Abstract:
A deployment device for controlling rate of movement of an instrument inside a conduit includes a mandrel having a coupling to affix the deployment device to the instrument and a controllable brake disposed in the mandrel, the brake controllably actuatable to maintain the mandrel and instrument at a selected speed within the conduit.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    Not applicable. 
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not applicable. 
       BACKGROUND OF THE INVENTION 
       [0003]    1. Field of the Invention 
         [0004]    The invention relates generally to the field of well logging instrument conveyance devices. More specifically, the invention relates to devices used to move a well logging instrument through the interior of a pipe string so that the well logging instrument can be deployed in a wellbore. 
         [0005]    2. Background Art 
         [0006]    Well logging instruments are used, among other purposes, to make measurements of physical properties of Earth formations that have been penetrated by a wellbore. Well logging instruments typically include one or more types of sensors to make the measurements of the physical properties. Signals from the sensors may be communicated to the Earth&#39;s surface by various forms of signal telemetry, and/or may be stored in various types of recording device disposed within the well logging instrument. 
         [0007]    As the well logging instrument is moved along the wellbore, a record of the signals generated by the sensors is made with respect to time and/or depth of the sensors within the wellbore. There are a number of different devices known in the art for moving the well logging instrument along the wellbore. The instrument may be affixed to the end of an armored electrical cable, which is unwound from w winch or similar spooling device to extend the instrument into the wellbore by the action of Earth&#39;s gravity. The instrument is withdrawn by rewinding the cable onto the winch. The well logging instrument may be moved along the wellbore by coupling it to the end of a coiled tubing, and unspooling and spooling the coiled tubing to move the instrument into and out of the wellbore. The instrument may also be coupled to the end of a threadedly coupled pipe, called a pipe “string.” The pipe string with the instrument attached to the lower end thereof is extended into the wellbore by threadedly coupling segments of pipe end to end. The pipe string is withdrawn from the wellbore by threadedly uncoupling segments of pipe. 
         [0008]    U.S. patent application Publication No. 2004/0074639 filed by Runia discloses another device for moving the well logging instrument along the wellbore. The system comprises a tubular conduit or pipe extending from the Earth&#39;s surface into the wellbore containing a body of wellbore fluid. A well logging instrument string is included that is capable of passing from a position within the conduit to a position outside the conduit at a lower end part thereof and capable of being suspended by the conduit in said position outside the conduit. In some embodiments the well logging instrument may include a pressure pulse device arranged within the conduit in a manner that the pressure pulse device is in data communication with the logging tool. The pressure pulse device is capable of generating pressure pulses in the body of wellbore fluid, the pressure pulses representing data communicated by the logging tool string to the pressure pulse device during logging of Earth formation by the logging tool string. 
         [0009]    In using the device disclosed in the Runia &#39;639 publication it has been found desirable to be able to control the speed of movement of the well logging instrument inside the conduit, particularly when the conduit is disposed in a vertical or nearly vertical wellbore. Conversely, it is necessary to provide some mechanism to move the well logging instrument along the interior of the conduit when the wellbore is highly inclined form vertical such that Earth&#39;s gravity is incapable of moving the well logging instrument sufficiently. 
       SUMMARY OF THE INVENTION 
       [0010]    A deployment device for controlling rate of movement of an instrument inside a conduit according to one aspect of the invention includes a mandrel having a coupling to affix the deployment device to the instrument and a controllable brake disposed in the mandrel, the brake controllably actuatable to maintain the mandrel and instrument at a selected speed within the conduit. 
         [0011]    Other aspects and advantages of the invention will be apparent from the following description and the appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  schematically shows a first embodiment of the logging system of the invention, using a casing extending in the wellbore. 
           [0013]      FIG. 2  schematically shows a second embodiment of the logging system of the invention, using a drill string extending in the wellbore. 
           [0014]      FIG. 3  schematically shows the embodiment of  FIG. 2  during a further stage of operation. 
           [0015]      FIG. 4  shows one embodiment of a deployment device according to the invention. 
           [0016]      FIGS. 4A and 4B  show alternative arrangements of a motor and a traction drive wheel. 
           [0017]      FIG. 4C  shows an alternative type of motor that may be used in some embodiments according to  FIG. 4A  or  4 B. 
           [0018]      FIG. 5  shows an alternative braking mechanism for a deployment device. 
