Hollow-Glass Sphere Application in Drilling Fluids: Case Study

Abstract

Abstract In an effort to continuously optimize drilling operations and economics, an operator examined the impact of adding hollow-glass spheres (HGS) directly to the drilling fluid formulation instead of performing underbalanced drilling operations. Both nitrogen and HGS were believed to reduce hydrostatic pressure of the mud column in the hole, resulting in higher drilling rates of penetration (ROP) and fewer mud losses to the wellbore. Invert emulsion fluid was blended with HGS on three drilling rigs using a specialized, environmentally acceptable mixing system to help reduce density. HGS concentration and fluid density were monitored and maintained while drilling over the period of one to three weeks for these three wells. The proper type of centrifuge and its setup is fundamental to maintaining low-gravity solids (LGS) at an acceptable level for proper fluid management while maintaining the desired concentration of HGS. Drilling mud density was reduced, as expected, and mud loss was minimized as a result. Overall costs were reduced because of less invert emulsion fluid loss, a reduction in the amount of lost-circulation material mixed compared to previous wells in the area, and less time spent on the drilling rig attributed to not having to stop to mix lost-circulation material or prepare new invert emulsion fluid volumes to replace losses. A significant ROP increase was not observed during this trial. The addition of HGS is a cost-effective solution to help reduce fluid loss in the Kakwa field of the Western Canadian Sedimentary basin. This trial helped reduce overall rig time, and fluid loss experienced was less than in previous wells in which this technology was not used. This paper provides information on HGS as an economic alternative to nitrogen to help reduce the hydrostatic pressure of invert emulsion drilling fluids using a small-footprint, environmentally acceptable mixing system.