One of the greatest dilemmas encountered when introducing and developing any type of new technology is knowing just how far to go. When does an industry innovation go beyond what is deemed to be
a natural development pace and become just plain risky? Some believe that the still expanding global subsea market and its related technologies are reaching just such a point.

There are a number of crucial projects around the world now nearing crunch dates that could, for better or worse, dramatically influence the oil industry's perception of just what is possible with subsea technology.
Inextricably linked on one hand to the fast-expanding deepwater market and on the other to the industry's push to develop more economic seabed tie-back options in shallow water zones, subsea technology is having to make dramatic leaps forward in order to be able to cope with the requirements demanded of it.
But this constant pushing back of the technology envelope contains an inherent risk, and oil companies are well aware of this. Many operators, for example, are extremely interested in projects such as Elf's Girassol development offshore Angola, which is employing several extremely innovative subsea technologies such as Kongsberg's GLL Host 2500 system.
Few however are prepared to commit themselves to using it on other projects just yet - they'd rather wait and see what happens. This is a clear indication that they too recognize this technology is incredibly innovative - but also carries a big question mark with it at this stage.
The same could be said of ABB's groundbreaking Subsis system to be used on Norsk Hydro's Troll C field offshore Norway. The seabed water separation and reinjection technology is due to be used soon on the field, and is very much a pilot scheme. ABB is of course confident - but again, most operators are preferring to adopt a "wait and see" policy before committing themselves to similar developments.
Both these projects are covered later in this feature, but the issue of industry confidence in subsea technology is still a major talking point.
As Ron Dee, a subsea engineer with one of the most pioneering companies in the field, Shell Technology E&P, commented recently at IIR's DeepTech 2000 conference in Aberdeen: "The introduction of new technology for subsea systems has always been tempered by the need to strike the correct balance between the need to keep functionality simple and reliable, and the growing trend for more functionality and the increased complexity that this brings."

Continuous improvement
"History has shown that existing product lines have been subject to continuous improvement with the consolidation or in some cases the increasing of product reliability, and that intervention techniques are continuously being devised for more ingenious and effective subsea intervention methods," Dee said.
He pointed out that quantum leaps in availability improvement could be achieved through further advances in AUVs and ROVs (to be covered in the next issue of Hart's E&P). Dee added: "The track record of the subsea industry over the last 30 years allows some justification to conclude on the optimistic premise that adoption of sound design practices and proven project execution methods coupled with the imaginative use of new technology should allow the use of subsea facilities to provide reliable and competitive solutions to extend the production lifetime of existing mature oil provinces, and to provide solutions for the development of the world's existing and maturing deepwater prospects."

The market
So what are the prospects for the global subsea market?
One of the favorite devices for monitoring its health is the size of the subsea well count. The latest tables and figures from Norland Consultants, based on existing discoveries alone, show that the number of subsea wells globally will be somewhere in the 300 to 350 range.
The analysis in Table 1, coherence installation of subsea facilities in the number of wells, transforms into capital investments shown in Table 2. As capital investments in subsea wells also include the drilling and completion cost elements, there is of course no absolute arithmetic conformity between the number of subsea wellheads installed in a year and the accompanying capital investments.

Capex per year
But Norland's further analysis, including the probability of new investments in the development of discoveries not yet made, indicates capex in the subsea segment of the field development sector will stabilize at levels between US $8billion and $8.5 billion per year in the period beyond 2002.
Not surprisingly, North America and northwest Europe dominate the subsea spend charts equally, with West Africa continuing to emerge as an increasingly vital subsea market.
By far the largest number of subsea wells have been completed in the 100- to 200m water depth range, with significant numbers existing in the 300- to 400m and 500- to 1,000m ranges also.
Dee went on in his presentation at the conference to give further breakdowns of the subsea market, technologies and reliability issues, some of which are further covered in Hart's E&P's Marine Technology section on page 73.
But it is worth pointing out here his comments as they relate to the issue of the perception of subsea technology by the industry.
The key point is indeed reliability. To realize a profitable return on the levels of capex outlined above requires the design and selection of facilities that are fully qualified for the intended service, meet the project reliability requirements and which can be maintained in a cost-effective and timely manner in the event that failure occurs.

