FLC® SUPREME Used in Depleted Reservoirs

Operators targeting the highly-depleted reservoir sections in the United Kingdom Continental Shelf (UKCS) typically experience mechanical instability. The types of instability may include: induced differential sticking, mud losses and wellbore collapse. Throughout this mature field, equivalent circulating densities (ECD) are often close to leak-off test (LOT) results lead to seepage losses through the Jurassic sandstone/claystone sequence. Operators fight the ability to run liners to target depth, often requiring re-drills to access production targets. In this particular program, fracture sizes were predicted to be larger than 500 microns (μm), requiring a specialized drilling fluid technology to prevent and avoid lost circulation and wellbore instability. 

In the 6-in. section, a sidetrack was drilled from 15,350-18,423-ft. measured depth (MD) using a 10.1 lb/gal oil-based mud (OBM) with residual FLC 2000®, an ultra-low invasion fluid additive in the drilling fluid. The FLC 2000 concentration (5 lb/bbl) was still in the mud system from the previous well, and the sand-bed-test (SBT) result was 6.5-cm, demonstrating the drilling fluid was able to create a seal against the fluid-rock interface. To protect against the larger fractures predicted, the program required an additional 2-3 lb/bbl FLC SUPREME in the active system, prior to drilling to the Upper Jurassic sandstone at 17,595-ft. MD.