IOGP Well Control Incident Lesson Sharing

During a well abandonment, trapped gas was released at 700ft RKB, from the tubing-casing annulus below an upper packer. Gas flowed very rapidly to surface causing a serious incident and a serious injury.

Below we have listed five WIPC syllabus areas and how it relates to this type of incident. These syllabus areas aim to help candidates understand the negative impact of this type of incident and importance of acting safely to minimise risk.

Gas trapped in the annulus below the packer was released into the wellbore when the packer mandrel was cut. The wellbore fluids, gas and water, were released at surface as the BOP was not closed around the shooting nipple, the annular BOP was likely damaged as the shooting nipple was ejected out of the well and the well could only be closed in using the blind shear rams.

• The risk of the trapped pressure was not identified at the planning stage.
• Barrier diagrams for most stages of the operation were missing from the programme.
• With zero pressure on the tubing and annulus the rig-site team were confident the risk of excess pressures coming to surface was minimal.
• A previous deep cut on the tubing had resulted in fluid losses being observed and based on this experience, and expecting a similar effect when releasing the upper packer, the decision was taken not to close the BOP in order to monitor the well via the trip tank. It is subsequently believed the losses were misdiagnosed and the volume change was actually compression of gas in the tubing x casing annulus.
• The fluid in the well was believed to have ~2,500psi overbalance on reservoir pressure reinforcing the belief that it was not necessary to close the BOP during tubing operations.
• The size and rig-up of the shooting nipple did not comply with company standards. The shooting nipple was locally manufactured, on the rig, and no QA/QC certification could be identified.
• The driller tried to stop flow by closing the annular BOP. When flow did not stop the driller evacuated the rig floor and the well was closed in by supervisors at the remote panel.
• The injured party was new to the rig but had no ‘buddy’ assigned and had not participated in any emergency drills on site.

• Management of Change refresher training for all personnel.
• Well Programmes to include barrier plans for all planned activities.
• Shooting Nipple to be considered as a component of pressure control equipment and subject to the same design, manufacture and inspection criteria.
• Review frequency of emergency drills to ensure key and new personnel are captured.

Below we have listed five WIPC syllabus areas and how it relates to this type of incident. These syllabus areas aim to help candidates understand the negative impact of this type of incident and importance of acting safely to minimise risk.

WI-SF-COM-01.01.01  The impact of a well control incident

• There was an impact to personnel – a service hand broke his femur when climbing over a locked gate to escape the wellsite.
• There was environmental damage, damage to equipment and reputational damage.

WI-SF-COM-02.02.02 Sources of abnormal annulus pressures

• The rig team did not recognise there could be trapped gas pressure in the annulus. Tubing was punched with the annular BOP open.

WI-SF-COM-02.03.01  Risk Management principles and practices

• The operational plan did not recognise the risk of trapped annulus pressure.
• the rig team made a poor assessment of the risks and decided to keep the annular BOP open.

WI-SF-COM-04.01.02 Well barrier elements

• There were no well barrier diagrams in the programme.

WI-SF-COM-02.05.01 Well control drills

• The new service hand had not previously participated in a drill.
• An emergency site exit gate was locked, but the new service hand was unaware of this.

Visit the IOGP website for a full list of all lessons shared to date: https://safetyzone.iogp.org/WCILessonsShared/WCILS/main.asp