Method and apparatus for measuring a wellbore

Abstract

There is provided a wellbore measuring apparatus including a tubular outer body connectable in line with a drill string. The apparatus includes arms pivotally coupled to the body. Each arm has a retracted position and is moveable from the retracted position to an extended position so that a free end portion thereof is radially away from an outer surface of the body. The free end portions of the arms have rounded configurations. The arms are angularly spaced apart around the body and arranged in a plurality of tiers. Each tier includes three or more of the arms. The tiers are spaced apart axially from one another along the body. Each arm of a first tier is angularly offset relative to the arms of a second tier. The apparatus includes sensors operatively connected to the arms, respectively, and via which a profile of a wellbore is measured.

What is claimed is: 
     
         1 . A wellbore measuring apparatus comprising:
 an outer body that is tubular and connectable in line with a drill string;   a plurality of arms pivotally coupled to the outer body, each said arm having a retracted position and being moveable from the retracted position to an extended position so that a free end portion thereof is radially away from an outer surface of the outer body, the free end portions of the arms having rounded configurations, the plurality of arms being angularly spaced apart around the outer body and arranged in a plurality of tiers, with each of the tiers comprising three or more of the arms, with the tiers being spaced apart axially from one another along the outer body, and with each said arm of a first said tier being angularly offset relative to the arms of a second said tier; and   a plurality of sensors operatively connected to the plurality of arms, respectively, and via which a profile of a wellbore is measured.   
     
     
         2 . A wellbore measuring apparatus according to  claim 1 , wherein the sensors are operable to directly or indirectly measure radial extension of each of the arms from the outer body. 
     
     
         3 . A wellbore measuring apparatus according to  claim 1 , wherein the sensors comprise proximity sensors which are able to sense a distance to a wall extending about the wellbore. 
     
     
         4 . A wellbore measuring apparatus according to  claim 1 , wherein the sensors comprise ultrasonic sensors. 
     
     
         5 . A wellbore measuring apparatus according to  claim 1 , wherein for each said arm the corresponding said sensor thereof couples thereto adjacent the free end portion thereof. 
     
     
         6 . A wellbore measuring apparatus according to  claim 5 , wherein the sensors comprise temperature sensors. 
     
     
         7 . A wellbore measuring apparatus according to  claim 1 , wherein the sensors generate signals that indicate pivot angles of the arms. 
     
     
         8 . A wellbore measuring apparatus according to  claim 1 , comprising a first said plurality of sensors which generate signals that indicate pivot angles of the arms and a second said plurality of sensors coupled to respective said arms adjacent the free end portions thereof. 
     
     
         9 . A wellbore measuring apparatus according to  claim 8 , including a processor which processes outputs of the first said plurality of sensors or the second said plurality of sensors to yield information specifying the profile of the wellbore. 
     
     
         10 . A wellbore measuring apparatus according to  claim 8 , including a processor which processes outputs of the first said plurality of sensors to yield information specifying the profile of the wellbore and which processes outputs of the second said plurality of sensors to yield information specifying the profile of the wellbore. 
     
     
         11 . A wellbore measuring apparatus according to  claim 1 , comprising a first said plurality of sensors which generate signals that indicate pivot angles of the arms and a second said plurality of sensors which comprise proximity sensors, wherein positions of the plurality of arms obtained via the first plurality of sensors are combined with output signals from the second plurality of sensors to determine locations of points on a wall extending about the wellbore relative to the apparatus. 
     
     
         12 . A wellbore measuring apparatus according to  claim 1 , wherein the free end portions of the arms are outwardly convex in longitudinal section. 
     
     
         13 . A wellbore measuring apparatus according to  claim 1 , wherein the free end portions of the arms are outwardly convex in longitudinal and lateral section. 
     
     
         14 . A wellbore measuring apparatus according to  claim 1 , wherein the plurality of arms are arranged around the outer surface of the outer body in a spiral or helical pattern. 
     
     
         15 . A wellbore measuring apparatus according to  claim 1 , including one or more actuators actuation of which causes the plurality of arms to move from the retracted positions to the extended positions so as to bias the free end portions of the plurality of arms into contact with a wall extending about the wellbore. 
     
     
         16 . A wellbore measuring apparatus according to  claim 1 , wherein each said tier comprises three or more said arms. 
     
     
         17 . A wellbore measuring apparatus according to  claim 1 , wherein for each said arm the corresponding said sensor is contained within a cavity thereof. 
     
     
         18 . A wellbore measuring apparatus comprising:
 an outer body that is tubular and connectable in line with a drill string;   a plurality of arms pivotally coupled to and angularly spaced apart around the outer body, the plurality of arms being arranged in a plurality of tiers, with each said arm having a retracted position and being moveable from the retracted position thereof to an extended position so that a free end portion thereof is radially away from an outer surface of the outer body, with the free end portions of the arms being outwardly rounded in longitudinal and lateral section; and   a plurality of sensors operatively connected to the plurality of arms, respectively, and via which a profile of a wellbore is measured, wherein for each said arm the corresponding said sensor thereof couples thereto adjacent the free end portion thereof.   
     
     
         19 . A wellbore measuring apparatus according to  claim 18 , wherein for each said arm the corresponding said sensor is contained within a cavity thereof. 
     
     
         20 . A wellbore measuring apparatus according to  claim 18 , wherein the sensors comprise ultrasonic sensors. 
     
     
         21 . A wellbore measuring apparatus according to  claim 18 , including a further plurality of sensors which generate signals that indicate pivot angles of the arms. 
     
     
         22 . A wellbore measuring apparatus according to  claim 18 , wherein each said tier comprises three or more said arms. 
     
     
         23 . A wellbore measuring apparatus comprising:
 a plurality of recesses arranged in a helical pattern;   a first plurality of sensors positioned within the recesses and via which a profile of the wellbore is measurable;   a plurality of arms arranged in a helical pattern, the arms being selectively moveable from retracted to extended positions so as to abut a wall extending about the wellbore; and   a second plurality of sensors operatively coupled to the arms and via which the profile of the wellbore is measurable.   
     
     
         24 . A wellbore measuring apparatus according to  claim 23 , wherein one said plurality of sensors generates signals that indicate pivot angles of the arms and another said plurality of sensors comprises ultrasonic sensors. 
     
     
         25 . A wellbore measuring apparatus comprising:
 an outer body that is tubular and connectable in line with a drill string;   a plurality of sensors operatively coupled to and axially spaced along the outer body, each said sensor being arranged to measure at least one characteristic of a wellbore, and with the plurality of sensors being arranged in axially spaced tiers and extending circumferentially about the outer body along a path which is helical; and   at least one rib coupled to and extending radially outwards from the outer surface of the outer body, with the at least one rib being helical in shape and extending between pairs of said sensors within a given said tier.