Multi-frac horizontal wells have uneven DLS (dog leg severity), inconsistent reservoir flow, high gas content, and sand infiltration. In conditions like these, uniform speed through the pump stroke may not an effective option. This arises the need for a two-speed mode where we can constantly monitor well performance against operator presets and then adjust pumping speed during the downstroke and upstroke separately.

A two-speed mode for a sucker rod pumping system is introduced to lower compression forces in rods and power consumption. Numerical modeling and an extensive field test verify the concept. This solution for variable speed drive systems reduces energy to rod string and can be applied in the controller without requiring any hardware adjustments.

During the down stroke, the plunger in a rod pump must descend through a barrel that is filled with fluid. The plunger must be pushed down into the barrel by a compressive force in order to match the pumping velocity. The compressive force may be large enough to cause buckling in the pull rod and the lowest section of the sucker rods. This paper is based on the idea of setting the VFD in two separate modes: normal in upstrokes and slow in the downstrokes. And we will perform measurements of the free fall velocity of a plunger in a liquid-filled barrel and the pushing force necessary to exceed the free fall velocity of the plunger in the barrel.

In this case study, compression measurement in rods is performed in 3 wells after putting them on two-speed mode. The down stroke and up stroke values in each well is evaluated by operating parameters such as:

  1. Rod air weight.

  2. Buckling forces.

The challenges of putting these wells in two-speed modes, both in the field and online, are discussed separately. A rubric-based comparison was performed on pumping efficiency among the three wells. A systematic approach of measuring wells performance based on nodal analysis is performed. The performance of wells before and after putting them in two-speed mode is discussed.

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