Patent ID: 7914006
Filing Date: 2011-03-29
Classification: E21B,F16J,Y10T

Abstract:
1. A subterranean drilling tool, comprising: a seal gland defined by a rotating surface and a static surface; a lubricant reservoir containing a lubricant; a seal formed of homogenous material composition throughout, the material composition comprising an elastomeric compound, the seal being located in the seal gland, the seal having an annular dynamic portion in sliding engagement with the static surface and an annular static portion in static engagement with the rotating surface, the seal sealing the lubricant from borehole fluid; a pressure compensator in communication with the lubricant reservoir and exposed to an exterior of the tool for equalizing pressure of the lubricant with pressure of borehole fluid; the elastomeric compound on the dynamic portion of the seal having greater cross-linking than the elastomeric compound within a remaining portion of the seal, defining a property that changes from a first level at an exterior of the dynamic portion to a second level within a core portion of the seal; the entire static portion being free of a property gradient; and wherein the dynamic portion is formed of the same material composition and has the same constituents as the remaining portion of the seal.