Sucker Rod Lubricants

Abstract Sucker rod pin failures not only result in high subsurface lift equipment expenditures but also increase well servicing expenditures and defer profits from unrecovered oil reserves. Analysis of the sucker rod pin failures show the major cause of the failure to be due to H2S corrosion pitting. This pitting occurs in the undercut portion of the sucker rod pin, thus, the loss of metal increases the rate of the fatigue failure because of continued cyclic stress during normal pumping operations. A new sucker rod lubricant program has been initiated based on field observations. The switch to molybdenum disulfide (moly) grease virtually stopped all H2S pitting in the sucker rod pin undercuts. The moly grease allowed proper shoulder-to-shoulder make-up of the sucker rod pin and coupling while at the same time minimizing the produced well fluid migration. An additional side effect in using the moly grease is reduced friction during make-up procedures, thus eliminating galling of sucker rod pins.