The inverted platform recovery required equipment to lift 340 tons. (Photos courtesy of TETRA Offshore Servicese)
The East Cameron 195-A platform operated by Maritech Resources Inc. was a producing platform sitting in 109 ft (33.2 m) of water until Sept. 23, 2005, when the winds and seas from Category 3 Hurricane Rita toppled the platform along with more than 50 others in the Gulf of Mexico (GoM).

Maritech contracted TETRA Offshore Services, a division of TETRA Technol-ogies Inc., to decommission the platform, address the risk of unintended flow from the associated wells, permanently plug and abandon (P&A) the wells, and clear a vast amount of debris caused by the storm for the block to be released by the US Minerals Manage-ment Service (MMS). This project was challenging in that the structure was toppled and the deck was ripped from the jacket at 40 ft (12.2 m) above the seafloor, requiring a large portion of the decommissioning project to be conducted underwater in the area between the point that the platform jacket was severed and the surface of the water.

To this point, many valuable lessons have been learned and many innovative procedures developed by the Integrated Services Group of TETRA Offshore Services in managing this decommissioning, well intervention, and platform recovery project of the East Cameron 195-A platform. One important factor that can be attributed to the success of this project is that all of the groups involved are internal business units of TETRA Offshore Services, which allows for efficient scheduling and the integration of personnel, equipment, and marine vessels throughout each phase. As in any complex recovery operation, several unexpected events threatened the efficiency of the project. However, since all of the involved groups were part of one company, challenges were met and overcome without jeopardizing the project schedule.

Project specifics

The project required the coordination of many disciplines. The TETRA Offshore Services’ Integrated Solutions Group analyzed, engineered, planned, and managed the project and used vessels, equipment, and personnel resources from its Offshore Plug and Abandonment, EPIC Divers & Marine (EPIC), EOT Cutting Services, and Heavy Lift business units to execute the project. Safety and environmental considerations were primary to the project team as they planned for the recovery of the deck and equipment, explosive severing of the jacket legs, and jacket recovery.

Following site clearance of the platform from atop some of the wells, the plan included bringing in a drilling rig to plug and abandon the wells, returning with a derrick barge to explosively sever the conductors, and then recovering the conductors and drilling template.

Production equipment was spread across a circular area of more than 0.5 miles (0.8 km). The wells were bent in different directions — in some cases 30 ft (9.2 m) below the mudline — requiring the project team to jet down below the bend in each of the conductors. This step was required to allow the well P&A team access to near-vertical sections of the inner well strings to eliminate the risk of leaks and prepare the well bores for abandonment.

Salvage plan

In April 2006, the initial offshore phase of the project began with operations conducted from TETRA’s Southern Hercules construction support barge. Seafloor surveys were performed by EPIC using side-scanning sonar and video tapes to obtain information on the actual condition and placement of debris from the platform and facilities. These surveys enabled the preparation of 3-D drawings of the damaged platform and wells, which enabled TETRA Offshore Services’ engineers to prepare a plan for the salvage operation that would be employed on the project.

The salvage plan was reviewed with Maritech and representatives of the MMS. The first procedure was to make safe the 10 wells associated with the structure by temporarily plugging each one. Nine of the wells were located internally and one externally. For approximately six months between April and October of 2006, seven of the 10 wells were temporarily plugged. Each of these seven wells was hot-tapped by equipment and technicians from TETRA’s EOT Cutting Services Group to make the wells safe by releasing remaining pressure and eliminating remaining hydrocarbons.

Next, wells were cut, exposing the casing strings, and temporary wellheads were installed. For the remaining three wells, a plan was developed to plug the wells as soon as the structural debris that prevented access to them was removed.

This removal of debris would be included in the deck/jacket recovery process.
Once all 10 wells were secure, the project team began to develop the next phase of the project, which would be submitted to Maritech and various regulatory agencies for approval. The approval of these plans was delayed by several obstacles, including changes requested by regulatory agencies, equipment availability issues, and the occurrence of other hurricanes. As a result, it would be 21?2 years before the East Cameron 195-A location experienced any further abandonment and decommissioning activity. During that time, the sister platform, East Cameron 195-B, was removed and the site trawled to receive a release from the MMS.

In May 2009, work on East Cameron 195-A resumed with the project team returning to the site to conduct the well intervention of the remaining three wells and to permanently plug all 10. The removal of the deck and jacket was completed by TETRA’s Heavy Lift Group from its DB-1 derrick barge, which removed a large portion of debris from the site. Diving operations were performed by EPIC.

Structural removal and debris recovery efforts were complex, as none of the rigging points that were used to install the structure were suitable for lifting the damaged platform components from the seafloor. The deck lifting points were calculated, and the basket was rigged by EPIC divers. The well guides were cut free of the jacket, and the jacket legs were severed. Next, the jacket was lifted and placed onto a material barge and shipped to shore.

Each of these lifts and the debris recovery portion of the project had to be conducted under strict diver safety protocols since the platform was ripped apart by Hurricane Rita. There was no way to know what each piece of the structure was connected to until it was rigged to the crane and lifted out of the water. Several lifts had unknown piping connections that caused the process to become more complicated and potentially hazardous to the divers. Ultimately, the work was successfully performed, and the salvaged material was sea-fastened to a material barge for safe transit to shore. This phase of the P&A process involved 37,243 manhours and was completed without any recordable safety incidents.

The next phase of the project will require the use of a drilling rig to permanently plug and abandon the remaining three wells. A derrick barge will be used to remove the conductor stubs and the well guides. Finally, the site will be trawled in accordance with MMS guidelines, and the East Cameron 195-A block of the GoM will be returned to the government for public use.