The energy or force present in an oil reservoir which causes the fluid to move toward the wells borehole and up to the surface when the reservoir is penetrated by the drill. A reservoir is very much like a pressure vessel; when a well is drilled into the reservoir it is as if a valve were opened to vent the pressure. There are several kinds of reservoir drives gas cap, solution gas, water, and artificial drives (q.v.).
Drive - The pulley or wheel, grooved for each hoist cable, which drives the elevator up or down.Drive Machine - The power unit which applies the energy necessary to raise and lower an elevator, material lift, or dumb waiter car or to drive an escalator, an inclined lift or a moving walk.
