Inhibitor squeeze treatments have been regularly carried out to prevent both sulphate and carbonate scale depositions in a North Sea field since 1990s. Some of the wells, in which the fluid is producing from the "clean" sandstone formation, had experienced a relatively short squeeze life when a conventional phosphonate scale inhibitor was squeezed. Through a research program, a polymer inhibitor was developed and a number of laboratory static and dynamic tests were conducted to evaluate the performances of the newly synthesized polymer inhibitor. Several field trials were also carried out with a satisfactory result.

This paper outlines the idea of how the new inhibitor chemistry was developed and how a special monomer was introduced to make the co-polymer inhibitor. The monomer was introduced to enhance the inhibitor adsorption property since it carries a special function group to have a good affinity to the reservoir rock. This special function group plays a key role for the newly developed scale inhibitor to offer a good squeeze life. The amount of the monomer had to be optimized in order to achieve a good balance to make the inhibitor to be desorbed/released from the reservoir rock. In addition, the environmental property of the polymer was also improved due to the introduction of the special monomer. A number of beaker and dynamic loop tests were carried out and the inhibitor showed an excellent efficiency in both sulphate and carbonate scale inhibition under the test conditions.

The paper also presents the detailed laboratory and field data. In addition, the treatment design strategy and deployment method of the scale inhibitor are discussed.

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