       
    
    
     DETAILED DESCRIPTION 
       [0019]      FIG. 1  shows a wellbore  1  formed in an Earth formation  2 , the wellbore being filled with drilling fluid. The wellbore  1  has an upper portion provided with a casing  4  extending from a drilling rig (not shown) at the Earth&#39;s surface  8  into the wellbore  1  to a casing shoe  5 , and an open lower portion  7  extending below the casing shoe  5 . A conduit, which in the present embodiment is a tubular drill string  9  containing a body of drilling fluid  10  and having an open lower end  11 , extends from the drilling rig (not shown) into the wellbore  1  whereby the open lower end  11  is disposed in the open lower wellbore portion  7 . A well logging instrument  12  capable of being lowered or raised through the drill string  9 , is retrievably suspended in the drill string  9  by a deployment device  12 A, which will be explained in more detail with reference to  FIG. 4 . The well logging instrument  12  includes one or more types of sensors, including, for example, a formation tester (FT) tool  14  having retractable arms  16 . The logging instrument may include a fluid pressure pulse device  18  arranged at the upper end of the FT tool  14 , whereby the FT tool  14  extends below the lower end part  11  of the drill string  9  and the pressure pulse device  18  is disposed within the drill string  9 . The FT tool  14  may be powered by a battery (not shown) and can be provided with an electronic memory (not shown) or other recording medium for storing measurement data, which for the FT tool  14  may include measurements of fluid pressure in the Earth formation  2  at selected depths therein. 
         [0020]    It is to be clearly understood that the FT tool  14  shown in  FIG. 1  is only an example of a well logging sensor or instrument that may be used with a deployment device according to the invention. It is within the scope of this invention that any known well logging sensor or instrument that can be moved through the inside of a tube or conduit may be used with a deployment device according to the invention. Such sensors and/or instruments include, without limitation, acoustic sensors, electromagnetic resistivity sensors, galvanic resistivity sensors, seismic sensors, Compton-scatter gamma-gamma density sensors, neutron capture cross section sensors, neuron slowing down length sensors, calipers, gravity sensors and the like. 
         [0021]    The fluid pressure pulse device  18  has a variable flow restriction (not show) which is controlled by electric signals transmitted by the FT tool  14  to the pressure pulse device  18 , which signals represent part of the data produced by the FT tool  14  during the making of measurements of the earth formation  2 . The upper end of the deployment device  12 A may be provided with a latch  20  for latching of an armored electrical cable (not shown) to the device  12 A for retrieval from the bottom of the drill string  9 . 
         [0022]    A wellhead  22  is typically connected to the upper end of the casing  4  and is provided with an outlet conduit  24  terminating in a drilling fluid reservoir  26  provided with a suitable sieve means (not shown) for removing drill cuttings from the drilling fluid. A pump  28  having an inlet  30  and an outlet  32  is arranged to pump drilling fluid from the fluid reservoir  26  into the upper end of the drill string  9 . 
         [0023]    A control system  34  located at the Earth&#39;s surface is connected to the drill string  9  for sending or receiving fluid pressure pulses in the body of drilling fluid  10  to or from the fluid pressure pulse device  18 . 
         [0024]    A second embodiment shown in  FIG. 2  is largely similar to the first embodiment, except with respect to the following aspects. The drill string is provided with a drill bit  40  at the lower end thereof, a measurement-while-drilling (MWD) device  42  is removably arranged in the lower end part of the drill string  9 , and the logging instrument  12  is shown as being lowered through the drill string  9 . The drill bit  40  is provided with a passage  44  in fluid communication with the interior of the drill string  9 , which passage  44  is provided with a closure element  46  removable from the passage  44  in outward direction and connected to the MWD device  42 . The lower end of the logging instrument  12  and the upper end of the MWD device  42  are provided with respective cooperating latching members  48   a ,  48   b  capable of latching the logging tool string  12  to the MWD device  42 . Furthermore, the deployment device  12 A may be provided with pump cups  50  for pumping the logging instrument  12  through the drill string  9 , either in downward or upward direction thereof. 
         [0025]    The closure element  46  has a latching mechanism (not shown) for latching the closure element  46  to the drill bit  40 . The latching mechanism is arranged to co-operate with the latching members  48   a ,  48   b  in a manner that the closure element  46  unlatches from the drill bit  40  upon latching of latching member  48   a  to latching member  48   b , and that the closure element  46  latches to the drill bit  40 , and thereby closes passage  44 , upon unlatching of latching member  48   a  from latching member  48   b.    
