Types

Description

Examples

Physical Component Barriers

“Something I can touch”

A physical component or mechanical device which has been designed and/or tested to prevent formation fluids from flowing unintentionally.

• Hydrostatically overbalanced

  fluid column

• Cement plugs
• Blowout preventer equipment
• Bridge plugs
• Casing
• Cement behind casing
• Valves
• Managed pressure drilling

Equipment

Operational Practice Barriers

“Something I can do”

An operational practice or action which requires human recognition to analyze data/trends and react appropriately to prevent or manage formation fluids flowing unintentionally.

• Flow checks
• Gas unit trending
• Pressure testing physical barriers
• Pit/trip/choke drills
• Monitoring for abnormal pressure indicators
• Setting alarms
• Effective communication between rig crew members

Quantity of Well Control Barriers

• Physical Components
  • Minimum of 2 in each potential flow path - 1 active (ex: hydrostatically overbalanced fluid column) & 1 in a “ready” state (ex: pressure tested blowout preventer).
  • Failure of the primary barrier must not result in the failure of the backup.

     

• Operational Practices
  • Unlimited – The more discussion, practice & verification that a team utilizes with regards to Well Control Barriers, the more effective that team is at building a Well Control Culture.

Placement of Physical Well Control Barriers

• Physical Barriers are to be placed as close to the source as possible to minimize the potential size of influx. Barriers placed in series are to be placed in such a manner that allows for testing and verification of each barrier independently.

   

• Physical Barriers which are placed and not able to be effectively pressure tested, will have its integrity verified by other means to ensure that the component is functioning as designed/intended.

   

• Physical Barrier locations must be known & documented at all times.

   

• Physical Barriers must be able to endure the environment (temp, fluid type, pressures, etc) in which it was placed for the period of time which it was intended.

Testing & Verification of Physical Well Control Barriers

• Physical Barriers must be pressure tested & should be pressure tested in the direction of expected flow. Pressure test amounts must be greater than the expected wellbore pressures at the location of the Barrier & should be less than the working pressure rating of the Barrier.
  • Positive Pressure Test – 5 min minimum time, low & high test pressure, documented acceptable pressure drop over time, volume to pressure up & bleed back is monitored.
  • Negative Pressure Test – Acceptance criteria for a good negative test must be agreed upon prior to test & plan must include procedure for failed negative test.

     

• If a Physical Component Barrier is not able to be effectively pressure tested, its integrity & position must be verified by another means and documented.

   

• Physical Barriers or situations in which the above guidelines cannot be followed, must be risk assessed, documented & mitigating procedures effectively communicated to all involved parties.