Abstract:
Apparatus, systems, and methods may operate to couple a tubular member to a bottom hole assembly, dispose at least one adjustable stabilizing member on the tubular member, and control at least one of a radial extension of the adjustable stabilizing member and an axial position of the adjustable stabilizing member relative to the bottom hole assembly to adjust a borehole trajectory, wherein the adjustable stabilizing member is adjustable in both radial and axial directions. Additional apparatus, systems, and methods are disclosed.

Description:
CLAIM OF PRIORITY 
       [0001]    This application is a continuation under 35 U.S.C. 111(a) of International Application No. PCT/US2009/040741 filed Apr. 16, 2009 and published as WO 2009/146190 on Dec. 3, 2009, which claims benefit of priority, under 35 U.S.C. Section 119(e), to U.S. Provisional Patent Application Ser. No. 61/045,344, filed Apr. 16, 2008, the benefit of priority of each of which is claimed hereby, and each of which are incorporated by reference herein in its entirety. 
     
    
     BACKGROUND 
       [0002]    Directional drilling bottom hole assemblies (BHA) are often required to build or drop inclination in the vertical plane and/or turn in the horizontal plane to reach a desired downhole target zones. A stabilizer may be attached to the BHA to control the bending of the BHA to direct the bit in the desired direction (inclination and azimuth). Radially adjustable stabilizers may be used in the BHA of directional drilling systems to provide an initial angle to the BHA with respect to the axis of the borehole to assist in turning the direction of the borehole. A radially adjustable stabilizer provides a wider range of directional adjustability than is available with commonly used fixed diameter stabilizers. This saves rig time by allowing the BHA to be adjusted downhole instead of tripping out for changes. However, even the use of radially adjustable stabilizers provides only a limited range of directional adjustments. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0003]    A better understanding of various embodiments can be obtained when the following Detailed Description is considered in conjunction with the following drawings, in which: 
           [0004]      FIG. 1  shows a schematic example of a drilling system according to various embodiments of the invention; 
           [0005]      FIG. 2  shows an example of a bottom hole assembly having axially adjustable stabilizers according to various embodiments of the invention; 
           [0006]      FIG. 3A  shows one example embodiment of an adjustable stabilizer having both radial and axial adjustability according to various embodiments of the invention; 
           [0007]      FIG. 3B  shows a cross section of the stabilizer of  FIG. 3A ; 
           [0008]      FIG. 3C  shows an alternative embodiment of an extendable member according to various embodiments of the invention; 
           [0009]      FIG. 3D  shows another alternative embodiment of an extendable member according to various embodiments of the invention; 
           [0010]      FIG. 4  is a block diagram of an example of an adjustable stabilizer according to various embodiments of the invention; 
           [0011]      FIG. 5A  shows another example embodiment of an adjustable stabilizer having both radial and axial adjustability according to various embodiments of the invention; 
           [0012]      FIG. 5B  is a cross section of the stabilizer of  FIG. 5A ; 
           [0013]      FIG. 6  is a block diagram of a portion of one embodiment of an adjustable stabilizer according to various embodiments of the invention; and 
           [0014]      FIG. 7  a shows an example of a stabilizer having a rotatable sleeve according to various embodiments of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0015]      FIG. 1  shows a schematic diagram of a drilling system  110  having a downhole assembly according to one embodiment of present invention. As shown, the system  110  includes a conventional derrick  111  erected on a derrick floor  112  which supports a rotary table  114  that is rotated by a prime mover (not shown) at a desired rotational speed. A drill string  120  that includes a drill pipe section  122  extends downward from rotary table  114  into a directional borehole  126 . Borehole  126  may travel in a three-dimensional path. The three-dimensional direction of the bottom  151  of borehole  126  is indicated by a pointing vector  152 . A drill bit  150  is attached to the downhole end of drill string  120  and disintegrates the geological formation  123  when drill bit  150  is rotated. The drill string  120  is coupled to a drawworks  130  via a kelly joint  121 , swivel  128  and line  129  through a system of pulleys (not shown). During the drilling operations, drawworks  130  is operated to control the weight on bit  150  and the rate of penetration of drill string  120  into borehole  126 . The operation of drawworks  130  is well known in the art and is thus not described in detail herein. 
