Maintain stable rheologies in low-ECD conditions

An operator in the Norwegian sector of the North Sea planned a 2,383-ft [726-m] sidetrack through a narrow hydraulic window in an overburdened section of a mature field. Successfully drilling to the 7¾-in shoe required a cost-effective drilling fluid with enhanced sag stability and a sufficiently low rheological profile that would reduce the ECD in the tight operating conditions.

Deliver excellent hole cleaning and overall drillability

M-I SWACO, a Schlumberger company, suggested using the RheGuard system with MicroBar additive to drill the sidetrack and run the 7¾-in liner. The RheGuard system maintains low rheology and reduces the risk of barite sag for extended static periods during casing or liner runs, emergency disconnects, and planned long-term logging programs. Compared with conventional API barite, the uniquely engineered and cost-effective MicroBar additive optimizes rheologies and overall drilling performance.

Exceeded all KPIs in successful field trial

The RheGuard system with MicroBar additive was used while drilling the 8½-in × 9½-in sidetrack to TD at 12,636-ft [3,851-m] MD and 10,061-ft [3,067-m] TVD. The 7¾-in liner was run and cemented without issues or losses. A programmed increase in the oil/water ratio (OWR) steadily decreased the rheological profile and ECD during drilling, and the RheGuard system maintained excellent hole cleaning. The system also generated sufficient viscosity to eliminate a sweep during the milling operation.

The third-party MWD and directional services provider lauded the hole-cleaning performance and adaptability of the MicroBar additive. After completing the operation, the cementing engineer said the gels were easily broken, which made displacement optimal when performing the foam cement job.