Surface pressure analysis can hamper stimulation decision-making

The energy industry has long used surface pressure response to monitor downhole events during matrix or fracture stimulation operations. However, only 60% to 70% of unconventional stages contribute to production, at least partly because not all stages are adequately stimulated.

One of the reasons for the poor performance is that surface pressures are inadequately precise to evaluate downhole events. In fact, engineers often misinterpret surface pressure data to miss three important downhole problems that alter the fluid entry points, limiting a well’s production performance:

• Problem No. 1: Your isolation plug failed. Even when the surface pressure response is positive for zonal isolation, fracture pressure or plug damage can result in isolation failure that allows fluids to enter the previous zone instead of the one you think you are stimulating.
• Problem No. 2: Your isolation ball broke. When the ball hits the seat, the initial surface pressure response may indicate a good seal. But if the ball is cracked, it soon falls apart, and fluid enters the previously stimulated stage.
• Problem No. 3: Your diverter did not work. When the diverter pill reaches the perforations, pressure noise may indicate a false positive diversion, or pressure may build too slowly to create a clear indication at surface, prompting a second pill. Either way, you understimulate part of your reservoir.

New service interprets high-frequency pressure pulses to verify downhole events

To improve stimulation efficiency and performance, what you really need to know is where the fluid flows. The Schlumberger WellWatcher Stim* stimulation monitoring service with high-frequency pressure analysis and proprietary algorithms can positively identify fluid entry points that indicate isolation failures—even when conventional pressure response is ambiguous or misleading.

The WellWatcher Stim service uses simple wellhead hardware and proprietary algorithms to verify that acidizing or fracturing fluids are reaching the intended target formations. If not, the isolation problems can be fixed immediately and the stage repeated—rather than deferring that zone’s production for a future restimulation campaign.

With accuracy benchmarked against more costly and complicated reservoir monitoring technologies, WellWatcher Stim service helps you verify optimal delivery of your stimulation and completion plan.

To learn more about the service, view the WellWatcher Stim service video.

*Mark of Schlumberger