Novel surfactants for cement spacer cleaning are being developed by Akzo Nobel Surface Chemistry plants in Dobbs Ferry, New York, and Stenungsund, Sweden. The products are designed to be both efficient and environmentally friendly, according to Ingemar Uneback, application development manager for petroleum applications in Europe.
When a well has been drilled, spacer fluids are introduced into the borehole to displace the drilling fluid and provide a clean and hydrophilic - water-wet - surface onto which to cement the lining. They work by spacing the drilling fluid in the wellbore from the cement slurry, which is pumped down to secure the liner to the borehole wall.
Current cleaning surfactants and other formulations do not provide a wholly satisfactory solution, especially when the drilling fluid is oil-based. Solvents are probably the most efficient product, but have the drawback of being environmentally harmful.
The new products have been proven to a high level of cleaning and removal efficiency with drilling fluids based on both natural and synthetic oils, while leaving the borehole wall hydrophilic. At the same time, they do not harm the environment since they are biodegradable.
Surfactants are chemical compounds that influence the inter-facial behavior between two liquids, a liquid and a gas, or a liquid and a solid. Their versatile properties make them suitable for a wide range of applications in the oil and gas industry.
50% better water flow
Surfactants developed by Akzo Nobel for use as flow improvers in water pipelines, for example, carrying water for injection into an oil reservoir, have recently undergone full-scale testing offshore. These are a combination of zwitterionic and anionic surfactants, which in laboratory tests have achieved a 40-50% improvement in water flow, in effect increasing the pipeline capacity. This compares with a 15-20% improvement typically achieved by the polymers commonly used for the same task. The surfactants are also readily biodegradable, while the polymers are not, Uneback says.
A further advantage is that the surfactants can be added upstream of the pump, as they self-heal after being subjected to the high shear forces involved in passing through the pump. Polymers, on the other hand, are destroyed by these forces.•
For more information, contact Ingemar Uneback, Akzo Nobel Surfactants. Tel +46 303 85155, fax + 46 303 88910, [email protected], www.surface.akzonobel.com.
