Record deepwater completion took extensive planning

May 7, 2002
The Discoverer Spirit drillship, owned by Transocean Sedco Forex Inc., drilled and completed a record deepwater natural gas well in the Gulf of Mexico for Marathon Oil Co. and partners.

Sam Fletcher
OGJ Online

HOUSTON, May 7 -- Houston-based Marathon Oil Co., its partners, and contractors put a great deal of planning into a record deepwater completion of a natural gas well in 7,200 ft of water early this year on the Camden Hills project in Mississippi Canyon Block 348 some 150 miles southeast of New Orleans.

Working in record deep water with costs averaging $400,000/day "was like going to the moon," said Marcus Allen, the 20-year veteran Marathon engineer who served as team leader for the Camden Hills project. "We had to anticipate every possible problem and plan how to handle it early on."

The MC348-1S well was completed in mid-February, with two frac packs and intelligent well control equipment, in 31 days of onsite work, without accident, and at a cost of $22 million. That was some 10% below the company's official Authorization for Expenditures (AFE) and 10 days sooner than its best-case scenario, said Marathon officials.

"We thought it would take 40 days to complete the well and 2 days to set the tree," Allen told OGJ Online.

It was the first subsea completion by Discoverer Spirit, the new drillship belonging to Transocean Sedco Forex Inc., Houston, and the first well completed to feed the Canyon Express natural gas gathering system. The job involved simultaneous operations by various vessels, including a ship laying pipeline, another ship laying control umbilicals, and, at times, a remotely controlled submarine vehicle (ROV).

Camden Hills find

arathon made the natural gas discovery on its Camden Hills prospect in the Gulf of Mexico in 1999. The MC348-1 well was drilled to 15,080 ft TD, cutting about 200 ft of gas pay (OGJ, Aug. 23, 1999, p. 42). Marathon is operator with 50.03% working interest in that lease, acquired in December 1998. Partners include Pioneer Natural Resources Co., Dallas, 33.3%; and TotalFinaElf E&P USA Inc., a unit of TotalFinaElf SA, 16.67%.

Eventually, production from Camden Hills, Aconcagua, and King's Peak dry gas fields—located in 6,200-7,200 ft of water on Mississippi Canyon Blocks 173, 217, 305, and 348 and Desoto Canyon Blocks 133 and 177— is be tied back to the Williams Cos. Inc. Canyon Station host platform in 299 ft of water, 55 miles from the most distant well.

Owners of the three fields—Marathon, TotalFinaElf, Pioneer Natural Resources, BP PLC, and Mariner Energy Inc., Houston —formed the Canyon Express project to develop the gas-gathering system and infrastructure to tie back the deepwater wells. Production of 500 MMcfd of gas from the subsea wells is expected by summer 2002.

Personnel activity

Close to 200 people were aboard the drillship at the peak of activity in completing the record deepwater well, said Allen.

"Each morning, there was a series of meetings of rig supervisors and engineers to review the activity of the past 12 hr and to outline plans for the new day. That was followed by safety sessions for the rig crew and crane operators and then meetings with the other contractors," he said. "By 10:30 a.m., everybody on board knew his part of the day's plan. We all came to appreciate that this degree of planning is what it takes for success."

That planning started well in advance of the actual work, of course. "We spent 1½ years planning this, thinking out all sorts of contingency plans in case anything were to go wrong," Allen said.

Although the completion process wasn't initiated until January, engineers from Marathon and TotalFinaElf met with drillship crews in October-November to talk through each aspect of the project.

"We got a lot of feedback on where to place equipment on deck to provide the easiest, quickest access when needed," said Allen. "One of the main takeaways from those meetings was how to optimize use of the vessels' two cranes. Based on feedback from the crew, we repositioned equipment on deck and took more crane operators offshore."

In addition, Marathon provided an incentive program for workers if they met or beat time allotments for different aspects of the job. "I guarantee you, even the cook was thinking each day of how to make the operation go more quickly and smoothly. We had everybody out there thinking about the job we had to do," Allen said.

Well completion

The completion process started in mid-January with workers running the 10,000 psi subsea production tree simultaneously while the riser was being run, thanks to the Discoverer Spirit's dual derricks system.

The $2 million, 100,000-lb Cameron tree was placed on target within 3° of its optimum orientation. "That's a lot of precision in 7,000 ft of water," Allen said.

The well's productive gas intervals, located around 15,000 ft, were flow tested at a rate of 30 MMcfd with minimal drawdown and are expected to have a peak rate capability of 50 MMcfd. The well was completed in two reservoirs with downhole valves that allow the reservoirs to be flowed separately or commingled. The valves and chokes will be operated from the processing platform 60 miles away.

Completion was designed to reduce any need for intervention. That design incorporates a process for injecting methanol to prevent hydrate formation.

"The crews did extremely well on their first completion well," said Logan Puckett, rig manager of the Discoverer Spirit. "We benefited a great deal from the knowledge base of the Discoverer Enterprise and BP, and we were able to make additional improvements with the help of a very cooperative client."

The previous deepwater subsea completion record was on the King's Peak MC 217 #3 well, completed at 6,407 ft of water in 55.9 days by another Transocean drillship, the Discoverer Enterprise.

Dual-activity drilling

Transocean Forex Sedco officials expect to keep saving time with the Discoverer Spirit 's dual-activity drilling system and by moving between the next four wells with the riser and BOP hanging off the rig's forward rotary table.

The drillship is under contract to Unocal Corp. through September 2005 but was sublet by TotalFinaElf and Marathon. It's in the process of completing the offset Aconcagua deepwater well for TotalFinaElf on Mississippi Canyon 305 and is scheduled to complete a second well for Marathon on the Camden Hills prospect by midyear.

Sharing the same rig to complete wells on their leases provides "obvious" synergies of equipment and personnel, said Marathon and TotalFinaElf officials. "The team approach is vital to success at these challenging water depths and types of completions," said Marathon officials.

"We learned a phenomenal amount of stuff on this first well. And we will take what we learned to the next well and other operations elsewhere in the world," said Allen.

"This is what it takes to operate in deep water today," he said. "As we become more familiar with the equipment and procedures for intelligent wells, we will become quicker (with installations)."

Development plans

Development plans call for the two Camden Hills wells to be produced through the shared infrastructure of Canyon Express, operated by TotalFinaElf.

Operators plan to equip eight of the proposed nine wells in the three fields with intelligent systems, part of the "innovative technologies" designed to "increase production and minimize workover needs to achieve the sought-after field efficiency during the productive life" of those fields (OGJ Online, Oct. 2, 2001).

Williams in Tulsa selected Paragon Engineering Services Inc., Houston, to help develop the Canyon Station platform. Paragon developed a process for recovery and reuse of chemical-grade methanol as a hydrate inhibitor for the nine subsea wells in the Canyon Express project (OGJ Online, Feb. 2, 2001).

The Canyon Express system is expected to be on stream by mid-2002 (OGJ Online, Oct. 31, 2001).

The Discoverer Spirit also drilled a well in a world record depth of 9,727 ft on Alaminos Canyon Block 903 in October. That drillship held the previous record of 9,687 ft, also on Alaminos Canyon Block 903 (OGJ Online, Nov. 19, 2001).

Contact Sam Fletcher at [email protected]