-Newtonian rheology of polymer solution is studied through numerical analysis.The results show that,the shear thinning property will leads to obvious non-smoothness of pressure derivative curve in early stage.Based on the result,a new approach is proposed which determines the polymer in-situ rheology from well test interpretation.