In situ catalytic upgrading of heavy oil using a pelletized Ni-Mo/Al2O3 catalyst in the THAI process

Abarasi Hart,Joseph Wood,Malcolm Greaves

doi:10.1016/j.petrol.2017.06.067

Abstract

Heavy oil and bitumen are difficult crudes to extract and upgrade, with additional transport and refining costs, because of their high viscosity, low API gravity, high asphaltenes, metals (V, Ni), and heteroatoms (N, S). Combining Toe-to-Heel Air Injection (THAI) with its catalytic add-on (CAPRI), a pelletized catalyst is incorporated along the outside of the horizontal producer well for in situ catalytic upgrading. This downhole upgrading process is one means to produce and partially upgrade heavy oil and bitumen with a reduced environmental footprint. In this study, the effectiveness of pelletized hydrodesulfurisation (HDS) Ni-Mo/Al2O3 catalyst for downhole catalytic upgrading was investigated at 350–425 °C, 20 bar, and 9 h−1 space velocity. The additional upgrading due to the presence of the catalyst was evaluated in terms of API gravity, viscosity, boiling point distribution, and sulfur and metals removals, before and after the experiment. The results indicate that the viscosity of the upgraded oil reduced by 1.7, 3 and 5 times less than the feed oil (0.49 Pa s) depending on the reaction temperature in the range 350–425 °C. The average increase in API gravity was approximately 2 to 5° while the gasoline yield showed an improvement of 2.5–13 wt.% above that of the original oil. There was also a modest reduction in the sulfur and metals (Ni + V) content of 2–8% and 1.3–9.2% (Ni + V), respectively. However, a possible limiting factor of the process was that rapid catalyst deactivation occurred due to coking.

Highlights

Conventional light crude oils have high mobility due to their low viscosity, usually less than 5 cP at reservoirs conditions
Canadian production of heavy crude and bitumen has risen to around 2 million Barrels of Oil Per Day (BOPD), Venezuelan extra heavy crude is around 1 million BOPD and long running heavy oil production is approximately 600,000 BOPD, for this to increase in the future will require more advanced production strategies, including advanced Enhanced Oil Recovery (EOR) processes like to-Heel Air Injection (THAI)
Xia and Greaves (2001a,b) reported the 3-D physical model studies of catalytic upgrading of Wolf lake heavy oil using THAI-CAPRI. They found that thermal upgrading alone (THAI) achieved about 9 points increase in the API gravity of the produced oil, while the API gravity of the produced oil by incorporating pelletized catalytic CAPRI section increased it by a further 3 to 7 API, with up to 85% recovery of original oil in place (OOIP)

Summary

Introduction

Conventional light crude oils have high mobility due to their low viscosity, usually less than 5 cP at reservoirs conditions. Unconventional heavy crudes and bitumen have little or no mobility in the reservoir, because of their very high viscosity, which can be several orders of magnitude. In comparison, heavy crudes are more difficult to produce and are more costly to recover and refine. This is because of their high viscosity, low API gravity, high asphaltenes, heteroatom, and heavy metals content. Heavy reserves are about 4–6 trillion barrels and are of a similar order, or greater, than conventional light oil (Zhang et al, 2012). The low quality of heavy oils can be significantly improved via in situ upgrading techniques, using the reservoir as a ‘free’ reactor

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