An alternative scale inhibition method using encapsulated scale inhibitor has been successfully used to control calcium carbonate scaling in the Ghawar Field oil wells of Saudi Aramco, Saudi Arabia. Field tests indicate that the Ghawar Field requires a low threshold scale inhibitor concentration for scale mitigation. The encapsulated phosphonate scale inhibitor treatment procedure is thus ideally suitable for scale control in such fields. Since 1994, a total of 89 wells have been treated with this procedure. After more than five years of treatment, there has been no reappearance of scale deposit on the treated wells except for two instances of scaling. Low treatment cost and the resulting long treatment life have provided an excellent incentive to treat more wet producers using the encapsulated scale inhibitor treatment method instead of treatment by conventional scale inhibitor squeezes. An additional benefit is realized from this encapsulated inhibitor method when treating marginal high water cut wells and wells located in low pressure areas by ensuring that the wells sustain flow after the treatments without the need for extensive livening work.

This paper presents the results of a field case study where calcium carbonate scaling was controlled using the encapsulated scale inhibitor treatment procedure. Treatment design, job procedure, inhibitor return monitoring, economic analysis and comparison with conventional squeeze treatments as well as future applications are presented.

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