With the oil industry moving into increasingly sensitive areas, the call for environmentally friendly cement chemicals is more important than ever. The focus on minimizing harmful chemical usage, and finding suitable replacement additives for cement systems, without compromising the properties of the slurry has been a priority for a long time.

Within the North-East Atlantic area, where environmental legislation is defined by the OSPAR commission1 , there is a definitive list of products that are considered to be non-harmful to the environment, known as PLONOR (Pose Little Or NO Risk).2 

This paper describes the development of some PLONOR cementing additives, the first use of an all-PLONOR cement slurry in the Norwegian sector of the North Sea, and the proposed use of a low fluid-loss, gas controlling cement slurry containing only PLONOR additives.

The challenge was to find a defoamer, dispersant and fluid loss additive from the chemicals on the PLONOR list. Although it is the additive with the lowest loading in the cement system, the defoamer was the biggest challenge. Since defoamer is required in all cement slurries, finding a PLONOR alternative was the most critical. The new dispersant and the fluid-loss additives are based on existing technology, but the challenge was to make the allowable PLONOR chemistry fit the functional requirements for use in a cement system.

One milestone of the project was achieved in January 2006, when the first ever cement job using only PLONOR additives was pumped in the North Sea. This was a slurry for a 13 3/8" casing that was used as a field test for the new PLONOR defoamer.

An operator has recently committed to pump the first PLONOR low fluid-loss, gas-tight cement slurry. This means that the next milestone is within reach in the near future.

You can access this article if you purchase or spend a download.