Equipment improvements
Norsk Hydro's (formerly Saga Petroleum's) chief engineer Jan Ingar Knudsen, speaking at the same DeepTech event, said simply: "The reliability of subsea equipment has to be improved. It is amazing how trivial problems shut down subsea fields even in shallow waters today. Sometimes you get the impression that the engineers have overlooked the fact that the equipment will be exposed to a certain water pressure. Moving into deepwater waters, the consequences of such failures are becoming more severe, and the industry has to take this problem seriously.
"In order to make the future subsea systems reliable, I am convinced that the subsea equipment manufacturers will develop systems and tools where the experience transfer from previous projects really works. This is the only way this industry can improve their performance, and they have to improve if the deepwater developments shall be attractive."
He pointed out that experience from subsea fields in shallow water taught that the need for maintenance and workover operations was also much higher than originally expected. Deeper water fields would be an expensive exercise with the vessels and equipment of today. "In the future there has to be developed equipment and methods to cut down the requirements to the vessels and the operation time. We will probably see a development with coiled tubing operations from lighter multipurpose vessels."
Dee meanwhile highlighted considerations such as the selection of qualified equipment and systems with a proven track record; the use of analytical tools to assess the functionality and operability of the complete subsea system for all operating modes; appropriate material selection; implementation of an effective quality management, control and inspection system; and adoption of a comprehensive test program to check for functional compliance and serviceability.
He said: "Even the best-designed and-operated systems fail. The reasons are varied and could for example be due to a design defect not captured and rectified by the test process, or damage sustained during construction or subsea intervention operations. Recognition of the vulnerability to failure of certain subsea components, and designing in the means to diagnose failure type and methods to recover and replace the affected component are critical to maximizing system uptime."

Variables
The subsea design and system engineer faced with this challenge needs to confront a number of variables in order to arrive at an overall optimized subsea design.
The need for products that have a validated design and have been extensively tested to confirm performance under representative functional and operational conditions is paramount.
Dee pointed out that Shell companies in the United Kingdom and United States have benefited from the FMC/Shell alliance which is providing the subsea facilities requirements for the Gulf of Mexico and the Shell subsea frame agreements with Cameron and ABB/Vetco Gray for UK projects. "The use of qualified products which have the flexibility for configuration to meet a range of applications has served the latter Shell operating units well.
"The benefits of standardization through the latter arrangements have resulted in cost, quality and schedule advantages for about 10 projects which have been completed in the last 5 years," he said.
He also stressed the importance for an effective quality assurance process, as neglect to fully implement and continuously monitor the effective operation of such a system "will result in inevitable and adverse consequences."
Shell is of course practicing what it preaches. It is carrying out an exercise via its subsea technology and services team in the Netherlands to compile a materials selection and application guide to help the company better benefit and learn from the hundreds of problems experienced by Shell companies over the past 20 years with material issues.

Highest possible production
So in order to achieve the highest possible subsea production system availability, subsea engineers have to do the above, on top of displaying the focus they have done in the past on using qualified and field-proven subsea facilities.
But it is also worth remembering that system design has also been driven by the requirement to minimize the need for retrieval of defective equipment, despite today using equipment that has an increased tendency to fail due to its more complex functionality.
For instance, structural steel and subsea pipework can generally be designed for a design lifetime of 20 years without requiring recovery. However, to expect components working in active rather than passive mode, such as choke valves and control modules, to survive such a period cannot be supported by the failure rates being sustained for such components.
The trend to incorporate increased functionality and complexity into subsea facilities continues with specific examples:
Shell's Draugen project water turbine-driven multiphase pump;
an electric submersible pump installed in Shell's Gannet E subsea well; and
the Troll pilot subsea separation system.
Dee comments: "These projects and others have definitely set the trend for subsea systems which will provide the subsea facilities enabling increased recovery, high production rates and longer offset distances between the subsea produced field and host platform.
"Current developments by Shell and the industry which are considering subsea wells and related systems with the capacity to produce up to 100,000 b/d or 500 MMcf/d per well over 100km for oil developments and 200km for gas developments could easily become a reality in the next 3 years, providing the technology can be developed with the reliability and cost to meet economic and safety criteria."
He added it would be unreasonable to expect a motor or pump in land-based service to remain operational for 20 years without the need for intervention and repair. "However, if the configuration and packaging of such systems can be achieved to meet field development capital limitations for subsea service and operationally effective, and low-cost intervention systems can be designed and deployed to realize subsea system availabilities similar or better than what is currently being achieved to date, then systems with increased complexity may find their way into both deep and shallow water service," he concluded.