Hebron Gravity-Based Structure

For the Hebron oil field’s gravity-based structure (GBS), MAPEI’s Mapeprimer M and Mapecoat CFS were used as a curing compound and for concrete protection in interior and exterior areas that would be in contact with harsh environmental conditions.

The Hebron oil field is located in the Jeanne d’Arc Basin of the North Atlantic Ocean, 217 miles (350 km) southeast of St. John’s, Newfoundland. Discovered in 1980, the field will produce an estimated total of more than 700 million barrels of recoverable resources. Located within the field is the Hebron gravity-based structure (GBS), which will pump 150,000 barrels of heavy oil a day.

According to the owners, the structure “consists of a reinforced concrete structure designed to withstand sea ice, icebergs and meteorological and oceanographic conditions. It is designed to store approximately 1.2 million barrels of crude oil.” The majority of the work on the GBS took place at the Bull Arm fabrication site in Trinity Bay, Newfoundland, with 3,500 workers on site during the construction.

The Hebron GBS project has delivered significant benefits to Newfoundland and Labrador, including employment and training of a diverse workforce, research and development opportunities, and fabrication and construction work, along with significant royalty and tax revenues.

MAPEI products on the jobsite

After being accepted as an approved supplier for the Hebron GBS project, MAPEI worked with distributor Apex Construction Specialties Inc. to provide a concrete-curing system with a protective coating for the GBS.

As part of a concrete slip-forming application (a construction technique in which concrete is continuously poured into a moving form to allow for simultaneous extrusion and finishing of the concrete), Kiewit-Kvaerner Contractors (KKC) employees applied Mapeprimer M over fresh concrete. After waiting an hour, they applied Mapecoat CFS with a notched trowel and then flattened it.

Mapecoat CFS is thixotropic and easy to apply, even in thick layers, on both horizontal and vertical surfaces. Mapecoat CFS was applied in two coats at about 1/8" (3 mm) of total thickness. After curing, Mapecoat CFS formed a flexible and robust coating that acted as a curing compound and protection for the concrete in areas that will be in contact with crude oil while the structure is in operation.

Operating in 12-hour shifts, the workers applied about 926 lbs. (420 kg) of Mapecoat CFS and 50 units of Mapeprimer M a day. At times, they would slip-form for four weeks nonstop on certain applications. Mapenet 150, a reinforcing mesh, was used where needed with the Mapecoat CFS.

In 2016, KKC employees also coated the interior shaft of the structure with Mapecoat CFS and Mapeprimer M. The diameter of the shaft is 115 feet (35 m) in width.

The Hebron GBS was scheduled to begin its oil production in the fourth quarter of 2017.