One successful method is to document the (1) Failure Type {tubing split, corrosion hole, rod box part, etc.) and location along with (2) the Failure Cause (corrosion hole due to wear or corrosion hole due to uniform pitting, rod break due to rods in compression, etc.). Omega Technologies offers a Well Failure Identification Chart (Tubing Failures, Rod&Pump Failures) that outlines the most common failures types, causes, and solutions. Omega Technologies also offers a Worksheet, which allows one to document the Type and Cause of failure so one properly address the problem. If a corrosion hole exists (Failure Type), then the common attack is to change inhibitors or look at treatment time. This technique may work for Corrosion spread all around the tubing (Failure Cause = Corrosion). However, a lot of corrosion holes are caused by the wear of rods or rod guides wiping off the inhibitor over 20% of the tubing (Failure Cause = "Corrosion due to Wear"). Thus, the best inhibitors and treatments will not eliminate the "Corrosion Due to Wear" failures. It needs to be addressed by causing the corrosion along a wear path to be spread around the tubing to extend the tubing life. Thus, Manual Tubing Rotation after a batch job (or periodically on continuos inhibitor treatments) will spread out the corrosion, since the previous wear area is moved and then coated with inhibitor (while a new wear area wipes off the inhibitor until the next rotation).
In general, if a good rod and pump design is implemented, most of the failures (in a non-sand environment) will be due to:
1. Tubing Split Wear . Solution: Tubing Rotator and/or roller rod guides.
2. Corrosion Hole due to wear wiping off inhibitor. Solution: Manual periodic tubing rotation.
3. Corrosion Hole due to poor chemical inhibition. Solution: Improve treatment method (circulation time and/or carrier fluids) or change chemical inhibitor type.
4. Rod Box or Body Break due to Wear(Use spray metal alloy couplings, roller rod guides, and/or rod rotator). Spray metal alloy couplings do not corrode and help move all the wear to tubing (if no rod body wear is present) with a much less wear rate due to very very little box friction. The tubing rotator will then spread out the remaining wear rate around the tubing to significantly increase the life of the tubulars. Roller Rod guides will help the rod body breaks and the tubing wear also, but not the "Corrosion due to wear" problems.
5. Other failures generally relate to (a) compression on rods (failures above the pump potentially solved with sinker bars or reduced with PVC lining), (b) too much wear friction in deviated holes (Rods are going in compression and tension and could be remedied with roller guides), (c) poor handling of equipment, (d) etc. Too Many to go over, but a helpful source may be found in the Norris Rod Companies Website on Failure Analysis or reviewing the Well Failure Identification Chart provided by Omega Technologies (Tubing Failures, Rod&Pump Failures).
