Calcium carbonate scale impacts oil production in a large number of fields worldwide. This scale is generally managed by acid washing to removal the scale and/or by performing scale inhibition treatments. The choice between inhibition and regular stimulation is cost driven, with high cost operations generally selecting inhibition. However, even in wells where inhibition is planned, some scale can be deposited either prior to scale inhibitor deployment, or after the end of the scale inhibition treatment life. Consequently, stimulation treatments are required in many wells, in order to remove calcium carbonate scale.

Combining scale inhibition with scale removal treatments offers several advantages. Firstly, in many operating areas, it would reduce the well intervention cost by making the operation a single intervention, offering significant economic benefits and a reduction in well intervention risk. Secondly, pumping a combined treatment not only reduces the risk of scale re-precipitation during the stimulation treatment, but it ensures that the zones that are stimulated are also inhibited. This directly protects value added by the scale removal treatment.

This paper details the development of combined scale removal and inhibition treatments, from project initiation to readiness for field trials. The main challenges that need to be addressed in order to achieve an effective combined treatment are discussed. Data from a laboratory study, investigating the potential for combining scale inhibitors in hydrochloric acid, organic acid and scale dissolver systems are presented and the most effective combined systems are identified.

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