The prime mover is the unit that first converts an energy source into a mechanical force. Typical prime movers are internal combustion motors, gas turbines, water turbines, steam engines and electrical motors. The discussion will be limited to the prime movers that are most used in modern well drilling and production operations. These are internal combustion motors, gas turbine motors and electric motors.
Internal Combustion Engines
The internal combustion engines considered in this section are piston-type engines. The combustion process in such engines are assumed to be constant volume, constant pressure, or some combination of both. Piston-type internal combustion engines are made up of a series of pistons that can move in enclosed chambers called cylinders. These engines can be designed in a variety of configurations. The most widely used configurations are the following:
- An in-line type engine has all cylinders aligned and on one side of the crankshaft (Figure 1). These engines are found in sizes from 4 pistons (or cylinders) to as many as 16.
- A V-type engine has an equal number of cylinders aligned on two banks of the engine. These banks form a V shape (Figure 1). These engines are found in sizes from 4 cylinders to as many as 12.
- An opposed-type engine has an equal number of cylinders aligned on two banks of the engine. These banks are horizontally opposed to one another on opposite sides of the crankshaft (Figure 2). These engines are found in sizes from 4 cylinders to as many as 8.
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| Figure 1: In line type engine and V type engine |
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| Figure 2: Opposed type engine |