Abstract:
A casing annulus is remediated by inserting a hose into a casing annulus, the hose having a nozzle on its lower end. An acoustic signal is directed into the annulus. A sensor in the hose receives the acoustic signal and transmits data from the sensor to the surface. The data represents the acoustic signal arrival time to the sensor, and an analyzer estimates the sensor depth based on the data. The hose is inserted from a reel into a wellhead above the annulus. An electrical transducer mechanically coupled to the hose creates the acoustic signal. The signal is propagated along the hose and transferred to the fluid in the annulus, where it then propagates further into the annulus. The transducer can be installed on a hose roller along which the hose is fed into the wellhead.

Description:
BACKGROUND 
   1. Field of Invention 
   The device described herein relates generally to the production of oil and gas. More specifically, the present disclosure relates to a system and method for acoustically measuring the nozzle depth of a casing annulus remediation system. 
   2. Description of Related Art 
   Hydrocarbon producing wellbores have casing lining the wellbore and production tubing suspended within the casing. Some wellbores may employ multiple well casings of different diameters concentrically arranged in the wellbore. In some instances, a casing string may develop a leak thereby pressurizing an annulus between the leaking casing string and adjacent casing. Other sources of leaks include tubing, packers, wellhead packoffs, and faulty casing cement bond. 
   Pressure in the annulus can be controlled by introducing a high specific gravity fluid into the annulus, thereby isolating the wellhead from the pressure. In addition to adding fluid directly to the top of the annulus through a wellhead, hydraulic hose systems have been used to inject fluid into the pressurized annulus. The hose generally includes a nozzle element lowered proximate to the annulus bottom where the fluid is discharged from the hose. Typically the hose is stored on a reel from which it is unrolled, and then inserted through an entry in the wellhead. Although the hose may be stiffened with internal pressure, it may still bend when forced through the labyrinth of turns encountered between the wellhead and annulus. Tight tolerances in the annulus may also contribute to hose bending. Thus the “effective” length of hose inserted may not correlate to the length of hose taken from the reel. 
   SUMMARY OF INVENTION 
   The method and device disclosed herein is useful for accurately determining a hose location used in conjunction with casing annulus remediation services. The system employs an acoustic wave generator that creates an acoustic signal within the annulus, and a sensor for receiving the acoustic signal. The casing annulus remediation system employs a hose having a discharge end. The sensor may be included with the hose. The discharge end is inserted through a port formed in a wellbore housing and further forced into a casing annulus beneath the wellbore housing. The sensor receives acoustic signals and transmits data to an associated analyzer representing the received acoustic signal and the time received. Thus knowing the time the signal was created, the median through which the acoustic signal propagates, and the time it was received by a sensor, the depth of the sensor when it received the signal can be determined. Moreover, since the distance between the sensor and the discharge end of the hose is a fixed distance, the hose depth can also be calculated based on the received time of the acoustic signal by the sensor. 
   Disclosed herein is a method of remediating a well, where the well includes a wellhead above a borehole on the well surface. At least one casing string extends from the wellhead into the borehole and an annulus, having fluid therein, is circumferentially adjacent the casing string. A port is also on the wellhead in fluid communication with the annulus. In one example the method comprises, inserting a hose into the annulus through the port to an elevation beneath the port. In one embodiment the hose has a selectively openable discharge nozzle and a sensor in data communication with the well surface. An acoustic signal is generated in the annulus and the acoustic signal is received by the sensor. Data is transmitted from the sensor to the surface, where the data is representative of the time the sensor received the acoustic signal. The sensor depth within the annulus is estimated based on the data transmitted to the surface. The method may further comprise comparing the estimated sensor depth with a predetermined sensor depth, and repeating steps of generating the signal, receiving the signal, and estimating the depth, until the predetermined sensor depth is at or lower than the estimated depth. Fluid may be selectively discharged from the hose nozzle when the nozzle is at a desired depth to remediate the casing annulus. The acoustic wave may be directed into the hose from outside of the wellhead, where the acoustic wave propagates along the hose. Once inside the annulus, the wave propagating along the hose can generate the acoustic signal within the annulus fluid. 