         [0026]    In  FIG. 3  shows the embodiment of  FIG. 2  during a further stage of operation whereby the logging instrument  12  has been latched to the MWD device  42  and the closure element  46  has been unlatched from the drill bit  40 . The drill string  9  has been raised a selected distance in the wellbore  1  so as to leave a space  52  between the drill bit  40  and the wellbore bottom. The logging instrument  12  is suspended by the drill string  9  in a manner that the FT tool  14  extends through the passage  44  to below the drill bit  40 , and that the pressure pulse device  18  is arranged within the drill string  9 . The MWD device  42  and the closure element  46  consequently extend below the logging tool string  12 . 
         [0027]    During normal operation of the embodiment of  FIG. 1 , the drill string  9  is lowered into the wellbore  1  until the lower end of the string  9  is positioned in the open wellbore portion  7 . Next the logging instrument  12  is lowered from surface through the drill string  9  by means of the deployment device  12 A, whereby during lowering the arms  16  are retracted. Lowering continues until the FT tool  14  extends below the drill string  9  while the pressure pulse device  18  is positioned within the drill string  9 , in which position the logging instrument  12  is suitably supported. The arms  16  are then extended against the wall of the wellbore and the FT tool  14  is induced to make its measurements of the Earth formation  2 . The measurement data may be stored in the electronic memory, and part of the logging data may be transmitted by the FT tool  14  in the form of electrical signals to the pressure pulse device  18 , which signals induce controlled variations of the variable flow restriction. 
         [0028]    Simultaneously with operating the logging instrument  12 , drilling fluid is pumped by pump  28  from the fluid reservoir  26  into the drill string  9  via inlet  30  and outlet  32 . The controlled variations of the variable flow restriction induce corresponding pressure pulses in the body of drilling fluid present in the drill string  9 , which pressure pulses are monitored by the control system  34 . In this manner the system operator can monitor the well logging operation and can take corrective action if necessary. For example, incorrect deployment of the arms  16  of the RFT tool can be detected in this manner at an early stage. 
         [0029]    After the logging run has been completed, the logging instrument  12  may retrieved through the drill string  9  to surface by wireline connected to latch  20 . Optionally the drill string  9  is then removed from the wellbore  1 . 
         [0030]    During normal operation of the embodiment of  FIGS. 2 and 3 , the drill string  9  is operated to drill the lower wellbore portion  7  whereby the closure element  46  is latched to the drill bit  40  so as to form a part thereof. The MWD device  42  induces fluid pressure pulses in the body of drilling fluid  10  representative of selected drilling parameters such as wellbore inclination or wellbore temperature. The use of MWD devices is known in the art of drilling, and will not be explained in more detail in this context. 
         [0031]    When it is desired to log the earth formation  2  surrounding the open wellbore portion  7 , the logging tool string  12  is pumped down the drill string  9  using pump  28  until the logging tool string  12  latches to the MWD device  42  by means of latching members  48   a ,  48   b . During lowering of the string  12 , the arms  16  of the FT tool  14  are retracted. Then the drill string  9  is raised a selected distance until there is sufficient space below the drill string for the FT tool  14 , the MWD device  42  and the closure element  46  to extend below the drill bit  40 . Upon latching of latching member  48   a  to latching member  48   b , the closure element  46  unlatches from the drill bit  40 . Continuous operation of pump  28  causes further downward movement of the combined logging tool string  12 , MWD device  42  and closure element  46  until the logging tool string  12  becomes suspended by the drill string. In this position (shown in  FIG. 3 ) the FT tool  14  extends through the passage  44  into the space  52  below the drill bit  40 , and the pressure pulse device  18  and closure element  46  extend below the FT tool in the space  52 . 
         [0032]    The arms  16  are then extended against the wall of the wellbore and the FT tool  14  is operated to measure the Earth formation  2 . The measurement data are stored in the electronic memory, and part of the data are transmitted by the FT device  14  in the form of electrical signals to the pressure pulse device  18 , which signals induce controlled variations of the variable flow restriction of the MWD device  42 . 
         [0033]    Simultaneously with operating the logging tool string  12 , drilling fluid is pumped by pump  28  from the fluid reservoir  26  into the drill string  9  via inlet  30  and outlet  32 . The controlled variations of the variable flow restriction induce corresponding pressure pulses in the body of drilling fluid present in the drill string  9 , which pressure pulses are monitored by the control system  34 . Thus, the operator is in a position to monitor the logging operation and to take corrective action if necessary (similarly to the embodiment of  FIG. 1 ). 
         [0034]    After measuring has been completed, the instrument  12  may be retrieved to surface through the drill string  9  by wireline connected to latch  20  at the top of the deployment device  12 A. During retrieval the closure element  46  latches to the drill bit  40  (thereby closing the passage  44 ) and the latching members  48   a ,  48   b  unlatch. Alternatively the instrument  12  can be retrieved to surface by reverse pumping of drilling fluid, i.e. pumping of drilling fluid down through the annular space between the drill string  9  and the wellbore wall and into the lower end of the drill string  9 . Optionally a further wellbore section then can be drilled, or the drill string  9  can be removed from the wellbore  1 . 
