Abstract:
An apparatus for controlling the direction of drill bit within a wellbore. The apparatus comprises a first housing with a first housing axis therein, and wherein the first housing has a first threaded opening having a first threaded opening axis. The first housing has a helical end. A second housing is included, and the second housing contains a second housing axis, and a second threaded opening having a second threaded opening axis configured to engage with the first threaded opening. A collar is included that has a helical collar end that engages the helical collar end and wherein the helical collar end is configured reciprocal to the helical end, and rotational displacement of the first housing relative to the collar will angularly displace the drill bit axis. The apparatus may further include spline members for locking the collar in place relative to the first and second housing.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    This invention relates to an apparatus for adjusting the orientation of a tubular. More specifically, but not by way of limitation, this invention relates to an adjustable bent housing apparatus, and a method of using the bent housing. 
         [0002]    In the search for hydrocarbon deposits, operators have found it desirable to drill deviated and horizontal wells. As those of ordinary skill in the art will recognize, there are numerous advantages to being able to drill directional wells. For instance, an operator may drill a horizontal well for hundreds of feet within a subterranean reservoir, thus enabling high rates of production of hydrocarbons once completed. Additionally, an operator may wish to drill several lateral wells from a single surface location. This list is meant to be illustrative. 
         [0003]    In order to obtain the angle of inclination necessary to drill these wellbores, numerous types of directional drilling apparatuses have been developed. One prior art technique includes use of a bent housing as part of the downhole mud motor. However, prior art downhole mud motors suffer from many deficiencies. For instance, some prior art devices require that the entire bent housing section be replaced if the operator wishes to adjust the drill bit axis relative to the bore hole. 
         [0004]    Therefore, an object of the present invention is an adjustable bent housing apparatus that can be adjusted on the drilling rig without the need to have a large inventory of bent housing sections at the drilling rig site. Another object of the present invention includes an apparatus that is durable and can withstand the tremendous stress placed on downhole equipment in the drilling process. Yet another object is the development of a system that accurately adjust the drill bit axis relative to the work string. These and many other objects will become apparent upon a reading of the following description. 
       SUMMARY OF THE INVENTION 
       [0005]    An apparatus for controlling the direction of drill bit within a wellbore is disclosed, and wherein the drill bit has as a drill bit axis and the drill bit is connected to the apparatus. In one embodiment, the apparatus comprises a first housing with a first housing axis therein, and wherein the first housing has a first threaded opening having a first threaded opening axis. The first housing has a helical end. A second housing is included, and the second housing contains a second housing axis, and a second threaded opening having a second threaded opening axis configured to engage with the first threaded opening, and wherein the second housing has an end surface. 
         [0006]    The apparatus further includes a collar having a radial collar end and a partial helical collar end, and wherein the radial collar end engages the end surface and the helical collar end engages the helical end, and wherein the partial helical collar end is configured reciprocal to the helical end, and rotational displacement of the first housing relative to the collar will angularly displace the first threaded opening axis from the second threaded opening axis so that the inclination of the bit axis is changed. The apparatus may further include means for locking the collar in place relative to the first and second housing. 
         [0007]    In one embodiment, the locking means includes a reciprocal set of splines. The splines may also be referred to as teeth, keys, or teeth or key like projections. The splines may also be referred to as a mechanical interlocking mechanism. More specifically, in one preferred embodiment, the locking means comprises a male set of splines formed on an inner portion of the collar and a female set of splines formed on an inner portion of the first housing. In another embodiment, the locking means comprises a female set of splines formed on an inner portion of the collar and a male set of splines formed on an inner portion of the second housing. Additionally, in one preferred embodiment, the first threaded opening is configured perpendicular to the helical end and the second threaded opening is configured perpendicular to the end surface. 
         [0008]    The first housing may have disposed therein an output shaft of a drilling motor, and the second housing may have disposed therein a drive shaft of the drilling motor, and wherein the drive shaft is connected to the drill bit. In one preferred embodiment, the helical collar end has a slope between 0.1 degrees and 10 degrees, and the helical end has a complimentary slope. 
         [0009]    A method of drilling a well with a drill bit is also disclosed. The method comprises providing a drill assembly within the well, with the drill assembly being connected to the drill bit via a drive shaft. The assembly comprises a first housing with a first housing axis therein, with the first housing having a first threaded opening having a first threaded opening axis, and wherein the first housing has a helical end. The tool further includes a second housing having a second housing axis, with the second housing having a second threaded opening having a second threaded opening axis configured to engage with the first threaded opening, and wherein the second housing having an end surface. The housing also includes a collar having a radial collar end and a helical collar end, and wherein the radial collar end engages the end surface and the helical collar end engages the helical end, and wherein the helical collar end is at a reciprocal angle to the helical end. The method further includes drilling the well with the drill bit at a first angle of inclination. 
