Regulatory authorities usually require OPCO’s to demonstrate the risk of hydrocarbon release from a well is ALARP (As Low As Reasonably Practicable) which means using:
- Best available equipment and current industry best practices.
To achieve this, most OPCO’s usually adopt a double barrier pressure containment envelope. In the natural flow example shown the primary barrier outlined in red and the secondary barrier outlined in blue.
For each element there will be acceptance criteria e.g:
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ISO 13679 procedures for testing tubing connections.
- Leak criterion for gas: 9 cc/15 min.
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ISO 14310:2008 Petroleum and natural gas industries –Downhole equipment --Packers and bridge plugs.
- Leak criterion for gas 20cc /10 mins
However when you introduce gas lift to the well you can significantly compromise the integrity of the primary containment envelope. Specifically ISO 17078-2, Flow control devices for side-pocket mandrels states:
- “These devices are designed and intended to prevent reverse flow through a flow control device. They are not designed nor intended to provide a tight shut-off pressure safety seal or to be a part of the safety system.”
OTC 20820 (published paper on gas lift valve reliability ) states:
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ISO 17078-2, is not an appropriate standard for wells needing the gas lift valve to be a part of the barrier.
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A new validation program for gas lift valves has been created. The acceptance criteria is more aligned with validation programs for comparable safety equipment.
- Strong evidence from both the lab and the field suggest that the valve developed to the validation program is considerably more robust and has an extended lifetime in harsh conditions. The increased robustness and lifetime will increase the safety level of the well and reduce intervention time and cost.
PTC developed its gas lift valves in response to this requiremen criteria. Uniquely, we understand, they also satisfy these criteria following erosion testing.
Remember: A well barrier valve is for the life of the well.........not just a factory acceptance test.
