Remotely operated tool speeds up conductor cuts

Bergen-based Beerenberg has won two contracts in the Gulf of Mexico for its newly developed Green Turtle conductor cutting technology, which it developed with partner CalDive International.

The patented technology is designed to provide a cost-effective method of cutting the conductor which is left protruding from the seabed after the well has been abandoned and the platform on which it was completed has been removed.

The Green Turtle is a cylindrical tool, measuring 13 m (42 ft) high and 3.6 m (12 ft) in diameter and weighing around 24 metric tons (26.5 metric tons). It is lowered over the conductor and excavates its way down to 15 ft (4.6 m) below the sea surface – the depth at which the conductor must be severed – by means of water or air jetting.

The Green Turtle tool has been designed to cut and retrieve the upper section of conductors from abandoned wells.

It then secures itself to the conductor, after which the cutting apparatus is activated, comprising four knives mounted on a circular frame. The knives’ cutting edge is formed of synthetic diamonds. Once the upper section of the conductor has been severed, it is retrieved to the surface still held in the tool’s grip.

According to chief technology officer Baste Tveito, the whole operation can normally be executed in a 12-hour shift, compared with five to six days for the conventional method, which involves the use of divers and either a diamond wire cutter or explosives. The Green Turtle method dispenses with diver risk, involves no damage to the local environment, and brings savings in time and cost, Tveito says. In addition, it has no inherent depth limitation, as is the case with manned diving operations.

In late June, Beerenberg and CalDive, which is responsible for the marine operation, including provision of a ship, were mobilizing for the first contract, which involves three wells for W&T. The partners also have a one-well contract for Apache, valued at NOK 2 to 3 million ($0.32 to $0.48 million). Further contracts are under negotiation.

The Green Turtle technology was developed by the two partners with financial assistance from Innovation Norway. Testing was only completed in May. The current tool can cut conductors up to 30-in. (76-cm) diameter. Once it has some operational experience, Beerenberg plans to build a second tool capable of cutting conductors up to 36 in. (91-cm).

The company has identified the Gulf of Mexico, with over 11,000 redundant wells waiting to be abandoned, as the optimum market for launching its technology.