Sucker Rod Pump

Pump off controllers (POC’s) that produce dynamometer cards are and have been the preferred method of detecting pump off in rod pump applications. In addition to detecting pump off, these devices provide several leading indicators such as run time, cycles, peak and minimum loads, gearbox and rod stress, and a variety of other data points. In order to do this, a load cell, a position measuring sensor and other technology is needed, thus driving up the cost of the traditional POC, and making it harder for a marginal producer to justify the expense of this type of POC. 

Dynamic sucker rod sucker rod modeling in deviated wells has proven difficult. Wave equation solutions – when applied to measured surface cards - have generally produced dubious pump cards. Recently acquired measurements collected from deviated wells using downhole dynamometers have inspired a new wave equation formulation and a modern finite difference implementation. The new model produces pump cards which are generally consistent with data measured downhole. The new model has been implemented in a commercial rod pump controller. 

Reciprocating rod pumps (RRP) have globally shown that with longer strokes increased productivity and reduced operational costs can be achieved over that of a progressive cavity pump (PCP) in clean to moderate solids producing wells. This has also been extended to suggest that with the right equipment mean time to failure can be increased.

Sucker rod pumping can experience reliability challenges when produced fluid contains solids. Any improvement in the ability for a sucker rod pumping system to handle solids would be highly beneficial.

A sucker rod pump is an essential component for rod pumping, but it has been limited by use of machined componentry and a ball/seat valve design. Today’s deep, gassy-sluggy, foamy, solids ladened, horizontal wells commonly have high initial liquid rates that are beyond the rate capacity of sucker rod pumping, which can require use of higher operating expense ESP’s or gas lift methods. Improving the rate capacity and reliability of sucker rod pumping in such challenging environments would be highly beneficial for producers.

As the complexity of well profiles on rod pumped wells increases, traditional rod rotators experience more frequent failures due to the challenging conditions. The consequence is a decline in well productivity, often accompanied by a significant increase in well maintenance costs. This session will examine common rod rotator failures and root causes. It will introduce a new alternative rod rotator designed to improve field performance and reduce operating expenses, including a comprehensive review of field trial results during the last 30 months.

In sucker rod pumps, work at the surface is translated to the pump downhole using a polished rod and rod string. Three factors reduce the energy available at the pump and decrease the efficiency of the rod pump installation.

Rod rotators are designed to distribute wear evenly around the circumference of sucker rods. However, in practice, rods, guides, and couplings frequently develop flat spots on one side, indicating uneven rotation. The industry has not adequately studied the implications of this condition on the entire pumping system. Instead, solutions have focused on implementing higher torque rotators or positive engagement mechanisms to force rod rotation.

The fatigue performance of sucker rods is intrinsically tied to their manufacturing processes and the mechanical properties of various grades. One of the most transformative advancements introduced in the past decade is the application of shot peening, a process that has emerged as a cornerstone of performance enhancement in the sucker rod industry.

The relative motion between sucker rods and tubing in rod-lifted wells, particularly in corrosive fluids, leads to degradation mechanisms that often cause material loss, commonly referred to as wear. In U.S. unconventional wells, this wear mechanism accounts for over 50% of the operational expenditure (OPEX) in rod-lifted systems.

Through the application of Root Cause Analysis, the primary mechanisms responsible for this wear—tribocorrosion and three-part abrasion—were identified. These mechanisms can occur individually or in combination.