Subsurface Pipe Dimension and Position Indicating Device

Abstract

A sensing system provides real time information as to the location of a stand in a tubular string at a predetermined elevation such as where the rams are located. This allows a determination of whether the upsets are aligned with the ramps or whether the stand is aligned with the rams in a manner that the rams will close on the tubular between the end upsets. The surrounding pipe has circumferentially spaced transmitters and receivers to allow a determination of the outer dimension of the pipe and to transmit such information to the surface by conductors or other means. The position of a tubular in an open hole can also be determined by sending a signal from the tubular to the open hole and back to the tubular. Different signal regimes are contemplated as well as power supply options.

I claim: 
     
         1 . A sensing system for detecting the outer dimensions of a tubular or a tool at a specific location or the position of a tubular or tool in cased or open hole, comprising:
 a plurality of spaced signal transmitters and signal sensors to detect the spacing of a stand of pipe from the cased or open hole at a predetermined depth or the shape of a tool at a predetermined depth;   a processor to compute the outer dimensions of said stand of pipe or said tool using data from said signal transmitters.   
     
     
         2 . The system of  claim 1 , wherein:
 said transmitters and sensors are in the same plane.   
     
     
         3 . The system of  claim 1 , wherein:
 said transmitters send one of an acoustic, vibration, pressure pulse or radio frequency signals that are reflected from said stand of pipe to said sensors.   
     
     
         4 . The system of  claim 1 , further comprising:
 a blowout preventer in the cased hole;   said processor indicating a small diameter between upsets or said tool as aligned with rams on said blowout preventer to allow said rams to close against said stand on said small diameter or to signal that said stand of pipe needs to be moved to prevent closing said rams on said tool.   
     
     
         5 . The system of  claim 1 , wherein:
 said sensors and transmitters are located in casing defining the cased hole.   
     
     
         6 . The system of  claim 1 , wherein:
 said sensors and transmitters are located on the stand of tubular.   
     
     
         7 . The system of  claim 1 , wherein:
 said sensors and transmitters do not reduce the drift dimension of casing defining the cased hole.   
     
     
         8 . The system of  claim 1 , wherein:
 said transmitters send a signal from said stand of pipe toward the open hole to sense position of said stand of pipe with respect to the open hole.   
     
     
         9 . The system of  claim 1 , wherein:
 said sensors and transmitters are circumferentially spaced, evenly or unevenly.   
     
     
         10 . The system of  claim 1 , wherein:
 said sensors and transmitters are powered locally or from a surface location of a borehole.   
     
     
         11 . A method of positioning a portion of a stand of a string between upsets in alignment with rams of a blowout preventer, comprising:
 sensing the distance from an outer surface of a stand of a tubular string to a wall of a surrounding tubular from a plurality of circumferentially spaced locations;   computing the outer dimension of the tubular or of a tool from said sensing;   repositioning said stand of a tubular before operating said rams if the outer dimension indicated is not the smallest known outer dimension of said stand located between opposed upsets or if a tool is aligned with said rams.   
     
     
         12 . The method of  claim 11 , comprising:
 performing said sensing in a common plane adjacent said rams.   
     
     
         13 . The method of  claim 11 , comprising:
 equally or unequally spacing pairs of transmitters and respective sensors that send and receive a signal reflected from said stand of a tubular.   
     
     
         14 . The method of  claim 13 , comprising:
 connecting said sensors to a processor to compute the outer dimension of the stand of tubular to allow real time communication of said outer dimension to a remote location.   
     
     
         15 . The method of  claim 14 , comprising:
 locating said processor near said rams or at a remote location.   
     
     
         16 . The method of  claim 11 , comprising:
 using transmitters and sensors in pairs to feed data to a processor to compute the outer dimension of the stand of pipe;   powering said sensors and transmitters locally or from a remote location.   
     
     
         17 . The method of  claim 11 , comprising:
 using as a signal to be sensed one of acoustic, vibration, pressure pulse or radio frequency.   
     
     
         18 . The method of  claim 11 , comprising:
 performing said sensing with pairs of signal transmitters and sensors located on said string or said surrounding tubular.   
     
     
         19 . The method of  claim 11 , comprising:
 determining the outer dimension of the stand op pipe even when the stand is not centered within the surrounding tubular.