The Kashagan oil field, located in the North Caspian Sea in the Republic of Kazakhstan, is believed to be the largest oil discovery in the past thirty years.

To unlock the field's full potential, in particular of the inner non-karstified region, most of the wells have been stimulated with 15% hydrochloric acid, pumped through-tubing in the earlier jobs while coiled tubing units have been later introduced as part of an optimization process.

Almost all initial stimulations have been assessed by well tests accompanied with production logging enabling to carry out a comprehensive analysis of the treatments.

It is known that, significantly larger portion of recoverable oil lies in the tighter non-karstified inner region and therefore an optimized and a successful stimulation practice is essential to an economic project success.

Furthermore, to achieve reservoir engineering stimulation objective of an average -3 skin along the selected perforated Unit 1 intervals, Fig1, it was recognized necessary to review all possible stimulation techniques and acid conveyance methods to maximize the chances to achieve such a challenging an objective.

This paper outlines, in a task and result step format process, an approach that was utilized to select the best stimulation methodology for all Kashagan geological facies and recommendations to formulate a stimulation technique which overcomes technical problem encountered during field operations. Examples are also included to show the results of base original and redesigning criteria.

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