THE PROBLEM.

The costs to operate and maintaining beam pumping units greatly affect the economics of producing oilfields worldwide. Labor and power costs are especially critical factors in the economic life of marginal fields.

To keep beam pumps performing optimally, producers must frequently rebalance and adjust stroke length to match changing well conditions. These adjustments translate into higher costs. Similarly, producers often use oversized units to minimize downtime, which can greatly increase electrical power costs. 

In addition, the limited range of equipment available for conventional beam pumping units can restrict their use in some areas. For example, units located on irrigated leases can interfere with sprinkler systems. Likewise, some remote locations lack the power supply needed to operate conventional units.    

THE SOLUTION.

Rosemond Manufacturing (RMI) of Spring, Texas has developed a new beam pumping system that solves many of the problems with conventional pumping units. The Ajusta Pump is engineered to reduce electrical - power consumption by  using an energy - efficient gear box that can be driven by a relatively small motor. The pumping unit also has a low profile, which enables operators to use it under irrigation sprinklers or in other areas where space is limited. 

RMI and RMOTC conducted a six - month test of the Ajusta Pump on a producing oil well at the RMOTC field testing site (Naval Petroleum Reserve 3). The test was designed to evaluate system reliability, electrical  consumption, production performance, equipment adjustment, and wind-generator capability.  

During the RMOTC field test, the Ajusta Pump 1/2-hp DC unit required less operator labor and used approximately half the electrical power of a conventional Model-25 unit. The tests also showed that the system is rugged, reliable, and operator-friendly. 

THE BENEFITS.

Ajusta Pump can provide several economic benefits over conventional beam pumping units:

THE FIELD PERFORMANCE.

An Ajusta Pump Model-2000 was tested under various operating configurations, and then a Model-25 (API25B53E30) conventional beam pumping unit was tested on the same well for comparison. The test compared the performance of the Ajusta Pump using both a 1/2-hp DC motor (with and without a wind turbine) and 1/2-hp AC motor to the  operation of the Model-25 pumping unit with a 2-hp AC motor.

Initially, the unit's 1/2-hp DC motor was powered by a wind turbine through an electronic DC controller, which rectified and "blended" utility power to supplement the output of the turbine when wind power was insufficient to drive the unit. For the second phase, the wind turbine was disconnected form the system to evaluate the DC system under utility power (through the DC controller). Next, the DC system was removed and the Ajusta Pump performance (using a 1/2-hp AC motor and utility power) was monitored. During the final phase of the test, the Model-25 unit (with a 2-hp AC motor and utility power ) was reinstalled on the well and evaluated. 

During the RMOTC test, the Ajusta Pump unit used 25% of the horsepower and consumed an average of 48% less electrical power than a Model-25. The Ajusta Pump also demonstrated significantly lower reactive power and significantly higher power factor than the Model-25 pumping unit. 

The RMOTC test also showed that the approximate times required to adjust the unit for stroke length, counter weights, and strokes per minute were respectively 1 hour, 1/2 hour, and 1 hour faster than adjustment times for the Model-25 unit.