First BOP Tethering Operation Performed Offshore Brazil

BOP tethering increases operational efficiencies, enabling the dynamic positioning rig to work through adverse weather conditions, performing services in shallow water depths, and ensuring that wellheads can bear high loads.

1 Project Overview

Oceaneering was selected by Petrobras in 2020 to provide BOP tethering services for the operator offshore Brazil.

The scope of work includes data acquisition and real-time riser analysis for dynamic positioning (DP) rig operations for multiple wells in water depths ranging 150-700 m.

2 Our Solution

Oceaneering’s Wellhead Load Relief (WLR) system is a compact, high-capacity BOP tethering system that is suitable for template and seabed anchoring. The WLR system mitigates wellhead fatigue, using adjustable tethers to enable efficient reconfiguration, eliminating the requirement for topside intervention during BOP jumps. The system is completely ROV-operated.

The WLR system consists of several tensioners individually tethered to the BOP. Each tensioner combines a hydraulic spooling unit with a hydraulic lock-and-pull mechanism to enable the ROV to pull tethers from slack to full 25-ton tension without any assistance from topside. The integrated load monitoring system ensures that the ROV can monitor and adjust tension force accurately in each WLR and acquire data to evaluate fatigue life and generate dynamic watch circles for DP rigs. The tensioner enables easy interfacing on all types of anchor points, both on templates and seabed, and has a 360-degree rotational range.

Brazil Bop Tethering Configuration

3 Challenges

The project needed to be designed specifically for Petrobras’ operations. While Oceaneering has performed BOP tethering successfully in other areas of the world, this operation would be the first time executed in Brazil. The conditions to execute the work scope would be very different from how the operation would be performed overseas.

Oceaneering imported the WLR tensioners and monitoring system for this project while the Suction Anchors were manufactured locally.

The anchors with tensioners integrated being launched by an anchor handling tug supply (AHTS) vessel stern roller, a monitoring system installed at the rig to run an hourly riser analysis and all equipment being connected to the BOP.

WLR With Load

4 Results

The BOP tethering system enables the DP rig to perform operations in adverse weather conditions, allowing drilling and workover activities to continue. This demonstrates the efficiency of using a DP rig instead of an anchored one for drilling and workover operations. Another benefit of this WLR system is that it can be used in older wells that were not designed to suffer high loads. These loads are carried by the tethering system and anchors.

On the first well at the Albacora field, the WLR system increased the operational window of the rig, opening the watch circle from 8 m to 53 m, allowing the feasibility of operations.

The operation successfully demonstrated and achieved the purpose of the project to minimize the loads on the wellhead with a red alert of 15 m minimum in a rig drift off situation.

Anchor Installed

5 Project Highlights

  • BOP tethering enables the DP rig to work through adverse weather conditions, performing services in shallow water depths, and ensuring that wellheads can bear high loads.
  • The DP rig’s operational window was increased due to the WLR system, opening the watch circle from 8 m to 53 m.
  • The tensioner enables easy interfacing on all types of anchor points, both on templates and seabed, and has a 360-degree rotational range.

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Wellhead Load Relief
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Company page Since our founding in the early 1960s, Oceaneering has expanded and grown globally to service several industries such as the offshore energy industry, defense, entertainment, material handling, aerospace, science, and renewable energy industries. In 1964, Mike Hughes and Johnny Johnson formed a Gulf of Mexico diving company called World Wide Divers. The company grew in response to increasing demand for their services and in 1969 merged with two other diving companies to form Oceaneering International, Inc. To solve the toughest challenges, we do things differently, creatively, and smarter. As your trusted partner, our unmatched experience and truly innovative portfolio of technologies and solutions give us the flexibility to adapt and evolve, regardless of market conditions. Our mission is to solve the unsolvable. We thrive by creating industry-changing technically creative solutions for the most complex operational challenges under water, on land, and in space. Our five core values establish a common culture and demonstrate what is most important for us as a company. Since the beginning, the company has transformed from a small regional diving company into a global provider of engineered products and services. Today, we develop products and services for use throughout the lifecycle of an offshore oilfield, from drilling to decommissioning. We operate the world's premier fleet of work class ROVs. Additionally, we are a leader in offshore oilfield maintenance services, umbilicals, subsea hardware, and tooling. We also serve the aerospace, defense, and theme park industries. Underpinning everything we do, safety is not only the foundation of our core values, but it is vital to our unmatched performance record and company culture. The industries we serve are as diverse as they are complex. Whether we are engineering deepwater umbilicals or developing robotics for aerospace applications, the safety and health of our employees, vendors, and customers is an integral part of our day-to-day business. If we are working, then our responsibility is to be working safely. Since our inception in 1964, we have placed a high value on employee safety—from diving services and subsea inspection to vessel-based installation operations. We have and will continue to evolve not only our health, safety, and environmental (HSE) processes, but those of the industries in which we work. Although we have been fatality-free since 1999, our HSE journey goes beyond statistics. As our portfolio of services has grown, we have continued to prioritize and advance our approach to HSE.