   Also disclosed herein is a casing annulus remediation system. In one embodiment the system includes, a hose having a first end insertable into a casing annulus and a second end adapted to be in fluid communication with remediation fluid. A selectively openable nozzle is affixed to the hose first end and an acoustic wave generator is also coupled to the hose, optionally proximate at the hose second end. An acoustic signal sensor may be mounted to the hose proximate to the hose first end. The system includes an analyzer in data communication with the sensor. A conductor is optionally included along the hose, coupled on one end to the acoustic signal sensor and on another end to the analyzer. The conductor can be any data signal conducting member, such as a wire, a fiber optic, or a braided wire formed within a wall of the hose. A hose insertion system may be coupled with the hose that includes a hose reel and hose rollers. Optionally, an acoustic wave generator is affixed on a hose roller. The remediation system may be included with a cased wellbore assembly. 

   
     BRIEF DESCRIPTION OF DRAWINGS 
     Some of the features and benefits of the present invention having been stated, others will become apparent as the description proceeds when taken in conjunction with the accompanying drawings, in which: 
       FIG. 1  is a side partial cross sectional view of a casing annulus remediation system having an acoustic depth indicator. 
       FIG. 2  is a perspective cutaway view of a portion of a hose used in the system of  FIG. 1 . 
       FIG. 3  is a side view of a drive roller having an acoustic transducer. 
       FIG. 4  is a side cross sectional view of an embodiment of a rotating hose coupling and hose for use with the casing annulus remediation system of  FIG. 1 . 
   

   While the invention will be described in connection with the preferred embodiments, it will be understood that it is not intended to limit the invention to that embodiment. On the contrary, it is intended to cover all alternatives, modifications, and equivalents, as may be included within the spirit and scope of the invention as defined by the appended claims. 
   DETAILED DESCRIPTION OF INVENTION 
   The present invention will now be described more fully hereinafter with reference to the accompanying drawings in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the illustrated embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout. 
   With reference now to  FIG. 1 , one example of a casing annulus remediation system  20  is shown in a side partial cross-sectional view coupled to a portion of a wellhead assembly  23 . In the embodiment shown, the remediation system  20  includes a hose insertion system  22  having rotatable rollers  24  with a hose  26  passing between the rollers  24 . A reserve length of hose  26  is illustrated coiled and stored on the hose reel  28 . The hose  26  extends from the rollers  24  into a valve assembly  30  in a direction opposite the hose reel  28 . The valve assembly  30  is flangedly connected to a flanged port  35  that is attached to a low pressure wellhead housing  32 . The low pressure wellhead housing  32  comprises a portion of the wellhead assembly  23 . The wellhead assembly  23  also includes an inner casing hanger  42  having casing  44  attached to its lower end. The low pressure wellhead housing  32  circumscribes the inner casing hanger  42  and forms an annulus space  36  therebetween. A passage  34  (shown in dashed outline) is formed through the low pressure wellhead housing  32  and aligned with an opening in the flanged port  35 . 
   The hose  26  is shown exiting the passage  34  and extending into the annular space  36 . Also within the annulus  36  is a casing hanger  38  affixed to the low pressure wellhead housing  32  and having casing  40  extending from its lower end. The casing  40  and inner casing  44  extend downward past the wellhead housing  32  below surface and adjacent a wellbore  5 . An annulus  46  resides in the space between the casing  40  and inner casing  44  and the region adjacent the wellbore  5 . The lower or first end of the hose  26  is shown disposed within the annulus  46  and having an attached fluid nozzle assembly  48 . The fluid nozzle assembly  48  is selectively operable to open and close to deliver remediation fluid from the hose  26  into the annulus  46  for the above described remediation operations. 
     FIG. 2  is a perspective cutaway view of a portion of a hose  26  illustrating metal braids ( 27 ,  29 ) formed within the wall of the hose  26 . The braids ( 27 ,  29 ) circumscribe the hose  26  axis and extend substantially along the length of the hose  26 . In one example of use, the metal braids ( 27 ,  29 ) comprise a conductor from which sensor  50  can send data signals through the hose  26  for data analysis. The material of the braids ( 27 ,  29 ) is not limited to metal, but can be any material capable of transmitting data signals, such as electrically conductive polymers and fiber optics. 
