Most wells completed in oil producing sands will flow naturally for some period of time after they begin producing. Reservoir pressure and formation gas provide enough energy to bring fluid to the surface in a flowing well. As the well produces this energy is consumed, and at some point there is no longer enough energy available to bring the fluid to the surface and the well will cease to flow. When the reservoir energy is too low for the well to flow, or the production rate desired is greater than the reservoir energy can deliver, it becomes necessary to put the well on some form of artificial lift to provide the energy to bring the fluid to the surface. The types of artificial lift available are illustrated in Figure 1-1. When gas lift is used, high-pressure gas provides the energy to enable the well to produce.
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