         [0035]    As will be readily appreciated by those skilled in the art, during deployment of the well logging instrument  12  into the drill string  9 , and during removal therefrom, it is desirable to be able to control the speed of movement of the instrument  12  within the drill string. A deployment device  12 A according to the invention is configured to control the speed of motion of the instrument  12  along the interior of the drill string  9 , and where appropriate, can provide motive power to move the instrument  12  along the interior of the drill string  9  during deployment or withdrawal of the instrument  12 . 
         [0036]    One embodiment of the deployment device  12 A will now be explained with reference to  FIG. 4 . The deployment device  12 A includes a generally cylindrically shaped mandrel  50  that can traverse the interior of the drill string ( 9  in  FIG. 1 ) or other pipe or conduit extended into the wellbore. The mandrel  50  may include a fishing neck  52  or similar latching device at its upper end to enable retrieval of the device  12 A under particular circumstances such as by wireline (electrical cable), or coiled tubing, for example should such retrieval prove necessary. The lower end of the mandrel  50  includes a threaded connector  54  or other mechanism to couple the deployment device  12 A to the upper end of the well logging instrument ( 12  in  FIG. 1 ). A pressure sealed compartment  50 A disposed in a portion of the mandrel  50 , which may be an enclosure or a separate module or “sub”  56 , includes power and control electronics disposed therein. Such electronics may include a rechargeable battery  62 , a programmable, microprocessor based system controller  58  and a motor driver  60 . 
         [0037]    In the present embodiment, the motor driver  60  can generate alternating current used to operate drive motors, as will be further explained. The motor driver  60  may also induce alternating current in such drive motors such that the motors provide electrically regenerative braking. The controller  58  can provide control signals to operate the motor driver  60  such that a substantially constant, or other controlled speed of movement of the deployment device  12 A along the interior of the drill string can be maintained. 
         [0038]    In the present embodiment, the drive motors can be induction motors formed by combination of high magnetic permeability steel traction wheels  66  that are held in frictional contact with the interior wall of the drill string (or other conduit) by a biasing device such as bow springs  64  acting on the wheels&#39; axles. The wheels  66  may each be disposed proximate to a corresponding induction coil  68 . One or more of the wheels  66  may include embedded permanent magnets  67  to assist in regenerative braking, as will be further explained. The particular biasing device shown in this embodiment is not intended to limit the scope of the invention. Alternative biasing devices may be used in other embodiments, such as pressurized hydraulic or pneumatic cylinders, coil springs, and shape memory metal springs, for example. 
         [0039]    As the deployment device  12 A moves downward inside the pipe or conduit by gravity, the rate of descent may be controlled by suitable current being passed through the induction coils  68  by the motor driver  60  so as to electrically brake the wheels  66 . Electrical power may be generated by such braking, and the generated power may be conditioned and supplied to the battery  62  to maintain its charge. Conversely, when it is necessary to supply motive power to move the device  12 A and the well logging instrument ( 12  in  FIG. 1 ) coupled thereto along the interior of the conduit, such as in highly inclined wellbores, the motor driver  60  may supply suitable alternating current to the induction coils  68  to cause the wheels  66  to turn, thus moving the mandrel  50 . The amount and rate of rotation and/or braking force may be selected by the controller  58  to maintain any selected rate of motion of the mandrel  50  along the inside of the conduit. Rate of motion of the mandrel  50  may be determined using, for example an accelerometer  57  or similar device in signal communication with the controller  58 . 
         [0040]    The present embodiment includes components intended to cause the wheels  66  to act as the rotors in an induction motor. It will be appreciated by those skilled in the art that the wheels  66  may be driven by alternative arrangements of a motor rotationally coupled to the wheels  66 .  FIG. 4A  shows one possible arrangement. One or more of the wheels  66  may in such embodiments include a ring gear  69  formed inward of the outer surface of the wheel  66 . A spur gear  75  coupled to the output shaft of a motor  73  may be placed in contact with the ring gear  69  to cause wheel rotation by operation of the motor  73 . The arrangement shown in  FIG. 4A  may also provide regenerative braking as the wheel  66  rotates the motor  73 . 
