When oil and gas arrive at a platform from a well on the seabed, they bring with them large volumes of water from the reservoir. The older a well is, the more water is produced. The purpose of the platform is to separate the oil, gas and water before loading the oil onto a tanker. The gas is transported by pipeline. Simply by raising water up to the deck of an oil rig and transporting chemicals down into a well, platforms on the Norwegian shelf use as much electrical energy as a large town.
Asle Hovda, founder and managing director at Seabed Separation, explained: “At present the separation process takes place in large tanks located on the platform deck. To get the well stream from the reservoir up to the tanks requires progressively more assistance from powerful pumps. This consumes electrical energy.”
In co-operation with SINTEF, Seabed Separation is developing equipment that can be installed on the seabed instead of the platform deck. The water will be separated there and either injected back into the reservoir or discharged, providing it is clean enough. From the separator, the gas and oil are transported to the nearest platform for further processing.
According to SINTEF Petroleum Research, because the water no longer has to be lifted, the electrical energy saved every day amounts to 20MWh, which is equivalent to 18 month’s consumption by an average household.
The total daily saving for all the platforms on the continental shelf is equivalent to the energy consumption of about 100,000 houses.
As well as the financial and energy savings, consumption of chemicals is also reduced, especially of antifreeze solution, which is currently widely used on the shelf. This also helps make the system more environmentally friendly than conventional methods.
According to Hovda, the system will make it possible to develop new oil and gas fields more cost-effectively. The technology can also be installed at existing fields, both on fixed platforms, mobile production units, and on the seabed. Moreover, module-based technology enables adaptation of the separation system to changing requirements throughout the life of a field, thereby maintaining higher rates of production.
Testing is currently in progress at SINTEF’s Multiphase Flow Laboratory at Tiller, near Trondheim. Currently, the technology is planned be on the market in 2018.
