Comparative Evaluation of Electrical Heating Methods for Oil Sand Reservoirs
对于稠油热采，传统的注汽过程通常只适用于相对浅层、渗透率高、厚储层赋存且均质的油藏。一种替代方法是应用电能，包括电加热器、电阻加热和电磁加热方法，可以在不适合注汽的油藏中产生热能，或者提高与注汽相比进行重油采收的经济性。
然而，目前最常用的电加热模拟方法是两个模拟器数据耦合，其中一个用于计算电加热，另一个用于计算油藏。本论文的工作提供了一个能够模拟和计算重油和油砂热采的所有电加热过程的单一模拟器，并且省略了在两个模拟器之间传递数据的计算负担和复杂性。
在本文中，我们开发了一个新的数值模拟器，处理了电加热器、电阻加热和电磁加热等三种电加热过程。新的物理过程模型被推导出来，并用于数值模拟。电流平衡用于建模油砂油藏中的电流流动，合理处理了相邻格点之间的电导率。通过对麦克斯韦方程进行转换，提出了描述磁场的亥姆霍兹方程，使得在非均质介质（如油藏）中得到电磁场解的可行性增强。
此外，目前还无法在单一模型中模拟这三种电加热过程，本论文的工作使得可以直接对这些不同的方法进行比较。通过两种情况来检验电加热在油砂油藏中的可行性：a) 包含加热源的水平井，b) 在两口水平井中都有加热源。比较了三种电加热过程中的温度、水饱和度和电耗的模拟结果。
Abstract
For thermal heavy oil recovery, conventional steam injection processes are generally limited to reservoirs of relatively shallow depth, high permeability, thick pay zones and homogeneity. An alternative approach of applying electrical energy, including methods of electric heater, electrical resistance heating and electromagnetic heating, can be used to generate heat in reservoirs that are not suitable for steam injection or to improve the economics of the heavy oil recovery compared with steam injection processes. However, in the current, the most widely used simulation method of electrical heating is the data coupling of two simulators, one is used for calculation of electrical heating and the other is used for calculation of a oil reservoir. The work in this thesis provides a single simulator that is capable of modelling all electrical heating processes for heavy oil and oil sands thermal recovery and the computational overhead and complexity of swapping data back and forth between two simulators has been omitted.
In this work, a new numerical simulator is developed that handles the three electrical heating processes, such as electric heater, electrical resistance heating and electromagnetic heating. New models regarding the physical processes of the electrical heating methods have been derived and used for numerical simulation. The electric current balance was used for the modelling of electrical current flow in oil sands reservoirs with an appropriate treatment of electrical conductivity between neighbouring grids. A Helmholtz equation for the magnetic field by deformation of Maxwell’s equations is presented that makes it feasible to find electromagnetic field solutions for an inhomogeneous medium, such as a oil reservoir.
Also, it has not been possible until now to model all three electrical heating processes in a single model and the work in this thesis enables a direct comparison of the different methods to be made. The feasibility of electrical heating in oil sands reservoirs is examined in two case categories: a) a horizontal well containing a heating source and b) a horizontal well-pair with heating sources located in both wells. Simulation results are compared in temperature, water saturation and electrical energy dissipation in the three electrical heating processes.
