Downhole tool with longitudinally offset fluid ports

Abstract

A rotational tool includes a shaft having a central fluid conduit within a housing, and one or more fluid conduits between the shaft and housing. The one or more fluid conduits are radially offset from the central fluid conduit. The shaft includes a plurality of fluid ports that extend radially and provide fluid communication between the one or more fluid conduits and the central fluid conduit. The fluid ports are longitudinally offset along the shaft to distribute any weakening of the shaft by the introduction of the fluid ports.

What is claimed is: 
     
         1 . A rotational tool, comprising:
 a shaft having a longitudinal axis and a central conduit extending in a longitudinal direction through at least a part of the shaft;   a housing at least partially enclosing the shaft;   one or more fluid conduits radially between at least a portion of the shaft and the housing;   a first fluid port providing fluid communication between the one or more fluid conduits and the central conduit; and   a second fluid port providing fluid communication between the one or more fluid conduits and the central conduit, the second fluid port being longitudinally offset from the first fluid port.   
     
     
         2 . The rotational tool of  claim 1 , the first fluid port having a first flow area and the second fluid port having a second flow area, the first flow area and the second flow area being different. 
     
     
         3 . The rotational tool of  claim 1 , the first fluid port and the second fluid port being angularly offset. 
     
     
         4 . The rotational tool of  claim 1 , the first fluid port being oriented at a first port angle of 20° to 70° relative to the longitudinal axis. 
     
     
         5 . The rotational tool of  claim 1 , the first fluid port being oriented at a first port angle relative to the longitudinal axis and the second fluid port being oriented at a second port angle to the longitudinal axis, the first port angle and second port angle being different. 
     
     
         6 . The rotational tool of  claim 1 , further comprising:
 a first fluid slot in an outer surface of the shaft and extending at least partially in a longitudinal direction from the first fluid port, the first fluid slot being in fluid communication with the one or more fluid conduits.   
     
     
         7 . The rotational tool of  claim 6 , the first fluid slot having between a 1° and 120° angular displacement. 
     
     
         8 . The rotational tool of  claim 6 , the shaft being configured to rotate relative to the housing, and the fluid slot extending uphole from the first fluid port and being oriented in a rotational direction of the shaft. 
     
     
         9 . A downhole tool, comprising:
 a shaft having an outer surface and a longitudinal axis;   a central conduit extending longitudinally through at least a portion of the shaft, the central conduit having a central conduit flow area; and   a plurality of fluid ports extending radially between the central conduit and an outer surface of the shaft, the plurality of fluid ports having a combined flow area of between 50% and 120% of the central conduit flow area, the plurality of fluid ports including:   a first fluid port having an opening at the outer surface; and   a second fluid port having an opening at the outer surface, the opening of the second fluid port being longitudinally offset from the opening of the first fluid port.   
     
     
         10 . The downhole tool of  claim 9 , the plurality of fluid ports being distributed circumferentially about the outer surface of the shaft at equal angular intervals. 
     
     
         11 . The downhole tool of  claim 9 , at least one of the plurality of fluid ports being in fluid communication with a fluid slot in the outer surface of the shaft. 
     
     
         12 . The downhole tool of  claim 11 , the fluid slot being non-parallel to the longitudinal axis. 
     
     
         13 . The downhole tool of  claim 11 , the fluid slot being curved. 
     
     
         14 . The downhole tool of  claim 9 , at least one of the plurality of fluid ports having a curved portion. 
     
     
         15 . The downhole tool of  claim 9 , at least one of the plurality of fluid ports having a variable flow area along its length. 
     
     
         16 . A downhole tool, comprising:
 a shaft having an outer surface and a longitudinal axis;   an inner fluid conduit extending through at least a portion of the shaft;   one or more outer fluid conduits radially offset from the longitudinal axis and the inner fluid conduit;   a first fluid port providing a first radial flow path and fluid communication between the inner conduit and the one or more outer fluid conduits, the first fluid port having a first opening at the outer surface of the shaft;   a second fluid port providing a second radial flow path and fluid communication between the inner fluid conduit and the one or more outer fluid conduits, the second fluid port having a second opening at the outer surface of the shaft; and   a third fluid port providing a second radial flow path and fluid communication between the inner fluid conduit and the one or more outer fluid conduits, the third fluid port having a third opening at the outer surface, wherein the first, second, and third openings are angularly offset and do not longitudinally overlap one another.   
     
     
         17 . The downhole tool of  claim 16 , a port region of the first fluid port having between a 1% and 90% longitudinal overlap with a port region of the second fluid port. 
     
     
         18 . The downhole tool of  claim 16 , a port region of the second fluid port having between a 1% and 90% longitudinal overlap with a port region of the third fluid port. 
     
     
         19 . The downhole tool of  claim 16 , a combined flow area of a first flow area of the first fluid port, a second flow area of the second fluid port, and a third flow area of the third fluid port being at least as large as a flow area of the inner fluid conduit. 
     
     
         20 . The downhole tool of  claim 16 , a combined flow area of a first flow area of the first fluid port, a second flow area of the second fluid port, and a third flow area of the third fluid port being at least as large as a flow area of the one or more outer fluid conduits.