Paper: Pumping Through Macaroni (Hollow) Sucker Rods

The use of Macaroni tuning is not new; for many years oil producers have been successfully pumping fluids through and around this tubing. However, these applications have generally been limited to wells above 3,000 feet. This limitation, imposed because of the failure of the mechanical joint in reciprocating service, can be materially altered or entirely eliminated if we understand the problems and design accordingly. To do this, we must first determine the forces which are present in pumping with Macaroni sucker rods and evaluate their magnitude. Some of the forces present are: dead weight of rods, dead weight of fluid, acceleration and deceleration, fluid friction and mechanical friction. All of these forces are present to some degree in a reciprocating rod string, and the sum of these forces constitutes the polish rod load.