Stimulate production in a long, slotted liner completion
An operator in Kazakhstan completed a well with a long (335-m
[1,100-ft]) interval through a hot (132 degC [270 degF]), naturally fractured
carbonate formation. The operator completed the well with a slotted liner
because the permeability contrast posed a high risk of cementing failure, and
an openhole completion was inadvisable because of the risk of formation
softening over time.
The well initially produced at about 40 m3/d [252 bbl/d] with
an ESP, but after about 18 months, production declined to 20 m3/d
[126 bbl/d], most likely attributable to skin increase from scale deposition,
fines migration, and formation sloughing. Based on the trend, the well was
about to reach its economic limit.
To improve the economics, the operator wanted to revive production with
a stimulation operation. The long lateral would need diversion to ensure
thorough stimulation fluid distribution, but the slotted liner eliminated the
use of mechanical technology or conventional diversion particles and viscous
acid systems that would likely plug the slots. In addition, the downhole
temperature would limit the penetration of conventional acid stimulation
fluids. For a new option, the operator turned to Schlumberger.
Optimize acid penetration and diversion technology
The Schlumberger engineers designed a stimulation treatment combining
OpenPath Reach service with single-phase retarded acid system and OpenPath
Sequence service with an S-system engineered composite pill.
OpenPath Reach service maximizes matrix or fracture stimulation
penetration with engineered acid system selection to ensure compatibility with
reservoir conditions and chemistry. The main acid system chosen for this well
was the single-phase retarded acid system, which penetrates deeply into the
reservoir before beginning to spend, even in high-temperature limestone