Perforate long horizontal interval of deepwater reservoir
Injector wells in a deepwater reservoir in Southeast Asia provide
integrated pressure support for production. One injector well, drilled in water
depth of more than 4,000 ft [1,219 m], has a nearly horizontal section that was
to be perforated over many separate intervals. Upon successful perforation, the
intervals would be hydraulically fractured to increase flow efficiency;
injectivity performance thereafter was expected to be 12,000 bbl/d.
Achieve extradeep, clean penetration with flexible control
The operator collaborated with Schlumberger to determine the
best-possible perforation methodology to meet test objectives. Realistic rock
properties were fed into SPAN Rock stressed-rock perforating analysis software.
Additionally, PURE system software was run to determine the optimal dynamic
underbalance pressure level that would ensure effective cleanup of the
perforation tunnels for better injectivity.
The results of the two studies were evaluated, and Schlumberger
recommended using PowerJet Nova extradeep-penetrating charges coupled with the
PURE system for optimal perforating operations. PowerJet Nova charges improve
efficiency by transferring explosive energy into the perforating jet,
dramatically increasing penetration. Whereas conventional perforating relies on
a large, static, initial underbalance that is established before guns fire, the
PURE perforating system enhances the dynamic underbalance immediately after the
perforation cavity is created, removing perforation debris and crushed-zone
damage and creating more-productive perforation tunnels.
These two technologies were used along with an eFire electronic firing
head to provide safer, more-efficient, and cost-effective perforating. This
unique system creates pressure pulses that are converted into a special
signature to communicate with the firing head. The system head does not require
prerecorded downhole parameters, providing total control over the perforating
Exceed injectivity expectations with optimal perforating configuration
The well section was perforated using the proposed charges, technique,
and firing mechanism. The perforation length totaled approximately 1,880 ft
[573 m] with an additional 1,110 ft [338 m] of spacer sections. During
perforation, downhole gauges measured a 2,500-psi [17.2-MPa] dynamic
underbalance, which facilitated effective cleanup of the perforation
Further, postperforation injection performance was measured at 18,000
bbl/d at the same injection pressure, a significant increase from the expected
injection rate of 12,000 bbl/d. Every stage of the operation was successfully
executed and completed, allowing fracture operations to begin.