Platform for growth - Shell’s Olympus tension leg platform

Standing 406ft tall and weighing in excess of 120,000t, Shell's Olympus tension-leg platform (TLP) is not only a towering feat of engineering; it is also a front-line weapon in the multinational's fight to extend the life of its prolific deepwater Mars field in the Gulf of Mexico (GOM) from 2035 to 2050.

Discovered in 1989 and brought online seven years later, the Mars field has, to date, produced 700 million barrels of oil equivalent (boe) and is thought to contain a billion more. Its strategic value to Shell's bottom line and to the US energy supply over the coming decades cannot be overestimated.

Shell's latest GOM project, Mars B, will add new field infrastructure including the West Boreas subsea system; oil and gas export technology, including a WD-143C shallow-water platform; and, crucially, the Olympus TLP. An emphatic vote of confidence in capital-heavy deepwater projects, Mars B aims to maximise recovery rates from the Mars field and nearby exploration discoveries.

"The cornerstone of Mars B is the Olympus tension-leg platform," confirms Derek Newberry, Mars B business opportunity manager. "It is a 24-slot, TLP, which means we can have 24 active wells at any point in time as we go forward. We also have a self-contained drilling rig that is designed to allow us to drill to approximately 22,000ft - or four miles - below sea level."

The Mars field is located in approximately 3,000ft of water in the Mississippi Canyon Protraction Area of the GOM, approximately 130 miles south of New Orleans. Olympus TLP will develop this play as well as provide process infrastructure for two recent deepwater discoveries, West Boreas and South Deimos, with reservoirs at a depth of 10,000-22,000ft - 2-4 miles below sea level.

"A characteristic of Olympus is that we are venturing into deeper water, but we are also going deeper subsurface," says Newberry. "The platform is designed to access deeper reservoirs than had been thought possible with the Mars A 24 TLP, which had been in production since 1996.

"Mars B really represents the first time we have added significant infrastructure to the deepwater GOM to extend the life of an existing deepwater asset. The size of the opportunity base meant we could integrate additional infrastructure to extend the field for many decades to come," he adds.

Seismic advancements

Olympus is Shell's sixth and largest TLP operating in the GOM, with a production capacity of roughly 100,000 barrels of oil equivalent a day (boe/d). Home to 192 personnel, it has a combined deck area 342,000ft² and centre-to-centre column spacing of 250ft. To put that in perspective, it has a similar footprint to One Shell Square, the company's 51-storey corporate headquarters in New Orleans.

"We took the learning from the Perdido platform, the shape of the column and supports, and that simplified the construction phase, and helped with process and personal safety," explains Newberry. "When we started to develop Mars, we thought the deepest reservoirs were three miles below sea level, but advancements in seismic technology meant that we found hydrocarbons at around four miles. So to access those reservoirs, we designed the rig with high capability automation."

The Olympus TLP not only pushes the boundaries in terms of design and scale. It also employs a host of leading-edge technologies, including a fibre-optic data-transfer system linked to the mainland.

"Several specific technology developments have been instrumental in the successful delivery of Mars B," says Newberry. "Olympus is the first TLP to be connected to One Shell Square via a fibre-optic cable with the ability to transfer a volume of data. We are seeing tremendous benefits from people collaborating in this virtual world, which allows offshore engineers and operators to work seamlessly with employees in our office.

"We also installed a remote-control room that has the same capability that we have in the offshore operations room on Olympus. We started production on 3 February and actually opened the subsea well from the remote control room onshore in One Shell Square, the first time we've ever done that.

"As we were preparing to bring on the second well, the fog came in, so we brought the subsea and surveillance engineers into the remote control room, and safely and efficiently brought on the well," he continues. "We believe we have already taken three months of offshore work into the office."

Shell also employed next-generation ocean-bottom node and wide azimuth (WAZ) surveying techniques for 4D data acquisition, and to optimise recovery rates from the deepwater reservoirs.

"We made two escalation discoveries in 2009-10, and those discoveries were really unlocked with ocean bottom nodes and WAZ," says Newberry. "With advancements in ocean-bottom nodes to acquire the data, we're getting high repeatability in our 4D surveys. We're almost at the point when we're watching how the reservoirs are behaving as if it's a movie in order to optimise recovery.

"In late 2003, early 2004, Shell drilled the Boreas exploration well in this area and we had very disappointing results - no hydrocarbons. So in 2007-8 we acquired this ocean-bottom node, wide azimuth sensing seismic survey, the first time Shell had done this in the GOM. We immediately saw a very strong seismic response indicating that there were hydrocarbons there.

"We drilled the West Boreas discovery in April 2009 and, as of today, West Boreas is producing 240,000 boe/d. Resilience and the application of new technology has taken a discovery in 2009 to a very short cycle time of production in 2014.

"One of the opportunities we now have is we have two TLPs on a single field - 24 slots on Mars and 24 well slots on Olympus," he continues. "The opportunity going forward is to take those key components and work out how we can effectively and efficiently take the benefits of that development synergy to optimise recovery from Mars B."

Integration and standardisation

The final investment decision on Mars B was taken in September 2010 and the Olympus TLP finally began production in February of this year. In the interim, employees in 37 US states were involved in the construction phase of the project when, according to Newberry, resource integration was critical.

"If someone was to ask me what do you take away from Mars B as a key to success going forward it would be summed up in that word: integration," he explains. "You have to be integrated across everyone who's going to be working on the venture. We had working yards in South Korea and on the Gulf coast of the US; we had marine vessels supplied from companies in Europe; and, in terms of the global supply chain, over 20,000 people worked on Mars B during the execution phase."

"These are large, complex developments, technology challenges, harsh environments, remote locations - the key to success is the integration of the team that is charged with realising these opportunities. The way I like to describe it is that we are integrated from the molecule of hydrocarbon located in the subsurface reservoir offshore all the way through the value chain to when we deliver it to our onshore marketing team in the US."

"We also have dedicated oil and gas export lines that depart from Olympus and head almost due north to an existing shallow water complex called West Delta 143," he continues. "There were two shallow water platforms there, A and B, and a third shallow-water platform, West Delta 143C. We have our own dedicated export solution from West Delta. Oil and gas makes landfall at South-East Louisiana, where it enters our downstream distribution locations."

Shell also leveraged years of exploration and production (E&P) experience in the GOM and globally, allowing the company to drive down operating costs, and prioritise personnel and process safety.

"How can we be competitive in deepwater? How can we have competitive costs? How can we operate safely and efficiently? Standardisation is a key component of that," says Newberry. "Olympus is the sixth TLP that Shell has put into the GOM, starting with Auger in 1993. That's a tremendous learning opportunity to take our standardisation and apply it time after time. We have the ability to take people who have worked in each of these developments, and carry that experience and learning through at a high level and at a competitive cost. We also want to apply new technology and innovations and build that into the standardisation going forward.

"A key theme that we used is that our grandchildren could be working on this TLP and that really was one of the cultures within the team when we were designing this - longevity, the safety orbit and the contribution going forward. We will extend the field life of Mars from 2035 to 2050. Mars B infrastructure is designed to be out there for almost 50 years."