Breathing new life into Mars

A decade and a half after its Mars TLP started production, Shell is gearing up for the Mars B development and its centerpiece, the Olympus TLP. Russell McCulley talks to Robert Patterson, Shell VP upstream major projects for the Americas, about one of the Gulf of Mexico's biggest brownfield extensions to date.

In September 2010, Shell handed down a final investment decision giving the green light for the Mars B development, including the Olympus TLP. The 24-slot platform will be the second for the prolific Mars field, which Shell operates with 71.5% interest alongside partner BP, which holds the remaining interest. The original Mars platform, onstream since 1996, was one of the first integrated drilling and producing TLPs in the deepwater Gulf after the Auger TLP of 1994, also operated by Shell in the Garden Banks area.

‘What's significant about the Olympus TLP is that it's a major brownfield extension of the life and production of the Mars area,' Patterson says. ‘Unlike other major infrastructure in the Gulf of Mexico, this will really be the first piece of major new infrastructure to continue and extend the development of a deepwater field that's been producing for quite some time.'

The Mars B expansion will draw production from an eight-block section of the Mississippi Canyon area: blocks 762, 763, 764, 805, 806, 807, 850 and 851. The new platform is also designed to receive production from Shell's nearby West Boreas and South Deimos discoveries. The TLP will have the capacity to process about 100,000boe/d, with first production anticipated in 2015.

Shell's in-house engineering team is leading the project's design in collaboration with Jacobs Engineering and Waldemar S Nelson & Company, which is largely responsible for the TLP's topsides planning. The project has moved into the fabrication stage, Patterson says, with a hull fabrication contract going out to Samsung Heavy Industries and an agreement with Kiewit Corp. for topsides construction at the company's Ingleside, Texas, yard.

The design of the Olympus TLP resembles previous Shell projects, with some important, if not outwardly visible, differences, Patterson says. ‘There's really been some learning and improvement over the years in simplifying the systems that are inside the hull itself,' he explains. That simplification includes ‘making all four columns passive columns, with equipment that operates more like a spar than some of the early generation fourcolumn TLPs or semisubmersibles.

‘Early TLPs were taking practice and approaches from semisubmersibles,' Patterson says. ‘This one really capitalizes on practices from spar technology, which helps to simplify what's in the hull. When you simplify what's in the hull, you make it a safer place to work because you don't have to regularly enter it. It also makes it a less complex and costly hull structure to build.'

Passive columns allow the bulk of maintenance and repair work to be done outside the hull, he says. ‘For example, you're able to pull ballast pumps from the base of the hull to the surface for repair, if needed, rather than having people enter the hull' to do repairs, Patterson says. ‘If people have to enter the hull, you have to have passageways for them, you need to have safety equipment for them, and you need to have procedures. That drives a lot of extra complexity in the design.'

Along with simplification, he says, Shell sought more standardization to the new project. ‘Our theme on this has really been to simplify and standardize. Simplification is an example of what we did in the hull, but to really build on the solutions that we have from our prior TLPs and try to standardize on those solutions as much as possible.'

The layout and equipment on board is ‘broadly standard', Patterson says. ‘The first step is to have a layout and orientation of equipment that's common and to use standardized solutions where appropriate,' he says. Standardization ‘helps us with the quality and speed of engineering. It helps us with the ability to apply lessons from our past TLPs, whether that's improved operability, safety or project planning. It helps with training, so that you're able to have people move from one platform to another.'

Mars B presented some ‘unique challenges', however. ‘One of those is in the capability of the drilling rig,' he says. ‘The drilling rig, in order to be able to fully develop the Mars field, has some additional hook load capability in order to be able to reach and drill some of the targets that we would like to reach – a two million pound hook load.' The rig was designed with the capacity to drill to 9100m managed depth.

A brownfield project like Mars B may require deeper wells, he says. ‘Some of the drilling in the area may go through zones that have already been depleted. So you may have some special pressure challenges to design for.'

Shell has not revealed the cost of the Mars B development or disclosed a detailed drilling plan for the project. The company has provided some plans for the West Boreas field, however, which like South Deimos will be developed as a tieback to the Olympus TLP. FMC Technologies has been contracted to provide six subsea production trees rated to 15,000psi each, subsea and topside controls, a manifold and other related equipment. Deliveries are scheduled to begin 3Q 2012. The field is in Mississippi Canyon block 762 in 3100ft water depths. Shell operates both West Boreas and South Deimos with 100% interest.

The Olympus TLP will be able to accommodate additional subsea tiebacks from potential developments nearby. The platform will also include a space and weight provision for additional waterflood capability if needed, Patterson says.

The structure is one of the first major deepwater projects to be built after the implementation of new metocean criteria following the devastating 2005 hurricane season, when the original Mars platform suffered extensive damage. ‘It's designed for a higher peak wave,' Patterson says. ‘The columns are taller than they would have been otherwise. That changes the center of gravity and some of the considerations for designing the whole system so it will perform as it should.'

Shell considered other design options for the Mars B development, Patterson says. ‘This was a good fit for a TLP, given its location and water depth and the reservoirs we were reaching. The challenge is in the wells: you want to find a way to safely and cost-effectively reach the opportunities that you have, and that drives the number of wells. Are they dispersed, or can you reach them from one location?' Water depth was another factor, he says. ‘This is in about 1000m of water, which is a good water depth for a TLP. You get motion characteristics and good cost characteristics from a TLP in that water depth.'

Having worked on a number of major deepwater projects, Patterson says he and his team are focusing on ‘safety, quality and productivity' in delivering Mars B. ‘And what helps us reach those goals is having the right expertise, the right teamwork, the right planning, the right relationships,' he says. ‘These are very complex floating systems, and any action that takes place by one technical discipline has an impact on everyone else. If something changes weight, or size, or location, it ripples throughout the system.' OE

The new platform is one of the first major deepwater projects to  be built for the Gulf of Mexico after the implementation of new metocean criteria following the devastating 2005 hurricane season, when the original Mars TLP’s topsides (pictured) suffered extensive damage. A major casualty was the platform rig, which had to be delicately lifted off by Heerema’s Hermod and transported to shore for repair (OE June 2006).

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