Deep water continues to demand cost effective, efficient solutions from manufacturing through operation. Existing designs of electrohydraulic (EH) control systems are large and complex, making them slow to produce, difficult to maneuver offshore, and inefficient to redress and maintain.
The Dash? Large Bore Subsea Safety System is an all-new EH system for large-bore subsea well-intervention applications. The system is simple to test and simple to assemble. It isolates the lower landing string in less than six seconds, disconnects from the lower landing string in less than 10 seconds, and provides seabed and upper landing string data for greater confidence during operations. Developed to meet the latest ISO and API standards, the Dash system was built on proven products, and is customizable to meet individual customer requirements.
Halliburton has collaborated with its customers to determine what is truly needed for EH systems. The Dash Large Bore Subsea Safety System reduces the required time to safely close and unlatch the subsea safety system during emergency conditions, and also provides greater integration flexibility. With the industry focused on efficiency, broad integration capabilities are critical for lowering cost. The Dash system delivers a customizable data-monitoring solution for both the subsea safety system and pass-through controls.
The Dash Large Bore system has been designed to ease assembly, simplify maintenance processes, communicate real-time landing string conditions, simplify re-latch operations, and provide faster activation response times. Ultimately, it produces a more reliable EH system.
With the Dash Large Bore system, we can lower the cost of deepwater development without compromising safety.
An operator in the Gulf of Mexico needed a well abandonment solution for two deepwater wells and required that the intervention be as quick, safe, and cost-effective as possible. Halliburton deployed its electrohydraulic (EH) Dash? large bore subsea safety system because it was easier and faster than traditional systems. The mobilization was successfully completed in only 30 days (two to three times faster than with traditional landing string systems), successfully delivering a plug and abandonment (P&A) solution with zero nonproductive time (NPT) or safety issues.
Efficiency and cost effectiveness are critical in deepwater completions and interventions because of the risks of high pressures, rig mechanical failures, extreme weather conditions, and other unexpected emergencies. Traditional electrohydraulic subsea safety systems are large and complex, with multiplery hour wasted translates to tens of thousands of dollars.
For the P&A operation on its two active wells in the Gulf of Mexico, the operator needed to mobilize the rig, along with coiled tubing (CT) and equipment, within one month. Halliburton was approached for an efficient, cost-effective solution that would:
– Mitigate the risks involved in active, high-pressure wells
– Provide a means of isolating the reservoir
– Ensure a complete annular seal
– Serve as the primary contingency during the CT intervention
– Connect with the tubing hanger running tool (THRT) to secure the well and retrieve the upper completion
– Be completed within the fast turnaround time.
Halliburton used the Dash large bore subsea safety system as the primary safety barrier. Engineered to be simple to assemble, test, and run in hole, the electrohydraulically controlled system can be isolated from the lower landing string in less than 6 seconds and disconnected from the string in less than 10 seconds. With a customizable data-monitoring solution for the subsea safety functions, pass-through controls, and surface control system, the Dash system enables operators to calculate optimal performance, avoid NPT, and streamline deepwater operations.
Halliburton Gulf of Mexico subsea operations and Testing & Subsea technology teams collaborated with the operator to customize the system in order to interface with the blowout preventer (BOP) and THRT and to provide dual barrier isolation, unlatch capability, and a way to cut the CT string. Halliburton initiated the Design of Service (DOS) process, which was led by a Halliburton subsea engineer working closely with the operator’s subsea team. The DOS process defined pre-job testing, BOP stack layouts, job procedures, and a project-specific risk assessment. Halliburton assured the operator that the system would meet company standards without adding risk.
The Halliburton team delivered a fully customized Dash system landing string in less than 30 days, after having conducted a full EH system integration test in just four days. A comparable hydraulic subsea safety system would have taken more than three months. The landing string was rigged up offshore over the well center in only 4 hours, up to three times faster than with traditional systems. The real-time monitoring of the flow and pressure measurements by smart, redundant electronic controls provided immediate feedback of the downhole operations, enabling the operator to be more confident about critical well control during P&A operations. No NPT or safety issues were reported. In total, the Dash system provided more than 30 days of safe, reliable operation for the deepwater P&A procedure.
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