As part of a technical project to increase wellhead gate valve integrity in ADCO’s NEB Field, the Drilling Division were exploring the technical capabilities of Valve Lubricant 601TM as a possible solution for the cavity retention and valve leakage issues they were experiencing with the incumbent valve grease being used in their Xmas trees.
Corrective Maintenance To Seal All Leaking Gate Valves For Adco North East Bab (NEB) Field – Abu Dhabi
The Problem
As part of a technical project to increase wellhead gate valve integrity in ADCO’s NEB Field, the Drilling Division were exploring the technical capabilities of Valve Lubricant 601TM as a possible solution for the cavity retention and valve leakage issues they were experiencing with the incumbent valve grease being used in their Xmas trees.
The well selected for the field trial was an oil producer, trace water cut with 1279ppm H2S and 3.4% CO2. The wellhead flowing pressure was 2276 psi and temperature was 70°C. The Xmas tree consisted of 5 x 4 1/16 5M Vetco Gray gate valves API 6A Trim HH, and all 5 gate valves were leaking:
- Lower Mater Valve (manually operated) 2 psi/min
- Upper Master Valve (hydraulically operated) 1 psi/min
- Production Wing Valve (hydraulically operated)1.88 psi/min
- Kill Line Wing Valve (manually operated) 1 psi/min
- Swab Valve (manually operated) 75 psi/min
The Solution
Once the system was isolated and line pressure bled-off, with all valves closed and zero cavity pressure, ADCO proceeded to inject approximately 8.5kg of Valve Lubricant 601TM into each valve cavity. The cavity pressure increase was monitored on the grease pump pressure gauge to indicate when the cavity was full. After valve lubrication, the well was flowed for 7 days and the results were:
- At a wellhead tubing head pressure 2342 psi, all 5 valves recorded a 0 psi/min leak rate
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