         [0010]    The method further comprises retrieving the drill assembly from the well, unscrewing the first housing from the second housing, and rotating the collar relative to the first housing hence axial displacing the radial end surface of the collar to the first housing. The method further includes adjusting the collar&#39;s axial position relative to the first housing and the second housing, by rotationally moving the collar relative to the first housing and therefore displacing the first housing relative to the collar in order to angularly displace the drill bit at a second angle of inclination. Next, the first housing is locked with the second housing. The method includes running into the well with the drill bit and drilling the well at the second angle of inclination. 
         [0011]    In one preferred embodiment, the step of locking the first housing with the collar includes engaging a spline located on said collar with a spline located on the first housing. 
         [0012]    In another preferred embodiment, the step of locking the first housing with the second housing includes engaging a thread connection located on the first housing with a thread connection located on the second housing. 
         [0013]    In one preferred embodiment, the step of adjusting the axial inclination includes rotational displacement of the first housing relative to the collar in order to align the first housing axis with the second housing axis. In another preferred embodiment, the step of adjusting the axial inclination includes rotational displacement of the first housing relative to the collar so that the first housing axis and the second housing axis is angularly displaced. In yet another embodiment, the step of adjusting the collar&#39;s axial position includes rotation displacement of the first housing relative to the collar so that the radial end surface of the collar is axially displaced. 
         [0014]    In another preferred embodiment, an apparatus for controlling the direction of a tubular is disclosed. In this embodiment, the apparatus comprises a first housing with a first housing axis therein, with the first housing having a first threaded opening having a first threaded opening axis offset from the first housing axis, and wherein the first housing has a helical end. The apparatus includes a second housing having a second housing axis, with the second housing having a second threaded opening having a second threaded opening axis offset from the second housing axis and wherein the second threaded opening is configured to engage with the first threaded opening, and wherein the second housing has an end surface. 
         [0015]    Additionally, this embodiment includes a collar having a radial collar end and a helical collar end, and wherein the radial collar end engages the end surface and the helical collar end engages the helical end, and wherein the helical collar end is configured reciprocal to the helical end. In a first position, rotational displacement of the first housing relative to the collar will align the first housing axis with the second housing axis and in a second position, rotational displacement of the first housing relative to the collar will deviate the first housing axis relative to the second housing axis. Means for locking the collar in place relative to the first and second housing may also be included. 
         [0016]    An advantage of the present invention is that angular adjustments can be made to the downhole motor assembly without the need for spare inventory at the rig site. The collar can be adjusted in the field. Another advantage is that the driller on the drill rig floor can make accurate changes to the orientation of the drill bit axis for precision geo-steering. Yet another advantage is that the driller can quickly make angular adjustments to the drill bit axis. 
         [0017]    Yet another advantage is that the apparatus can be used for controlling the direction of a tubular, wherein the tubular can be used in applications wherein it is necessary to change and/or adjust the orientation of the tubular i.e. when a bend is needed in a tubular. 
         [0018]    A feature of the present invention is the first and second housing that share a common axis, and wherein this common axis is offset from the axis of the threaded openings contained within the first and second housing. Another feature is a collar that contains a helical end profile that mates with a reciprocal profile end face on one of the housings. Yet another feature is the splines on the collar and the mating splines of the housing which allow for locking the desired angular displacement into the drilling assembly. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]      FIG. 1  is a planar view of the first housing of the preferred embodiment. 
           [0020]      FIG. 2A  is a planar view of the collar of the preferred embodiment. 
           [0021]      FIG. 2B  is a top view of the collar seen in  FIG. 2A . 
           [0022]      FIG. 2C  is a planar view of the unwrap length of the collar depicted in  FIG. 2A . 
           [0023]      FIG. 3  is a cross-sectional view of the second housing of the preferred embodiment. 
           [0024]      FIG. 4A  is a planar view of the assembled apparatus of the preferred embodiment at a zero degree angle of inclination orientation. 
           [0025]      FIG. 4B  is a cross-section view of the apparatus seen in  FIG. 4A . 
           [0026]      FIG. 5A  is a planar view of the assembly apparatus of the preferred embodiment at a one hundred and eighty degree (180) angle of inclination orientation. 
           [0027]      FIG. 5B  is a cross-section view of the apparatus seen in  FIG. 5A . 
           [0028]      FIG. 6A  is a planar view of the first housing and collar at a zero (0) degree angle of inclination orientation. 
           [0029]      FIG. 6B  is a planar view of the first housing and collar at a one hundred and eighty (180) degree angle of inclination orientation. 