         [0016]    During drilling operations a suitable drilling fluid (commonly referred to in the art as “mud”)  131  from a mud pit  132  is circulated under pressure through drill string  120  by a mud pump  134 . Drilling fluid  131  passes from mud pump  134  into drill string  120  via fluid line  138  and kelly joint  121 . Drilling fluid  131  is discharged at the borehole bottom  151  through an opening in drill bit  150 . Drilling fluid  131  circulates uphole through the annular space  127  between drill string  120  and borehole  126  and is discharged into mud pit  132  via a return line  135 . Preferably, a variety of sensors (not shown) are appropriately deployed on the surface according to known methods in the art to provide information about various drilling-related parameters, such as fluid flow rate, weight on bit, hook load, etc. 
         [0017]    A surface control unit  140  may receive signals from downhole sensors and devices via a sensor  143  placed in fluid line  138  and processes such signals according to programmed instructions provided to surface control unit  140 . Surface control unit  140  may display desired drilling parameters and other information on a display/monitor  142  which may be used by an operator to control the drilling operations. Surface control unit  140  may contain a computer, memory for storing data, data recorder and other peripherals. Surface control unit  140  may also include models and may process data according to programmed instructions, and respond to user commands entered through a suitable input device, such as a keyboard (not shown). 
         [0018]    In one example embodiment of the present invention, a steerable drilling bottom hole assembly (BHA)  159  may comprise a measurement while drilling (MWD) system  158  comprising various sensors to provide information about the formation  123  and downhole drilling parameters. BHA  159  may be coupled between the drill bit  150  and the drill pipe  122 . 
         [0019]    MWD sensors in BHA  159  may include, but are not limited to, a device for measuring the formation resistivity near the drill bit, a gamma ray device for measuring the formation gamma ray intensity, devices for determining the inclination and azimuth of the drill string, and pressure sensors for measuring drilling fluid pressure downhole. The above-noted devices may transmit data to a downhole transmitter  133 , which in turn transmits the data uphole to the surface control unit  140 . In one embodiment a mud pulse telemetry technique may be used to communicate data from downhole sensors and devices during drilling operations. A transducer  143  placed in the mud supply line  138  detects the mud pulses responsive to the data transmitted by the downhole transmitter  133 . Transducer  143  generates electrical signals in response to the mud pressure variations and transmits such signals to surface control unit  140 . Alternatively, other telemetry techniques such as electromagnetic and/or acoustic techniques or any other suitable technique known in the art may be utilized for the purposes of this invention. In one embodiment, hard wired drill pipe may be used to communicate between the surface and downhole devices. In one example, combinations of the techniques described may be used. In one embodiment, a surface transmitter receiver  180  communicates with downhole tools using any of the transmission techniques described, for example a mud pulse telemetry technique. This may enable two-way communication between surface control unit  140  and the downhole tools described below. 
         [0020]    BHA  159  may also comprise a drilling motor  190  and stabilizers  160  and  162 . In one embodiment, at least one of stabilizers  160  and  162  may be an adjustable stabilizer used to assist in controlling the direction of borehole  126 . As discussed previously, radially adjustable stabilizers may be used in the BHA of steerable directional drilling systems to adjust the angle of the BHA with respect to the axis of the borehole. A radially adjustable stabilizer provides a wider range of directional adjustability than is available with a conventional fixed diameter stabilizer. This adjustability may save substantial rig time by allowing the BHA to be adjusted downhole instead of tripping out for changes. However, even a radially adjustable stabilizer provides only a limited range of directional adjustments. 
