Facing the risk of lost circulation during cement placement in a vertical 16‑in open hole with challenging isolation requirements spanning over 4,000 ft, SLB deployed an innovative mixing technique to prepare and pump a record volume of high-performance lightweight cement slurry on‑the‑fly. Cement evaluation logs confirmed circumferential coverage across the entire open hole delivering the isolation requirements to secure all zones of interest.

Several weak zones were encountered while drilling a long 16-in intermediate open hole section. After completing the logging, a geo-mechanical model helped define the ECD window between the pore and fracture pressures for well stability while cementing.  This information escalated the risk of lost circulation during the upcoming 13⅜-in casing cementing job which could affect the well integrity if isolation is not achieved.  The goal was to achieve the challenging isolation requirements while maintaining the safe operating window for well stability while cementing.

In response to the challenging placement conditions, SLB worked closely with Saudi Aramco to deploy an innovative solution to deliver a record volume of high-performance lightweight slurry mixed continuously. The high-performance lightweight slurry design was mixed on-the-fly at 12.2 ppg for a total volume of 646 oilfield barrels within a ±0.2 ppg tolerance. The wellsite execution was a success with full circulation obtained during the cement placement. The cement log evaluation confirmed achievement of the zonal isolation requirements. 

The successful execution of the high-volume job established this novel mixing method for high‑performance lightweight cement as the best practice for cementing long intermediate casings across weak formations with challenging zonal isolation requirements.

Technical Details

For more information, read the technical paper at SPE-206191-MS