Asphaltene deposition is an ever-increasing problem at Kuwait Oil Company fields and in many fields worldwide. KOC is one of the oil companies that is suffering from asphaltene problem. The degrees of these problems within the KOC fields range from moderate to severe. Most of the asphaltene depositions are in the well tubing of deep reservoirs and in the surface flow lines. Due to these depositions, it has been estimated that the overall loss in oil production is approximately 100,000 BOPD. At one time, one of the fields was completely shut-in due to the severe asphaltene deposition problems. A joint industry project; Downhole Asphaltene Remediation Treatment (DART), was initiated to develop a chemical that could be used to delay deposition of asphaltene in the tubing and reservoir. This project was based on developing 'new' chemical to control, prevent, or delay asphaltene deposition in well tubing and in the near wellbore area. The project's key objectives were:
The chemical treatment would not cause formation damage to the well
Screen current and new dispersant/ inhibitor chemistries
Field trial(s) of chemical blend in KOC
Approximately 270 different chemistries were sourced or synthesized and tested with various crudes. One inhibitor was selected to perform field trial tests in one of the reservoirs at KOC. The chemical treatment was operationally successful, fulfilling the first objective with no indication of formation damage. Production rates, well productivity index and skin remained the same as before the treatment. Due to the short producing history, results remain inconclusive on the effectiveness of DART for delaying asphaltene deposition. DART chemical returns have shown a rapid decrease in inhibitor efficiency and a caliper log showed indications of asphaltene deposition in the tubing. This paper will demonstrate the work process of the project, the results of the field trial of the asphaltene inhibitor before and after treatment, and lessons learned and recommendations.
Asphaltene precipitation from petroleum reservoir fluids has proved to be a difficult problem to define and study. It is recognised to present serious problem in numerous oil systems worldwide. Asphaltene precipitation may occur deep in the reservoir formation and cause permeability reduction as well as contributing to serious plugging problems in oil well tubing and surface facilities. Formation plugging and wettability changes are a result of the destabilization of colloidal asphaltene in an oil reservoir, which then can affect the amount of oil produced during oil recovery (1). This phenomenon ranks as one of the highest-costing and most important safety problems in the production operation of the oil industry. There have been two approaches in dealing with asphaltene problems: One is associated with well maintenance by either improved technology in clean-up methods for unplugging lines by asphaltene dissolution; The second has been focused on anticipating the precipitation of asphaltene and prevent it by keeping it dispersed. Kuwait Oil Company is one of the oil companies that is suffering from asphaltene problems. Most of asphaltene deposition has been found in the well tubing of deep reservoirs and in the surface flow lines (2).