         [0021]    As shown in the embodiment of  FIG. 2 , the distance, L 1 , between bit  150  and first stabilizer  160  is a factor in determining the bend characteristics of BHA  159 . Similarly, the distance, L 2 , between first stabilizer  160  and second stabilizer  162  can be another factor in determining the bend characteristics of BHA  159 . Considering first stabilizer  160 , the deflection at bit  150  of BHA  159  is a nonlinear function of the distance L 1 , such that relatively small changes in L 1  may significantly alter the bending characteristics of BHA  159 . With radially movable stabilizer blades, a dropping or building angle, for example A or B, can be induced at bit  150  with the stabilizer at position P. By axially moving stabilizer  160  from P to P′, the deflection at bit  150  can be increased from A to A′ or B to B′. In one embodiment, a stabilizer having both axial and radial adjustment may substantially extend the range of directional adjustment, thereby saving the time necessary to change out BHA  159  to a different configuration. In other embodiments the stabilizer may be axially movable. The position and adjustment of second stabilizer  162  adds additional flexibility in adjusting BHA  159  to achieve the desired bend of BHA  159  to achieve the desired borehole curvature and direction. In one embodiment the second stabilizer  162  has the same functionality as the first stabilizer  160 . While shown in two dimensions, proper adjustment of stabilizer blades may also provide three dimensional turning of BHA  159 . 
         [0022]    In one example, see  FIGS. 3A and 3B , an adjustable stabilizer  1  for use in BHA  159  described above comprises an axially movable sleeve  2  mounted on a mandrel  5 . Movable sleeve  2  comprises a blade actuation assembly  11 . Blade actuation assembly  11  comprises a radially extendable member, for example blade  15 , an actuator  40 , and a power source  50 . In the example shown in  FIG. 3A , radially extendable blade  15  and  15  actuating member  17  are mounted in groove  36  in sleeve  2 . While only one actuation assembly  11  is detailed here, multiple actuation assemblies  11  may be incorporated in similar grooves  36  located around the circumference of sleeve  2 . Radially extendable blade  15  and actuating member  17  have mated tapered surfaces such that axial motion of actuating member  17  in a first direction extends blade  15  radially outward from 20 centralizer  1 . In one example, blade  15  and actuating member  17  are engageable, for example, with a longitudinal dovetail groove (not shown). This engagement allows movement of actuating member  17  in a second direction opposite the first direction to cause blade  15  to radially retract. Actuating member  17  may be powered axially by an actuator  40  through a rod  35 . 
         [0023]    Actuator  40  may be any suitable device capable of axially moving actuating member  17 , for example an electromechanical actuator or, alternatively, a hydraulic actuator. Cavity  41  may be formed in sleeve  2  to contain a power source  50  for supplying electrical and/or mechanical power to actuator  40 . Cover  55  acts to seal cavity  50  from the surrounding environment. Electrical power may comprise batteries. In one embodiment, a hydraulic supply system  46  may be powered by the batteries to supply hydraulic power to a hydraulically activated actuator  40 . Controller  45  controls the movement of actuator  40  and hence movement of radially extendable blade  15 . In one example, actuator  40  is a hydraulic cylinder that extends rod  35  to force actuating member  17  into radially extendable blade  15  to radially extend outward toward the wall of borehole  126  (see  FIG. 1 ). When multiple radially extendable blades  15  are incorporated around sleeve  2 , each blade  15  may be independently  5  controlled. In addition, each blade  15  may be adjusted to any position between a collapsed position and a fully extended position. One or more sensors  65  may be incorporated in actuator  40  to measure the displacement of and/or the force applied by each radially extendable blade  15 . Other radially extendable member alternatives are shown in  FIGS. 3C and 3D .  FIG. 3C  shows actuator  80  extending actuating member  81 . Actuating member  81  is engaged with swing arm  82 . Swing arm  82  is pivoted about pin  83  such that extension of actuating member  81  forces swing arm  82  outward. Retraction of actuating member  81  causes swing arm  82  to retract inward. In another example, see  FIG. 3D , hydraulic cylinders  90  act directly against extendable blade  91  causing blade  91  to extend and retract according to the motion of cylinder rods  92 . As used herein, the term radially extendable member encompasses all such examples. 
