Ultradeepwater drillship spuds first well

Dean E. Gaddy
Drilling Editor

The Deepwater Pathfinder ultradeepwater drillship, owned by a venture of Conoco Inc. and R&B Falcon Corp., is shown drilling its first well, on the Magnolia prospect in the Garden Banks area of the Gulf of Mexico. Photo by Dean Gaddy.

Conoco Inc.'s and R&B Falcon Corp.'s next-generation drillship, the Deepwater Pathfinder, spudded its first well Jan. 30 in the Gulf of Mexico. This is the second ultradeepwater (5,000 ft of water) drillship to enter the gulf fleet since the Glomar Explorer began work in August 1998.

According to Offshore Data Services, about $9.8 billion will be invested in ultradeepwater floaters beginning with the February 1998 delivery of Petroserv's semisubmersible, Louis- iana, and ending with the delivery of R&B Falcon's semisubmersible, RBS-8D, in March 2001 Table 1 [159,179 bytes].

Pathfinder

The $260 million Pathfinder began operations on the Magnolia prospect on Garden Banks Block No. 783, drilling in 4,668 ft of water. "We felt it prudent to test the rig first before placing it in extremely deep water," said Bill Brister, Conoco's Gulf Coast regional manager.

The Glomar Explorer, owned by Global Marine Inc., currently holds the water-depth record of 7,718 ft on Atwater Valley Block No. 118. Later this year, however, the Pathfinder may be moved to an ultradeepwater location in 7,800-8,000 ft of water.

Conoco estimates it will take 74 days, at a cost of $26 million, to drill the well to an estimated TD of 18,000 ft. The Magnolia prospect will be plugged and abandoned once testing is complete. Day rates for the rig command $195,000.

Conoco's next well, contingent on the success of the Magnolia prospect, could be on an Atwater Valley block or a Green Canyon block. However, once the Atwater and Green Canyon pros- pects are completed, Conoco may look to put the drillship out for hire.

Its sister ship, the Deepwater Frontier, will join the Pathfinder in March 2000, where it will begin drilling a wildcat off New Zealand.

Continued commitment

Brister feels the Pathfinder remains a good investment, despite current low oil prices. "If we knew 2 years ago what we know now, we would still have proceeded with building the Pathfinder. It's important to keep in mind that, even if we discovered a big play as we speak, it would take 5 years to see any return on our investment."

Conoco is one of the leading deepwater leaseholders in the Gulf of Mexico with interests in 295 leases, amounting to 1.2 million acres see map [106,911 bytes]. The company's acreage is spread across four different geologic plays. Recently, Conoco and Exxon Corp. agreed to share interests in 59 deepwater Gulf of Mexico blocks, adding a 50% interest in 29 new blocks to Conoco's holdings.

Conoco's deepwater budget for 1999 will remain near its 1998 level of $80 million. Worldwide, however, Conoco's 1999 exploration, production, and natural gas budget has been cut back to $1.3 billion from $1.8 billion in 1998.

Advanced drilling package

The 727-ft long, 138-ft wide, and 66-ft deep Pathfinder contains advanced drilling technologies utilizing fully automated pipe-handling equipment and a 6,600-hp active heave-compensating draw works (OGJ, May 25, 1998, p. 61).

Drilling systems include:

750-ton, Varco TDS-8S ac top drive.
2 million-lb, 48 ft by 40 ft derrick with 1.5 million lb hookload capability
15,000-psi Cameron BOP system with Shaffer multiplex conrols.
Four National 14P-220, 2,200-hp, 7,500-psi mud pumps.

Active heave draw works

The Pathfinder's active heave-compensating draw works supplants two prior technologies:

A traditional active heave-compensation system that lifts and lowers the block assembly in response to measured heave.
A passive heave-compensation system that employs a dampening effect created by means of compressed air.

In its place, the Pathfinder's active heave draw works, developed by Hitec Drilling & Marine Systems Ltd., controls the position of the traveling block by varying the motor speed of the draw works (OGJ, July 21, 1997, p. 68).

The draw works counteracts heave by winding wire off and on to the drum relative to the observed motion of the vessel. Motion-reference units are mounted on the derrick, dead-line, and on the hull next to the moon pool.

"At first we were unsure if this would work," said Michael McKee, staff well operations foreman for Conoco. "There was a lot riding on it, considering this was an untested technology (that was impossible to simulate in the laboratory)."

However, the technology has proved to be a success. "The active heave draw works has surpassed all our expectations (by maintaining) the drillstring's motion stability in the sub-meter range," said Bill Hill, rig manager for R&B Falcon Inc.