Patent ID: 9631465
Date: 2017-04-25
CPC Classifications: E21B,F04D,G01P

Claim:
1. A method for maintaining a downhole pump impeller of a geothermal downhole pump in a geothermal production well, comprising the steps of: locating a line shaft of the downhole pump to a selected depth in the geothermal production well, monitoring the depth of a lowermost distal end of said line shaft in the geothermal production well using a monitor positioned at a lowermost distal end of said line shaft in order to prevent damage to said impeller, determining that the depth of the lowermost distal end of said line shaft has significantly changed, and taking a corrective action to return the depth of the lowermost distal end of said line shaft to said selected depth in order to maintain and prevent damage to said impeller, wherein the depth of the lowermost distal end of line shaft distal end is monitored by the monitor, by directing a beam of light emitted from a housing mounted on an outer portion of the downhole pump onto a plurality of reflective elements located on the line shaft distal end, and determining whether a receiver mounted in said outer portion receives light reflected from said one of said plurality of reflective elements, and wherein the plural reflective elements are arranged in a circumferentially spaced array in a plane normal to the shaft at the line shaft distal end.