Position sensor for determining operational condition of downhole tool

Abstract

Downhole tools, such as a sliding sleeve or an openhole type packer, include position indicators. The position indicators can include one or more magnets disposed in predetermined positions in the outer housing and the insert of the sliding sleeve. A casing collar locator (CCL) can be used to detect the magnets and determine the relative positions of the housing magnets and insert magnets. The relative positions of the magnets can be used to determine the operational condition of the downhole tool, i.e., whether a sliding sleeve is open or closed or how much a sealing element of an openhole type packer had to expand to seal an annulus.

1 . A downhole apparatus, comprising:
 a fixed member coupled to tubing and having one or more first signal inducing devices affixed thereto in one or more first predetermined locations; and   a movable member moveable relative to the fixed member, the movable member having one or more second signal inducing devices affixed thereto in one or more second predetermined locations,   wherein the first and second devices induce signals indicative of their positions relative to one another from which the position of the movable member relative to the fixed member is determined.   
   
   
       2 . The apparatus of  claim 1 , wherein the downhole apparatus comprises a packer having a housing for the fixed member and having a piston for the movable member. 
   
   
       3 . The apparatus of  claim 1 , wherein the downhole apparatus comprises a sliding sleeve having an outer housing for the fixed member and having an insert for the movable member. 
   
   
       4 . The apparatus of  claim 3 , wherein the outer housing has a plurality of first openings, and wherein the inset has a plurality of second openings, the second openings aligning with the first openings when the insert has a first position within the outer housing. 
   
   
       5 . The apparatus of  claim 3 , wherein an open or closed condition of the sliding sleeve is inferred from the determined position of the insert relative to the outer housing. 
   
   
       6 . The apparatus of  claim 1 , wherein the first and second signal inducing devices are selected from the group consisting of magnets, radio frequency identification devices, radioactive pills, and ferromagnetic components. 
   
   
       7 . The apparatus of  claim 1 , wherein the one or more first signal inducing devices comprise a plurality of first signal inducing devices positioned a predetermined distance from one another along a longitudinal axis of the fixed member. 
   
   
       8 . The apparatus of  claim 7 , wherein a speed of a detection tool passing through the downhole apparatus is determined using the predetermined distance between the plurality of first signal inducing devices and using a time interval between signals induced from the first signal inducing devices. 
   
   
       9 . The apparatus of  claim 7 , wherein the detection tool comprises a collar locator tool, a magnetically sensitive device, a radio frequency identification device reader, or a radiation detector. 
   
   
       10 . The apparatus of  claim 1 , wherein a variable distance between at least one of the one or more first signal inducing devices and at least one of the one or more second signal inducing devices is determined using a speed of a detection tool passing through the downhole apparatus and using a time interval between signals induced from the at least one first and second signal inducing devices. 
   
   
       11 . A downhole sliding sleeve, comprising:
 an outer housing having one or more first signal inducing devices affixed thereto in one or more first predetermined locations; and   an insert disposed and longitudinally moveable within the outer housing, the insert having one or more second signal inducing devices affixed thereto in one or more second predetermined locations,   wherein the first and second devices induce signals indicative of their positions relative to one another from which the position of the insert within the housing is inferred.   
   
   
       12 . The sleeve of  claim 11 , wherein the outer housing has a plurality of first openings, and wherein the inset has a plurality of second openings, the second openings aligning with the first openings when the insert has a first position within the outer housing. 
   
   
       13 . The sleeve of  claim 11 , wherein the first and second signal inducing devices are selected from the group consisting of magnets, radio frequency identification devices, radioactive pills, and ferromagnetic components. 
   
   
       14 . The sleeve of  claim 11 , wherein the one or more first signal inducing devices comprise a plurality of first signal inducing devices positioned a predetermined distance from one another along a longitudinal axis of the outer housing. 
   
   
       15 . The sleeve of  claim 14 , wherein a speed of a detection tool passing through the apparatus is determined using the predetermined distance between the plurality of first signal inducing devices and using a time interval between signals induced from the first signal inducing devices. 
   
   
       16 . The sleeve of  claim 14 , wherein the detection tool comprises a collar locator tool, a magnetically sensitive device, a radio frequency identification device reader, or a radiation detector. 
   
   
       17 . The sleeve of  claim 11 , wherein a variable distance between at least one of the one or more first signal inducing devices and at least one of the one or more second signal inducing devices is determined using a speed of a detection tool passing through the apparatus and using a time interval between signals induced from the at least one first and second signal inducing devices. 
   
   
       18 . The sleeve of  claim 17 , wherein an open or closed condition of the sliding sleeve is inferred from the determined variable distance. 
   
   
       19 . A downhole apparatus, comprising:
 a fixed member coupled to tubing;   a movable member movable relative to the fixed member;   first means affixed to the fixed member for inducing signals indicative of position;   second means affixed to the movable member for inducing signals indicative of position; and   means for determining the position of the movable member relative to the fixed member based on the relative positions of the first and second means for indicating position.   
   
   
       20 . The apparatus of  claim 19 , wherein the first or second means for inducing signals indicative of position comprises means for inducing a plurality of signals along a longitudinal axis of the apparatus. 
   
   
       21 . The apparatus of  claim 20 , wherein the means for determining the position comprising means for determining a speed of a detection tool passing through the apparatus from the plurality of signals. 
   
   
       22 . The apparatus of  claim 19 , wherein the means for determining position comprises means for detecting signals induced by the first and second means. 
   
   
       23 . The apparatus of  claim 19 , wherein the means for determining the position comprising means for inferring an open or closed condition of the apparatus based on the determined position of the movable member relative to the fixed member. 
   
   
       24 . A downhole position determining method, comprising:
 detecting one or more first devices affixed to a fixed member of a downhole apparatus in one or more first predetermined locations;   detecting one or more second devices affixed to a movable member of the downhole apparatus in one or more second predetermined locations; and   determining the position of the movable member relative to the fixed member from the relative positions of the first and second devices.   
   
   
       25 . The method of  claim 24 , further comprising inferring an operational condition of the downhole apparatus based on the determined position of the movable member relative to the fixed member.