Increasing Multizone Efficiency

Traditional ball-drop systems for multizone hydraulic-fracturing operations require deployment of balls and ball seats of successively smaller sizes, moving from heel to toe of a lateral. This process may require increased surface pressure and pumping horsepower to continue the necessary flow rate. Operators compensate by deploying additional casing and pumping larger volumes of proppant. Weatherford’s i-Ball Multizone Fracturing System (Fig. 2), which can be run as part of the ZoneSelect system, eliminates downhole-pressure buildup and associated logistics and storage concerns with the use of a single ball-and-seat size. The diameter of the system (close to that of the tubing) enables an unlimited number of zones to be stimulated, and the zones are fracture stimulated one at a time. Then, the sleeves retract to a size that is close to the inside diameter (ID) of the host tubing. This action reduces frictional force, enables a more-efficient fracture at each zone, allows for a smaller-ID fracturing string, and, in some cases, facilitates fracturing operations through the completion. The technology has been tested in openhole and cemented wellbores and is rated to 10,000 psi with a temperature envelope of 32 to 350°F. It is highly tolerant of downhole debris, such as lost-control material and fracturing sand and proppant. In April of this year, 400 of these sleeves will be run between four operators, running an average of 30 sleeves per well.

Fig. 2: Weatherford’s i-Ball Multizone Fracturing System uses a single ball-and-seat size



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