3-D Physical Modeling of Hybrid Steam and Oxygen Injection for In-Situ Recovery of Oil Sands

摘要

Alberta (Canada) has the third largest proven reserves of oil in the world, mostly comprised of bitumen and heavy oil. To date, Steam Assisted Gravity Drainage (SAGD) has been the only commercially viablein- situ recovery technology for the Athabasca Oil Sands, but the current economic conditions have made the SAGD technology challenging, even for some high quality reservoirs. Moreover, from an environmental perspective, large water usage and high carbon emissions also make SAGD difficult to sustain. Due to the current low oil prices and rising penalties on carbon emissions, there is a need to develop improved recovery technologies that are more thermally efficient, with reduced environmental impact and at the same time economically feasible to develop. One of the technologies that has the potential to overcome these economic and environmental shortcomings is a hybrid steam and in-situ combustion process (ISC) called SAGDOX, as this process offers advantages over pure steam injection such as greater energy efficiency, lower water usage and reduced carbon emissions. The SAGDOX (SAGD and Oxygen Injection) process, which is proprietary to Nexen (Kerr, 2015), combines the benefits of both SAGD and ISC processes. Steam is used to preheat and pre- condition the reservoir, also aiding in carrying heat from the combustion zone towards the rich oil saturation zone. One of the main advantages of SAGDOX is the elimination of most of the nitrogen that otherwise would be injected when using air and this reduces the amount of non-condensable gas (NCG) in the reservoir substantially. Heat delivery to the formation using a combination of steam and enriched air injection is more energy efficient than pure steam injection and reduces the steam-oil ratio compared to SAGD. This also lowers the volumes of steam condensate in the produced fluids and thus reduces the produced water handling and processing requirements. The purpose of this study is to provide data to evaluate the feasibility of the SAGDOX process using a 3-D laboratory physical model. A description of the physical model is provided along with the method of operation. The results from two tests are presented and the findings from the experimental studies are also discussed.