   A sensor  50  is schematically illustrated in the hose  26  proximate to the lower end and above the fluid nozzle assembly  48 . A connector  51  is schematically depicted connected to the sensor  50 . The connector  51  is operable to convey data communication between the sensor  50  and the surface. The connector  51  may comprise a signal conducting member, such as a wire, with or inside the hose  26  or the metal braids ( 27 ,  29 ). 
   An acoustic transducer  52  is schematically illustrated operatively coupled to the hose  26  at the surface via a coupling  54 . The transducer  52  may directly contact the hose  26  to impart vibrational energy into the hose  26 . In this embodiment the coupling  54  comprises a mechanical means of communicating acoustically energy from the transducer  52  to the hose  26 . Optionally, the transducer  52  may induce vibrations in the hose  26  through a pulsed electro-magnetic field. In this embodiment the coupling  54  comprises a fluctuating magnetic field. The acoustic transducer  52  produces vibrations in the hose  26  via the coupling  54 . The vibrations in the hose  26  form acoustic waves propagating through the hose  26  to form an acoustic wave within the annular space  36 ; the acoustic wave then travels to within the annulus  46 . Optionally, an acoustic transducer  25  may be included directly on one or both of the rollers  24  for transmitting an acoustic wave through the roller  24  and to the hose  26 . 
     FIG. 3  illustrates a longitudinal view of an example of a roller assembly  21  that comprises a pair of rollers  24 . The rollers  24  comprises a spool body  31  having a cylindrical base  39  with flange members  41  coaxially aligned with the base  39  on each of its ends. On one side of a flange member  41  is affixed an example of an acoustic transducer  25 . A spring  55  is coaxially disposed adjacent a roller  24 , as discussed in more detail below, the spring  55  comprises a compressive force to the rollers  24  to better engage the hose  26  as it passes therebetween the rollers  24 . The acoustic transducer  25  is connected to a power source  33  for providing power to operate the acoustic transducer  25 . In the example shown, the transducer  25  includes a piezoelectric sleeve  45  that converts electrical energy from the power source  33  into mechanical vibrations. Terfenol™ is one example of the sleeve  45  material. Also shown is a coil  47  circumscribing the sleeve  45 , the coil  47 , which may be comprised of a copper winding, is in electrical communication with slip rings  49 . The slip rings  49  are cylindrical bands disposed around the coil  47  that are rotatable with the coil  47 . Brushes  53  connected to the power source  33  contact the slip ring  49  outer circumference, thereby providing an electrical path between the power source  33  and coil  47  for exciting the sleeve  45 . 
     FIG. 4  illustrates one example of a rotary coupling assembly  64  on the upper or second end of the hose  26 , and an embedded sensor  50   a  on the first or lower end of the hose  26 . The hose  26  lower end is shown disposed within the annulus  46 . The coupling assembly  64  comprises a cylindrical annular housing  66  open on one end and hollowed out to receive a cylindrical spindle  70  therein. A series of bearings  72  circumscribe the spindle  70  and fit into corresponding hemispherical recesses formed on the inner surface of the housing  66  and the outer surface of the spindle  70 . Seals  74  are also provided in annular recesses along the outer surface of the spindle  70 . A fluid inlet  68  is formed into the housing  66  on the end opposite its opening. A passage  71  is formed along the axis of the spindle  70  extending therethrough. The spindle  70  includes an axial bore on its end that extends out from the housing  66 . The bore is formed to receive a hose nipple  76  therein and is coaxially aligned with the passage  71 . The hose nipple  76  includes a passage  77  formed along its axis and aligned with the passage  71  in the spindle  70 . The hose nipple  76  has a male end contoured on its outer surface to mate with a female portion of the hose  26  having corresponding contours on its inner surface. The passage  77  within the hose nipple  76  is similarly aligned with a fluid passage  43  formed along the hose  26  axis. A fluid supply system (not shown) provides pressurized remediation fluid to the rotary coupling assembly  64  via the opening  68 . The aligned passages ( 71 ,  77 ,  43 ) therefore provide fluid communication from the fluid supply system into the hose  26 . Moreover, the rotating spindle  70  enables the hose  26  to be placed on the reel  28  without tangling the hose  26  while rotating the reel  28 . 