           [0030]      FIG. 7  is a schematic view of the mud motor of the present invention in a straight orientation within a wellbore. 
           [0031]      FIG. 8  is a schematic view of the mud motor of  FIG. 7  in a bent orientation within a wellbore. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0032]    Referring now to  FIG. 1 , a planar view of the first housing  2  of the most preferred embodiment will now be described. The first housing  2  has a first outer cylindrical surface  4  that extends to surface  6 , and wherein the surface  6  has a generally helical profile  8 . The first outer cylindrical surface  4  will have an inner portion (not shown in this view), and wherein the dashed line  10  depicts the center axis of the portion formed from cylindrical surface  4 . 
         [0033]    Extending from the surface  6  will be the threaded opening seen generally at  12 , sometimes referred to as the pin connection  12 . The threaded opening  12  includes the outer cylindrical surface  14  that extends to the outer spline members seen generally at  16  which in turn extends to the indentation  18 . The splines are teeth-like projections extending from the pin connection  12 . As seen in  FIG. 1 , the indentation  18  stretches to the external threads  19 , and wherein the threaded opening surface  12  has external threads  19 . The external threads  19  terminate at the outer cylindrical surface  20 . The center axis of the threaded opening  12  is represented by the dashed line  22 . As per the teachings of the present invention, the center axis  22  is offset from the center axis  10 , as shown in  FIG. 1  by the numeral  99 . 
         [0034]    Referring now to  FIG. 2A , a planar view of the preferred embodiment of the collar  26  will now be described. The collar  26  includes an outer cylindrical surface  28  that extends to the first radial end  30 . It should be noted that like numbers appearing in the various figures refer to like components. The collar  26  has a center of axis  31 . The collar  26  also contains the collar helical end profile, seen generally at  32 , and wherein the collar helical end profile  32  is reciprocal to and configured to engage the helical profile  8  (helical profile  8 , seen in  FIG. 1 ). The helical profile  8  may also be referred to as a cam surface  8 , and the collar helical end profile  32  may be referred to as a ramp  32 . 
         [0035]      FIG. 2B  is a top view of the collar  26  seen in  FIG. 2A . The collar helical end profile  32  is shown, along with the outer cylindrical surface  28 . The collar  26  contains the inner diameter surface  34 , and wherein the inner diameter surface  34  contains the splines  36  (sometimes referred to as the female set of splines  36 ). The splines  36  will engage with the splines  16  in order to lock the collar  26  in position relative to the first housing  2  as will be more fully explained later in the description.  FIG. 2C  is a planar view of the entire length (i.e. unwrapped view) of the collar  26  seen in  FIG. 2A , and wherein the collar helical end profile  32  is illustrated. The profile  32  has a sloping surface  38  that extends to the upward facing shoulder  40 , wherein the upward facing shoulder  40  extends to the sloping surface  38 . As noted earlier, the profile  32  is configured to engage with the helical profile  8  of the first housing  2 . The first radial end  30  is also shown. 
         [0036]    Referring now to  FIG. 3 , a cross-sectional view of the preferred embodiment of the second housing  42  will now be described. The second housing  42  is generally cylindrical in shape. The second housing  42  has a first outer surface  44  that extends to the second, smaller outer diameter surface  46  which terminates at the radial end  48 . Extending radially inward is the inner diameter portion  50 . The inner diameter portion  50  has a center of axis denoted by the dashed line  52 , which is also the center of axis for the cylindrical outer surfaces  44 ,  46 . 
         [0037]      FIG. 3  also illustrates the threaded opening, seen generally at  54  (sometimes referred to as the box connection  54 ), and wherein the threaded opening  54  is configured to engage the threaded opening  12 . As shown in  FIG. 3 , the threaded opening  54  is tilted (i.e. inclined) relative to the outer surfaces  44 ,  46 . The threaded opening  54  contains internal threads  55 . As illustrated in  FIG. 3 , the threaded opening  54  has a center of axis denoted by the dashed line  56  (sometimes referred to as the titled box angle), and wherein the center of axis  56  is offset from the center of axis  52  by the angle denoted  58 , which in the most preferred embodiment is between 1.5 and 2.0 degrees. The box connection  54  extends to the indentation  60  which in turn extends to the inner surface  62 . The inner surface  62  then extends to the eccentric inner surface  64 , and wherein the eccentric inner surface  64  allows for the junction of the inner diameter portion  50  and the inner surface  62 . The second housing  42  contains the radial end  66 . 
         [0038]      FIG. 4A  is a planar view of the assembled apparatus  68  (sometimes referred to as the adjustable bent sub  68 ) of the preferred embodiment at a zero degree angle of inclination orientation. As shown, the shoulder  40  of the collar  26  abuts the shoulder  69  of the first housing  2 . Also, the radial end  30  of the collar  26  abuts the radial end  66  of the second housing  42 . As shown, the center of axis  10  of the housing  2  and the center of axis  52  of the housing  42  are aligned, and therefore, at zero orientation. 
