Apparatus, system and method for pumping gaseous fluid

Abstract

An apparatus, system and method for pumping gaseous fluid are described. The centrifugal pump of the invention homogenizes at least a portion of the gas and liquid contained in produced well fluid thereby improving the efficiency of the pump in electric submersible pump (ESP) applications and decreasing the downtime of the ESP system. The impeller of the invention comprises an increased inlet area. The centrifugal pump of the invention comprises a single shroud located on the bottom side of an impeller, an increased inlet area of the impeller and an increased clearance gap between the impeller and a diffuser. One or more truncated vanes extend substantially upstream from the single shroud, wherein each truncated vane sits at a mid-pitch location between untruncated vanes starting from the bottom side of the impeller.

What is claimed is: 
     
         1 . An impeller for an electric submersible pump assembly comprising an increased inlet area. 
     
     
         2 . The impeller of  claim 1 , wherein the increased inlet area is between about 1.75 and about 2.5 times an inlet area of a conventional inlet area. 
     
     
         3 . The impeller of  claim 1 , further comprising a single shroud located on a bottom side of an impeller. 
     
     
         4 . The impeller of  claim 3 , wherein the single shroud extends radially about a hub. 
     
     
         5 . The impeller of  claim 3 , further comprising at least two untruncated vanes extending substantially upstream from the single shroud and at least two truncated vanes extending substantially upstream from the single shroud, wherein each truncated vane sits at a mid-pitch location between untruncated vanes starting from the bottom side of the impeller. 
     
     
         6 . The impeller of  claim 5 , wherein the truncated vanes are between about 50% and about 75% of a chord length of the untruncated vanes. 
     
     
         7 . The impeller of  claim 5 , wherein the truncated vanes are undivided. 
     
     
         8 . The impeller of  claim 5 , comprising three truncated vanes and three untruncated vanes. 
     
     
         9 . The impeller of  claim 5 , comprising two truncated vanes and two untruncated vanes. 
     
     
         10 . The impeller of  claim 5 , comprising four truncated vanes and four untruncated vanes. 
     
     
         11 . The impeller of  claim 1 , further comprising an increased clearance gap between an impeller and a diffuser. 
     
     
         12 . The impeller of  claim 11 , wherein the increased clearance gap is between about 0.060 inches and about 0.180 inches wide. 
     
     
         13 . The impeller of  claim 1 , wherein an impeller is configured to operate at about 8000 to about 12000 suction specific speed. 
     
     
         14 . A centrifugal pump comprising:
 an impeller inward of a diffuser, the impeller comprising a top side and a bottom side, the top side open to the diffuser, and wherein the impeller further comprises:
 a single shroud located on the bottom side of the impeller and arranged radially about a hub; 
 an untruncated vane extending substantially upstream from the single shroud; and 
 a truncated vane extending substantially upstream from the single shroud; and 
   an increased clearance gap between the impeller and the diffuser.   
     
     
         15 . The centrifugal pump of  claim 14 , wherein there are at least two untruncated vanes and wherein the truncated vane sits at a mid-pitch location between the at least two untruncated vanes. 
     
     
         16 . The centrifugal pump of  claim 15 , wherein there are three untruncated vanes and three truncated vanes, and wherein each truncated vane sits at a mid-pitch location between the untruncated vanes. 
     
     
         17 . The centrifugal pump of  claim 14 , wherein the increased clearance gap is between about 0.060 inches and about 0.180 inches wide. 
     
     
         18 . The centrifugal pump of  claim 14 , wherein the truncated vane is between about 50% and about 75% of a chord length of the untruncated vane. 
     
     
         19 . The centrifugal pump of  claim 14 , further comprising a bushing and a flanged sleeve located directly upstream of the hub. 
     
     
         20 . The centrifugal pump of  claim 14 , further comprising a bushing and a flanged sleeve located directly downstream of the hub. 
     
     
         21 . The centrifugal pump of  claim 14 , further comprising a first bushing and a first flanged sleeve, wherein the first bushing and the first flanged sleeve are located directly upstream of the hub, and a second bushing and a second flanged sleeve, wherein the second bushing and second flanged sleeve are located directly downstream of the hub. 
     
     
         22 . The centrifugal pump of  claim 21 , wherein the bushings and flanged sleeves comprise tungsten carbide. 
     
     
         23 . A method for pumping gaseous fluid comprising:
 placing a centrifugal pump into a well containing gaseous fluid;   operating the pump to induce the fluid to flow towards the surface of the well;   causing at least a portion of the fluid to flow through an increased clearance gap between an impeller and a diffuser; and   minimizing phase separation of the fluid by reducing a pressure differential between a pressure side and a suction side of an impeller vane.   
     
     
         24 . The method of  claim 23 , wherein the pressure differential is reduced by increasing an inlet area of the impeller. 
     
     
         25 . The method of  claim 24 , wherein the inlet area is increased by replacing the impeller vane with a truncated vane. 
     
     
         26 . The method of  claim 25 , wherein the impeller comprises at least two untruncated vanes, and wherein the truncated vane is placed at a mid-pitch location between the at least two untruncated vanes starting from a bottom side of the impeller. 
     
     
         27 . The method of  claim 23 , further comprising the step of carrying at least a portion of the axial thrust on the centrifugal pump with a flanged sleeve and a bushing located directly upstream of the impeller.