Patent ID: 9617841
Date: 2017-04-11
CPC Classifications: E21B

Claim:
1. A generally spherical frac-ball used alone or in combination with other similar balls carried within a fracturing fluid to seal off portions of a drilled well to facilitate the fracturing of formations surrounding the well, the generally spherical frac-ball comprising: a generally spherical core having a core diameter and a surface; a pair of hemispherical shells positioned concentrically about the core and secured to each other along an equatorial seam, the pair of hemispherical shells combining to form a generally spherical shell having an internal diameter, a frac-ball diameter, and a shell thickness, the internal diameter of the spherical shell incrementally larger than the core diameter; a layer of epoxy resin positioned between the core and the shell; and a plurality of standoffs positioned on the core surface, the plurality of standoffs having a height generally equal the incremental difference between the core diameter and the internal diameter of the spherical shell, wherein when the pair of hemispherical shells are positioned around the core the spherical shell and the core are generally concentric; wherein the frac-ball construction provides a strong but machinable overall structure with an outer surface that is corrosion resistant, has a specific gravity that is higher than the fracturing fluid, and is easy to manufacture.