HOUSTON—Deep Gulf Energy hopes to flow first oil from its Kodiak development in the U.S. Gulf of Mexico’s Mississippi Canyon area in the fourth quarter of 2015, marking triumph over a myriad of challenges.

The company has tackled not only high pressure, high temperature (HP/HT) conditions but a subsea tieback to its host, the Devil’s Tower truss spar platform, more than 6 miles away.

Speaking to a full house gathered for a Marine Technology Society luncheon in September, Danny Hough, vice president of development, described how technology is pushing the project forward.

That, and a great deal of ingenuity in a rough area.

With water depths of less than 5,000 feet, subsea conditions are inhospitable, with temperatures of about 275 F and pressure of less than 15,000 psi.

“It’s not impossible, but it is a difficult subsea well,” Hough said.

But Deep Gulf was fortunate, he said, because the previous operator’s samples enabled Deep Gulf to conduct flow assurance work early.

Kodiak was discovered by BP in 2008. The well logged more than 400 net feet of Middle and Lower Miocene oil pay. An appraisal well drilled a year later didn’t meet BP’s reserve expectations, but Deep Gulf was interested and bought BP’s working interest in the field in 2012.

The company was faced with the onerous task of building a corrosion resistant alloy flowline, Hough said.

“On top of that we had to add some equipment to the topside of Devil’s Tower. The temperature of fluid approaching Devil’s Tower can be about 250 F,” he explained. “We had to cool this stuff down. It required a lot of heating exchange and coolers.”

Deep Gulf set about finding solutions to obstacle after obstacle.

Corrosion

HP/HT and carbon dioxide ganged up to create a corrosive environment, Hough said.

Finding material to withstand such conditions was the challenge. “There wasn’t anything we could put in there that would last the life of this field,” he said.

Solving the problem mean coming up with something different—625 alloy that can withstand temperatures ranging from cryogenic to heat in the four-digit range.

“This system is corrosion resistant.”

Flowline

The pipeline is lined with a corrosion resistant alloy layer inside the carbon steel pipe. The process wasn’t easy and it wasn’t cheap, according to Hough.

“The challenge was getting something that we could weld to on top of all of that,” he said. The process required a pressure of 35,000 psi.” he said.

A German company needed multiple attempts to finally accommodate the pressure.

Buoyancy

To accommodate the tieback, Deep Gulf added nine open-hole horizontal buoys to the mooring lines to reduce their weight, a necessity for supporting riser and umbilical loads on the platform. Hough said the spar is designed for about 3,000 feet of water but it sits in 5,600 feet of water. Each has a redundant tether for added security.

The buoys were dropped into and filled with sea water to upright them. They were then lowered for installation to a coil tubing line. Nitrogen was injected into the buoy, displacing the water and lifting the mooring line, he said..

“That’s a lot of moving targets. That was a really a challenge for the ROV team, but they did a great job.”

The presence of wax and asphaltene further complicated the project. Among the solutions was installing insulation to keep the flowline hot to avoid problems inside.

Finale

Finally, the Kodiak well was “successfully drilled and completed, which is a huge achievement,” Hough said.

“The flowline riser pipe is welded. The umbilicals are being loaded out on the Deep Blue [pipelay and subsea construction vessel] and ready for installation. The modules are installed,” he added. “And with what’s occurred to this point, first oil is projected during the last quarter of 2015.”

Velda Addison can be reached at vaddison@hartenergy.com.

Offshore