As a wireline engineer, there are moments that define your approach to safety, operations, and equipment maintenance. One such moment happened during a routine perforation operation, which turned into a valuable learning experience. It all started with a misrun during a TCP (Tubing Conveyed Perforation) operation on stage one. The firing pin failed to initiate the detonation of the first perforating gun, which caused a chain reaction that led to all the other guns failing to fire. This was a sobering reminder of how crucial it is to ensure that every component of the wireline toolstring is working as expected before beginning any operation.
The Incident: A Routine Perforation Operation Turns Into a Setback
We had just finished preparing the gunstring for a TCP perforation, which involved firing a series of guns at multiple depths to create perforations in the casing of the well. The firing head was built according to the standard procedure, following both the manufacturer’s recommendations and our internal protocols. As part of the job, we launched a ball through the tubing to initiate the firing sequence.
The ball was pumped down the tubing, and when it seated, the pressure signature we observed indicated the firing head had activated. This was the moment when everything should have gone as planned, with the first perforating gun firing. As expected, the gunstring was then pulled up to the next interval.
But here’s where the problem began. The engineer, stationed at the wellhead with the shot detection device, could hear some noise that resembled the sound of the guns firing. However, no pressure spikes or any other usual indicators confirmed that the guns were indeed firing. Despite this, we proceeded with the standard procedure, moving the string every 6 minutes, waiting the usual extra safety time, and continuing to monitor the situation.
When we pulled the string back to surface for troubleshooting, the situation became clear: none of the guns had fired. Worse, the top gun was found to be flooded, indicating a serious issue with the firing mechanism. Further inspection revealed that the ball-seat piston in the firing head had sheared, but the detonator had not been struck by the firing pin. The failure of the firing pin was traced back to a failed o-ring, which caused the top gun to flood and prevented the detonation from taking place.
The Root Cause: The Failing O-Ring
The investigation into the issue revealed that the firing pin had failed due to the o-rings on the pin itself. The failure of these o-rings led to the top gun flooding, which meant that the perforating gun could not fire as intended. The sealing surfaces and all other points of contact for the o-rings were checked thoroughly, but no physical damage was found. This left us with a perplexing question: why had the o-rings failed despite no visible damage?
The root cause was ultimately linked to the design of the high-pressure ball drop firing pin. The old design of the firing pin had o-rings that were prone to failure under certain conditions. This failure prevented the firing pin from striking the detonator, thus preventing the guns from firing.
Actions Taken: A Commitment to Change
Once the root cause was identified, immediate action was taken to address the issue and prevent it from happening again in future wireline services:
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Communication Across Teams:
The incident was promptly communicated to all TCP personnel. We emphasized the importance of inspecting the firing pins before assembly, ensuring that no faulty or outdated components were used in any future operations. -
Design Change in Firing Pins:
The manufacturer responded to our findings by changing the design of the high-pressure ball drop firing pin. While the part number for the firing pin remained the same, the design improvements were aimed at making the o-rings more reliable and reducing the chance of failure in high-pressure situations. -
Updated Inventory Management:
Our team made it mandatory to remove all old-style firing pins from inventory. Going forward, only the new-style pins would be used for any ball drop procedures, ensuring that the toolstring was equipped with the latest, most reliable components.
The Importance of Attention to Detail: A Valuable Lesson for Wireline Engineers
This incident was a stark reminder of how vital attention to detail is in wireline operations. Whether we’re performing wireline well logging, using a pipe caliper tool for pipe recovery, or conducting perforating services, the smallest failure in equipment can lead to major disruptions. In this case, a simple failure of the o-rings in the firing pin resulted in a complete misrun, wasting valuable time and resources.
Wireline technologies, from wireline control systems to perforating guns, are sophisticated and require constant monitoring and maintenance to ensure that they perform as expected. This experience has reinforced the importance of not cutting corners when it comes to equipment checks, especially when working with critical tools like firing heads and well perforation systems.
Looking Forward: Continual Improvement in Wireline Operations
Moving forward, we have strengthened our procedures for pre-job inspections and equipment testing. We now pay even closer attention to every detail, from ensuring that the wireline equipment, logging cable, and perforating systems are functioning properly to verifying that all seals, o-rings, and components are in excellent condition before deployment.
The lesson learned from this incident is clear: when it comes to wireline services, whether you’re working on cased hole wireline services or conducting production logging, there’s no room for oversight. Every piece of equipment must be inspected, every component tested, and every procedure followed with precision.
Conclusion: A Commitment to Excellence in Wireline Services
Wireline operations are complex, and every tool plays a crucial role in ensuring the success of the job. From wireline trucks to perforating guns and downhole cameras, each component must work seamlessly together to achieve the desired results. The failure we encountered due to the firing pin’s o-ring is a reminder of the need for constant vigilance and continuous improvement in wireline practices.
By adopting these lessons and continually refining our procedures, we remain committed to providing reliable wireline solutions for our clients. Whether it’s performing wireline perforating, cement bond logging, or any other service, we strive to ensure that every job is completed efficiently, safely, and to the highest standards.