Working on oil and gas wells, several measures are applied to build confidence in our wells, commonly referred to as “Well integrity” The Norsok D-010 standard, defines “Well Integrity” as “application of technical, operational and organizational solutions to reduce risk of uncontrolled release of formation fluids and well fluids throughout the life cycle of a well”, a definition that is shared by many others.
This gives the impression that technical, operational and organizational solutions are equally important. The fact is though; only the technical solutions (well barrier elements) will physically contain the pressure and the hydrocarbons. Thus, this part of the solution is far more important than the operational and organizational part.
Figuratively speaking; technical solutions accounts for 90% of the well integrity.
Organization and operational solutions are of course relevant, but merely as a lubricant in the management system. They will not in themselves stop any uncontrolled release of formations fluids or well fluids if the technical barriers are defect.
Recognizing this, and the challenges encountered several thousand meters below surface, it makes sense to have technical (physical) barriers in place. Moreover, redundancy should be in place to cater for equipment failure, engineering errors, operational incidents and misinterpretation of Mother Earth’s behavior.
The two-barrier philosophy principle is described by a primary envelope in direct contact with the pressure source, and a secondary barrier outside of this, as a hat-over-hat arrangement. This is a robust solution to safeguard well activities, and no matter where the pressure tries to escape, there will be protection behind it. This will also allow repair to an element while the other envelope is containing the pressure.
This philosophy will allow incidents to happen to any element in the barrier envelopes, but still contain the pressure and hydrocarbons and prevent the incident from escalating into an accident.
The precondition is of course that there is verification of the elements capability to withstand the exposure, and that the performance and status of the elements is monitored over time.
To use Well Barrier Schematics for this purpose is very powerful and clear to all stakeholders.
Looking at known industry accidents, in hindsight people have neglected either the qualification and/or the monitoring part. If well barrier schematics had been prepared beforehand, it is quite probable that these accidents would not have happened, because the “writing was on the wall”.
The below example is from a world know incident that happened a few years ago, the working arrangement clearly has two weaknesses, that in the end caused a blowout.
The use of well barrier envelopes and elements is a logical start for true well integrity management. Once the elements are defined their competency is verified and monitor as necessary. Using an FMECA risk assessment will allow assessment of failure modes, consequences and apply appropriate mitigating measure where this is deemed necessary. This also allows establishment of appropriate monitoring and inspection program for the wells, adapted to the associated risk.
On this basis, each well barrier element in the barrier envelopes is accounted for in our wells, and the wells are given a definite well categorization status to confirm they are safe and sound, have weaknesses or need for special attention.
Manage your well barrier element integrity - Manage your well integrity - Have peace of mind.