Umbilical‑less subsea completions: Reduced interface risk with eROCS and OTHOS

ERLEND HELGERUD, Optime, a Halliburton service 

Tubing hanger installation is one of the most risk‑sensitive phases of subsea well construction. Conventional methods rely on surface-controlled hydraulics, long umbilicals, and multiple mechanical interfaces. Each interface increases operational exposure and extends critical-path time. As operators move into deeper water and more complex architectures, these interfaces create additional execution risk. 

Fig. 1. Tubing hanger handling on the rig deck illustrates the surface equipment, manual handling, and coordination required during conventional installation sequences.

This article describes a subsea execution model made possible through the capabilities of the eROCS and OTHOS systems. These technologies remove control umbilicals, tubing hanger orientation joints, and blowout preventer (BOP) alignment systems from the installation sequence. The model maintains full subsea control and precise orientation while it reduces system complexity. 

TUBING HANGER INSTALLATION UNDER INCREASED COMPLEXITY 

Tubing hanger installation sits at a critical transition between drilling and completion operations and requires precise control and accurate orientation to support efficient subsea tree installation, Fig. 1. Even minor deviations can create delays, force remedial work, or introduce downstream interface issues. 

Traditional methods rely on hydraulic umbilicals that connect surface power units to subsea tools. Crews must manage reels, clamps, fittings, and pressure tests, and handle tools carefully on deck. Conventional orientation methods also depend on tubing hanger orientation joints and dedicated BOP alignment hardware. Each component adds mechanical interfaces, additional steps, and dependencies between activities, which deepwater conditions exacerbate through high rig dayrates, limited deck space, and narrow weather windows. 

REEVALUATE WHERE CONTROL RESIDES 

Fig. 2. The Enhanced Remote Operated Control System (eROCS) relocates power, actuation, communication and monitoring to the subsea domain, to allow umbilical‑less control during completion operations.

One way that operators address these challenges is to reconsider where control, power and monitoring functions reside during subsea operations. A subsea‑based control model shifts power and monitoring functions from the rig to the subsea domain and reduces dependence on surface equipment and physical connections. 

eROCS is the third generation of remotely operated control systems developed through iterative field experience, Fig. 2. The system supports the completion phase before a well enters production and delivers electrical power, hydraulic power, hydraulic distribution, advanced instrumentation, and third-party interfaces through one integrated unit. 

Internal batteries supply electrical power to pumps, electronics, and control valves. A dedicated reservoir supplies hydraulic control fluid. Integrated pressure, temperature and flow sensors deliver real-time system data and support data-powered decision-making during critical operations. Umbilical-less communication establishes continuous feedback between the subsea system and the surface without physical umbilicals. 

Digitally controlled hydraulic valves regulate pressure precisely without multiple header pressures, solenoids, isolation valves, or complex manifolds. With combined electrical precision and hydraulic power in a compact architecture, eROCS delivers full subsea control, redundancy, and lower system complexity. 

ORIENTATION WITHOUT ALIGNMENT HARDWARE 

Fig. 3. Subsea completion infrastructure highlights the importance of precise tubing hanger orientation for efficient subsea tree installation and downstream connections.

Accurate tubing hanger orientation remains essential, particularly for vertical subsea tree applications, Fig. 3. Misalignment can delay tree installation, complicate flowline connections, and increase offshore work. 

Traditional orientation solutions often rely on tubing hanger orientation joints (THOJ) and BOP alignment systems. These methods require precise mechanical alignment and coordinated tool sequences. When tolerances fall outside limits, operators may reposition equipment or conduct additional runs, which increases rig time and personnel exposure. OTHOS removes these requirements. The system uses a gyro-guided orientation approach. It determines heading with an integrated gyrocompass and holds orientation with a dedicated tubing hanger orientation pin inside the BOP. Continuous feedback supports each step of the installation sequence. 

By eliminating THOJ and BOP alignment hardware, OTHOS reduces the number of mechanical interfaces and achieves internal orientation accuracy independently of BOP alignment. This approach clarifies each installation step and minimizes interdependency between activities. Operators benefit from repeatability: consistent well orientation reduces the likelihood of remedial work and helps maintain schedule integrity. 