         [0039]      FIG. 4B  is a cross-section view of the assembled apparatus  68  taken along line A-A from  FIG. 4A .  FIG. 4B  depicts the engagement of the collar helical end profile  32  with the helical profile  8  as well as the radial end  30  abutting the radial end  66 . The first housing  2  is threadedly connected to the second housing  42 . As oriented in  FIGS. 4A and 4B , the axis of the assembled apparatus  68  would be aligned with the drill bit axis. 
         [0040]      FIG. 5A  is a planar view of the assembled apparatus  68  of the preferred embodiment at a 180 degree angle of inclination orientation. In this embodiment, the first housing  2  and the second housing  42  have been separated, and the collar  26  has been repositioned by removing from the splines means, rotationally repositioning the spline means, and then threadedly connecting the first housing  2  and the second housing  42 . Hence, the shoulder  40  of collar  26  has been rotationally separated from the shoulder  69  of first housing  2 , as seen in  FIG. 5A .  FIG. 5B  is a cross-section view of the assembled apparatus  68  taken along line B-B of  FIG. 5A .  FIG. 5B  depicts the center axis  10  of the first housing  2  as well as the center of axis  56  of the second housing  42 . The numeral  98  depicts the angle of inclination which is 2 to 4 degrees. 
         [0041]    The numeral angle  98  would be the sum of the tilted box angle  58  and the first housing angle  99  (angle between item  10  and item  22  seen in  FIG. 1 ) with 180 degree angle of inclination rotation. 
         [0042]    As oriented in  FIGS. 5A and 5B , the center of axis  56  would be offset from the drill bit axis. Put another way, the assembled apparatus  68  represents an adjustable bent sub of a downhole motor assembly in the tilted mode due to the 3 to 4 degree angle of inclination. 
         [0043]    Referring now to  FIG. 6A , a planar view of the first housing  2  and the collar  26  at zero (0) degree angle of inclination orientation will now be described. This view is the view of  FIGS. 4A and 4B , except the second housing  42  has been removed. Note that the line  70  represents the level of the radial end  30 . In  FIG. 6B , which is a planar view of the first housing  2  and collar  26  at a one hundred and eighty (180) degree angle of inclination orientation, the collar  26  has been rotationally displaced by lifting the collar  26  from the splines and repositioning the collar  26  onto the splines (i.e. the collar  26  has been rotated relative to the first housing  2 ). Hence, the collar  26  was disengage from the spline means, rotated, and the spline means were then re-engaged to the position seen in  FIG. 6B . The line  72  represents the level of the radial end  30  relative to the previous level  70  after this rotational displacement. Moreover, the delta H represents the amount of lateral movement of radial end  30  after the rotational displacement. 
         [0044]    As mentioned earlier, the adjustable bent sub  68  will be part of a downhole mud motor assembly used in drilling subterranean reservoirs. Referring now to  FIG. 7 , which is a schematic view of a mud motor assembly, seen generally at  72 , within a wellbore  74 . As readily understood by those of ordinary skill in the art, the mud motor  72  contains the power section  76 , the adjustable bent housing apparatus  68  and the bearing section  78 . The bearing section contains a drive shaft (DS) that will be connected to the drill bit  80  for drilling the wellbore  74 . The power section  76  contains an output shaft (OS) that is connected to the drive shaft (DS). The power section generates a rotational movement to the output shaft (OS), which in turn is transferred to the drive shaft. The drill bit  80  will be turned by the drive shaft in order to drill the wellbore  74 . The downhole mud motor assembly  72  is connected to a work string  82 . 
         [0045]    As seen in  FIG. 7 , the adjustable sub  68  is oriented in the straight mode i.e. the center of axis  84  of the drill bit  80  is aligned with the center of axis  10  of the first housing  2 .  FIG. 8  is a schematic view of the mud motor of  FIG. 7  in a bent orientation within the wellbore  74 . More specifically, the center of axis  10  of the first housing  2  is offset by an angle of three (3) degrees relative to the center of axis  84  of the lower housing  42 . As seen in  FIG. 8 , the drill bit  80  will drill in a deviated direction due to the adjustable bent sub&#39;s orientation. 
         [0046]    Although the invention has been described in terms of specified embodiments which are set forth in detail, is should be understood that this is by illustration only and that the invention is not necessarily limited thereto, since alternative embodiments and cooperating techniques will become apparent to those skilled in the art in view of the disclosure. Accordingly, modifications are contemplated which can be made without departing from the spirit of the described invention.