Abstract
Dealing with the heat losses associated with steam-assisted gravity drainage (SAGD) experiments has been an issue for which different heat loss prevention techniques have been developed and utilized in the literature. The aim is to minimize the amount of heat losses from the porous medium to the surrounding environment. Excessive heat losses negatively affect quantifying the energy requirements of the SAGD experiments. In this study, an inverted-bell vacuum chamber was employed to minimize the excessive heat losses while steam was injected under different superheating levels. Local temperatures along the glass micromodels’ height and width were recorded on a real time basis. Details of the heat losses associated with our pore-scale SAGD visualization experiments are described in this paper. According to the results presented, employing extremely low vacuum conditions resulted in effective heat loss prevention in a sense that the convective element of heat loss could be neglected. As a result, radiation heat transfer was the only mechanism of heat transfer that contributed to the heat loss from the micromodels’ surfaces. In each pore-level SAGD experiment, the overall steam consumption to produce one unit of the mobile oil was corrected based on the heat loss analysis of the process to account for the additional volume of steam which was condensed because of the heat loss. The net cumulative steam consumed, corrected for the heat losses, was in very good agreement with the predictions made based on the theory of gravity drainage and its application in performance analysis of the SAGD process.
Highlights
The steam-assisted gravity drainage (SAGD) process is considered as one of the most prominent bitumen recovery methods
A novel method for heat loss prevention during the course of in situ bitumen recovery using the SAGD process was utilized with the aid of a high-precision inverted-bell vacuum chamber
Fractional instantaneous heat losses from the porous media under radiation heat transfer mechanism were calculated during the actual pore-scale SAGD experiments considering the fraction of the swept area of glass micromodels, real-time bitumen-steam interface tracking, and energy dissipation calculations using information derived from the heat loss experiments
Summary
The SAGD process is considered as one of the most prominent bitumen recovery methods. The mobile oil and water condensate move approximately parallel to the steam chamber/bitumen interface towards the producer Using this recovery technique, bitumen can be extracted in a systematic manner with very high ultimate recovery factor values which are significantly greater than those achieved using the conventional steam flooding processes. The energy intensity of a thermal process of heavy oil and bitumen recovery is defined as the volume of steam, in terms of its cold water equivalent (CWE), which is needed to produce one unit volume of the mobile oil. This production characteristic of the SAGD process, which specifies the economics of this thermal recovery method, is called the cumulative steam to oil ratio (CSOR). Details of the heat loss analysis associated with our porescale SAGD visualization experiments are described
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