Leveraging artificial lift to optimize production

Fig. 1. Artificial lift solutions play an important role in helping optimize production with existing wells.

As oil and gas companies seek to maximize existing wells, artificial lift technologies will continue to play a pivotal role in meeting the demands of increasingly challenging well conditions. 

As production declines1 to a certain rate, almost all wells utilize artificial lift technologies (Fig. 1)—often a rod lift system—to take advantage of its greater drawdown capabilities. However, as wells become deeper and more deviated, operators have been forced to run heavier rod strings through tight corners, resulting in increased sideload and wear on rod lift system components.  

The low production levels associated with rod lift wells make margins especially tight, and it benefits operators to explore new tactics to extend the life of their rod lift systems. Rod rotators are one such way to minimize the effects of increased sucker rod sideloads in more complex wells, by evenly distributing wear around the circumference of the rod and centralizer if utilized.  

THE NEED FOR ROD ROTATORS 

Fluid levels continuously drop as production falls, requiring operators to land pumps lower, as well. In addition, drilling deviated or directional wells requires operators to land the pump down and around the corner below the kickoff point, dramatically increasing wear on the rod string and tubing. These trends have made rod rotators essential components of a reciprocating rod lift system. 

ROD ROTATOR OPERATION 

Rod rotators are selected, based on string weight, and are installed on a pumpjack’s bridle to help minimize wear on the sucker rod string. As the pumpjack operates, the rod string descends into the wellbore and ascends again on each stroke. Should there be any anomalies in the wellbore or tight corners and deviations, the rod string will continually experience wear on one particular part of the rod, leading to erosion and ultimately, to failure. 

The role of the rod rotator is to ratchet and subsequently rotate the rod to distribute wear around the entire diameter of the rod string to extend the run life of pumps, rods and centralizers. This occurs upon the pumpjack’s stroke. 

RECENT IMPROVEMENTS TO ROD ROTATORS  

Various rod rotator sizes are available, to help optimize production performance results. Cam and ratcheting mechanisms ensure movement occurs in a single direction.  
In addition to such improvements, configuration and material enhancements help increase efficiency in the field. Regular speed and slow gear options allow oilfield companies to maximize the dynamics of their site. Slow gear configurations turn half as quickly as regular speed configurations, which can be advantageous for rod strings with additional torque. Slowing down rotation in a deviated well or around hard bends enables the rotation to be distributed over more strokes, for improved efficiency and easier turning. 
 
Oilfield companies are likely familiar with W-302 rod rotators, which are most commonly used. The end caps of the W-302 rod rotator feature a ratchet pawl system that may be a common failure point. These failures often go unnoticed, leading companies to run rod lift systems without the string rotating as intended. When a wear-induced failure occurs, companies face significant nonproductive time (NPT) and a costly workover job. Fortunately, improvements to the design of rod rotators—including the creation of W-303 and W-304 rod rotators—has resulted in substantial enhancements to rod rotator reliability and rod string longevity. 

ROD ROTATORS DESIGNED SPECIFICALLY FOR DEVIATED WELLS 

The newly enhanced SPM™ W-303 and W-303 Slow Gear (SG) rod rotators, for example, help solve common operational challenges, Fig. 2. The rod rotators not only feature advanced lubrication and carburization but also undergo extensive third-party validation testing during and after manufacturing, to help ensure dependable longevity in the field. Specialized lubricant and heat treatment processes allow the rod rotators to withstand rigorous operating demands. 

Fig. 2. The newly enhanced SPM Rod Rotator W-303 is engineered to withstand rigorous operating demands.

Rather than the ratchet pawl system typically used by W-302 rod rotators, the W-303 rod rotator features a one-way bearing for an accurate and unmistakable fit on the rod rotator drive shaft, which makes the rod rotator more robust and more durable in challenging operating conditions. Employing an end cap with a solid face and grease zerk enables companies to apply grease to the bearings and ensure that the end cap is sealed off from precipitation or moisture that could lead to rusting. Used in conjunction with a properly centralized or guided sucker rod string, companies can significantly improve overall system run life—and production outcomes. 

W-303 rod rotators and one-way bearings are also available as a conversion, to provide flexibility. This enables companies to perform a retrofit in the field and upgrade a W-302 rod rotator into a W-303 rod rotator in a single 10-min. process. 

Rod string life also can be extended with the W-303 rod rotators or W-303 conversion kits. This is impactful, as industry standards2 indicate operators can expect significantly greater run life with a properly running rod rotator for their rod strings. 

A SOLUTION FOR DEEPER, MORE DEVIATED WELLS 

As companies land pumps deeper and pursue more deviated wells, specialized rod rotator solutions are needed for these types of challenging applications. These wells can sometimes be drilled as an “S bend,” as the multiple planned deviations create additional drag and friction on rod strings. Rotating in these circumstances is especially difficult and can result in significant side load and torque on the rod rotator. 

For such a scenario, a rod rotator like the SPM™ W-304 (Fig. 3) that offers a larger main load bearing can handle up to 50,000 pounds of peak polished rod load, allowing companies to hang heavier rod strings and operate larger pumps off the rotator. A side thrust bushing promotes greater tolerance of the additional stresses of deeper, more deviated wells—including tight wells with long laterals, such as those commonly found in the DuVernay and Montney Formations. 

Fig. 3. The SPM Rod Rotator W-304 can handle up to 50,000 pounds of peak polished rod load to accommodate heavier rod strings and larger pumps.

By implementing advanced rod rotator solutions, oil and gas companies can experience notable performance improvements. For example, a Canadian oil and gas company that had been using conventional W-302 rod rotators found that the components wore down to the point of failure every month. Installing the SPM W-304 rod rotator allowed the component to last for months at a time, delivering a longer run life. This ultimately saved the operator NPT and the expense of replacing rod rotators once a month—a process that requires 60–90 min. of downtime, plus the cost of the part. 

ENHANCING PRODUCTION FOR OLDER WELLS 

Mature wells that are deeper and more complex incur more rod and tubing wear and upgrading rod rotators to more robust versions—either through retrofit or replacement—enables companies to not only extend the life of their rod lift systems but also minimize NPT and overall costs, while optimizing production. Artificial lift technologies, such as rod lift systems, continue to be vital to allow oilfield companies to maximize the ROI of older assets. 

REFERENCES 

1. Production Forecasting Decline Curve Analysis. https://petrowiki.spe.org/Production_forecasting_decline_curve_analysis#:~:text=Decline%20curve%20analysis%20(DCA)%20is,fluids%2C%20are%20usually%20the%20cause. 

2 Production Technology. Rod Rotator Extends the Life of Rod-Pumped Wells. https://production-technology.org/rod-rotator-extends-the-life-of-rod-pumped-wells/  

About the Authors

SCOTT MACFARLAND

SPM™ Oil & Gas, a Caterpillar Company

SCOTT MACFARLAND is the sales manager, Distributed Products, at SPM Oil & Gas. Throughout his 19-year career, he has focused on oilfield service products that maximize production output.