The oil industry’s frontier lies in ultra-deep ocean zones that until recently were considered too treacherous for drilling. But a variety of highly specialized technologies – including innovative control and communications applications – enable oil companies to afford-ably extract crude from primordial rock 8 km (5 miles) below sea level.

Using systems uniquely engineered to connect subsea assets and topside controls, major producers have tapped into remote mother lodes buried offshore Brazil and West Africa as well as in the Gulf of Mexico. Near the Texas coast, for example, a reservoir roughly equal to the size of Houston holds enough oil and natural gas to produce up to 130,000 b/d. That compares to approximately 6,000 b/d for the average well on Saudi Arabian sands.

Advanced control and communications systems are equally essential to help maximize hydrocarbon recovery from brownfields, which remain major investments for offshore oil and gas companies. In fact, a major producer today may spend as much as 70% of its annual budget to keep oil flowing from mature subsea sites.

Systems integrator CSE W-Industries has played a critical role in helping global oil companies expand into extreme underwater environments and extend the life of aging offshore wells. The company has an installed base of more than 60 master control stations (MCSs) – the brains that govern operations in subsea wells.

Challenge

W-Industries began developing topside MCS equipment in 1995, when the subsea oil industry was still in its infancy. Back then, the process was relatively simple – topside controls connected to conventional subsea fields of four to eight wells. The MCS communicated with the subsea equipment at 1,200 baud, performing basic monitoring of subsea sensors; controlling subsea valves, choke valves, interlocks, and shutdown sequences; and interfacing with topside control systems.

By the end of the 1990s, the subsea field sizes monitored by the MCS grew to 50-plus wells, a significant load increase on the legacy MCS. W-Industries recognized it needed to provide a higher capacity MCS platform to support the larger field sizes with communications and processing capabilities. However, the space allotted for the system’s hardware couldn’t grow because of the tight confines on offshore facilities.

“As we ventured to develop our new MCS to meet the new requirements in the industry, solid subsea communication capabilities became the top priority in our new MCS design,” said Raouf Hadad, subsea controls business unit manager for W-Industries. “Unlike a conventional process control system, which has thousands of hardwired IO [integrated operations] points, the MCS typically handles less than a hundred topside IO points. Still, it has to collect tens of thousands of subsea data points via its communication channels with the subsea control modules (SCMs). Communications capabilities are the backbone of the MCS, and our success in meeting the subsea industry’s challenges depended on those.”

Hadad and his colleagues thoroughly investigated potential platforms, including single-board computer solutions and programmable logic controllers from various vendors. In 2001, they decided to standardize on the Allen-Bradley ControlLogix programmable automation controller (PAC) from Rockwell Automation.

“ControlLogix gave us the essential combination of the robustness, reliability, powerful processing capabilities, and communications flexibility,” Hadad said.

Fast forward a decade. With the advance in subsea technology, operators wanted to go beyond deploying conventional production wells and started deploying subsea processing equipment – subsea three-phase separation and subsea boosting (pumps and compressors).

“Naturally, with the advancement in subsea processing technology, the MCS on topsides had to keep up with these new demands,” Hadad said. “Now, instead of just opening and closing valves and monitoring pressures and temperatures, the MSC is controlling and monitoring PID [proportional integral derivative] loops on separators, pumps, compressors, and other subsea equipment.

“All this equipment is more critical and needs more built-in redundancy and diagnostics than conventional equipment, hence more data, and faster data coming via fiber-optic communication lines from the subsea,” Hadad continued. “Of course, the MCS has to process these data more swiftly and send the appropriate control signal back to subsea to adjust valve position or to adjust these pump/compressor speed.”

W-Industries recognized the changing requirements and undertook another stage of MCS design evaluations to ensure it could support the subsea industry’s evolution.

Solution

W-Industries tapped into the Rockwell Automation PartnerNetwork program to bring in Online Development Inc. (OLDI), which designs and manufactures automation products to help simplify data transfer, control, and communications tasks. OLDI has a computing module called the special applications module (SAM) that is integrated into the Logix architecture used for the MCS on the platform. W-Industries runs its custom data handling program on SAMs installed in the ControlLogix chassis.

“Once we were able to identify a solid communication solution with the SAM, the decision to stay with the

ControlLogix platform was easy,” Hadad said. “We also had a huge installed base of ControlLogix, and we wanted to give customers a solution that could accommodate their existing systems along with new tiebacks.

“The combined solution of being able to communicate with older and newer subsea tiebacks simplifies our job because we don’t have to worry about different platforms and different interfaces on each installation. The Logix-based solution allows us to support and communicate natively with older generation SCMs and the new generation of SCMs effectively.

“We solved the need for the subsea communication interface with the SAM, and we solved the topside interface with ControlLogix and with its broad spectrum of integration capabilities.”

Results

The combined MCS solution has been a success for the company. Several major oil companies have selected the system, recognizing its broad capabilities plus the huge value-add of integrating the upgraded MCS with subsea units without the need for additional topside space.

In fact, one multinational producer ditched plans for a new building after hearing W-Industries’ presentation about the ControlLogix/SAM solution. “We told the customer, ‘You don’t need to add another building. This will replace the old MCS,’” Hadad recalled. “The new MCS supports older fields with older interfaces along with new tiebacks using the SAM. It’s just a matter of adding a different interface module – without even enlarging the cabinet.”

This unique solution also has positioned W-Industries for strong future growth because it was engineered to handle even more subsea communications than the oil companies need today.

“It was important for us to have a future-proof solution because production equipment is expected to continue proliferating on the ocean floor,” Hadad said. “As the technology goes deeper and gets better, operators are going to demand faster data rates. We can deliver them.”

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