Abstract:
Devices and methods for logging a wellbore condition. A logging-on-demand tool is used which includes a logging tool housing assembly carried by a running string and a logging tool that is retained within the logging tool housing assembly and is selectively movable between a retracted position, wherein the logging tool is retained radially within the logging tool housing assembly, and a deployed position, wherein the logging tool is extended axially from the logging tool housing assembly

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The invention relates generally to tools and methods used for logging of wellbore conditions. In certain particular aspects, the invention relates to systems and methods for selectively deploying logging devices and other tools in connection with hole-enlarging reaming operations. 
         [0003]    2. Description of the Related Art 
         [0004]    Wellbore logging instruments are generally relatively fragile and vulnerable to damage during run in operations, especially when conveyed on drill pipe or coiled tubing. 
         [0005]    They can be damaged by drilling debris, ledges, wellbore restrictions and other forms of obstruction within the wellbore during run-in, making them inoperable before they reach the desired depth at which they will log wellbore conditions. 
       SUMMARY OF THE INVENTION 
       [0006]    The invention provides devices and methods for incorporating a logging instrument or other device into a deployable logging-on-demand tool. In a described example, a deployable logging-on demand tool includes a logging tool housing assembly and a logging tool that is retained within the logging tool housing assembly. The logging tool is moveably retained within the logging tool housing assembly and is generally protected during tripping into the wellbore by being substantially contained within the logging tool housing assembly. When desired, the logging tool can be deployed by selectively extending it axially outwardly from its protective logging tool housing assembly. Thereafter, logging operations can be conducted. If desired, the logging tool can then be selectively retracted into the logging tool housing assembly. 
         [0007]    In a described embodiment, the logging tool housing assembly that protects the logging tool includes a hole-enlarging reaming bit, such as an EZCASE® or Core™ bit, which permits logging operations to be conducted in conjunction with operations to enlarge portions of the wellbore. The bit provides a central axial opening through which the logging tool can be disposed during deployment. Also in a described embodiment, the logging tool housing assembly includes an outer tubular housing and an inner mandrel that resides within the outer housing. The logging tool resides radially within the inner mandrel and is axially moveable with respect to the inner mandrel. 
         [0008]    In described embodiments, the deployable logging-on-demand tool includes a valve mandrel that is affixed to the upper ends of both the outer housing and the inner mandrel. The valve mandrel, in conjunction with the outer housing and inner mandrel, preferably includes a deployment mechanism that permits the logging tool to be selectively extended from and retracted into and/or retained within the inner mandrel of the deployable on-demand logging tool. In a described embodiment, the deployment mechanism features a first fluid flow path in the form of a deployment fluid flowpath that will direct the flow of drilling fluid into a housing bore in the radial interior of the inner mandrel in a manner which will axially extend the logging tool axially outwardly from the radial interior of the deployment sub. Also in a described embodiment, the deployment mechanism features a second fluid flow path in the form of a retraction fluid flow path that directs the flow of drilling fluid along a path that will cause the logging tool to be retracted within the deployment sub. In the event that the logging tool is in an extended position, directing the flow of drilling fluid along the second fluid flow path will retract the logging tool into the deployment sub. In a described embodiment, the deployment mechanism also features a third flow path that will direct flow of drilling fluid in a normal circulation manner so as to lubricate the bit and/or clean the wellbore. 
         [0009]    In a described embodiment, the flow of drilling fluid into the first or second flow paths is controlled by a valve piston that is responsive to the fluid flow rate of drilling fluid from the surface. In a described embodiment, the valve piston is disposed within a piston bore that is defined within the valve mandrel. Also in the described embodiment, the valve piston defines an axial blind bore within which has a valve piston fluid port that permits fluid to exit the blind bore. The valve piston fluid port may be selectively aligned with either of the first or second flow paths in order to selectively deploy the logging tool or retract the logging tool. In a described embodiment, the valve piston is spring biased to a first position within the piston chamber that aligns the valve piston fluid port with the flow path for retracting the logging tool. 
         [0010]    According to an exemplary method of operation, the logging-on-demand tool is disposed into the wellbore on a running string and, in some embodiments, is operated to enlarge or ream the wellbore using the hole-enlarging reaming bit. During this stage of operation, drilling fluid is flowed into the running string at or below a first level of flow rate (“A”). Alternatively, the logging-on-demand tool may be disposed into the wellbore and operated to conduct logging without performing any reaming. 
         [0011]    When a depth is reached at which it is desired to conduct logging, the rate of drilling fluid flow into the running string is increased to a second predetermined threshold level (“B”) that is sufficient to shift the valve piston within the valve mandrel. Drilling fluid is then flowed through the deployment fluid flowpath to move the logging tool to the deployed position. Logging can be conducted at depth and, if desired, logging can be conducted as the logging-on-demand tool is withdrawn from the wellbore. 
