Diversion service distributes fluid more thoroughly
After testing fluid and additive compatibility, tubing corrosion, and
composite pill degradation under the downhole conditions, Schlumberger
recommended an OpenPath Sequence diversion stimulation service with a low
volume of SDA self-diverting acid as a fit-for-purpose treatment design.
To ensure stimulation of the entire interval, the engineers designed and
modeled a treatment schedule to isolate high-permeability zones and natural
fractures with engineered, acid-compatible composite pills so subsequent fluid
would stimulate lower-permeability zones. The stimulation design also reduced
the volume of acid required to achieve thorough stimulation.
Production increases—especially in low-permeability zones
The treatment was pumped as designed with an acid preflush followed by
four cycles of hydrochloric acid, three cycles of composite pills and SDA acid,
Clean-up time after the treatment was 20% faster because of the reduced
volume of SDA acid as compared with previous treatments in the area. No sludges
or emulsions have been seen. Some partially degraded composite pill components
(particulates or fibers) were seen in the flowback tanks; all of them degraded
within 1 week at ambient temperature, confirming that
any material left in
the formation—at higher temperature—would have fully degraded.
After cleanup, the well’s oil production increased 70% from 20 to
34 m3/d [126 to 214 bbl/d], and gas production increased 145% from
29 to 71 m3/d [1,024 to 2,507 cf/d] in the stimulated interval.
After hydrocarbon flow stabilized, the operator ran a production logging
tool to determine the final flow. With no diversion or poor diversion, the
high-permeability zones would receive most of the fluids and therefore deliver
the most production improvement. Based on the production data for this well,
however, the production improvement is highest in lower-permeability zones,
which confirms the diversion technology prevented overtreating the
high-permeability and naturally fractured zones.