Beam lift - a study of important parameters : (1) well bore orientation effects on liquid entry into the pump. (2) Pumping unit counterbalance effects on power usage. (3) Pump friction and the use of sinker bars.
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This study will discuss three different aspects of rod pumping. Chapter 1 will focus on flow regimes associated with low-pressure horizontal wells. By understanding how oil and gas interact with each other both in the horizontal and vertical portions of the wellbore, downhole pump assemblies can be optimized to increase pump fillage. The addition of a flexible dip tube into the horizontal section of the wellbore allows for the ability to set the pump above the kickoff point but is only effective the dip tube can be engineered to be submerged in the fluid. Chapter 2 is an evaluation of the effect of pumping unit counterbalance on power consumption. If the pumping unit is out of balance, it will generate power during portions of the stroke. The Motorwise motor controller attempts to save power by shutting off the motor and allowing the rotational inertia of the unit to operate the pump. Although this device does save power on pumping units that are out of balance, it was concluded that it was of little use if the operator can maintain balance of the pumping unit. Chapter 3 discusses the role of viscous friction in rod string design and the importance of sinker bars in counteracting compression forces at pump level. On the downstroke, the plunger must overcome any mechanical friction as well as the viscous friction from fluid flowing through the traveling valve and the annular space between the plunger and inside of the barrel. In a barrel completely full of liquid, the plunger will establish a free fall velocity. If the plunger is required to fall faster than free fall, the plunger must be pushed. If the plunger can reach terminal velocity with additional weight, the increase in viscous friction inside the pump equals the weight added. Thus, the critical plunger velocity for the onset of buckling of a ¾” sucker rod varies depending on the viscosity of the fluid. Adding a single 1.5”, 25-foot sinker bar is sufficient to counteract the compression from viscous pump friction up to practical pumping speed limits.