         [0012]    If it is desired to retract the logging tool back into the logging tool housing assembly, an operator will either stop or significantly reduce the drilling fluid flow rate (below flow rate level “A”) to permit the valve piston within the valve mandrel to be shifted back to its initial position. Thereafter, drilling fluid is flowed into the running string at or around the first flow rate level “A.” As this fluid flows into the valve mandrel, it will be to directed along the retraction fluid flowpath, which will return the logging tool to its retracted position. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    For a thorough understanding of the present invention, reference is made to the following detailed description of the preferred embodiments, taken in conjunction with the accompanying drawings, wherein like reference numerals designate like or similar elements throughout the several figures of the drawings and wherein: 
           [0014]      FIG. 1  is a side, cross-sectional view of a wellbore containing a running string with a logging-on-demand tool constructed in accordance with the present invention. 
           [0015]      FIGS. 2A and 2B  are a side, cross-sectional view of portions of the logging-on-demand tool shown in  FIG. 1 , with the logging tool portion of the tool in a retracted position. 
           [0016]      FIGS. 3A and 3B  are a side, cross-sectional view of portions of the logging on-demand tool of  FIGS. 2A and 2B , now with the logging tool portion of the tool in a deployed position. 
           [0017]      FIG. 4  is an axial cross-section taken along lines  4 - 4  in  FIG. 2B . 
           [0018]      FIG. 5  is a side, cross-sectional view of the wellbore shown in  FIG. 1 , now with the running string being removed and logging being conducted. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0019]      FIG. 1  depicts an exemplary wellbore  10  that has being formed in the earth  12 . A running string, generally indicated at  14 , is shown disposed within the wellbore  10 . The running string  14  extends from the surface  16  and, in this example, is being used to enlarge/ream the diameter of the wellbore  10  from a first, reduced diameter  18  to a second, enlarged diameter  20 . This reaming operation may be cutting virgin material from the wellbore  10  or, alternatively, the reaming operation may be conducted to re-enlarge the wellbore  10  after it has contracted following drilling. In another alternative embodiment, the running string  14  can be disposed into a wellbore without any enlarging/reaming being done. The running string  14  includes lengths of drill pipe  22  which are affixed to one another in a manner known in the art. An exemplary logging-on-demand tool  24 , constructed in accordance with the present invention, is located on the distal end of the running string  14 . The running string  14  defines a flowbore  26  along its length for the transmission of drilling fluid from the surface  16  down to the logging-on-demand tool  24 . 
         [0020]    The logging-on-demand tool  24  is shown in greater detail in  FIGS. 2A and 2B ,  3 A and  3 B, and  4 . The exemplary logging-on-demand tool  24  includes a valve mandrel  28  that is affixed by threaded connection  30  to drill pipe  22 . The lower end of the valve mandrel  28  is affixed to a logging tool housing assembly, generally shown at  32 . The logging tool housing assembly  32  is controlled by the valve mandrel  28  and is operable to selectively deploy and retract a logging tool  34 . The exemplary logging tool  34  is generally cylindrical and typically incorporates a number of sensors that are capable of detecting desired wellbore conditions such as pressure, temperature, gamma, electrical resistivity, angle and azimuth. Typically, logging tools of this nature are customized to sense whichever wellbore conditions are desired by the well operator. In one embodiment, the logging tool  34  is a battery-powered, memory-based wellbore logging device of a type to known in the art. In alternative embodiments, the logging tool  34  might have power provided from the surface  14  using, for example, wired pipe to facilitate surface readout of wellbore parameters sensed by the logging tool  34 . 
         [0021]    The exemplary logging tool housing assembly  32  includes an outer housing  36  and an inner mandrel  38  that is located radially within the outer housing  36 . The upper end of the outer housing  36  is affixed to the valve mandrel  28  at threaded connection  40 . The inner mandrel  38  is affixed to the valve mandrel  28  at threaded connection  42 . 
         [0022]    In the depicted embodiment, a hole-enlarging or reaming drill bit  44  is secured to the lower end of the outer housing  36  at threaded connection  46 . Suitable bits for use as the hole-enlarging bit  44  include the EZCASE® and Core™ bits which are available commercially from Baker Hughes Incorporated of Houston, Tex. The hole-enlarging bit  44  defines a central opening  48 . 
