DOWN-HOLE CATALYTIC UPGRADING OF HEAVY OIL AND BITUMEN TO MEET TOMORROW’S ENERGY NEEDS: THE THAI-CAPRI PROCESS 1
Abarasi Hart1*, Gary A. Leeke1, Malcolm Greaves2 and Joseph Wood1 School of Chemical Engineering, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK 2 IOR Research Group, Department of Chemical Engineering, University of Bath, BA2 7AY, UK
Abstract The CAtalytic upgrading PRocess In-situ (CAPRI) incorporated with Toe-to-Heel Air Injection (THAI) for oilsands recovery and upgrading, was simulated at the laboratory-scale using a fixed-bed reactor. The technology combines in situ down-hole combustion and catalytic cracking to convert heavy feedstock into light oil. The degree of upgrading was evaluated in terms of API gravity, viscosity reduction, and distillation characteristics of the produced oil as a function of temperature, the use of guard-bed catalyst, hydrogen and hydrogen pressure. It was found that the viscosity reduced by 82%. Keywords THAI-CAPRI, Heavy oil, Bitumen, Energy Introduction Crude oil is currently a primary source of energy globally. However, the continuous decline of light oil reserves has shifted attention to large deposits of untapped heavy oil and bitumen energy resources. These resources are characterised by high viscosity and density, high asphaltenes and heteroatom (e.g., S, N, V, Ni, etc.) content, high cost of production, low American Petroleum Institute (API) gravity, and low market value, which hinders their exploitation. Conversely, heavy oil and bitumen account for about 70% of the world’s total 9-13 trillion barrel oil resource (Zhang, et al., 2012). Therefore, the viability of these resources is dependent on recovery and upgrading technology that will convert them to light oil in an economical and environmentally friendly manner. In the light of this, the Toe-to-Heel Air Injection (THAI) and incorporated CAtalytic upgrading PRocess In-situ (CAPRI) were developed for the recovery and upgrading of heavy oil and bitumen (see Figure 1). Previous work by Shah et al. (2011) has shown that asphaltenes, coke and metal deposition drastically deactivates the catalyst. In this study, Co-Mo and Ni-Mo quadrilobe catalysts were used and the degree of catalytic upgrading in THAI-CAPRI was evaluated as a function of temperature, the use of guard bed catalyst, hydrogen and hydrogen pressure. The use of guard-bed catalyst and hydrogen to reduce coke formation and impact of metal deposition was also investigated.
Thermal cracking
Reservoir formation
Producer Well Mobile Oil Zone (MOZ)
Cold Heavy Oil
Combustion front
Enriched Air and steam
Advancing Combustion Front
Catalytic cracking in situ
Mobilised Fluid
Heel
Annular Catalyst
Toe
Figure 1. Schematic diagram of the THAI-CAPRI Process Experimental The feed oil was supplied by Petrobank Energy and Resources Ltd., obtained from the WHITESANDS THAI Pilot trial, Alberta, Canada. The physical properties of the feedstock are as follows: density (0.9801g/cm 3), viscosity (490mPa.s) and API gravity (~13oAPI). The CAPRI experimental runs were conducted in a fixed-bed reactor which is operated in the down-flow mode to ensure complete wetting of the catalyst bed (see Figure 2). The gas product and light oil from the reactor passed into the gas-liquid separator. The pressure in the reactor was controlled by the back pressure regulating valve. The light oil product was withdrawn continuously
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from the separator, while the gas product was vented or sent to the refinery gas analyser (RGA) for composition analysis. The reactor consists of a stainless steel tube of 1cm inside diameter, 40.5cm length and 20.2cm catalyst bed length. The upstream and downstream zones of the reactor contain glass beads to ensure efficient contacting of the feedstock and gas (i.e., N2 or H2). Feed oil reservoir
Vent Vent
Mixing Chamber
Oil Reservoir
Reactor Furnace Reactor
Catalysts Reactorbed Vent Vent N2 N2 80% CO 12-14% CO2 2-3% CH4 2-4%
Refinery Refinery Gas Gas Analyser Analyser
Gas-liquid separator
Gas-liquid separator Refinery Gas Analyser
It is clear that hydrogen-addition improved the API gravity and viscosity of the produced oil significantly. This may be attributed to hydrogenation of aromatics and hydro-cracking reactions. Additionally, H2-addition further increased the API gravity by 2oAP and further viscosity reduction by 2-6%. The amount of coke deposited on the catalysts was measured by thermogravimetric analysis (TGA). Figure 5 illustrates TGA curve of coked Co-Mo catalyst after used. The mass fraction of coke reduced from 57.4 wt. % in N2 atmosphere to 32.6 wt.% in H2 atmosphere. This confirms that less coke was deposited on Co-Mo because of hydrogenation and removal of heteroatom in the presence of H2.
Produced oil Drain Sample Drain
Figure 2. Diagram of the experimental setup
Results and discussion The extent of upgrading at the following conditions: reactor pressure, 20bar; weight hourly space velocity (WHSV), 9.1h-1; reaction temperature, 350-425oC; and H2-to-oil flow ratio, 200mL/mL was evaluated. The API gravity and viscosity reduction as a function of time-onstream are presented in Figures 3 and 4, respectively.
Figure 5. Spent catalyst coke content Conclusions The THAI-CAPRI was investigated. It was found that the produced oil improved in API gravity and viscosity by H2-addition. Also, it was observed that use of guard bed and H2 reduced coke formation. Acknowledgement The authors acknowledge the support of PTDF, EPSRC, and Petrobank Energy and Resources Ltd. References
Figure 3. Effect of hydrogen-addition on API gravity of produced oil using Co-Mo catalyst
Figure 4. Effect of hydrogen-addition on viscosity of produced oil using Co-Mo catalyst
Shah A., Fishwick R.P., Leeke G.A., Wood J., Rigby S.P., and Greaves M., (2011). Experimental optimisation of catalytic process in situ for heavy-oil and bitumen upgrading, Journal of Canadian Petroleum Technology, 50 (11-12), 33-47 Zhang H.Q., Sarica C., Pereya E., (2012). Review of high-viscosity oil multiphase pipe flow, Energy & Fuels, dx.doi.org/10.1021/ef300179s