         [0024]    In the example of  FIGS. 3A and 3B , axial motion of sleeve  2  may be accomplished by axial motion of the drill string. Slots  10  are formed in mandrel  5  such that pins  30  on an inner diameter of sleeve  2  are engageable in slots  10  at multiple axial positions along mandrel  5 . Sensors  12  may be installed along mandrel  5 . Likewise detectors  13  may be installed axially spaced apart along sleeve  2  to detect sensors  12  and transmit signals to controller  45  to determine the location of sleeve  2  along mandrel  5 . In one example, sensors  12  may be radio frequency identification devices (RFID) that are interrogated by detectors  13  to determine sleeve  2  location. Information regarding sleeve  2  location and blade  15  extension can be used to predict BHA performance and borehole trajectory. In one example, controller  45  may be operatively coupled to transmitter/receiver  66  for sending and receiving signals. 
         [0025]      FIG. 4  shows a functional block diagram of one example of the adjustable stabilizer  1  of  FIGS. 3A and 3B . Controller  45  may comprise circuits  71 , a processor  70 , a memory  72  in data communication with processor  70 , sensors, and communication circuits and devices. Control of actuating member  17  and radially extendable blade  15  may be from programmed instruction resident in controller  45  or from telemetered instructions received by controller  45  from an external source, for example, a downhole MWD system in the BHA, or from the surface transmitter  180  (see  FIG. 1 ). Such signals may be transmitted using any suitable technique including, but not limited to, electromagnetic wave telemetry, mud pulse telemetry, wired pipe telemetry, and acoustic telemetry using the drill string as the transmission medium. In one example, controller  45  may be operatively coupled to transmitter/receiver  66  for sending and receiving signals. In one embodiment controller  45  selectively controls the axial movement or the longitudinal movement or both movements of the stabilizer blades to control the pivot point of the BHA to facilitate the adjustment of the downhole angle, and hence the steering ability of the BHA. For example, data signals may be transmitted indicative of the position of extendable blade  15 , and instructions may be received to change the position of extendable blade  15 . Similarly, data may be transmitted to indicate the position of sleeve  2  along mandrel  5 . In one embodiment, navigation devices  47  are incorporated in sleeve  2  to determine the pointing vector of the bottom hole assembly. Such navigation devices may comprise magnetometers, inclinometers, and gyroscopic devices. Data signals indicative of the sensor values and or calculated pointing vector results may be transmitted to a downhole MWD system in the BHA and/or to the surface for analysis. In one embodiment, a desired well trajectory model may be stored in memory  72  of controller  45 . Calculated trajectory values from the navigational sensors may be compared to the stored trajectory model and suitable adjustments may be made to the position of extendable blades  15  based on the comparison. In addition, a suggested change in the axial position of sleeve  2  on mandrel  5  may be transmitted to the surface for execution thereof. In one example, transmission of such data may be made to MWD system  158  for retransmission to the surface. 
         [0026]    In one operational example of the system described above, navigational sensor data are used downhole to calculate a suggested change in the axial position of sleeve  2  on mandrel  5 . The suggested change is transmitted to MWD system  158  where it is retransmitted to the surface. Simultaneously, controller  45  extends blades  15  into contact with wall  156  of borehole  126  thereby holding sleeve  2  fixed against wall  156 . With sleeve  2  fixed against wall  156 , drill string  122  may be suitably rotated to disengage pins  30  in slots  10 . Drill string  22  may then be raised or lowered at the surface and suitably rotated to reengage pins  30  in slots  10  at the new axial location thereby changing the axial location of sleeve  2  relative to mandrel  5 . Data signals may be transmitted from the surface to indicate that the change has been made. These signals are received and sent to processor  45 . Processor  45  polls sensors  12  and detectors  13  to determine the actual position of sleeve  2  relative to mandrel  5  and determines if the appropriate change has been made. If the appropriate change has not been made, controller  45  transmits, via transmitter/receiver  66 , new change signals to the surface and the procedure is repeated until the appropriate change has been made. When the appropriate axial change has been made, controller  45  directs actuator  40  to position blade  15  at the appropriate radial position and drilling commences. This procedure may be repeated whenever the detected wellbore trajectory deviates from the stored model by a predetermined value. 
