Greener technology targets Saskatchewan's heavy oil resources.

Saskatchewan's oilpatch has earned a name for itself by embracing technological innovation. Think of the billion-dollar C[O.sub.2] storage/enhanced oil recovery project underway in the province's southeast, or the enthusiastic championing of horizontal well drilling.

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Once again, Saskatchewan is home to the development of a new technology with the potential to inject years of extra life into mature oil reservoirs. Solvent vapour extraction (or SVX), a family of environmentally attuned oil recovery processes, is being field tested in the Lloydminster area by a consortium of oil producers and expert researchers.

The field pilots are a key part of JIVE (Joint Implementation of Vapour Extraction), a three-year, multi-faceted study managed by the Regina-based Petroleum Technology Research Centre (PTRC). With total cash and in-kind funding of $40 million from government and industry, JIVE's goal is to develop and demonstrate SVX for heavy oil recovery.

SVX involves injecting a gaseous hydrocarbon solvent, generally propane or butane, into a reservoir through either horizontal or vertical wells. The solvent dissolves into the oil, thinning it enough to flow to a production well. Methane, used as a carrier gas for the solvent, may provide some pressure drive to assist production.

SVX is field-specific: the reservoir's geology, rock/fluid properties and production history will dictate the choice of solvent, production strategy and well configuration. JIVE's field pilots are in three distinctly different reservoirs in Saskatchewan and Alberta. The pilot hosts--Nexen Inc., Husky Energy and Canadian Natural Resources Limited--together account for 60 per cent of Saskatchewan's heavy oil production.

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These companies recognize the urgency of finding viable ways to sustain production from Saskatchewan's scarcely tapped, often stubborn, heavy oil resources. Heavy oil recovery in the province is forecasted to decline 50 per cent over the next decade. Current production methods recover on average nine per cent of the sludge-like petroleum. The remaining heavy oil in the province is worth about $1 trillion at today's prices. Depending on the application, SVX recovery rates are expected to range from a conservative 30 per cent to 50 per cent of a reservoir's oil in place.

The JIVE hosts believe that by sharing experiences from the pilots, they can speed the pace of technology development. Under JIVE, the industry partners and researchers meet every month to contribute ideas and data to a continuous input-feedback loop.

"The discussions among the industry partners are refreshingly candid," notes Dr. Patrick Jamieson, general manager, technology and reservoir evaluation, Nexen Inc. "We are learning quickly from each other's successes and failures, and it's a big advantage to be able to tweak our pilot test strategies using the pooled knowledge gained from this program."

The field pilots dovetail with a concurrent program of laboratory studies and predictive scaled physical modeling and numerical simulation. This work is being carried out by research teams from Saskatchewan and Alberta. The high-pressure, three-dimensional model being used in JIVE to mimic reservoir conditions and predict and optimize process performance is the largest, most capable of its kind in the world. A mobile laboratory is available to provide immediate, on-site analysis of the pilots as they progress.

Two key technical questions are how to speed the inherently slow rate of solvent dissolution into the oil and how to recover as much of the pricey solvent as possible for recycling.

SVX represents a clean break from current technology as it uses no water and only a fraction of the energy of popular thermal methods like steam-assisted gravity drainage (SAGD). The green advantages of SVX won't necessarily drive applications in Saskatchewan's heavy oil reservoirs, which are mostly too thin to suit thermal methods. However, SVX's eventual worldwide potential for cleaner, less energy-intensive enhanced oil recovery in a broader range of reservoirs is tremendous.

"This project is making it clear that solvent vapour extraction--depending on how widely applicable and economic it ultimately proves to be--is likely to occupy an important niche and perhaps even predominate among competing heavy oil recovery technologies," Dr. Jamieson affirms. "The icing on the cake is that it has a much smaller environmental footprint than its thermal counterparts."

Brian Kristoff is Manager of Enhanced Oil Recovery Field Development for the Saskatchewan Research Council.