BP to re-tender Mad Dog 2 FEED on Atlantis concept
BP is preparing the second call for tender on the front end engineering and design (FEED) for the Mad Dog-2 offshore platform based on the semi-submersible concept used for Atlantis in the US part of the Gulf of Mexico.
Originally BP intended to develop the second phase of Mad Dog with single point anchor reservoir (SPAR) type of platform such as proposed by Technip.
Therefore Technip and AMEC carried out a complete FEED work, up to the final costs estimate in order to support the final investment decision (FID) and move into the engineering, procurement and construction (EPC) phase.
Unfortunately the costs estimate was spiraling up along the FEED progress at the same speed as the weight of the topsides to be landed on the SPAR platform.
Budgeted at $10 billion capital expenditure, Technip and AMEC ended up with costs estimates flying somewhere between $18 and $20 billion with topsides exceeding the 30,000 tonnes.
BP LoSal water treatment process to fit in Mad Dog-2
These Mad Dog 2 topsides are challenging because of the size of the field development and the technologies envisaged by BP.
As one of the largest oil and gas fields in the Gulf of Mexico, Greater Mad Dog is retaining more than 4 billion barrels of oil equivalent (boe) approximately 225 kilometers south of Louisiana in the Block 738 of the Green Canyon.
With Mad Dog-2, BP is targeting to produce from 120,000 to 140,000 barrels of oil equivalent (boe) per day.
In addition to increase the production with a new production platform, BP intends to enhance the recovery rate at the whole scale of the field in introducing its proprietary flooding technology LoSal.
Experienced in Alaska and utmost North Sea some some companies such as BP and Statoil, the injection of water with low salinity has proven to be extremely efficient to improve the recovery rates in old fields.
With this technology Statoil is expecting to ramp up its average recovery rate from 50% to 65% in the coming years.
Branded as LoSal by BP, this technology comes along with some constraints in the offshore environment as it requires an advanced water treatment process to inject 280,000 barrels of water per day (b/d) with the finely tuned salinity.
Therefore the addition of this water treatment plant, plus the additional power supply to operate it on the Mad Dog 2 is the cause of the engineers headache to fit it in the topsides given for this project.
KBR completed Mad Dog-2 plaform conceptual study
To substitute the SPAR and its limits in that respect, BP has explored with deep offshore engineering companies different solutions including:
- Tension leg platforms (TLP) from Houston Offshore Engineering
- Heave and vortex-induction-motion semi-submersible (HVS) platforms from Technip
- Conventional semi-submersible platforms from Aker Solutions and from KBR
From these investigations, BP and its partners came to the conclusions that an Atlantis semi-submersible type of platform could reduce the weight of the topsides down to 25,000 tonnes.
Designed by the team made of KBR and its shipyard GVA in Sweden, this Atlantis type of semi-submersible platform offers a high level of integration between the topsides structure and the jacket structure.
From this concept, BP and its partners BHP Billiton (BHP) and Chevron are now intending to move ahead into the FEED phase in order to keep Mad Dog 2 time frame on track.
In this project these companies hold the respective interests:
- BP 60.5% is the operator
- BHP Billiton 23.9%
- Chevron 15.6%
With a call for tender to be issued in Q2 2014, BP is willing to proceed on fast track with the Mad Dog 2 platform along the FEED phase and the EPC phase in order to anchor it in the Gulf of Mexico still by 2018.
