Several processing options have been developed to accomplish near-well-bore in-situ upgrading of heavy crude oils. These processes are designed to pass oil over a fixed bed of catalyst prior to entering the production well, the catalyst being placed by conventional gravel pack methods. The presence of brine and the need to provide heat and reactant gases in a down-hole environment provide challenges not present in conventional processing. These issues were addressed and the processes demonstrated by use of a modified combustion tube apparatus. Middle-Eastern heavy crude oil and the corresponding brine were used at the appropriate reservoir conditions. In-situ combustion was used to generate reactive gases and to drive fluids over a heated sand or catalyst bed, simulating the catalyst contacting portion of the proposed processes. The heavy crude oil was found to be amenable to in-situ combustion at anticipated reservoir conditions, with a relatively low air requirement. Forcing the oil to flow over a heated zone prior to production results in some upgrading of the oil, as compared to the original oil, due to thermal effects. Passing the oil over a hydroprocessing catalyst located in the heated zone results in a product that is significantly upgraded as compared to either the original oil or thermally-processed oil. Catalytic upgrading is due to hydrogenation and results in about a 50% sulfur removal and an 8°API gravity increase. Additionally, the heated catalyst was found to be efficient at converting CO to additional H 2 . While all of the technologies needed for a successful field trial of in-situ catalytic upgrading exist, a demonstration has yet to be undertaken.
The classical concept of in situ combustion kinetics assumes the high-temperature combustion of a coke-like phase which has been deposited by thermal cracking reactions occurring ahead of the hightemperature front. Although this model appears adequate to describe the behaviour of low-pressure, high-air flux tests on most oils under dry and normal-wet conditions, its limitations are apparent when evaluating the performance of most high-pressure experiments, especially those carried out at high oxygen concentrations and low oxygen fluxes.A comprehensive program on low-and high-temperature oxidation kinetics was therefore undertaken with the aim of understanding the mechanisms associated with in situ combustion.Accordingly, the highlights of findings from a ramped-temperature oxidation study on Athabasca Oil Sands is presented in this article. The results have significantly expanded the knowledge of in situ combustion kinetics, but perhaps the most important observation arising from the work is the recognition of the significance of the low-reaction rate region existing at the temperatures intermediate between those associated with lowtemperature oxidation and high-temperature combustion reactions. The kinetics in this temperature range are characterized by decreasing oxygen uptake and energy generation rates with increasing temperature. This behaviour is analogous to the negative temperature gradient region described in conventional combustion literature. The ability of an oil to transcend the negative temperature gradient region appears to dictate its ultimate in situ combustion behaviour, and it appears that many field projects and tests utilizing high pressures and oxygen-enriched air operate in the low-temperature oxidation mode because of this phenomenon.
Figure 1 provides a schematic of the matched reactor apparatus. AbstractOils that are potential candidates for in situ combustion recovery processes are often screened by means of their oxidation characteristics; in particular, the kinetics of the ignition process and the transition from low temperature to high temperature oxidation through what is known as the "negative temperature gradient region." A ramped temperature oxidation apparatus, consisting of two identical tubular reactors mounted in a common heating block, was developed to observe these characteristics. The active reactor contained core which was saturated with oil and water, while the reference reactor contained only clean core. Inert gas was flowed through the reference reactor and an oxygen-containing gas was flowed through the active reactor while both were simultaneously heated at a fixed rate. Measured temperatures from the reactors, and produced gas composition and post test core analysis of the active reactor, allowed determination of the oxidation mode and transition behaviour.The apparatus was used to conduct a detailed parametric study of the oxidation characteristics of Athabasca Oil Sands bitumen. The test operating procedure matrix involved various levels of pressure, gas injection rate, oxygen content of the injected gas and maximum ramp temperature. The principal finding from the 45 test study was the need to maintain high reaction temperatures (>380˚ C) in order to mobilize and produce heavy oils and bitumens under conditions of dry in situ combustion. 2Journal of Canadian Petroleum Technology FIGURE 1: A schematic flow diagram of the matched reactor apparatus. Special Edition 1999, Volume 38, No. 13 6 Journal of Canadian Petroleum TechnologyFIGURE 12: Temperature profiles for Test 27 [65% O 2 , 105 m 3 (ST)/m 2 h flux, 7,090 kPa]. FIGURE 14: Residual hydrocarbon saturations for Test 27 [65% O 2 , 105 m 3 (ST)/m 2 h flux, 7,090 kPa]. FIGURE 13: Oxygen uptake/carbon consumption for Test 27 [65% O 2 , 105 m 3 (ST)/m 2 h flux, 7,090 kPa]. FIGURE 15: Temperature profiles for Test 45 [22% O 2 , 105 m 3 (ST)/m 2 h flux, 4,190 kPa]. FIGURE 16: Product gas composition for Test 45 [22% O 2 , 105 m 3 (ST)/m 2 h flux, 4,190 kPa]. CSChE, and CHOA.Catherine Laureshen is an instructor in the common core engineering program at the University of Calgary, and teaches for both the mechanical engineering as well as the chemical and petroleum engineering departments. She is also a founder and one of the co-ordinators of the Engineering Drop In Centre, which provides one-on-one assistance to first and second year students in the engineering program. Dr. Laureshen holds B.Sc. and Ph.D. degrees in mechanical engineering from the University of Calgary. She has been a member of the In Situ Combustion Research Group in the department of chemical and petroleum engineering for the past ten years, focussing on the improved recovery of conventional oil and also has research interests in the two-phase flow and environmental areas. Catherine has authored or co-au...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.