As a wireline engineer, the smallest detail can make all the difference between a smooth operation and a costly mistake. During one of our recent jobs, a routine TCP (Tubing Conveyed Perforation) operation took an unexpected turn due to issues with the ball drop firing head. What we thought was a simple misstep in the pressure settings ended up teaching us a valuable lesson about the importance of correct pinning pressures and proper maintenance.
The Incident: Unseen Actuation and Its Consequences
We were performing a standard ball drop perforation on a well, where the ball was dropped, and we pumped more than the required coil volume to seat the ball and actuate the firing head. However, despite our efforts, we saw no signs of the expected actuation—no pressure build and drop. With no indication of success, we continued with the operation, expecting the firing head to activate as it always had before.
But upon pulling the gunstring back to the surface, we discovered that the firing head had indeed actuated and all the guns had fired while still at the bottom of the well. This unexpected actuation was not catastrophic, but it certainly wasn’t ideal. The problem lay in how the firing head had been pinned—specifically, the pressure at which the ball drop firing head was set.
The Root Cause: Misunderstanding Pinning Pressures and Redressing Practices
Upon further investigation, we identified the root cause: the ball drop firing heads were being redressed immediately after each previous job, but the engineers involved weren’t always the ones who had performed the maintenance. In many cases, the o-rings had been sitting in storage for months, exposed to varying environmental conditions. This contributed to inconsistencies in the pressure settings during the job, and eventually, to the unwanted actuation of the firing head.
Additionally, the pinning pressure, which is crucial for proper firing head operation, had been set incorrectly in some instances. This discrepancy meant that the firing head actuated prematurely, causing the perforating guns to fire when they weren’t supposed to, resulting in a misrun.
Action Items: Changing Best Practices for Future Jobs
In response to this incident, we developed a new best practice for setting the correct pinning pressures for ball drop firing heads to ensure that this problem wouldn’t occur again. These new procedures have been integrated into our standard operating procedures (SOPs) for redressing and pinning the firing head. Here are the key changes we’ve made:
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Pinning Pressure Adjustments
We’ve established specific pinning pressures based on the well conditions:-
For dead wells, such as toe stages, the pinning pressure will be set at ~3500 psi.
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For live wells, like those with screen-outs, the pinning pressure will be set at ~4000 psi.
By tailoring the pinning pressures to the specific well conditions, we ensure that the firing head operates properly and doesn’t trigger prematurely.
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Redressing Firing Heads Before the Job
We’ve made it a requirement that firing heads are only redressed immediately before the job, during the gun assembly process. This ensures that the firing heads are not exposed to long-term environmental factors that could affect their performance. -
Thorough Inspection and Maintenance
All components, particularly o-rings and sealing surfaces, are thoroughly inspected and replaced if necessary before every job. This practice minimizes the risk of o-ring failure, which was a contributing factor to this incident.
The Bigger Picture: Preventing Future Misruns in Wireline Services
This experience taught us a valuable lesson about the critical importance of adhering to the best practices and ensuring that every component of the wireline toolstring is in perfect working condition before it’s deployed. In wireline operations, especially when dealing with wireline logging, wireline perforating, or well perforation services, even small mistakes can have far-reaching consequences.
Tools like the wireline truck, perforating guns, and logging cable all play pivotal roles in completing successful jobs, but without attention to the finer details—such as correct pinning pressures and proper tool maintenance—problems can arise.
Wireline engineers need to be diligent about the pre-job checks, including verifying the correct pinning pressure for ball drop firing heads, and ensuring that tools are properly redressed and tested before each use. By incorporating these lessons into our daily practices, we minimize the risk of future misruns and improve the efficiency and safety of our operations.
Looking Forward: Strengthening Our Wireline Services
With this experience in mind, we are taking proactive steps to ensure that similar issues are avoided in the future. These improvements to our procedures for pinning pressures, tool redressing, and maintenance checks will help to eliminate the possibility of premature firing head actuation and other related issues.
By applying these best practices, we continue to enhance our wireline services, ensuring that every perforation well job, cased hole wireline service, or downhole pipe recovery operation is performed safely and accurately. This process will also make us more adaptable to new wireline technologies, keeping us at the forefront of the wireline services oil and gas industry.
Conclusion: A Commitment to Precision and Safety in Wireline Operations
The lesson learned from this incident is a powerful reminder of the need for precision in wireline operations. From cased hole logging to wireline perforating, every component must be checked and maintained to avoid costly errors. By continually improving our processes and ensuring that the latest wireline tools and technologies are used correctly, we uphold the integrity of our wireline services, ultimately ensuring that every job is executed with the utmost safety, efficiency, and precision.
This experience has made us stronger and more focused, with a renewed commitment to best practices in wireline operations. We continue to provide complete wireline solutions, whether for wireline well logging, perforating services, or pipe recovery, always striving to improve and deliver the best possible service to our clients.