As the Innovation Director at Aquaterra Energy, I’ve had the privilege of working on a wide range of subsea intervention projects over the years. While many people associate this type of work with deepwater operations, the reality is that the majority of subsea wells worldwide are actually located in relatively shallow waters, less than 150 meters deep.
Through my experience, as well as the insightful discussion I recently had with my colleague Martin during an Aquaterra Energy Tech Talk ‘Reassessing the standard approach to shallow water subsea intervention’, I’ve identified five key strategies that I believe are crucial for success in shallow water subsea intervention projects. Let me share them with you:
1 – Leverage jack-up rigs and lift boats
One of the most important strategies is to seriously consider using jack-up rigs or lift boats for your shallow water intervention work, rather than defaulting to more expensive floating vessels. With the increased capabilities of these types of units, they can often access water depths of 120-150 meters, which covers the majority of existing subsea wells. By removing the need for heavy subsea pressure control equipment, you can significantly reduce the structural loads on the wellhead, which is especially critical for aging infrastructure.
2 – Prioritise early analysis
Engaging with offshore analysis experts early in the planning process is absolutely crucial. By leveraging detailed modelling and simulation, you can make informed decisions that balance cost, safety, and operational efficiency. This is in contrast to a more gut-feel approach, where you might end up specifying equipment that is over-engineered and unnecessarily expensive. Early analysis also allows you to identify potential issues before they become problems in the field.
3 – Ensure code compliance
When it comes to subsea intervention, the pressure control equipment is essentially the primary well barrier, so ensuring full code compliance is critical. This means not only meeting the requirements of standards like API-17G and ISO 13628-7, but also verifying that the hardware can withstand the dynamic loading and pressure/temperature cycling it will be exposed to. Cutting corners here can have serious consequences.
4 – Manage fatigue carefully
Fatigue is a major consideration, especially when working on older subsea wells that may have accumulated significant damage over their lifetime. Our analysis has shown that the fatigue accumulation can be orders of magnitude lower when using a jack-up rig versus a floating vessel. This provides much more confidence in the long-term integrity of the subsea equipment
5 – Innovate for the future
As we look towards the growing CCS market, the learnings from complex subsea well abandonments are proving invaluable. The CCS market economics often do not support relief or intersect well drilling to deal with problematic legacy wells. Expanding intervention tieback engineering / well re-entry services and techniques to new challenges like finding sub-mudline previously abandoned legacy wells, then vertically tieing back and vertically re-entering them can provide cost-effective solutions for securing legacy infrastructure and preparing sites for long-term CO2 storage. Continued innovation in this space will be key to unlocking the full potential of CCS.
By keeping these five strategies in mind, I believe operators can set themselves up for success in their shallow water subsea intervention projects. It’s all about leveraging the right technologies, engaging the right expertise, and constantly pushing the boundaries of what’s possible. I’m excited to see how the industry continues to evolve in this space.
I work with a team of engineering experts that are well-versed in these strategies and can help you navigate the complexities of shallow water subsea intervention. From detailed riser and conductor analysis and engineering to innovative equipment solutions such as our completion and workover riser system and CCS legacy well vertical re-entry solutions, we have the capabilities to ensure your projects are executed safely, efficiently, and cost-effectively.
Get in touch to learn more about how our team can support your shallow water subsea intervention needs.