Operators of the latest atmospheric diving system, the Newtsuit, are not called divers. They are pilots and have to be specially trained.
Newtsuit looks like an astronaut's outfit. Four thrusters enable it to fly through water, controlled by the pilot's foot pads. It has 20 joints to maximize mobility, carries a 48 hr oxygen supply, and has a 1,000 ft depth limit.
The suit, developed by International Hard Suits, Vancouver, is supplied and operated out of Aberdeen by a joint venture between subsidiary company GMC Candive Ltd. and subsea contractor Rockwater Ltd.
The venture has six suits in operation on drilling rigs working off the U.K.: two each on High Seas Driller, Sedco 706, and Glomar Arctic 1. They are used largely on well workovers and maintenance.
DEPLOYMENT
Newtsuit is deployed by means of a cage in the same way as a remotely operated vehicle. It can descend to 1,000 ft in 30 min and return to the surface in less. While one suit is working, a second is kept at the surface on standby.
Dive duration is typically 6 hr. A crew of 12 is needed for a 24 hr shift: two superintendents, two supervisors, four pilots, and four technicians. That compares with a crew of more than 20 for saturation diving on a similar task.
One advantage of the suit is safety because there is no need for decompression. The total equipment requirement is less than for saturation diving: 40 metric tons total freight for a two-suit system, compared with 150 metric tons. Deck space requirement is 26 ft by 26 ft, much less than for equivalent saturation diving gear.
Rockwater's first project using the suit was subsea well maintenance for Amerada Hess Ltd. in Ivanhoe and Rob Roy fields on U.K. Block 15/21. This required 13 dives to 450 ft, totaling 40 hr.
Since then Rockwater has clocked more than 250 hr in the water using Newtsuits in more than 80 dives. The deepest work was at nearly 600 ft in Magnus field on Block 211/12a for BP Exploration Operating Co. Ltd.
COMPARISON
Off Norway, where legislation makes diving a last resort, Den norske stats oljeselskap AS hired Stolt Comex Seaway AS, Haugesund, Norway, to deploy Newtsuits from Seaway Condor diving support vessel in two dives to 260 ft during hookup of the Block 15/9 Sleipner A platform.
The first dive was to clean a flange seal. The second was to attach wiring to pipeline covers, a job normally carried out by ROVs. Statoil wanted to see how the suit compared with ROVS, concluding that Newtsuit will not replace ROVs but could take on many diving tasks, particularly in deep water.
"The aim is to minimize the need for saturation diving, which must be followed by days in decompression," said Geor Mellgren, Statoil's subsea services manager. "The new suit helps to cut saturation dives on producing fields, but we will still need deepsea divers for pipeline welding."
Copyright 1993 Oil & Gas Journal. All Rights Reserved.
