The high pressure washpipe assemblies used in oil well drilling are subjected to difficult sealing conditions. A conventional washpipe packing fails in only a few hours when subjected to 6,000 psi or greater mud pressure. Replacement of the failed washpipe packing assembly typically requires the bottom hole assembly to be tripped back into the casing which can result in significant downtime.
Kalsi Engineering has developed two technologies, that when combined, provide a robust sealing solution for high pressure washpipe assemblies. One enabling technology is a version of our hydrodynamic rotary seals that has an extrusion resistant plastic lining energized by an elastomeric seal body: The Plastic Lined Kalsi Seal. The other enabling technology is our patented metal backup ring hardware arrangement, which significantly reduces the extrusion gap clearance the rotary seals are exposed to.
This video shows the high pressure rotary seal test fixture in operation. The test was conducted for 1,000 hours at 7,500 psi on a 2.75” (69.85mm) shaft rotating at 330 rpm. The plastic lined rotary seals were supported by radially pressure-balanced backup rings and ran on a floating washpipe.
The 7,500 psi, 1,000-hour high pressure seal test
We tested Plastic Lined Kalsi Seals with radially pressure balanced metal backup rings for 1,000 hours at 7,500 to 7,800 psi (51.71 to 53.78 MPa) lubricant pressure. The 2.75” (69.85mm) seals ran on a floating washpipe rotating at 240 feet/minute, duplicating the surface speed of a 4.875” (123.83mm) OD washpipe rotating at 200 RPM. The ISO 150 viscosity grade seal lubricant was maintained at 130°F (54.4°C) to simulate the anticipated temperature of the drilling mud.
The high pressure seals were made with our -303 material combination. They were in excellent condition at the conclusion of the 1,000-hour test, as shown below, and could have kept running for much longer.