Abstract
Water production in the North-east of Syria has increased significantly in recent years. As a result costs per barrel of oil have increased and the field's production is currently constrained by the facilities capacity.
PLT surveys combined with a reservoir study showed that good-quality sands were not properly swept by the water, probably due to poor connectivity in the reservoir. It was anticipated that these un-swept sands could contribute to production if the watered out sands were shut-off.
A newly developed gel-cement has been used to shut-off the watered out sands in a cost-effective manner. The gel-cement system combines the properties of two shut-off techniques:
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Cement for mechanically strong perforation shut off.
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Gel for excellent matrix shut off.
The gel, used as ‘mix water’ of the cement, will be squeezed into the matrix creating a shallow matrix shut off. The cement will remain in the perforation tunnel as a rigid seal. This system showed superior shut off performance in the laboratory compared to normal cement squeeze techniques. Selective perforation of the hydrocarbon zones will reestablish the oil production. The shut off zones can be reopened later in the well's life when artificial lift has been installed.
In the first field trial 84 meters of perforations (gross) were squeezed of with the gel-cement in a single attempt. After re-perforation of the top and the middle zone the well produced at a strongly reduced water cut, i.e. 25–33% compared to 60–62% before the treatment, and an increased oil production, i.e. 3000 bopd compared to 1000 bopd before the treatment. The oil production declined to 2000 bopd over a year. The water cut gradually increased over that period to 56%.