         [0023]    The exemplary valve mandrel  28  features a mandrel body  50  with a piston bore  52  defined within the body  50 . The piston bore  52  has an open upper end  54  and a closed lower end  56 . An axially moveable valve piston  58  is disposed within the piston bore  52 . The valve piston  58  defines an axial blind bore  60  within. A plurality of lateral valve piston fluid ports  62  are formed through the valve piston  58  to permit fluid communication between the blind bore  60  and the region radially surrounding the valve piston  58 . In one embodiment, a plurality of collets  64  extends axially upwardly from the valve piston  58 . 
         [0024]    The collets  64  each present a radially outwardly extending tab  66 . The tabs  66  are shaped and sized to reside within an annular groove  68  that is inscribed in the piston bore  52 . In the initial, run-in position shown in  FIG. 2A , the tabs  66  reside within the groove  68 . 
         [0025]    A compression spring  70  is also disposed within piston bore  52  between the valve piston  58  and the closed lower end  56  of the piston bore  52 . The spring  70  biases the valve piston  58  upwardly within the piston bore  52 . Landing shoulders  72  are also disposed within the piston bore  52 . 
         [0026]    A number of fluid passages are defined within the body  50  of the valve mandrel  28 . A circulation fluid passage  74  extends axially through the body  50  and serves to transmit drilling fluid from the drill pipe  22  through the valve mandrel  28  to the logging tool housing assembly  32  below. A plurality of deployment fluid passages  76  extend between the piston bore  52  and the housing bore  78  that is defined within the inner mandrel  38  of the logging tool housing assembly  32 . Retraction fluid passages  79  extend from the piston bore  52  to the inner mandrel  38 . In the depicted embodiment, there are eight retraction fluid passages  79 , but there may be more or fewer than eight, if desired. Additionally, bleed nozzle passages  81  and  83  are formed within the body  50  of the valve mandrel  28 . The first bleed nozzle passage  81  extends from the piston bore  52  to the exterior of the valve mandrel  28 . The second bleed nozzle passage  83  extends from the housing bore  78  to the exterior of the valve mandrel  28 . Bleed nozzles  85  are preferably provided for each of these passages and permit excess fluid that is within the piston bore  52  or the housing bore  78  to be bled out to the exterior of the valve mandrel  28  during operation. Conversely, the passages  81 ,  83  and bleed nozzles  85  permit fluid from the surrounding wellbore  10  to flow into the piston bore  52  or housing bore  78 . 
         [0027]    Several axial fluid flowbores  80  are formed within the inner mandrel  38 . As can be seen in  FIGS. 2B and 3B , radial ports  82  interconnect the axial flowbores  80  with the housing bore  78 . Referring once again to  FIGS. 2B and 3B , it can be seen that the inner mandrel  38  includes landing shoulders  84  which project radially inwardly into the housing bore  78 . In addition, fluid seal  86  projects radially outwardly from the logging tool  34 , and fluid seal  88  projects radially inwardly into the housing bore  78 .  FIG. 4  illustrates that there are eight fluid flowbores  80  which are angularly spaced around the inner mandrel  38 . There may be more or fewer than eight, if desired. However, the fluid flowbores  80  should be formed to be aligned with the retraction fluid passages  79 , and it is suggested that there be the same number and angular spacing for the flowbores  80  as for the fluid passages  79  in order to accomplish this. 
         [0028]    Collets  90  extend axially from the logging tool  34  and include outwardly-directed tabs  92  that are shaped and sized to reside within an annular groove  94  that is inscribed within the housing bore  78 . The collets  90 , tabs  92  and groove  94  provide a releasable latch for the valve piston  58 . Those of skill in the art will understand that the releasable latch may have a number of other constructions, such as releasable balls and matching detents. In the initial run-in, retracted position shown in  FIG. 2B , the tabs  92  reside within the groove  94 . Lugs  95  protrude radially from the logging tool  34 . 
         [0029]    In exemplary operation, the running string  14  is disposed into the wellbore  10  and may be used to expand/ream the wellbore  10  as illustrated in  FIG. 1  by moving the logging-on-demand tool  24  in the direction of arrow  96 . At this time, the logging-on-demand tool  24  is in the configuration shown in  FIGS. 2A and 2B . During this portion of operation, drilling fluid is flowed down through the flowbore  26  of the running string  14  at a first predetermined level (“A”) that is below the point necessary to shift the valve piston  58  within the piston bore  52 . Fluid is transmitted through the circulation fluid passage  74  to the coaxial space  90  located between the outer housing  36  and the inner mandrel  38  and down to lubricate the bit  44 . Also during operation, drilling fluid is also transmitted into the blind bore  60  of the valve piston  58 . Drilling fluid entering the blind bore  60  will be transmitted via lateral valve piston fluid ports  62  outside of the valve piston  58 . Because the collets  64  of the valve piston  58  are secured within the groove  68  of the piston bore  52 , the valve piston fluid ports  62  are aligned with the retraction fluid passages  79  causing drilling fluid to flow downwardly into the axial fluid flowbores  80  within the inner mandrel  38 . The fluid that enters the axial flowbores  80  is then transmitted through the radial ports  82  into the housing bore  78  and acts upwardly against the fluid seal  86 . This fluid pressure acting upon the fluid seal  86  will tend to bias the logging tool  34  axially upwardly within the housing bore  78 . Some fluid flowing into the housing bore  78  above the seal  88  may flow upwardly and out of the housing bore  78  through bleed nozzle passage  83 . This upward flow, together with the interconnection of the collets  90  with the groove  94  will also help to retain the logging tool  34  in the retracted position shown in  FIG. 2B . 
