Apparatus and method

Abstract

An apparatus and method to measure the position of a portion of a pump assembly within a well particularly for use in an oil or gas well and for downhole pumps driven by a drive shaft running from a surface motor. The apparatus comprises at least one measurement device which senses the position of a portion of a pump assembly downhole. The information can be used to position a rotor of the pump assembly at a position relative to a pump housing of the pump assembly to produce fluids from the well at an increased rate. Where two measurement devices are provided, they can count the number of revolutions of the drive shaft of the pump assembly at two spaced apart points. The strain or torsion within the drive shaft can then be calculated.

1 . An apparatus for determining the position of at least a portion of a pump assembly in a borehole, the apparatus comprising: 
 a detection device adapted to detect the position of the portion of the pump assembly within the borehole, the detection device connectable to a borehole;    a communication device adapted to relay information on the position of the portion of the pump assembly within the borehole to a controller.    
     
     
         2 . Apparatus as claimed in  claim 1 , wherein the detection device has a first part which is connectable to the borehole and a second part which is connectable to the pump assembly.  
     
     
         3 . Apparatus as claimed in  claim 1 , wherein the detection device comprises a magnet and a magnet sensing device.  
     
     
         4 . Apparatus as claimed in  claim 1 , wherein the detection device is adapted to detect the longitudinal displacement of the portion of the pump assembly within the borehole.  
     
     
         5 . Apparatus as claimed in  claim 4 , comprising a movement mechanism, adapted to vary the longitudinal displacement of the portion of the pump assembly.  
     
     
         6 . Apparatus as claimed in  claim 5 , wherein the movement mechanism is adapted to vary the longitudinal displacement of the portion of the pump assembly in response to the longitudinal displacement of the portion of the pump assembly detected by the detection device.  
     
     
         7 . Apparatus as claimed in  claim 1 , wherein the portion of the pump assembly comprises an elongate member and the detection device comprises a first measurement device adapted to measure the extent of rotation of the elongate member at a first point and the apparatus further comprises a second measurement device adapted to measure the extent of rotation of the elongate member at a second point; and a comparison mechanism adapted to compare the rotation measured by the first measurement device and the rotation measured by the second measurement device.  
     
     
         8 . Apparatus as claimed in  claim 7 , wherein the elongate member is adapted to connect a rotatable member, which in use, is provided in a well, to a rotating mechanism which in use, is provided at the top of or above the well.  
     
     
         9 . Apparatus as claimed in  claim 8 , wherein the rotatable member is an artificial lift device.  
     
     
         10 . Apparatus as claimed in  claim 8 , wherein the rotating mechanism is a motor.  
     
     
         11 . Apparatus as claimed in  claim 7 , wherein each measurement device is connected to the comparison mechanism and is adapted to transmit information thereto.  
     
     
         12 . Apparatus as claimed in  claim 7 , wherein each measurement device is adapted to sense each complete revolution of the elongate member.  
     
     
         13 . Apparatus as claimed in  claim 7 , wherein each measurement device counts the number of revolutions of the elongate member.  
     
     
         14 . Apparatus as claimed in  claim 7 , further comprising a control device connected to the elongate member, the control device being adapted to vary the speed of the elongate member in response to the torsion calculated by the comparison mechanism.  
     
     
         15 . Apparatus as claimed in  claim 7  comprising more than two measurement devices.  
     
     
         16 . Apparatus as claimed in  claim 15 , comprising a third and fourth measurement device which co-operate with the first and second measurement devices such that the apparatus is adapted to sense each half-revolution of the elongate member at the first and second points.  
     
     
         17 . Apparatus as claimed in  claim 7 , wherein the measurement device at the first point comprises at least one sensing device adapted to monitor at least one of the speed of rotation and the direction of rotation of the elongate member.  
     
     
         18 . A method for determining the position of at least a portion of a pump assembly in a borehole, the method comprising the steps of: 
 providing a detection device within the borehole;    detecting a position of the portion of the pump assembly within the borehole; and    relaying the information on the position of the portion of the pump assembly within the borehole to a controller.    
     
     
         19 . A method as claimed in  claim 18 , used to determine the longitudinal displacement of the portion of the pump assembly.  
     
     
         20 . A method as claimed in  claim 19 , wherein the longitudinal displacement of the portion of the pump assembly is adjusted in response to the detected longitudinal displacement of the portion of the pump assembly.  
     
     
         21 . A method as claimed in  claim 18 , wherein the portion of the pump assembly comprises an elongate member and the method further comprises the steps of: 
 rotating at least a portion of the elongate member;    measuring the extent of rotation of the elongate member at a first point;    measuring the extent of rotation of the elongate member at a second point; and    comparing the extent of rotation of the elongate member at the first and second points.    
     
     
         22 . A method as claimed in  claim 21 , wherein the method is used to determine the torsion of an elongate member suspended within a well.  
     
     
         23 . A method as claimed in  claim 22 , wherein the method is used to determine the torsion of a drive shaft extending from a motor to a pump within the well.  
     
     
         24 . An apparatus for determining the position of at least a portion of a pump assembly within a well, the apparatus comprising: 
 a portion of a pump assembly;    a detection device adapted to detect the position of the portion of the pump assembly within the borehole, the detection device being connectable to a borehole; and    a communication device adapted to relay information on the position of the portion of the pump assembly within the borehole to a controller.    
     
     
         25 . Apparatus as claimed in  claim 24 , wherein the portion of the pump assembly comprises an elongate member and the detection device comprises a first measurement device adapted to measure the extent of rotation of the elongate member at a first point; the apparatus further comprising a second measurement device adapted to measure the extent of rotation of the elongate member at a second point; and a comparison mechanism adapted to compare the rotation measured by the first measurement device and the rotation measured by the second measurement device.  
     
     
         26 . Apparatus as claimed in  claim 25 , further comprising a motor and a rotatable member.  
     
     
         27 . Apparatus as claimed in  claim 25 , wherein the first measurement device is provided above the well.  
     
     
         28 . Apparatus as claimed in  claim 25 , wherein the second measurement device is provided in the well.  
     
     
         29 . Apparatus as claimed in  claim 25 , wherein the first point is proximate to the motor and the second point is proximate to the rotatable member.  
     
     
         30 . Apparatus as claimed in  claim 25 , wherein each measurement device comprises a magnet and a magnet sensing device at least one being provided on the elongate member and the other being provided proximate to but not connected to the elongate member such that one is rotatable with respect to the other.  
     
     
         31 . Apparatus as claimed in  claim 30 , wherein the magnet is provided on the elongate member and the magnetic sensing device is provided proximate to but not connected to the elongate member.  
     
     
         32 . Apparatus as claimed in  claim 25 , further comprising production tubing and wherein the magnetic sensing device of the second measurement device is provided on the production tubing.  
     
     
         33 . Apparatus as claimed in  claim 25 , wherein the comparison mechanism is provided at the surface.