Reciprocating Rod Lift #1

I thought that there might be some interest in a discussion of innovators, major design improvements, and major milestones in reciprocating rod lift.

This is not meant to be a definitive work but more topics for discussion. Comments are very welcome. Let’s have fun with it!

When discussing this subject the pieces that come to mind are the pumping unit, sucker rods, prime movers, and downhole pumps. There are other important components, such as tubing anchors, polished rods, packers, etc. but to keep this focused and not be the length of War and Peace, I will focus on the pumping unit primarily with further discussion on rods, prime movers, and downhole pumps. I plan to offer these discussions in multipart form. Below are topics for future discussion.

The rod lift system is unique in that a change in any part of the system can and will almost always affect the loading and performance of every other part of the system. Changing the pumping unit geometry will affect the loading on the unit as well as the loading and performance of the pump, rods, and prime mover. Change the prime mover design and it will affect the pumping unit, rods and pump, and so on. Thus a singular design choice must be made with consideration to every other component. Thankfully there is excellent software to predict these loadings and the performance with each change of component. Srod by Gibbs originally Nabla is owned by Lufkin and Rodstar by Svinos is now owned by Champion X. These programs will help with the selection of various components.

Rod lift has long been the default selection for artificial lift. Oil company equipment engineers would often start their design utilizing rod lift and then look for reasons that they couldn’t use it and may determine that some other form was necessary.

National Supply Company, Oilwell Supply, Bethlehem supply, Lufkin Industries,?(started out as a sawmill manufacturer) American Manufacturing, which among other industrial manufacturers such as Continental –Emsco and Parkersburg among others, made steel or steel fabrications, gear reducers or foundry products and were early major manufacturers of pumping units although most have now exited the business. In the middle to the late part of the last century, there were approximately 400 pumping unit manufacturers and most, like, National, Oilwell, Bethlehem, and Continental Emsco have now exited various parts of the business or sold out. Several of these companies made sucker rods and downhole pumps, further leveraging their raw material products.??

There were many innovations in the design of components for the pumping unit and other rod lift components. Adjustable counterbalance, twin crank arms, Herringbone gears, closed apex vs open apex herringbone gears, single, double and triple reduction reducers, conventional, beam balance, air balance, Class 3 geometry (Mark II) Reverse mark or improved geometry units, central power units, long slow stroke units, self-adjusting counterweights, etc. compressed air as counterbalance which could be adjusted with little effort and allowed for the design of the largest capacity units, and Nitrogen over hydraulic units as well as low profile units.

During the late 1970’s and early 1980’s there was a global shortage of gear reducers, this shortage led to, very long lead times, and a lot of companies entering the business that didn’t really understand the loads, operating conditions and requirements to serve the pumping unit market. Companies also designed units that did not require gearboxes or supplied gear reducers that were inappropriate for the application (truck transmissions, large reduction sheaves, industrial boxes that had case hardened gears and thus couldn’t withstand the variable loads, overloads and load spikes)

Sucker rods:

With the development of large capacity long stroke units, sucker rods and pump capacity became the limiting factor for rod lift. This capacity has been expanded due to new designs and innovations.

Hardened rods, light weight rods, continuous rods that only used top and bottom couplings, lightweight rods made of fiberglass that included tremendous elasticity, special metallurgy, special rod couplings, carbon rods, and rod rotators.

Rod and tubing pumps:

Specialty pumps, oversized tubing pumps, bottled-up pumps. Every pump company has a myriad of special designs so I’ll limit my discussion to some of the major innovations and leave it to the discussion participants to talk about other noteworthy designs.?

Prime movers:

Central power units, single-cylinder and multi-cylinder engines, NEMA B, NEMA D and Ultra High Slip electric motors, hydraulic motors, and automation-capable engines.?

As one can see each of these components has special designs meant to address various challenges and applications. There are no do-all, fix-all solutions in this system. This article's benefit is recognizing that there are many different solutions to a rod lift challenge.

#energy #reciprotatingrodlift #oilandgas #permianbasin #pumpingunits #innovations