Heterogeneous limestone reservoir presents acid stimulation
A multilayer limestone reservoir located in the Sabriyah field of Kuwait
is highly heterogeneous with natural fractures and multiple perforation
intervals. To attain economical productivity for a vertical well in this
reservoir, Kuwait Oil Company required an acid fracturing treatment designed to
achieve good fracture conductivity, an extended fracture length, and effective
diversion of some of the acid stimulation from the upper section of the
formation to the lower section.
OpenPath Sequence service provides effective solution
Schlumberger recommended using OpenPath Sequence service to divert the
acid stimulation to the target zones. The service accomplishes diversion
through the use of a composite pill made of a proprietary blend of degradable
fibers and multimodal particles that provides consistent, effective isolation
plugs. Covering multiple reservoir layers in the same stage, the treatment also
provides high leakoff control.
The treatment alternated between three acid stimulation stages and two
diversion stages of OpenPath Sequence system composite pills to cover all
perforation intervals and accomplish diversion from the upper reservoir to the
Productivity index increases more than 300%
Diversion within the perforated intervals after placement of the
OpenPath Sequence system composite pills was indicated by diversion pressures
of 500 to 1,600 psi [3.45 to 11.03 MPa] and instantaneous shut-in pressure
changes. Effective diversion was also confirmed by injection log data based on
stationary spinner and temperature measurements.
Injection logging performed after the prejob injection and after each
diversion stage indicated coverage of all perforation intervals. The injection
flow profile for the upper reservoir intervals improved 70% after the first
diversion stage and more than 150% after the second diversion stage. Injection
logging also confirmed fracture initiation and propagation in the lower
reservoir after the second OpenPath Sequence service diversion stage.
Production in terms of barrels per day improved by 243% after the
treatment was complete. In addition, the productivity index increased more than