The emergence and evolution of subsea processing has been inevitable. Operators have acknowledged its driving forces for some time. Whether or not subsea processing would become standard practice has never been a question of “if” — it has been “when?” The answer is, now.

As explorationists probe increasingly deeper waters, production engineers are doing some

Figure 1. The CAMFORCE boosting module integrates technology from Cameron, Curtiss-Wright and Leistritz in a single, versatile package. (All figures courtesy of Cameron).
serious thinking about ways to safely and economically produce from those depths. The costs of building and operating floating production facilities have become so high that only a few of the newly discovered fields can justify the investment — these are characterized as high-rate, high-volume, fields with small footprints. However, such fields are rare. A more likely scenario involves producing several small, satellite fields to a centralized production facility — the so-called “hub and spoke” technique. By extending the area served by a single facility, operators can get the volumes and rates they needed to build a viable economic model.

All deepwater development signs pointed to subsea processing as a key enabling technology. Besides improved productivity, the driving forces are clear: long tiebacks from widespread wellheads to gathering manifolds and risers, the need to establish and maintain flow assurance over great distances, and the rising cost of topsides deck space.
In April 2007, Cameron announced the launching of CAMFORCE Subsea Processing Systems. The new venture will provide multiphase boosting, separation and other enabling technologies to the emerging market.

Pointing to its synergy with the company’s recent introduction of other complementary subsea systems, John Carne, President of Cameron’s Drilling & Production Systems Group, said, “CAMFORCE is the natural next step in subsea systems evolution, from subsea trees and controls, through our introduction of the CameronDC all-electric production and control system.”

On the critical path
In developing the system, the company drew heavily from its core capabilities in trees, manifolds and processing systems. The new venture development was augmented by new products and processes from the research group as well as key acquisitions and partnerships. For the latter, the company tapped world-class providers of power distribution and control systems, motors and pumps.

Subsea multiphase pumping systems
After a century of service to the aerospace, defense and energy industries, Curtiss-Wright Flow Control Corp.’s Electro-Mechanical Division became a joint-venture partner with the company. It will supply subsea multiphase pumping systems by integrating its expertise in designing rugged, reliable motors with Leistritz pumps and associated power distribution and control systems. The result will be subsea boosting modules that can be used at wellheads, subsea gathering stations or at deepsea riser terminals, wherever they are needed to keep production flowing (Figure 1).

With more than 100 successful installations of its multiphase pumps in surface and platform applications, and extensive experience in other industrial processing uses, Germany’s Leistritz Pumpen GmbH became a natural source for twin-screw pumping units specially packaged for subsea operation. Based on a simple concept that’s been in use since Archimedes, the reliable, versatile pumps are characterized by their toughness that gives them longevity in demanding environments.

From within the company came extensive experience in developing and installing subsea
Figure 2. The MARS module enables seamless application of many subsea processing and well technologies, including boosting, metering, injection and stimulation.
trees and manifolds, including the SpoolTree system. And the company’s Petreco Process Systems Division is an experienced provider of custom-engineered process packages that perform separation, filtering and treatment of all produced fluids and solids. Petreco technology will be the basis of the company’s two-phase all-electric seabed separation units. The company has introduced new complementary technology in all-electric controls, which is part of the CameronDC all electric production and control system being installed for Total E&P North Sea following successful subsea testing in Norway and on BP’s Magnus field. Additionally, new flowline connection systems have been developed that enhance flow assurance for deepwater installations.

The use of electricity to control and actuate components of subsea systems came after extensive research. Analysis of historical data and sensitivity studies conducted by Total E&P concluded that some electrical systems could deliver as much as 27.8% reduction in production downtime compared to hydraulic systems in ultradeepwater applications.

“Subsea USB port”
A critical link was forged with the March, 2007, acquisition of DES Operations Ltd., of Aberdeen, UK. DES brings advanced production enabling technology to the mix, including its Multiple Application Re-injection System (MARS) that allows installation of subsea processing systems directly onto the subsea completion (Figure 2). Characterized as “a subsea USB port,” the system allows the installation of separation, chemical injection and pumping systems, among other things. Its design enables it to land on top of an existing tree and attach to the choke body without disturbing anything. According to Hal Goldie, president of Cameron Subsea Systems, “It’s minimally invasive. You don’t have to make or break connections in the field to install it,” he said. “And if you still need a choke, we can install one in the MARS package.” The company said the system can be operated by all types of intervention vessels.

Backwards compatible
A major benefit of the system is that it’s backwards-compatible. This means it can be used to upgrade existing systems without redesigning the field architecture. System modules can be installed when and where needed to support field expansion or emerging requirements. Using the MARS module as the enabler, the possibilities are almost limitless, according to the company. The system allows safe, pre-engineered access to the subsea completion for almost any purpose, from boosting, to well stimulation to metering and control. The company believes that the ability to more easily install multiphase metering on individual wells will offer benefits because operators will be able to tell which wells are under-performing. Most importantly, they will be able to determine which wells have the greatest potential for improvement. The overall objective is to add longevity to the field production systems and reduce the need for well interventions.

Scalable design
Presently, the pump system is rated for 5,000 psi and is designed for operation in up to 6,000 ft (1,830 m) of water. The separation system is designed for operation in up to 10,000 ft (3,049 m) of water, and can withstand 10,000 psi shut-in pressure. However, both designs are scalable up or down as environmental requirements change.