Couplings are machined to achieve an end-face width as large
as possible for maximum pin shoulder contact area. Pins are
machined so that all pin ends have exactly the same dimension from
the shoulder to the pin end and the shoulder and pin nose are exactly
true relative to each other. Pin ends also receive wet fluorescent
magnetic particle inspection and are shot-peened to improve micro-finish
and enhance fatigue resistance. The torque buttons are locked
into place so the connections always break on the same side during
work over.
This connection can be applied to all new or inspected used rod
strings, API or non-API sizes. Tension/torsion testing was
performed at CFER labs in Edmonton Alberta, Canada using 20,000
lb. tension and torque to failure. The PRO/KC connection averaged
250% more torque to failure than API samples of the same size and
material specs.
Extensive fatigue testing was performed at Southwest Research
Institute in San Antonio, Texas on 1.0 inch PRO/KC connections and
API 1.0 inch connections using loads of 69,500 lb. tension and 7,800
lb. compression at 10 cycles per second. The PRO/KC connection
averaged 600% more cycles to failure than API connections.
The PRO/KC was field tested by a major oil company on a 3,900
foot well in eastern New Mexico with a progressive cavity pump installed.
Prior to PRO/KC installation, this well had been pulled 15
times in a 38 month period with multiple rod string failures. Once
installed, the PRO/KC string performed flawlessly for 13 ½ months
enduring 5 separate failure events, 2 of which resulted in failure
of surface components and 3 were down-hole. The top drive
hex shaft failed; the polish rod thread sheared; the top drive belts
burned off; the polish rod coupling split.
These failures were related to pump rotor seizure which results
in tremendous forces being applied to the rod string during which
no PRO/KC connections failed. The fact that the PRO/KC System
was able to withstand this brutal punishment is a testament to its
robustness.
Contact Permian Rod Operations for more information and arrange
for a trial string for your toughest well. Preventing work-overs
due to premature connection failures will pay substantial dividends
with less downtime and lost production. |