A joint venture of Bentec and Consafe has developed this "world's most advanced offshore drilling facility" for installation on Shell Expro's Brent Charlie platform in the North Sea. Two drillers will control almost every operation of the New Derrick Equipment Set from the safety of a cabin. Here, the rig is in Consafe's Burntisland, Scotland, yard after testing and commissioning.
New equipment is destined for drilling and well workover assignments off the U.K.
Shell U.K. Exploration & Production will soon take delivery of what is billed as the world's most advanced offshore drilling rig. It is scheduled for installation this summer on Brent Charlie platform in the U.K. North Sea.
The rig, designated the New Derrick Equipment Set (NDES), was developed by Bentec Drilling & Oilfield Systems, a unit of Deutsche Tiefbohr AS of Bad Bentheim, Germany, and built by Consafe (Burntisland) Ltd., Fife, Scotland. Onshore testing and commissioning is complete.
In addition, Reading & Bates (U.K.) Ltd., Aberdeen drilling contractor, let a 60 million kroner ($9 million) contract to Maritime Hydraulics AS, Kristiansund, Norway, for delivery of a RamRig drilling package.
Maritime Hydraulics said RamRig represents a new approach to drilling and workovers. It is designed to cost less and weigh less than conventional rigs and to be operated by fewer crewmen.
Meantime, U.K. North Sea operators had this activity under way:
- Phillips Petroleum Co. U.K. Ltd. placed development of U.K. Judy and Joanne fields back on track by choosing to reinject gas that originally was intended for sale to Enron Europe Ltd.
- Unocal U.K. Ltd. could be the next company to fall foul of environmental campaigners over platform abandonment if it proceeds with announced intentions for its Heather field platform.
- Wintershall (U.K.) Ltd. plans to develop its Windermere gas discovery in U.K. Block 49/9b as a satellite of Markham field. Markham, astride the U.K.-Netherlands boundary, is operated by Lasmo Nederland BV.
Off Norway, state owned Den norske stats oljeselskap AS began production from Yme oil field, the smallest stand alone field development in the Norwegian sector to date.
Yme, in North Sea Block 9/2, holds estimated reserves of 36 million bbl of oil. It was developed using a storage tanker and a jack up drilling rig converted for production (OGJ, Feb. 19, p. 58).
Statoil expects production to reach 50,000 b/d this summer.
A smaller satellite, with estimated reserves of 11 million bbl of oil, was discovered after development had begun. Yme Beta East field is to be brought into production in May or June using Yme platform facilities.
NDES
NDES is a fully mechanized rig capable of drilling to 22,000 ft. It will be operated by only a driller and his assistant, with mechanized equipment carrying out most drill floor operations.
A spokesman for the Bentec-Consafe joint venture said, "This project is a manifestation of where the oil and gas industry has been heading for the past few years. The project criteria addressed key issues such as safety, the environment, cost reduction, and fitness for purpose".
Bob Baker, leader of the Brent Charlie drilling team, said the new rig is required by the redevelopment plan for Brent field. The field's Bravo, Charlie, and Delta platforms are undergoing major refurbishment (OGJ, Aug. 7, 1995, p. 32).
"The NDES design was driven by reconfiguration of Brent field to extend its prolific life," Baker said. "A big element was a decision to reduce reservoir pressure to increase gas production.
"In a few years we will stop water injection and start pumping water out to release gas held in solution. But there comes a point at which reservoir pressure will be so low that no further oil can be produced.
" We want to get out as much oil as possible before we reach that point. Hence we need to change the wells beforehand and therefore need to redrill and reconfigure them."
The redevelopment plan showed there is little oil at risk from depressurization in the area of Brent A and B platforms, but there is a significant amount threatened in the C and D platform areas.
A second drilling rig has been installed on Delta platform. It is conducting well workovers before the platform is shut down for refurbishment.
On Charlie platform, to be shut down for a period this summer, there was not enough room to install a second rig. The old derrick has been removed.
"We decided to replace the old rig with one that is more modern and smaller," Baker said.
"The smaller footprint will enable vertical access to adjacent wells for wireline and tubing operations and allow an increase in racking capacity. With the old rig, maximum well depth was 13,500 ft, but now we will need capacity to store enough drillpipe to reach 22,000 ft."
Baker said state of the art mechanization increases operational safety and enables drilling to be controlled by two people in the drillers cabin, with a third occasionally being needed on the drill floor for thread inspection.
"For most jobs, we will need only the two people in the cabin," Baker said. "Though they will control drilling, the level of automation ensures that if they try to make a mistake the equipment won't let them. At first the drillers were concerned they would not be able to operate the system, but we demonstrated it to them with the help of an 8 year old boy."
