Subsurface resources such as oil, gas, and water are typically recovered by drilling a bore hole from the surface to a subterranean reservoir or zone that contains the resources. The bore hole allows oil, gas, and water to flow to the surface under its own pressure. For low pressure or depleted zones, rod pumps are often used to lift the fluids to the surface.
To facilitate drilling and production operations, cavities are often formed in the production zone. The cavity allows the well bore to be more readily intersected during drilling operations and collects fluids during production operations. The collection of fluids allows pumps to be operated intermittently when the cavity is full, which reduces wear on the pump.
Short extensions called a “rat hole” are often formed at the bottom of the cavity to collect cuttings and other drilling debris. As the subsurface liquids collect in the well bore, the heavier debris falls to the bottom of the rat hole and is thereby both centralized and collected out of the cavity. To avoid being clogged with debris, inlets for rod and other downhole pumps should be positioned within the cavity above the rat hole. In addition, the pump inlet should be positioned fairly low in the cavity to avoid vapor lock (i.e., below the fluid waterline). Traditional methods of positioning the pump inlets, however, are often inaccurate and inefficient, leading to clogging or vapor lock and increased maintenance and operation costs for the well.
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