Pemex (Petroleos Mexicanos) planned to drill wells in an exploration campaign in the Gulf of Mexico. Successfully drilling and evaluating ultradeepwater wells is a challenging process involving narrower mud weight windows, shallow geohazards, and seismic velocity uncertainties affecting pore pressure modeling. Pemex needed to find an LWD solution that effectively mitigated these risks and enabled setting the casing at the correct depth.
Pemex and SLB collaborated to develop a compact BHA configuration with the SonicScope 825 multipole sonic-while-drilling service in combination with a dual-reamer design. The SonicScope 825 service would be placed closer to the bit, which would detect drilling hazards sooner. Additionally, the shorter BHA would allow Pemex to drill a short pilot hole and place casing at the needed depth.
The innovative BHA configuration—a compact design with two reamers and the SonicScope 825 service—saved Pemex two days of rig time by eliminating the need for additional logging and reaming. The quality log data provided by SonicScope 825 service was used to successfully drill the well and set the casing at the correct depth. The sonic data was used for real-time geomechanics and monitoring of the wells. As high-quality, real-time data was acquired, the holes were underreamed to deliver a hole size suitable for running the casing designed in the well program. The technology provided by SLB helped Pemex drill the wells in an area with high-risk, unconsolidated formations in the shallow sections, along with increasing pore pressure and complex geology in the deeper sections.
