Obtain high-quality LWD measurements in challenging appraisal wells
In a field in the Northern Australian basin, the upper formations consists of soft, unconsolidated sediments, while deeper zones pose drilling challenges due to reactive shale, circulation losses, and stick/slip. In previous wells, these attributes led to high risk of wellbore instability, bottomhole assembly damage, stuck pipe, and more.
To improve drilling operations, further explore the field's development potential, and aid key decision making, an operator planned to drill and evaluate an appraisal well. With limited evaluation data from the formations in the upper sections, the operator wanted to acquire high-quality LWD acoustic measurements that would reduce uncertainty and mitigate overall operational risk.
Deliver accurate, real-time acoustic measurements
Schlumberger petrotechnical experts recommended using the SonicScope 900 multipole sonic-while-drilling service along with the arcVISION array resistivity compensated service in the 16-in section. The SonicScope service combines high-quality monopole and quadrupole measurements to deliver robust compressional, shear, and Stoneley wave data for accurate pore pressure and fracture gradient estimates. In addition, the arcVISION service provided real-time resistivity, gamma ray, inclination, and annular pressure-while-drilling measurements.
Drilled with ROP up to 245 m/h while capturing high-resolution LWD data
Despite drilling challenges, the operator achieved an ROP of up to 245 m/h [804 ft/h] while drilling the 16-in section, doubling the planned ROP of 100 m/h [328 ft/h]. Using the SonicScope and arcVISION services, the operator was able to acquire accurate, reliable acoustic data—even in the unconsolidated upper section where severe washouts prevented quality logging data acquisition from wireline-conveyed measurement tools.
To obtain compressional slowness in the upper zone, Schlumberger used a leaky compressional mode (Leaky-P) processing that provides accurate data in this environment and is unique to the service. Standard monopole and quadrupole measurements were processed and delivered, providing a robust comparison with Sonic Scanner acoustic scanning platform data. The operator used these numbers to understand the limitations of the borehole geomechanics, ensuring optimal well path designs for future development wells and, ultimately, improving project economics.