   The end of the hose  26  disposed within the annulus  46  includes an embodiment of the sensor  50   a  embedded within the hose  26  wall and shown electrically connected to the wire braids ( 27 ,  29 ). The wire braids ( 27 ,  29 ) extend through the hose  26  wall to the surface and into electrical communication with slip rings ( 79 ,  80 ) provided on the hose  26  proximate to the rotary coupling assembly  64 . Corresponding electrical brushes ( 82 ,  83 ) are shown in electrical communication with the slip rings ( 79 ,  80 ) via the dashed lines there between. The brushes ( 82 ,  83 ) are further in electrical or data communication with the analyzer  58 , therefore providing an electrical communication loop between the sensor  50   a  and the data analyzer  58 . 
   In one example of use, an acoustic wave is generated within the hose  26  above the surface and outside of the wellhead assembly  23 . The vibrational acoustic wave then travels along the hose  26 , through the valve assembly  30  and wellhead assembly  23 , and into the annular space  36 . Once inside the annular space  36 , the hose vibration creates a corresponding acoustic signal, illustrated by curved lines  56 , within the fluid residing in the annular space  36 . The fluid can be a liquid that has leaked within the casing annulus, or it can be a gas from within the wellbore, or ambient air. Continued propagation of the acoustic waves  56  continues into the annulus  46  where it can be received by the sensor  50 . The sensor, which can be a piezo electric device, senses the acoustic wave  56  and transmits data to an associated analyzer, such as via the illustrative coupling  60  to the analyzer  58 . Optionally, the data signal can travel through the connector  51 , back up the hose  26 , where it is received on surface and then transferred to the analyzer  58  via the coupling  62 . The coupling  62  comprises any means of transmitting communication from the connector  51  to the analyzer  58 . The coupling  62  may comprise the rotary coupling assembly  64 , it can be wireless telemetry, a direct connection between the connector  51  and the analyzer  58 , or any other manner of transferring data from the connector  51  to the analyzer  58 . 
   The analyzer  58  may include an analog to digital converter as well as digital signal processing. The analyzer  58  is configured to receive the signal data through the coupling  62  and determine the time of travel of the acoustic signal through the annular space  36  and annulus  46 . Using a calculated acoustic signal travel time, the analyzer  58  can also determine a depth of the sensor  50  when it received the acoustic signal. An accurate estimate of the sensor  50  depth can in turn provide a means for determining an accurate depth of the fluid nozzle assembly  48 . 
   In one mode of operation, the acoustically measured depth of either the sensor  50  or the fluid nozzle assembly  48  is compared to a desired depth. In one example, a desired depth is a depth at which the fluid nozzle assembly  48  can be activated to allow fluid through the hose  26  to fill the annulus  46  for remediation or other wellbore service operations. It is well within the capabilities of those saddled in the art to adequately determine a desired depth. If, on the other hand, it is determined the sensor  50  and/or fluid nozzle assembly  48  is above the desired depth, the acoustic sequence of sending acoustic signals and processing the received acoustic data can be repeated while continuously urging the hose  26  deeper within the annulus  46 . When recorded data indicates the sensor  50  or fluid nozzle assembly  48  is at or below the desired depth, the fluid nozzle assembly  48  can be selectively opened for remediation operations. 
   It is to be understood that the invention is not limited to the exact details of construction, operation, exact materials, or embodiments shown and described, as modifications and equivalents will be apparent to one skilled in the art. In the drawings and specification, there have been disclosed illustrative embodiments of the invention and, although specific terms are employed, they are used in a generic and descriptive sense only and not for the purpose of limitation. Accordingly, the invention is therefore to be limited only by the scope of the appended claims.