Enhanced recovery

Ultradeep Resistivity Tool Maps Waterfloods Effectively

This paper describes the deployment of an ultradeep electromagnetic directional-resistivity instrument to map injection-water movement.

Ultradeep resistivity tool.
Fig. 1—Ultradeep resistivity tool. Transmitter and receiver antennas are located on separate drill collars, which can be separated by other LWD tools to optimize the spacing and the BHA. Tx = transmitter, Rx1 = Receiver 1, Rx2 = Receiver 2.

Abu Dhabi’s thick Lower Cretaceous carbonate reservoirs experience injection water overriding oil. The water is held above the oil by negative capillary pressure until a horizontal borehole placed at the reservoir base creates a small pressure drawdown. This causes the water above to slump unpredictably toward the horizontal producer, increasing water cut and eventually killing the well under natural lift after a moderate amount of oil production. Water slumping is difficult to forecast using the reservoir model.

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