RamRig
Reading & Bates' RamRig package, slated for delivery in 8 months, will be installed on the Iolair semisubmersible support vessel.
It will consist of a derrick equipment set and a handling system for subsea christmas trees.
Iolair's first job as a well intervention vessel is to be in Foinaven field in the West of Shetland area off northern Scotland, currently under development by operator BP Exploration Operating Co. Ltd.
RamRig does not have a conventional derrick. It has two ram guides on which are mounted a traveling yoke assembly, instead of the usual drawworks and traveling block.
Phil Langhorne, Reading & Bates' conversion manager for Iolair, said the rig was bought as a construction support vessel, but is to be upgraded to carry out well intervention.
Judy, Joanne
The U.K. Department of Trade & Industry approved Phillips' plan to install an $82 million gas reinjection plant on Block 30/7a Judy platform, which is expected to enable first oil production Apr. 1, 1997.
Phillips had intended to place Judy and Joanne gas on stream early this year, but Enron decided to take no gas for the first year of its purchase contract.
Phillips delayed gas development because associated gas had been sold to Enron and oil production could not proceed without gas production, using the platform as it stood (OGJ, Sept. 25, 1995, p. 38).
Judy and Joanne originally were expected to produce about 65,000 b/d of oil and as much as 260 MMcfd of gas.
Now Phillips expects to start liquids production at 30,000-40,000 b/d, with gas reinjected for later delivery to Enron. The new plant is believed to have capacity to reinject 200 MMcfd of gas.
Although early production will be lower than intended, Phillips said the reinjection project is expected to increase ultimate hydrocarbon recovery by more than 5%. Judy and Joanne's combined reserves were earlier estimated at 97 million bbl of liquids and 796 bcf of gas.
Meanwhile, Phillips is drilling two wells of a planned four well program to probe satellite reservoirs within development reach of Judy platform (OGJ, June 12, 1995, p. 38).
Phillips has completed work on the fields' production, processing, and transportation facilities. Overall costs are said to remain within budget, even with gas reinjection.
Phillips Chairman and Chief Executive Officer Wayne Allen said while discussions over production of Judy-Joanne gas dedicated to Enron will continue, there is no basis for changing the terms of the existing gas sales contract.
Enron offered no comment on its decision not to take Judy-Joanne gas. The move is thought to be due to a flood of gas from new fields entering the U.K. market ahead of supply market liberalization.
Partners in Judy and Joanne are operator Phillips 36.5%, Agip (U.K.) Ltd. 33%, and British Gas Exploration & Production Ltd. 30.5%.
Heather abandonment
Unocal said it plans partial removal of Block 2/5 Heather platform in a 30-50 million ($45-75 million) decommissioning program. This will involve removal of most of the topsides and toppling much of the jacket to yield clearance of at least 55 m below sea level.
A Unocal official said, "We know Greenpeace is totally opposed to this approach to decommissioning, but our viewpoint is that whatever we leave behind will be clean steel."
Heather's drilling, production, and quarters platform measures 236 m from seabed to top of derrick and has topsides weighing 12,200 metric tons and a 17,300 metric ton steel jacket.
Heather began production in 1978. It currently produces about 7,500 b/d of oil, but production is not expected to be viable beyond 1998.
Unocal will be ready to submit an abandonment plan to the U.K. Department of Trade & Industry (DTI) in the third quarter, but submission cannot occur without DTI first publishing its own decommissioning requirements.
The Unocal official said, given that it would take 2 years for a complete decommissioning program, abandonment of Heather platform could take place before the end of 1999.
However, Unocal hopes to prolong the platform's life. The company in 1995 received an exploration license for Block 2/4, in which lies the West Heather prospect. If this proves to be a commercial find, Heather platform could be used to handle its production.
A number of U.K. operators have proposed platform abandonment plans since environmental campaigners and European government pressure last year forced Shell U.K. Exploration & Production to abort a plan to dump its Brent spar loading buoy in deep water.
However, these all will involve complete removal because they are in less than 55 m of water. Heather's abandonment proposal is the first since Brent spar to involve dumping.
Windermere
Wintershall's Windermere field, with estimated reserves of 100-125 bcf of gas, will be developed using a simple unmanned platform. Production is slated for early 1997.
Lasmo said gas will move through an 8 in. pipeline to Markham ST-1 platform in U.K. Block 49/5. From there it will pass through a 12 in. in-field pipeline to the Markham processing platform in Dutch North Sea Block J6, and from there to Den Helder terminal.
Windermere will be the second third party field development to use Markham facilities. Earlier this year, Elf Petroland BV placed on stream small J3-Charlie field using a single well drilled from Markham's Dutch platform.
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