Flow Characteristics of Steam and Gas Push in the Presence of Heat Thief Zones Overlying Oil Sands Deposits

Abstract

This paper presents the effects of the top water-bearing zone on the performance of the steam and gas push, i.e., nitrogen as a non-condensable gas injected with steam into an oil sands deposit. The flow characteristics of fluid mixtures are examined in the presence of different-sized water-bearing formations overlying oil sands deposits, i.e., a finite aquifer with no-flow boundaries and an infinite aquifer with continuous mass flux. The performance efficiency is investigated by respectively implementing the cumulative steam to oil ratio, a simple thermal efficiency parameter, and the oil production on the surface. The top water-bearing area serves as a heat thief zone and negatively impacts bitumen recovery; furthermore, it increases the cumulative steam to oil ratio while decreasing the simple thermal efficiency parameter, as well as the oil production rate. When the steam chamber encounters the top aquifer, a severe heat loss occurs. As increasing mol % of nitrogen, the producing time with energy efficiency increases but the chamber growth is limited. The specific operational conditions would be possible for the finite-sized aquifer, while the continuous water influx and the significant heat loss obstructs the thermal processes for the infinite aquifer.

Optimization of Fast-steam-assisted gravity drainage for the energy-efficient operations at a heterogeneous oil-sands reservoir

“…the concentration of mass transfer through some breakthrough zones, is not avoided due to reservoir heterogeneity. If thief zones, such as the water-bearing area overlying the oil-sands reservoir obstructs the vertical growth of the steam chamber and decreases the efficiency of the thermal process (Austin-Adigio et al, 2017;Lee et al, 2017), this study shows that the Fast-SAGD that enhances the lateral chamber growth would be one of the possible solutions. The oil-sands formation used in this work has a relatively high permeability, so it was not difficult to inject steam without any preheating for CSS process.…”

Improvement of Steam Injection Processes Through Nanotechnology: An Approach through in Situ Upgrading and Foam Injection

“…The temperature in each of the nodes was measured using integrated thermocouples along the steam generator output line and the entire sample-holder in order to corroborate the improved thermal conductivity. The drop-in temperature in general is due primarily to the tortuosity of the medium [92,93], to the energy transfer from the steam to the fluids (water and oil) [94], and the composition of the rock (99% silica) can be considered as heat sinks [95]. On the other hand, the change in temperature for the system after the nanofluid injection was lower than in the absence thereof.…”