         [0027]    In another example, see  FIGS. 5A and 5B , an adjustable stabilizer  501  having a radially and axially selectively adjustable blade assembly  511 . Radially and axially selectively adjustable blade assembly  511  comprises a blade actuation assembly  11 , as described with reference to  FIGS. 3A and 3B , mounted on a carrier  520  that slides axially in groove  536  formed in stabilizer sub  525 . Radially and axially adjustable blade assembly  511  further comprises a second power source  550 , a second controller  545 , a power system  546  and a second actuator  560  located in sub  525 . In one example power source  550  comprises batteries. In one example, power system  546  is a hydraulic power system driven by second power source  550 , providing hydraulic power to second hydraulic actuator  560 . Second actuator  560  extends rod  565  to axially position carrier  520  in groove  536 . Position sensor  561  may measure the movement of rod rod  565  to determine the axial position of carrier  520 . The combined actuation of actuator  40  and second actuator  560  enables radial actuation and axial movement of extendable blade  15 . While only one such radially and axially movable blade is shown in detail, multiple such assemblies may be located around the circumference of sub  525 . 
         [0028]    Second controller  545  and controlling actuator  560  may be located in sub  525  and be in communication via transmitter/receiver  566  with controller  45  on carrier  520 . In addition, second controller  545  may be in communication with an MWD system located in BHA  159  and/or a receiver at the surface. 
         [0029]    Communication may be by wireless and/or hard wired techniques known in the art. In one embodiment, electrical power is supplied to second controller  545  through hard wired pipe in drill string  122 . In one embodiment, see  FIG. 6 , second controller  545  has a processor  570 , circuits  571 , and a memory  572 , similar to that of controller  45 . 
         [0030]    Second controller  545  may act as a master controller for controlling both radial extension of extendable blade  15  and the axial position of carrier  520 . For example, second controller  545  may receive raw and/or processed navigational data from navigation sensors  47 . This data may be used to determine the three-dimensional pointing vector of a BHA including adjustable stabilizer  501 . Model 573 of desired borehole  126  trajectory may be stored in memory in controller  545 . In one embodiment, controller  545  may compute the borehole  126  trajectory based on the navigational sensor measurements and compare the calculated trajectory with a desired trajectory stored in memory. Controller  545  may then adjust the radial position of blade  15  and/or the axial position of blade  15  necessary to steer borehole  126  back to the desired trajectory. Alternatively, controller  545  may calculate a new trajectory to a desired target and adjust the radial and/or axial position of blade  15  to follow the new trajectory. 
         [0031]    In one embodiment, see  FIG. 7 , adjustable stabilizer  701  comprises at least one radially and axially adjustable blade assembly  511  disposed on a sleeve  720  that is coupled to sub body  725  through bearings  710 . Sleeve  720  and sub body  725  are rotatable relative to each other. Radially and axially adjustable blade assembly  511  operates as described with regard to  FIGS. 5A-6 . In operation, one or more blades  15  may be extended to contact wall  156  of borehole  126  (see  FIG. 1 ) providing the appropriate bend to the bottom hole assembly to steer the borehole in the desired direction. In this embodiment, the bottom hole assembly, including sub body  725  may be rotated to rotate bit  150 . 
         [0032]    This Detailed Description is illustrative, and not restrictive. Many other embodiments will be apparent to those of ordinary skill in the art upon reviewing this disclosure. The scope of embodiments should therefore be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. 
         [0033]    The Abstract of the Disclosure is provided to comply with 37 C.F.R. §1.72(b) and will allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. 
         [0034]    In this Detailed Description of various embodiments, a number of features are grouped together in a single embodiment for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as an implication that the claimed embodiments have more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed embodiment. Thus the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separate embodiment.