Alpha Thames Subsea Ltd

Operations Division at:- Fyfield Business & Research Park, Fyfield Road, Ongar, Essex, CM5 0GN

Tel: +44 (0)1277 364736 Email:



Major advances in the development of seabed production and processing technology now promise valuable benefits for offshore oil producers. Separating water and gas from the oil at the seabed avoids wastefully pumping unwanted by-products thousands of metres to platforms or FPSOs on the surface. As the industry moves into increasingly deeper water the cost benefits of seabed separation become correspondingly greater.

While many oil companies are still just taking a first cautious look at the technology, the British company Alpha Thames Subsea, has been developing subsea processing technology for over ten years. As part of Kockums Holdings which is, in turn, owned by SAAB Technologies of Sweden, Alpha Thames has gained a significant lead in understanding the complex engineering encountered with deep ocean projects and developed and built its own unique system.

To broaden the availability of its seabed technology Alpha Thames Subsea is able to licence its extensively patented design to oil companies or contractors and work in partnership with their own engineering departments. This is seen as a valuable way of contributing the specialised subsea engineering expertise that would make such projects prohibitively expensive for companies proposing to start them from scratch in-house. Savings in development time will provide a competitive lead and enable oil companies to benefit from the new technology more quickly.

What is equally important is that the Alpha Thames Subsea system also offers a solution to operators with fields onshore in distant and swampy regions. The principal problem with such fields is that even the most basic separation plant still demands a level of infrastructure and support that can often prove uneconomical. The solution comes from the development of the AlphaPRIME modular processing system. The design is based on a self-contained System Module that repackages conventional field proven technology into one extensively patented system. This performs all of the manifold, pumping and separation tasks within a single unit that can be easily and completely removed for workshop maintenance or modification. The design also provides the operator with a unique level of flexibility and future-proofing as he can adapt the module at any time to suit changing field conditions.

When in its subsea configuration the AlphaPRIME system can operate in conjunction with a floating production facility or with fixed platforms that may be more than 50 km away. The same benefits are available when it is used in a swamp environment from where it can supply a distant production facility through an export pipeline. This significantly changes the economics of marginal fields that may have proved uneconomical to develop using traditional methods.

The AlphaPRIME system has been estimated as being capable of boosting subsea well production by up to 75 per cent. This is achieved by performing gas and water phase separation on the seabed to ensure that the export pipeline performs at its full capacity and carries only oil. The first AlphaPRIME system has been built in Sweden at the yard of Kockums Holdings, and Alpha Thames Subsea is now inviting enquiries from oil companies interested in using the design for a subsea or transition zone field application.

The benefits of the AlphaPRIME system derive from the use of a single autonomous Systems Module that incorporates all of the well's manifold, pumping, flow control and processing units. The module is electrically powered and, weighs 25 to 45 tons depending on throughput requirements and is completely retrievable for maintenance or modification. If required, an AlphaPRIME system can begin life by operating as a straightforward manifold centre and be upgraded later. This might include the addition of further production capabilities such as the gas and/or water separation that may become necessary as the characteristics of the field change during its life cycle. The ease of recovery of the AlphaPRIME system also ensures that it can be modified to accommodate new technologies as they become available.

An entire AlphaPRIME installation can be operated remotely without any personnel being present to maintain or control it. It is an all electric system that simply requires a power supply. When used in transition zones power can, if appropriate, be supplied by a diesel generator within the module itself. Whenever maintenance or upgrading is necessary the entire module is quickly and easily removed and transported to a workshop environment where the work can be carried-out safely and the entire system can be fully tested before it is returned to the field. Because an AlphaPRIME system will usually operate with two System Modules in place, production can be maintained during maintenance operations by diverting the well flow to the spare module.

Although it is ideal for deep water applications, an AlphaPRIME system can be installed in water of any depth and begins with the positioning of a docking module either directly onto a single pile, or pile structure that contains no valves or moving parts. The docking module is connected to a power supply and currently uses normal multiple bored well head connectors that enable flow lines to be tied-in conventionally. This is typically followed by the rapid installation of two self-aligned production System Modules that, once connected to the docking manifold, enable production to commence. Because the modules can be retrieved with equal speed and because no maintenance work need be conducted in the field, support vessel charter costs are significantly reduced.

When the AlphaPRIME system enters service in its subsea configuration it has been calculated that it will reduce production costs by $2 to $3 per barrel, a figure that includes investment and maintenance. By separating water or produced gas at the well head, from where it can be re-injected, the operator is not paying to pump it to the surface or overland to a production facility. This has the additional benefit of eliminating other problems associated with hydrates and multiphase flow.

Because an AlphaPRIME system can be situated a considerable distance from surface or on-land facilities it can now be expected to play a valuable role in the reactivation of satellite or abandoned fields. Although its concept is unique, the design of the AlphaPRIME system is fundamentally an imaginative application of trusted and field-proven technology that appears set to re-write the economic rules of oil production.