Special water chemicals are used in the North Sea oil fields to stop harmful – and very costly – scale forming in the pipelines.
Oil production in the North Sea is carried out with pipelines that extend to tens of kilometers and depths of 3,000 meters, while harsh weather and tremendous underwater pressures pose their own challenges.
One less obvious but equally serious aggravation is that of the salt ion precipitation and settling-out on pipes, equipment and on rock formations. If untreated, this can impair production efficiency and damage equipment, incurring enormous potential costs. It is no wonder that Kemira sees the North Sea as an important reference case for the chemicals it manufactures to deal with this challenge. These products are known as scale inhibitors.
Prevention rather than removal
“A great deal of sea water is used for injection in the North Sea fields as a secondary oil recovery method,” explains Markus Mäntysaari, Marketing Managerof Kemira’s Oil & Mining segment in the EMEA region.
“In this process, sea water comes into contact with the water under the sea bed which has completely different characteristics, and the two kinds do not mix well. The scale that forms in pipes as a result can cause severe damage, halting production and blocking the pores and channels through which the oil flows to the production hole.”
In the North Sea, says Mäntysaari, there is a particular problem with barium sulphate scale. “Barium sulphate scale is extremely difficult to remove. The better option is to inhibit the scale formation.”
The North Sea is a stepping stone
Kemira supplies scale inhibitors to oil industry service companies which apply the chemicals repeatedly to the production line. Thanks to advanced “tagged” polymers developed by Kemira, the service companies are able to monitor the dosage and accurately assess the optimal doses and intervals between applications. This in turn means greater cost efficiency for oil producers. With tagged polymers it is possible to shorten necessary production stoppages and therefore decrease their costs.
“North Sea production may be dwindling but it provides a perfect scenario for Kemira to demonstrate our offering,” says Pedro Materan, VP ofKemira’s Oil & Gas customer segment. “We have been developing these products for at least ten years, but we are looking to the future. According to our estimates, the use of scale inhibitors will increase in the Gulf of Mexico, and the offshore fields of Brazil, West Africa and China.”
Stringent requirements
Strict regulations in the North Sea mean that Kemira has needed to develop inhibitors that meet two main criteria: first, they must biodegrade within tightly defined periods, and second, bioaccumulation in the maritime environment – in fish, for example – must be at the lowest possible levels.
“Our customers everywhere will require increasingly efficient water chemicals to meet such criteria, and we have to keep listening to what our customer base is saying and gear our development in that direction,” says Markus Mäntysaari. “I think we are well on the right track.”
Text: Tim Bird
Original article published in Kemira’s stakeholder magazine Waterlink 3/2009