Hollow glass spheres (HGS) help to reduce slurry density without significantly affecting strength development. Halliburton pioneered the research and development of hollow microsphere cement additives with lab report tests dating from 1977. By the early 1980s, Halliburton was routinely designing and blending cement slurries inclusive of hollow glass spheres for field use to achieve lighter-weight cements with high compressive strength and low density (non-foamed).
If drilling fluid has been lost to the formation during drilling, cement slurry can also be lost to the formation during cementing operations. If cement is lost to the formation, the top of cement (TOC) will be reduced and may lead to the need for remedial cementing operations, negatively impacting schedules and budgets. Hollow glass spheres can be used to drastically reduce the density of the cement to be placed across the interval to which drilling fluid was lost.
Using Halliburton’s iCem Service, slurry designs can be optimized with the required downhole properties at a density low enough o provide complete circulation and achieve the desired top of cement.
The use of hollow glass spheres can help
Increase primary cementing success in low fracture gradient areas
Increase primary cementing success – reduction in remediation costs
Allows delivery of production quality cement at low densities
An operator intended to develop a low pressure gas reservoir in a sandstone formation and the reservoir had been depleted by previous production. The fracture gradient, already low in the virgin reservoir, was anticipated to be significantly reduced. Lost circulation and formation damage were recognized as significant drilling hazards. A low density drilling fluid was required to drill and complete the low pressure environment.