PURE Clean Perforations System | Dynamic Underbalance | Schlumberger

PURE

Clean perforations system

The PURE clean perforations system minimizes or eliminates perforation damage by optimizing the well’s dynamic underbalance, which is the transient underbalance that occurs just after creation of the perforation cavity. Proprietary design software specifies a custom perforating configuration and the optimal completion process.

This approach generates and controls the dynamic underbalance, rather than relying on the estimated reservoir pressure to create underbalance. The PURE perforations system is successfully performed in hard- and soft-rock formations, oil and gas reservoirs, and sandstones and carbonates and also minimizes disruption of the cement/sandface hydraulic bond.

Removing perforation debris and crushed-zone damage

Perforation cleanup by the PURE system is independent of the initial underbalance that conventional perforating relies on. Extensive experiments at the Schlumberger Productivity Enhancement Research Facility (PERF) conclusively show that it is the maximum dynamic underbalance—not the initial underbalance established before the guns are fired—that governs perforation cleanup. And producing the optimal dynamic underbalance requires the design method we use to specify a PURE system: taking the reservoir, wellbore and fluids, perforating hardware, and completion geometry all into consideration.

The cleanest possible perforations mean efficient communication between the reservoir and the wellbore for enhanced acidizing and hydraulic fracturing operations and ultimately maximized production.

PURE Clean perforations system
The PURE clean perforations system optimizes the dynamic underbalance, the transient underbalance produced just after the perforation cavity is created. On the graphic, differential pressure (between the simulated wellbore pressure and the pore pressure) for tests 1 through 4 showed that the maximum dynamic underbalance varied from 400 to 1,300 psi.
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