Foaming agents are to be tried out by Statoil on its Statfjord field in the North Sea in a bid to improve oil recovery from this reservoir.
Injection of such substances has previously been tested on Snorre, which lies in the same area and transferred to Statoil operatorship at the New Year.
“Very promising results have been achieved on Snorre with this solution,” explains Tone Botnen, senior reservoir engineer in Statfjord’s reservoir exploitation sector.
“One of its wells produced about 1.5 million barrels of extra oil during the trial, at a cost of NOK 10 million. And Snorre’s reservoir properties are similar to those found on Statfjord.”
The foam-assisted water alternating gas (Fawag) technology is based on adding a foaming agent to the water being injected into the field.
When gas is subsequently injected, foam blocks the pores of the reservoir rock. This forces the gas into new parts of the formation to displace oil towards the production wells.
“We’ve initiated a pilot well on Statfjord B, and have plans for a second one,” Ms Botnen reports. “It’ll take about a year to see whether results live up to expectations.”
Statfjord’s injection system was converted in the late 1990s from water alone to water alternating gas (WAG). This represents a precondition for using Fawag.
The technology is simple to use, has low investment and operating costs and releases no environmentally-harmful substances, with the foaming agent adsorbed in the formation.