Fig. 4. A combined execution model integrates subsea‑based control with simplified orientation, reducing surface equipment and mechanical interfaces during critical‑path operations.

A COMBINED EXECUTION MODEL 

A model that combines subsea-based control with simplified orientation removes the umbilical and significantly reduces surface equipment while preserving control and accuracy, Fig. 4. In this configuration, eROCS delivers subsea power, actuation, communication and monitoring, while OTHOS delivers precise tubing hanger orientation within the same operational framework. 

The effect becomes clear on the rig floor and deck. Crews manage fewer high‑pressure lines and less equipment during rig‑up and rig‑down. A smaller surface footprint allows more parallel activity and simplifies logistics planning. Clear subsea feedback confirms tool response without reliance on long hydraulic lines or complex surface diagnostics. 

This approach reduces the number of interfaces on the critical path and delivers a more direct and predictable installation sequence. 

OFFSHORE VALIDATION ON THE NORWEGIAN CONTINENTAL SHELF 

Field operations on the Norwegian Continental Shelf demonstrated a shorter installation sequence, fewer mechanical interfaces, and more predictable execution. Post-operation reviews noted simplified planning, reduced operational risk, and improved rig flexibility. Installations achieved consistent tubing hanger orientation without deviation from the planned heading, which confirmed repeatability rather than isolated success. Crews also reported lower drill floor exposure, because fewer manual handling tasks and less high-pressure equipment were required on deck. 

IMPLICATIONS FOR SUBSEA WELL DELIVERY 

Umbilical-less control and simplified orientation preserve the fundamental tubing hanger installation sequence while providing a practical means to reduce surface equipment, manage risk and personnel exposure, and maintain the accuracy, reliability, and traceability required for modern well delivery. This reinforces a broader principle that operators achieve measurable gains in safety, predictability and efficiency when they remove interfaces rather than compensate for them. 

Recent field deployments of eROCS and OTHOS confirm successful offshore execution of umbilical-less tubing hanger installation, with reduced surface equipment and mechanical interfaces during the completion phase.  

INTERFACE REDUCTION AS A FOUNDATION FOR CONSISTENT OFFSHORE EXECUTION 
 
Halliburton’s installation of umbilical-‑less tubing hangers signals a shift in how operators manage execution risk during subsea well construction. Rather than add equipment layers to mitigate complexity, this approach addresses risk at its source and removes interfaces that traditionally sit on the critical path and introduce operational dependency. 

Conventional tubing hanger installation architectures depend on extensive surface infrastructure, mechanical alignment hardware, and multiple handoffs between systems. Each interface increases coordination requirements and increases failure exposure during execution, with limited tolerance for deviation. Reduced dependency simplifies planning, shortens critical path sequences, and increases execution margin. 

Subsea-based control and internalized orientation consolidate power, actuation, and heading determination within a single operational framework. Repeatability improves execution, because control and orientation no longer depend on surface equipment alignment or long hydraulic connections. Field results demonstrate that this architecture supports consistent outcomes without reliance on compensation systems or additional tooling. 

Taken together, these developments reflect a broader principle in modern subsea well delivery: operators achieve improvements in safety, predictability, and schedule certainty when they remove interfaces rather, than attempt compensation. Umbilical-less tubing hanger installation preserves the fundamentals of completion operations while it refines how control and orientation occur during one of the most risk-sensitive phases of the well lifecycle. This execution model illustrates how interface reduction can serve as a practical foundation for consistent, lower-risk subsea well delivery. 

ERLEND HELGERUD leads technology development, engineering, and project management for subsea control, intervention, and umbilical‑less systems at Optime, a Halliburton service. His work centers on digital hydraulics, wireless subsea communication, and remotely operated control solutions that support more efficient offshore operations. Mr. Helgerud holds a Master of Science in systems engineering and a Bachelor of Engineering in computer engineering from the University of South‑Eastern Norway.