Abstract

Sabiriyah Mauddud is one of the largest carbonate reservoirs in North Kuwait on active water flood since last 20 years using sea water as the injectant. The reservoir is purely a depletion drive reservoir, responding to water flood quickly in terms of increase in reservoir pressure as well as preferential flow of injectant into the nearby producers, thus stressing the existing water handling capacities at the gathering centers. Almost 40% of the injected water re-circulated between the injectors & producers, thus disabling the complete benefit of the ongoing water flood activities. A new initiative has been tried at two of the injectors for cyclic injection for optimal balance between pressure requirements and water cut levels.

While water flooding Sabiriyah Mauddud, surprises in terms of rock & fluid understanding influenced quick water cut build up, reaching to more than 90% in some wells. A comprehensive G&G; Reservoir engineering and surveillance data aided to understand the connection factors between the injectors and producers. A fit for purpose tool developed to evaluate the water re-circulation has been used to short list the wells with "bad" water, requiring attention to control. As such bad water had been mainly due to direct short circuiting with the nearby injectors, team decided to go for handling such water from injector management point of view rather than working over the well for conformance related isolation of water producing zone. Cyclic water injection is the best solution so as to minimize the water re-circulation and stay within the operating range of the ESP in the associated producers, with properly spaced cycles of closure & opening. The initiative has been implemented at two of the injectors recently with positive results.

The cyclic injection has reduced the water cut at the associated producers up to 30%, thus improving the oil cut significantly. This has reduced the water handling requirements at the gathering centers. The closing action planned for few high water cut wells has been canceled as a result of this strategy. The concept is planned to be implemented in remaining injectors of Mauddud once there are evidences of bad water re-circulation in multiple wells associated with these injectors.

Water flood & production efficiency using cyclic water injection approach is a proven way to manage undesirable water encroachment in producers in Sabiriyah Mauddud, the results of which are interesting & worth sharing with the global professionals.

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