         [0030]    When desired, the logging tool  34  can be deployed from the logging-on-demand tool  24  by selectively extending the logging tool  34  outwardly through the central opening  48  of the bit  44 , as illustrated in  FIG. 3B . To move the logging tool  34  from the retracted position shown in  FIG. 2B  to the extended position shown in  FIG. 3B , an operator at the surface increases the rate of flow of drilling fluid to or above a predetermined level (“B”) that is sufficient to cause the collets  64  of the valve piston  58  to be released from the groove  68  and the bias of the compression spring  70  overcome. It is suggested that this predetermined level be set significantly above normal operating levels for drilling fluid flow rate so as to avoid inadvertent deployment of the logging tool  34 . The valve piston  58  will then shift downwardly within the piston bore  52  (see  FIG. 3A ) and bottom out against landing shoulders  72 . At this point, the valve piston fluid ports  62  will be aligned with the deployment fluid passages  76 . Drilling fluid will flow through the deployment fluid passage  76  and into the housing bore  78 . Fluid pressure within the housing bore  78  above the logging tool  34  will urge the logging tool  34  downwardly through the central opening  48  of the bit  44  (see  FIG. 3B ). The lugs  95  protruding from the logging tool  34  contact the landing shoulders  84  of the housing bore  78 , thereby ensuring that the logging tool  34  does not completely exit the housing bore  78 . 
         [0031]    In this deployed position, the logging tool  34  can be operated to detect wellbore conditions. Since the construction and operation of logging tools is well understood in the industry, they will not be described in any detail here. 
         [0032]    If it is desired to return the logging-on-demand tool  24  to its retracted position, the operator will stop the flow of drilling fluid, or significantly reduce the flow of drilling fluid (below level “A”), into the running string  14 . The flow rate reduction permits the spring  70  to bias the valve piston  58  upwardly within the piston bore  52  to the position shown in  FIG. 2A . The tabs  66  of the collets  64  will reengage the groove  68  in the piston bore  52 . In this upper position, the valve piston fluid ports  62  of the valve piston  58  are once again aligned with the retraction fluid passages  79 . The operating will now begin to flow drilling fluid into the running string  14  at the first, reduced flow rate “A.” Drilling fluid entering the retraction fluid passages  79  will flow downwardly into the axial fluid flowbores  80  within the inner mandrel  38 . As this fluid flows through the ports  82 , it will cause the logging tool  34  to be retracted back upwardly into the housing bore  78 . 
         [0033]    According to an exemplary method of operation for logging wellbore conditions, the logging-on-demand tool  24  is disposed into the wellbore  10  and rotated by the drilling string  14  to cause the drill bit  44  to enlarge the wellbore  10 . The logging-on-demand tool  24  is moved downwardly in the direction of arrow  96  in  FIG. 1 . At this time, the logging-on-demand tool  24  is in the retracted position shown in  FIGS. 2A and 2B . After the logging-on-demand tool  24  has reached the desired depth, downward movement of the is tool  24  in the direction of arrow  96  is halted. The flow rate of drilling fluid into the drilling string  14  is increased to a predetermined level sufficient to cause the valve piston  58  to move axially downwardly within the piston bore  52 . Drilling fluid will then be transmitted through the deployment fluid passage  76  to the upper portion of the housing bore  78 , and the logging tool  34  deploys as described above. Thereafter, the logging-on-demand tool  24  monitors various wellbore conditions. In one embodiment, the logging-on-demand tool  24  is operable to monitor desired wellbore conditions as the tool  24  and drilling string  14  are being withdrawn from the wellbore  10 , as illustrated by arrow  98  in  FIG. 5 . 
         [0034]    Those of skill in the art will recognize that numerous modifications and changes may be made to the exemplary designs and embodiments described herein and that the invention is limited only by the claims that follow and any equivalents thereof.