Sonardyne has published a case study detailing how Trendsetter Vulcan Offshore utilized the company’s Subsea Monitoring, Analysis, and Reporting Technology (SMART) alongside Compatt 6 transponders too assist an operator in correcting a misaligned wellhead at a deepwater location.
Deepwater operations present considerable challenges, necessitating cutting-edge subsea technology and installation methods. While many projects proceed smoothly, there are instances where innovative solutions for deepwater interventions become essential.
Identifying the Challenge
Trendsetter Vulcan Offshore (TVO),based in Houston,faced a formidable task when called upon to assist an operator in addressing a misaligned wellhead situated over 2,000 meters underwater. The wellhead had sustained bending, raising concerns about potential damage to surrounding components.
TVO’s mission was to restore the wellhead to a vertical position, facilitating access for remediation and abandonment procedures to ensure it might very well be permanently sealed. A critical aspect of this operation was to execute the task with utmost precision to avoid any additional harm to the wellhead.
Innovative Solutions Proposed
TVO devised a creative solution involving a ring of six subsea tensioning systems anchored to suction piles arranged in a circle around the wellhead. Each tensioning system was linked via ropes to a Trendsetter-supplied lower riser package (LRP) affixed to the wellhead. By methodically adjusting the tension on the ropes, the team aimed to realign the wellhead.
To ensure safety and control during this process, TVO required a monitoring system that could deliver:
- Real-time feedback on tension data from each of the six load pins installed on the LRP.
- Real-time inclination data from the wellhead itself.
Traditional Deepwater Intervention Methods
Historically, inclination data has been gathered through visual inspections using divers or, in deeper waters, remotely operated vehicles (ROVs). Similarly, tension data was obtained from visual displays on the tensioning systems, also requiring ROV access.
These conventional methods can substantially prolong operations, especially given the 30-40 meter radius of the tensioning systems, even if only two were actively engaged during the righting process. additionally,visual readings can be prone to errors.
Another option involves deploying battery-operated accelerometers and inclinometers via ROV, but this method necessitates retrieving the devices after each measurement, leading to extended operational timelines, possibly spanning several days.
Adopting a SMART, Real-Time Intervention Strategy
Instead, TVO successfully implemented a wireless, smart underwater monitoring solution that provided near real-time inclination and tension data to the surface operations team, with only a three-minute delay. This system utilized two of Sonardyne’s SMART devices and six Compatt 6 transponders.
The internal inertial measurement unit within each SMART device calculated pitch and roll data from two points adjacent to the LRP, enabling TVO to determine the wellhead’s bend angle accurately.
This facts was transmitted acoustically via the SMART’s internal modem to the surface every three minutes.The Compatt 6 transponders were connected to the load cell shackles at each tensioning point on the LRP, relaying tension readings to the surface with updates occurring in under a minute.
Accomplished Outcomes
The operation to realign the wellhead was completed in just three hours, utilizing an ROV to adjust the winches at two key tensioning units sequentially. In contrast, traditional methods would have required several days.
Throughout the process, the TVO team and the operator maintained a continuous near real-time visualization of the wellhead’s inclination and the tension applied at each system. This was facilitated through an internet-based dashboard developed by TVO, allowing team members, including the operator, to monitor the operation from anywhere globally.
making Informed Decisions with SMART Technology
“This was a unique challenge. Numerous studies and approaches were evaluated before deciding on the best course of action. Our solution,utilizing Sonardyne’s SMART devices and Compatt 6 transponders,proved highly effective,” stated Kim Mittendorf from TVO.
“We were able to control the two tensioners with the precise amount of tension needed in near real-time. while the ROV was adjusting the winch over 2,000 meters below, we could observe the direction of the wellhead’s movement and changes in pitch and roll angles.
“All data was live-streamed to a website, enabling both offshore and onshore personnel to monitor the operation in near real-time. This openness supported their decision-making and provided reassurance to proceed as planned.”
Ensuring Safe Well Abandonment
After the wellhead was realigned,the tensioning and monitoring systems remained in place to facilitate safe intervention and final abandonment operations. During this phase, data transmission rates were adjusted to once every few hours.
For added redundancy, two suction piles were equipped with relay Compatt 6 transponders due to concerns about potential line-of-sight issues with the topside transceiver. Additionally, the ROV was outfitted with a ROVNav 6 transceiver as a backup communication method. Though, these contingencies were needless, as the SMART devices and Compatt 6 transponders successfully communicated directly with the topside transceiver.
Success in Deepwater Wireless Well Intervention
The entire operation was a resounding success. Thanks to the engineering expertise of TVO and the monitoring capabilities of Sonardyne, the operator was able to safely and efficiently decommission this challenging deepwater wellhead.
Initial doubts regarding the use of hydro-acoustic data transmission were alleviated, and the project’s success has fostered greater confidence in this technology for future applications.
