Needs cost-effective and low-ECD drilling solution

An operator using a conventional oil-based mud (OBM) experienced losses when drilling across a troublesome fault zone in the 7,139-ft [2,176-m] section of a well offshore Denmark. The operator needed a more cost-effective approach to effectively address the primary concerns—reduce ECD values and reduce losses while running and cementing the 9?-in × 10¾-in casing.

Optimizes drilling properties

To overcome the challenges, M-I SWACO, a Schlumberger company, suggested the RheGuard system. It is formulated with the MicroBar additive to enable drilling and landing the casing in challenging intervals. The additive’s low rheology and equally low sag potential made it an optimal solution. Additionally, the additive reduces barite sag for extended static periods, which are typical in prolonged casing or liner runs, emergency disconnects, and planned long-term logging programs.

Maintains low rheology without sacrificing drillability

Displacement using the RheGuard system coincided with the kickoff of a sidetrack after the operator experienced heavy losses of conventional OBM while drilling the fault. The sidetrack, which had a deviation between 20° and 80°, was drilled at 4,079-ft [1,407-m] MD. The interval was drilled to TD in eight days. Throughout the section, the RheGuard system maintained a stable low-rheology profile with a pretreatment of ONE-MUL* liquid emulsifier package and lime, which delivered oil wetting and encapsulation of the drill solids and MicroBar additive particles.

Even after navigating through a tight spot at 10,912-ft [3,326-m] MD, the operator encountered no major problems when pulling out for the casing run.

The operator deemed its first use of the RheGuard system containing MicroBar additive successful. The combination maintained low rheological properties without compromising drilling parameters or the overall drillability of the fluid system. The stability of the RheGuard system allowed casing to be run and cemented effectively.