Canada-Newfoundland Offshore Petroleum Board has put the proposed $5.7billion Hebron heavy oilfield development on the Grand Banks out to public consultation.
If the ExxonMobil-operated project makes a smooth passage, the plan is for construction of the main concrete gravity-base structure to start in 2012 at Newfoundland’s Bull Arm fabrication yard, which was originally opened for the province’s first offshore development – Hibernia.
Like Hibernia, Hebron will be developed using a stand-alone GBS platform designed to withstand extreme ice conditions, including brushes with icebergs.
Hebron is Canada’s largest offshore project by far at present. It is expected onstream around 2017 and will create hundreds, even thousands, of local construction and engineering jobs.
The preliminary GBS concept features a single main shaft supporting the topsides, encompassing all wells, and may also incorporate an inner wet shaft to provide direct access to any pre-drilled wells.
Field life is expected to be at least 30 years, and it is likely that the platform will have a processing capacity of 160,000-235,000 barrels per day of oil, plus the ability to handle large quantities of water. A gas-injection package will also be fitted.
The GBS will be designed to store about 1.5-1.9million barrels in multiple, separate storage compartments and export will be by shuttle tanker.
An offshore loading system (OLS), complete with a looped pipeline and two separate loading points, will be installed to offload the oil on to ice-strengthened tankers for transfer to the Newfoundland transshipment terminal or for transport directly to market.
Exxon says several methods could be used for laying the pipelines related to the OLS and that the approach will be selected as part of the detailed engineering and construction planning effort.
The current plan is to open up a cluster of reservoirs – Ben Nevis, Hibernia and Jeanne d’Arc H and B reservoirs within the Hebron field area, and gas storage in the Ben Nevis reservoir of the West Ben Nevis field.
Water injection will be required as the primary drive mechanism for the Hebron field to improve overall oil recovery. Estimated oil recovery for the base development will be about 755million barrels.
According to Exxon’s submission to the board, the total number of wells for the base case project will be in the range 35-45, of which perhaps 13 could be pre-drilled to assist with production ramp-up.
In addition, there is opportunity for the development of further oil accumulations in the Hebron project area, depending on the drilling results, production performance (of wells from the initial development), studies, possible delineation wells, new seismic data or some combination of these.
The report says that, for example, the Ben Nevis reservoir in the Ben Nevis field could be part of an optional later phase of development subject to filing a supplemental development plan.
Overall, Ben Nevis is the core of the Hebron project and is expected to account for about 80% of the oil produced.
“However, the reservoir quality is expected to be of a lower quality when compared to other producing fields in the Jeanne d’Arc Basin, for example Hibernia or Terra, and the medium 20Deg API crude in this pool presents production challenges as the viscosity can be 10-20 times higher than that of water,” says the report.
However, the Jeanne d’Arc and Hibernia pools are of higher oil quality, though there is a downside, namely that reservoir quality is poorer, lower recovery rates are expected and development costs will be higher. Hebron has a relatively low gas-to-oil ratio, but Exxon expects that there will be enough present to facilitate oil production.