Downhole tools

Abstract

A fluid operated apparatus in the form of a flow cap, is mounted on an end of a downhole tool or sub, which itself has a screw thread fitting to a further tool, sub or tubular. The cap provides a number of fluid flow channels arranged in a spiral pattern upon the outer surface. The handedness of the channels matches the handedness of the screw thread fitting so that fluid flow from ports in the tool or sub, acts to tighten the screw thread fitting. A water injection valve including a flow cap is described.

1 . A fluid operated apparatus for use on a downhole tool or sub comprising, a screw thread formed on an upper end thereof for connection to a further tool, sub or tubular from which it is appended, the apparatus having an outer surface upon which is arranged one or more fluid flow channels, each channel having a fluid inlet arranged at an upper end and a fluid outlet arranged at a lower end, distal from the screw thread, and each channel being formed as a portion of a spiral having a handedness, the handedness being the same as the screw thread at the upper end. 
   
   
       2 . A fluid operated apparatus according to  claim 1  wherein the apparatus is a male connector with the upper end being a female connector. 
   
   
       3 . A fluid operated apparatus according to  claim 2  wherein the upper end is also a male connector. 
   
   
       4 . A fluid operated apparatus according to  claim 1  wherein one or more channels are each formed as a portion of a helix on the outer surface. 
   
   
       5 . A fluid operated apparatus according to  claim 1  wherein there are a plurality of channels equidistantly spaced around the outer surface. 
   
   
       6 . A fluid operated apparatus according to  claim 1  wherein the apparatus comprises a substantially cylindrical body with the channels arranged along a substantial length of the body. 
   
   
       7 . A fluid operated apparatus according to  claim 1  wherein the apparatus includes a bull nose at an end thereof. 
   
   
       8 . A fluid operated apparatus according to  claim 1  wherein each channel is separated from an adjacent channel by a channel wall. 
   
   
       9 . A fluid operated apparatus according to  claim 8  wherein a width of the channel wall is less than a width of the channel. 
   
   
       10 . A fluid operated apparatus according to  claim 9  wherein the width of the channel is substantially the same along its length. 
   
   
       11 . A fluid operated apparatus according to  claim 1  wherein the tool or sub includes one or more port arranged to provide fluid flow adjacent to the inlets of the channels. 
   
   
       12 . A fluid operated apparatus according to  claim 1  wherein the tool is an adjacent valve appended from a wireline lock or packer. 
   
   
       13 . A method of self tightening a screw thread on a string, tool or sub in a well bore, comprised the steps:
 a) locating upon a string, tool or sub an apparatus according to  claim 1 ;   b) running the string, tool or sub into the well bore;   c) with the string, tool or sub positioned in the well bore, causing fluid flow to enter the channels, the direction of the fluid flow being non-parallel to the handedness of the channels;   d) using fluid pressure created in the channel to urge the apparatus to turn in direction matching the handedness of the screw thread on the string, tool or sub and thereby tightening the screw thread.   
   
   
       14 . A method according to  claim 13  wherein the tool is an injection valve and the fluid flow is injected fluid travelling through the valve in a downhole direction.