Numerical Simulation For Wellbore And Formation Temperature In Water Injection Wells

Study on wellbore and formation temperature in water injection wells is the theoretical base of temperature logs in an injection profile and important in reservoir description and reservoir numerical simulation. The heat transfer in a vertical wellbore and porous formation (injection formation and adjacent rocks) is studied in this thesis. A downhole temperature model with one hole and multiple injection zones is built by analyzing carefully the heat transfer in water injection wells. Simulation on wellbore and formation temperature in water injection wells is the theoretical foundation for quantitative interpretation for temperature logs in an injection profile. A good water injection scheme is proposed by simulating on different injection conditions and formation parameters.On the basis of the conservation equation of continuous medium and in combination with mechanics of fluid through porous media and the heat transfer theory in porous media, conservation equations in porous media (continuous equation, momentum equation and energy equation ) are derived, When constructing the downhole temperature model, heat transfer in a wellbore is considered as the heat transfer in a vertical tube, the flow in a wellbore considered as sufficiently parallel flow, heat transfer in injection zones considered as heat conduction and convection in porous media, the flow in injection zones considered as flow through porous media, heat transfer in adjacent rocks considered as heat conduction in porous media. Base on these principles and multiple injection zones in waterflooding schemes, dynamic coupled boundary conditions between wellbores and injection zones, wellbores and adjacent rocks, injection zones and non-injection zones are constructed. Combining the temperature distribution of wellbores with the temperature distribution of formations, we construct a closed and conservative equation group with initial and boundary conditions.An alternating direction implicit finite difference method (ADI) is used to solve the downhole temperature model. Downhole temperature distribution in different injection and formation conditions (for example injection time, shut-in time, injection velocity, water injection temperature, adjacent rocks, saturation, porosity ) has been simulated. By analyzing the simulated results we can conclude that temperature logging can distinguish water entry zones from non-water entry zones through hot-water injection for short periods of time, enlarging water injection velocity, selecting reasonable shut-in time. Also when interpreting temperature logging, we must consider the effects of porosity, saturation and adjacent rock lithology on temperature profile. It is a economical and reasonable way to use short, fast, hot water injection in order to change the condition that temperature log can't delineate water injection profile.