BP is closing in on its chosen development concept for its Mad Dog Phase Two project in the deepwater Gulf of Mexico, although the operator is still officially playing its cards close to its chest.

Concepts on the drawing board for Phase Two in Green Canyon Block 738 have included integrated semisubmersible platform options (from Technip, KBR-GVA and Aker Solutions), a downsized version of the originally-preferred giant spar (from Technip) on which spiralling forecast costs last year prompted BP’s decision to re-examine the whole idea, and a Tension Leg Platform (from Houston Offshore Engineering). The spar option was with subsea production and injection wells, with export lines tied into the Mardi Gras field infrastructure.

However, DI hears the semisub is now the likely choice, with BP understood to be preparing to issue a call to tender in the second quarter for a full FEED based along the lines of its deepwater Atlantis field semisub in the GoM.

Lamar McKay, BP’s chief executive for upstream operations, says the development has still not met a crucial development decision gateway in order to proceed. “It did not pass what I consider the FID – a full authorisation gate. It was coming up to that, and we decided that that project was not the best project it could be, so we made a difficult decision to send the [project] team away and rework it with the partners,” McKay said during a recent BP investor presentation.

“I think we are going to come back with something that is much better than what it was,” he added, admitting that the project has suffered some delay. “But we think it was worth it in the end. It was a rationale based on the project’s economics but it was not as good as it could be,” he said.

Bill Utt, chairman, president and CEO of KBR, alluded to the project in his company’s fourth quarter and 2013 full year results but without giving much away: “We are also increasing our activity in the Gulf of Mexico, including our work for BP on the Mad Dog project, where we see several pre-FEED and FEED projects in 2014.”

Production capacities for the eventual chosen platform have been suggested at up to 130,000 b/d of oil and 75 MMcf/d of gas compression, with 280,000 b/d of water injection capacity.

BP is planning to use its advanced LoSal (low salinity) water treatment and injection process to help enhance the field’s recovery rate, which has been partly to blame for the difficulty in keeping the platform’s topsides weight down. The operator is now hoping that an Atlantis-style semisub facility could see that topsides weight kept to around 25,000 tonnes, rather than the 30,000 tonnes plus weight that was being seen on the original spar design.

The Greater Mad Dog field itself is estimated to hold more than 4 Bboe of reserves, with an onstream date still pencilled in for 2018. Operator BP has a 60.5% stake in the project, with its partners being BHP Billiton (23.9%) and Chevron (15.6%).

Offshore