Operator Reduces Cost Using Electro-Hydraulic Subsea Test Tree

Overview

Before contacting Halliburton, an operator contracted EH SSTT equipment and services through a dedicated multi-year rental contract with another service company. Although the equipment was field-proven with an established run history, the subsea controls were complex in design, and every function on the completion landing string, including the tubing hanger running tool (THRT), operated in an EH manner, opposed to direct hydraulic (DH) technology. DH controls are inherently simpler and less forceful than EH controls, yielding increased reliability and extended subsea equipment life until redress (maintenance) is necessary.

The operator’s previous multifaceted system operated each hydraulic function on the completion landing string in an EH manner and required hundreds of complex hydraulic tubing runs assembled inside the slim-OD riser control module. This system required the maximum amount of SOVs and DCVs, which, in turn, required more time for maintenance in between wells and deployments, increasing overall costs. Additionally, the operator consistently paid a premium for services rendered by the former service company compared to other service offerings on the market.

When market prices began to decline, the operator was challenged to continue with the same level of EH SSTT capability on a significantly reduced budget concurrent with the industry downturn. This is where Halliburton’s technology came into play—Veto™ subsea safety system and DASH® emergency response module—earning the operator’s future subsea projects and replacing the former service company.

Status Quo

Although the ultimate decision to use DH vs. EH technology is typically operator-specific, most operators in the GoM use DH controls for SSTTs. This decision is usually driven by cost, risk, trends, and operator philosophy. This operator specifically required EH capability and functionality of well control safety equipment, including SSTT systems, based on the company’s philosophy, risk assessment, and mitigation plan.

Solution

Halliburton offered a simplified EH control package for ESD/EQD functionality with redundant DH controls and a data acquisition system for both surface and downhole functions. DH control of the hydraulic functions during normal operations is a simpler control system design, offering improved reliability and safety, greater potential for reduced POB, quicker turnaround and mobilization time, and reduced stress on tee vendor tools.

Also included was the Veto system, which offers the capability to fail-safe, close cut, and seal with the upper ball on the wireline without pressure assist, in addition to enhanced CT cutting capabilities. This compact system is a comparably safer mechanism that helps reduce operational risk and offers more space out options within the BOP stack.

Result

Once the simpler EH solution with enhanced capabilities was deployed, it significantly reduced the total cost to the operator. The operating company was able to achieve more subsea equipment deployment before redress, directly improving planning timelines, project budgets, and overall efficiency in multiple wells.

The reduced cost, quick turnaround time, and simplicity of the system encouraged the operator to continue working with Halliburton, realizing the value of using DH controls during normal operations to increase system reliability in combination with the capability of EH controls for emergency response with data acquisition for surface and subsea functions.

The operator provided positive feedback and placed two complete packages (surface and subsea) on dedicated retainer in addition to retaining Halliburton technical experts throughout the campaign.