Monitoring service helps optimize stimulation efficiency
Schlumberger proposed the WellWatcher Stim service to monitor the
stimulation operation in nearly real time. With minimal setup time and location
footprint, the economical service can verify events such as fluid injection
point and fluid diversion. The service improves overall stimulation efficiency
and can provide insights leading to improvements in perforation, completion, or
To enable the service, the treatment team temporarily installs a
high-frequency pressure transducer on the wellhead for analysis through an
acquisition system on the stimulation vessel. During the stimulation operation,
engineers use a proprietary algorithm to analyze the data for high-resolution
pressure variations and transient events. For more details about the technology
and its application, see SPE-182451.
For this well, the service could be used to determine, from an
instantaneous shut-in event, the fluid injection point, which would indicate
sleeve and ball isolation efficiency.
Analysis reveals incomplete isolation, enabling rapid recovery
The operator agreed to use the technology during a multistage
stimulation treatment of a chalk formation in the North Sea. For the first
three stages, analysis of the treating pressure response and WellWatcher Stim
service confirmed that the sleeves performed as expected and stimulation fluids
entered the intended zones as designed.
For the fourth stage, the treating pressure response was ambiguous but
injection tests indicated that fluid was entering the intended sleeve, so the
stimulation treatment was pumped.
However, subsequent WellWatcher Stim service analysis determined from
the shut-in pressure response that the treatment had entered the same reservoir
section as the prior stage, indicating incomplete isolation—most likely
the result of a ball breaking or unseating after the injection test.
The operator decided to drop a second actuation ball to try to improve
the isolation. For this second ball, the treating pressure response was more
pronounced, suggesting more complete isolation. The stimulation treatment was
repeated. The final treating pressure and WellWatcher Stim service data agreed
that the stimulation treatment reached the intended zone.
Furthermore, the service showed that most, if not all, of the
stimulation fluid was entering only one of the three sleeves in the zone. The
same phenomenon was seen in other zones as well because the bullheaded
treatments are not designed with any diversion technology to help distribute
the fluid when formation permeability varies.
As a result, the operator is scheduled to monitor a future well during
an OpenPath Sequence diversion stimulation service designed to distribute fluid
to contact the formation behind all of the sleeves in each zone.