Deep water drilling: extracting oil and gas from the Jasmine Field

Published: 17th October 2013 | Issue 26

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Discovered in 2006 by Conoco Philips, the Jasmine field in the Central North Sea was the largest oil and gas find for more than a decade, consisting of a 701 metre Triassic reservoir of natural gas and condensate. It’s the fourth field to be developed by Conoco Phillips under its J-Block licence and is expected to produce a peak of 88,000 barrels of oil equivalent per day when in comes fully on stream later in 2013.

Technical Challenges and Solutions
The extreme depth of the water at Jasmine Field has meant drilling is carried out at high pressure and high temperatures, with attendant demands on all components utilised. Control Components Inc (CCI), a leading global manufacturer of severe service control and isolation valves for the power, oil, gas and nuclear industries manufactured eight of the process control valves for the wellhead platform. These required electro - hydraulic actuation incorporating positional control to open and close the valves against full flow / line pressure operating conditions. CCI contacted Midland- ACS, a Xylem company specialising in control systems for harsh and hazardous environments, to produce bespoke actuators for its process control valves. Valve sizes and strokes ranged between 40mm and 203mm with valve shut off thrust requirements up to 23,000 kg.f. Owing to the location and space limitation within the installation, it was necessary to provide alternative solutions that could be accommodated while providing the required operating characteristics.

Three different actuators were designed and manufactured by Midland-ACS at its Wolverhampton facility to meet the demanding operating specifications required on the wellhead platform. The first actuator needed stay put fail fix capability (should loss of electrical power supply, loss of command signal or loss of hydraulic supply occur, the actuator remains in its Fail Fix (stay put) condition). Midland-ACS designed a bespoke double-acting hydraulic actuator with power to open and power to close. The actuator has full range positional control in response to a 4 – 20 mA IS command signal and HART re-transmitted valve position signal. The ACS 604EXIAHART position controller is certified to Hazardous Area Zone 1 Group IIB T3 IP66 EExia. It runs on a 24vDC I.S. power supply controlled by a 4 – 20 mA I.S. analogue command signal and has an operating speed of 20 seconds nominal and adjustable, over an operating temperature range of minus 20degC – plus 50degC.

The second ACS 604EXIAHART position controller is a single acting controller with hydraulic power to open and fail to close action incorporating a hydraulic accumulator spring method. Like the double-acting controller, it has full range positional control in response to a 4 – 20 mA I.S. analogue command signal and HART re-transmitted valve position signal. The fail condition is fail closed on loss of electrical power supply or loss of command signal. Certified for use in Zone 1 Group IIB T3 IP66 EExia hazardous areas and temperature ranges from minus 20degC to plus 50degC, it requires a 24v DC I.S. power supply and operates at speeds of typically 20 – 60 seconds, both nominal and adjustable. There is the facility for local manual operation using selector switches on the controller itself.

The third Midland-ACS actuator is also single acting, with hydraulic power to open and ‘Fail to Close’ action but incorporates a mechanical compression spring installed within the assembly. It will Fail Close on loss of electrical power supply, loss of command signal or loss of hydraulic supply. This device has local visual valve position indication and should loss of the hydraulic operating medium (hydraulic mineral oil) occur, can be operated using a hand pump (where specified) in an emergency.

Due to the operating extremes on the well platform, all the bespoke Midland-ACS actuators designed for the Jasmine Field are protected by a two pack epoxy multi coat paint system designed specially for corrosive/ abrasive environments.

Midland ACS
Tel: 01902 305 678
www.xylemflowcontrol.com/midland-acs

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