Drilling advances

You have your drilling and production organization, and, as is typical within most companies, never the twain shall meet. However, with non-productive time (NPT) in the deep- and ultra-deepwater putting canyon-like dents in drilling budgets, a small Houston company believes it’s high time for a meeting of the disciplines, at least where controlling subsea components is concerned. “Historically, drilling controls and production controls have always been kept totally separate,” said Margaret Buckley, control systems project/product manager for DTC International, Inc. “But, their purpose is the same, and that is to take a signal from the surface, and open and close valves.”

For about 16 years, DTC has proved up that axiom, exemplified in a recently developed ROV-compatible modular control system, that is equally effective in drilling, workover or production applications. Known as the MODSYS subsea control system, the functions for the self-monitoring technology can be inserted, as required, much like the childhood Erector Sets of yore, DTC says. “This is a completely across-the-board system for drilling, intervention or production,” said Buckley.

In a presentation to the Drilling Engineering Association (DEA) in June, Buckley said the lightweight, easily-configurable system takes the economic pain out of deep- and ultra-deepwater equipment repairs and replacements that can take up to seven days, at spread costs, running upwards of $1 million/day. “Now that we’re going into deeper and deeper waters, the biggest issue on the drilling side is downtime. When any little thing goes wrong, you have to shut in, disconnect, pull the riser and make the replacement, all while the rig is sitting idle,” she said. “The MODSYS allows an ROV to descend with a replacement module and install it in four to eight hours.”

Genesis of MODSYS. With 80-plus combined years of experience in subsea drilling and completion systems, co-founders Dana Beebe, president and CEO, and Bill Parks, vice president of technology development, first envisioned the recently engineered MODSYS in the early 1990s while designing and building the next-generation deepwater workover systems for an integrated subsea company. “We realized then, that based on the electronic advancements that were coming out at the time, that we could really miniaturize control systems,” said Beebe.

Facing bureaucratic diffidence, Beebe and Parks in 1997 formed the Deepwater Technology Company and began laying the groundwork for what is now a universally applicable, ROV-compatible system. “Our first goal was to make a universal subsea control system that could be used for drilling, workover or production, because to us it made no sense to keep going down these parallel paths, when the functionality is exactly the same. We use a standardized, segmented unit that is easily configured for specific jobs without affecting the basic unit,” said Beebe.

“Our second goal was to make it small enough and in compatible modules, so that it’s ROV-retrievable. We take the premise that it (a subsea component) will fail at some point, so how do we mitigate the costs of that failure? By making it serviceable with an ROV, you can swap out a component and be back on-line before you return to the surface.”

Borrowed components. DTC established a three-prong strategy for the development project that relied on proven technologies, engineered the capacity to recognize when components needed replacing, and then made replacements with minimal interruption to operations.

Reliance on field-proven components, Buckley said, was first and foremost, and extended to those validated in other disciplines and industries. The system, for instance, employs critical electrical connectors and solenoids from the aircraft industry, and couplings that have long been used on the production side. “We’re not re-inventing the wheel. Reliability is the key, so we start with the best field-proven components and monitor them to see how they are performing. There’s been enough good work done on individual components, so we’re grabbing the best of what’s out there, regardless of what field it may come from,” she said.

The differentiator, Buckley said, lies in its compact, lightweight packaging that contains standardized, easily interchangeable modules, each of which is tested in hyperbaric chambers at depth to ensure integrity, once deployed in deep water. DTC also is working to alleviate any compatibility issues that could arise with the autonomous underwater vehicles (AUV) under development for deepwater intervention. “It all starts with the same latching mechanism and the same OD and length. The entire system is designed around a standardized package that can be adapted for whatever needs to go into the control system for a particular application,” she said.

Buckley told DEA that the MODSYS delivers real-time data analysis to identify subsea component degradation before failure. “It monitors the electrical signals and how the solenoid is behaving; we monitor pressures vs. time downstream of the solenoid, and pressure vs. time downstream of all the regulators and directional valves. All this comes back in real time, and if wear is being indicated, we can make painless, unnoticeable replacements on-line,” she said.

In a related development, DTC International has served as project leader on a nearly completed RPSEA (Research Project to Secure Energy for America) project, “Deepwater Subsea Test Tree and Intervention Riser System.” According to RPSEA, the project will design a fully integrated subsea well intervention system for up to 12,000-ft water depths, at working pressures and temperatures as high as 20,00 psig and 350°F, respectively.