The paper is concerned with mathematical modeling of heat and mass transfer in subsurface geothermal systems. Heat exchanger is driven as a vertical channel in an impermeable rock massive. The temperature of rock is driven in accord with a usual thermal conductance equation on a cylinder coordinates basis. The boundary conditions between the rock and heat exchanger are given by the equality of a thermal flow.
One of the methods of oil production intensification is water vapor injection into oil reservoirs. The efficiency of this process generally depends on the amount of useful heat utilized in the oil reservoir. One of the most important parameters of thermocouple treatment of the reservoir is the amount of heat di rectly supplied to the oil reservoir. For its determination it is necessary to know the heat energy losses in surface communications and oil wells, as well as losses associated with heat exchange processes in the oil reservoir and surrounding rocks. High heterogeneity of oil reservoirs complicates the use of continuous steam injection into oil reservoirs. The time required to warm up the reservoir to a given temperature is a determining factor for theoretical analysis of heat losses due to the unsteady heat exchange process in such conditions. The paper presents the basic principles of the heat loss estimation method, as well as the results obtained in determining the relationship between the time required to warm up the oil reservoir to a given temperature and the temperature of steam.
This paper presents analytical methods for investigating the processes of unsteady conjugate heat transfer complicated by the motion of the filtered sphere boundary. The investigations were carried out on the basis of formulation and solution of the following problems: conductive heating of an infinite rod connected to a variable heat flow on the combustion surface, which moves at a constant speed; convective heat transfer in a gasification channel connected to an increase in its length; filtration heat transfer of gas and coolant in an inhomogeneous medium with initial conditions on a moving boundary. Graphs of the acceptance dependences are presented.
The theory of filtration heat transfer received the greatest development in connection with the development of geothermal resources. In the problems of mining thermal physics, as a rule, the real collector of the circulation system is replaced by a model. Each calculation scheme contains values characterizing intensity of heat transfer processes. An analysis of theoretical studies and experimental data on heat transfer coefficients and effective thermal conductivity is carried out. Some recommendations are made regarding the application of these coefficients in existing models of filtration heat transfer. Large scatter in the experimental data and lack of clear theoretical dependences indicate the necessity of reasonable choice of coefficients and making calculations for comparative analysis of different heat transfer models.
