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What happened?
A light workover unit was rigged up on the well, and a blowout preventer (BOP) was installed and tested.
The well had been killed by bullheading 10 pounds per gallon (1.20 kilograms per litre) brine and was static when operations began.
The crew released the production packer, pulled three stands of tubing and rigged up spoolers and a sheave for downhole service lines before pulling out of hole the following day.
The crew closed the full open safety valve on the tubing and the annular. The rig operator instructed a crew member to close the casing valves and the BOP kill line valves, and stated that he verified this.
The crew secured the well and left the unattended location overnight. The next day, the operator representative found gas flowing at a high rate from the open BOP kill line valves.
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Why did it happen?
Open valves allowed wellbore fluids to be released uncontrolled.
There was no process or procedure to validate well barriers before shutting in and securing the well overnight.
There was no requirement to disable open-ended valves by locking them in place and mechanically plugging them before leaving the well site.
There was no process requiring physical on-site security or cameras when a well location was near population centres or a public right of way. Vandalism could not be ruled out.
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What did they learn?
Develop a procedure that standardises how a well should be shut in and secured overnight during daylight-only operations.
The procedure should specify the barriers required to leave the well shut in, secured and unattended.
Valves should be disabled by locking them in place and should not be left open-ended.
Develop a well-site security plan with physical security services for sites left unattended overnight near population centres.
The site security plan should include how long the site will remain unattended.
Each barrier should be rigorously verified, and the well should be continuously monitored during a temporary suspension.
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Ask yourself or your crew
How could a valve be left open when a well is shut in and secured on our site?
What barriers and verification checks do we use before leaving a well unattended?
How do we ensure open-ended valves are locked in place and mechanically plugged?
How do we know that our well barriers and monitoring arrangements remain effective during a temporary suspension?
What site security arrangements are needed when a well is left unattended near population centres or a public right of way?
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What happened?
A light workover unit was rigged up on the well, and a blowout preventer (BOP) was installed and tested.
The well had been killed by bullheading 10 pounds per gallon (1.20 kilograms per litre) brine and was static when operations began.
The crew released the production packer, pulled three stands of tubing and rigged up spoolers and a sheave for downhole service lines before pulling out of hole the following day.
The crew closed the full open safety valve on the tubing and the annular. The rig operator instructed a crew member to close the casing valves and the BOP kill line valves, and stated that he verified this.
The crew secured the well and left the unattended location overnight. The next day, the operator representative found gas flowing at a high rate from the open BOP kill line valves.
Why did it happen?
Open valves allowed wellbore fluids to be released uncontrolled.
There was no process or procedure to validate well barriers before shutting in and securing the well overnight.
There was no requirement to disable open-ended valves by locking them in place and mechanically plugging them before leaving the well site.
There was no process requiring physical on-site security or cameras when a well location was near population centres or a public right of way. Vandalism could not be ruled out.
What did they learn?
Develop a procedure that standardises how a well should be shut in and secured overnight during daylight-only operations.
The procedure should specify the barriers required to leave the well shut in, secured and unattended.
Valves should be disabled by locking them in place and should not be left open-ended.
Develop a well-site security plan with physical security services for sites left unattended overnight near population centres.
The site security plan should include how long the site will remain unattended.
Each barrier should be rigorously verified, and the well should be continuously monitored during a temporary suspension.
Ask yourself or your crew
How could a valve be left open when a well is shut in and secured on our site?
What barriers and verification checks do we use before leaving a well unattended?
How do we ensure open-ended valves are locked in place and mechanically plugged?
How do we know that our well barriers and monitoring arrangements remain effective during a temporary suspension?
What site security arrangements are needed when a well is left unattended near population centres or a public right of way?
On a light workover unit, tubing pulling operation was prepared then suspended for the day. The well had been shut-in, secured for the night and left without any presence on location. The next day, gas was found flowing at high rate from a wellhead valve left open. This case reminds the importance of a rigorous verification of each barrier and the need to keep a continuous monitoring of the well during a temporary suspension.
