Foam-Assisted WAG: Experience from the Snorre Field

The Foam Assisted WAG (FAWAG) has been a large-scale demonstration of foam for gas mobility control. Foam has been applied at the Snorre, North Sea Brent-type sandstone reservoir, for different purposes. First initiated as a gas shut-off production well treatment, thereafter as two large-scale gas mobility control processes. Combined water and gas injection (WAG) is the main oil recovery method at the Snorre field. Early gas breakthrough in some production wells has limited the oil production. Gas production control is one of the major reservoir management challenges on Snorre. Foam for mobility control has the potential to improve gas sweep in the Snorre WAG process. Results from the last trial on the Western fault block were very conclusive. Gas breakthrough was delayed, but equally important the Gas-Oil-Ratio (GOR) was considerable lower than gas injection cycles prior to the foam treatment. The paper summarizes all the foam field trails at the Snorre field, with emphasis on interpretation of the last foam application on the Western fault block. The Snorre FAWAG is the world's largest application of foam in the oil industry. The logistics involved transport of 2000 tons of chemicals from central Europe to the field location. The application of FAWAG has qualified foam as a gas mobility agent for North Sea reservoirs. Large volumes of gas have been stored in the reservoir. The expenses for FAWAG on Western Fault block (WFB) was 1M USD, and additional oil recovery value was ∼ 25-40M USD at current oil prices.