Well Processing - Subsea Water Injection and Treatment (SWIT) for Increased Oil Recovery

Well Processing is a provider of engineering solutions for subsea processing. We are an independent design house, supplying technology and licenses. Well Processing is jointly owned by:

• Poseidon Group AS
• Sørco AS

This blend of topsides treatment and subsea expertise gives Well Processing a resource base of more than 400 engineers and specialists.

SUBSEA WATER INJECTION AND TREATMENT (SWIT)

Water injection is the most common way of increasing oil recovery. It works by maintaining reservoir pressure and driving oil towards the producing wells.

"Rethink Water Injection" has been our objective. The natural solution is to keep the distance from the water intake to the injection point as short as possible. Hence, Well Processing has developed a technology that enables water injection and treatment on the seabed. The patented treatment technology can be used for all reservoir applications.

This new method of treating seawater subsea equals or surpasses traditional topsides treatment in prevention of reservoir souring and blocking with solids, thereby allowing a more effective waterflood system than would otherwise be possible.

A single 'cable only' interface makes an easy add-on for development of both topsides and subsea developed fields at any stage of field life.

Benefits include:

• Increased oil recovery via more effective field drainage
• Greater flexibility for the field water flood design
• Significantly reduced cost
• Reduced weight and space topsides
• Reduced environmental impacts
• No seabed pipelines or long deviated wells
• Valuable well slots used for production instead of water injection

NEW METHOD OF TREATING SEAWATER SUBSEA

There are three main areas where the SWIT water treatment system contains significant levels of innovation. All three techniques either simplify or add to the robustness of the subsea treatment system as compared to topsides treatment. Proof of innovation is borne out by the recent patents awards and runner up at the 2006 ONS innovation awards:

• Solids removal 100% removal of inorganic solids >30 microns can be expected
• Reservoir souring control via continuous sterilisation of injected water
• Water injection system sterilisation via shock dosing of dissolved solids biocides

SWIT RECOVERS MORE OIL

• Injection at optimal points in the reservoir - enables more effective oil displacement
• Well slots on the platform can be used for production not injection
• Feasibility of water injection is not limited by the distance from existing infrastructure

SUBSEA WATER INJECTION AND TREATMENT SAVES COST

By utilizing SWIT water injection lines and umbilicals from the host platform are eliminated. Sitting directly above the optimum injection point, the wells can be vertical, reducing drilling costs up to 50%. A typical SWIT could deliver around 200m³/h of treated seawater - 10km away. This means that three units could meet a 100,000bpd water injection demand.

The modular SWIT unit interfaces to any standard subsea Christmas tree. Its all electrical platform interface is simple to connect, with control and power through a single high voltage cable. A high cost umbilical is not needed.

Furthermore, project costs may be reduced as existing topside water injection equipment can operate unchanged while new water treatment capacity is added on the seabed.

SAFETY AND ENVIRONMENTAL GAINS

Treating water subsea reduces the use of chemicals like biocide, hypochlorite, oxygen scavenger, filtration aids etc. It requires less power due to lack of lift pumps, booster pumps and reduced pipeline losses.