Drill shale formation with limited offset well knowledge
While drilling a shallow-water well offshore China, an operator needed
to better understand the complex, high-pressure formation to successfully drill
the 8.5-in section with 31.8° deviation in a high stick/slip environment.
Without extensive data from a predefined model or offset wells, real-time pore
pressure monitoring and seismic tie-in would provide the necessary information
to help the operator drill the well and mitigate risk. By using advanced
multipole sonic-while-drilling technologies that obtain robust real-time and
recorded measurements, the operator could more successfully drill while
obtaining insight and information for future wells.
Obtain multipole sonic data while drilling
Schlumberger recommended using the SonicScope multipole
sonic-while-drilling service, which combines high-quality monopole and
quadrupole measurements to deliver real-time compressional and shear
information—along with Stoneley data—in any formation, regardless of
mud slowness. These measurements enable more confident decisions while
drilling, helping eliminate unnecessary casing strings, mitigate risk and
improve safety, reduce nonproductive time, and save drilling days and
costs.
Achieved drilling objectives with high-quality measurements
This operation marked the first time that the SonicScope service was run
in China. Using the service, the operator achieved drilling objectives,
monitoring pore pressure in real time despite the high stick/slip risk in the
shale formation. Using real-time sonic and density logs, high-quality
synthetics were generated for accurate surface-to-seismic correlation in the
time-depth domain. For a full petrophysical evaluation, the service was run in
combination with EcoScope multifunction logging-while-drilling service and
TeleScope high-speed telemetry-while-drilling service.
The data obtained by the SonicScope service enabled the operator to
optimize well placement and mitigate risk when drilling the complex,
high-pressure reservoir. After POOH, data recorded by the SonicScope service
was delivered to the operator’s technical experts for future prestack AVO
surface seismic inversions.