         [0041]    Another arrangement is shown in  FIG. 4B , in which the wheel  66  includes a ring gear  69 A disposed on a surface proximate the wheel axle. A motor  73 A may have on its output shaft a worm gear  75 A in contact with the ring gear  69 A. Rotation of the motor  73 A will thus drive the wheel  66 . The arrangement shown in  FIG. 4B  may be advantageous when it is desirable not to enable motion of the deployment deice ( 12 A in  FIG. 1 ) except by operation of the motor  73 A. 
         [0042]    An alternative type of motor that may be used in embodiments such as shown in  FIGS. 4A and 4B  will now be explained with reference to  FIG. 4C . The motor ( 73  in  FIG. 4A  or  73 A in  FIG. 4B ) in the present embodiment can be an hydraulic motor  73 B. The hydraulic motor  73 B has its inlet and outlet lines,  173 B,  273 B, respectively, coupled to a two-port, three-way valve  94 . The three way valve  94  may be actuated by a solenoid  96 . The solenoid  96  may be operated by a circuit corresponding to the controller and motor driver ( 58 ,  60 , respectively in  FIG. 4 ). In the center position, shown in  FIG. 4C , the three way valve  94  couples the inlet line  173 B to the outlet line  273 B of the motor  73 B to enable the motor to be rotated freely by the wheel ( 66  if the embodiment of FIG.  4 A is used) which it drives. Thus, when the three-way valve  94  is in the center position, the deployment device may move relatively unhindered. 
         [0043]    When it is determined that braking force is needed, the three-way valve  94  is moved to the leftmost position in  FIG. 4C . The outlet line  273 B of the motor  73 B is then coupled to an accumulator  90 . The accumulator  90  can be conventional in design and include a piston  92 A biased by a spring  92 B to maintain hydraulic pressure on one side of the piston  92 A. Thus, the motor  73 B pumps fluid against pressure in the accumulator  90  so as to provide resistance to rotation by the wheel. Fluid to be pumped by the motor  73 B is supplied by the three way valve  94  connecting the inlet line  173 B of the motor  73 B to a reservoir  92 . When used as a brake, the motor  73 B will provide some regenerative charging of the accumulator  90 . 
         [0044]    When it is determined that motive force is required for the deployment device, the three way valve  94  may be moved to the right hand position in  FIG. 4C , so as to couple the inlet line  173 B of the motor  73 B to the pressurized fluid in the accumulator  90 , thus driving the motor  73 B. 
         [0045]    In some embodiments, pressure charge may be maintained in the accumulator  90  by a separate pump  73 C which may be driven by a separate motor, or a turbine exposed to flow of fluid in the wellbore or other type of drive mechanism. The pump  73 C transfers fluid from the reservoir  92  to the accumulator  90  to maintain pressure therein. The outlet line of the pump  73 C may include a check valve  98  to prevent leak off of pressure through the pump  73 C when the pump is not operating. 
         [0046]    Another embodiment of a braking mechanism that may be used in substitution of or in addition to the inductive traction device explained above will now be explained with reference to  FIG. 5 . The mandrel  50  may include near the upper end fluid inlet ports  76  which admit drilling fluid from inside the conduit (drill string) as the deployment device s moved downwardly through the conduit. Fluid may be urged to flow through the inlet ports  76  by a seal cup  80  or similar fluid deflecting device disposed on the outside of the mandrel  50 . The moving fluid travels inside the mandrel  50  and past blades on a turbine  70 . The pitch of the turbine blades may be adjusted by a pitch controller  72 . The pitch controller  72  may be under functional control of the controller ( 58  in  FIG. 4 ). Adjusting the blade pitch to be more parallel with the fluid flow direction decreases the amount of fluid flow that is converted to rotation of the turbine  70 , and consequently, the amount of resistance to fluid flow created by the turbine  70 . Conversely, within certain limits adjusting the blade pitch to be more transverse to the fluid flow will increase the resistance to fluid flow and the amount of flow energy converted to rotational energy of the turbine  70 . The turbine  70  may be rotationally coupled to a generator or alternator  74  to convert rotational energy into electric power to charge the battery ( 62  in  FIG. 4 ). The controller ( 58  in  FIG. 4 ) may continuously operate the pitch controller  74  to adjust the turbine blade pitch such that a selected speed of movement of the instrument ( 12  in  FIG. 1 ) is substantially maintained. 
         [0047]    It will be readily appreciated by those skilled in the art that other forms of regenerative braking may be used to control the speed of motion under gravity of a logging instrument inside a conduit. Such regenerative braking may include rotating a hydraulic pump to convert motion into hydraulic pressure, for example. 
         [0048]    While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as disclosed herein. Accordingly, the scope of the invention should be limited only by the attached claims.