Patent Abstract:
The present invention provides a hydraulically actuated downhole adjustable bent housing for use in directional drilling of bore holes and wells that allows adjustment of the housing from aligned to a bent configuration without raising or lowering the drillstring. The present invention also provides a method of directionally drilling a bore hole or a well using an downhole adjustable bent housing that can be operated without raising or lowering the drillstring.

Full Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention provides a downhole adjustable bent housing for use in directional drilling of wells used to recover oil and gas, and a method for directionally drilling a well to recover oil and gas. 
     2. Background of the Related Art 
     Wells are generally drilled to recover natural deposits of hydrocarbons and other desirable, naturally occurring materials trapped in geological formations in the earth&#39;s crust. A slender well is drilled into the ground and directed to the targeted geological location from a drilling rig at the surface. In conventional “rotary drilling” operations, the drilling rig rotates a drillstring comprised of tubular joints of drill pipe connected together to turn a bottom hole assembly (BHA) and a drill bit that are connected to the lower end of the drillstring. The BHA typically comprises a number of downhole tools including adjustable bent housings, drill collars and mud motors, and is generally within 30 feet of the drill bit at the end of the drillstring. During drilling operations, a drilling fluid, commonly referred to as drilling mud, is pumped down the interior of the drillpipe, through the BHA and the drill bit, and back to the surface in the annulus around the drillpipe. Mud motors are often used to rotate the drill bit without rotation of the drillstring. Pressurized mud pumped down the interior of the drillstring is used to power the mud motor that is mechanically coupled to and turns the nearby drill bit. Mud motors offer increased flexibility for directional drilling because they can be used with stabilizers or bent subs which impart an angular deviation to the BHA in order to deviate the well from its previous path and in the desired direction. 
     Surface adjustable bent housings are downhole tools that make up part of the BHA and are typically connected either between the mud motor and the drill bit or above the mud motor and the drill bit. Such bent housings are designed to provide an angular deviation in the BHA to directionally orient drilling action at the drill bit. A surface adjustable bent housing may be adjusted to a particular setting by tripping the drillstring and setting the bent housing to impart a desired angular deviation to the well. 
     A downhole adjustable bent housing offers savings in rig time and well costs because it is adjustable without being removed from the well. A downhole adjustable bent housing that is positionable, or deployable, from the surface can be used to efficiently influence the drop or build angle of the boring direction of the drill bit. The angle of attack of the drill bit and the resulting direction of the well can be guided using the downhole adjustable bent housing. 
     It is well known in the drilling industry how to obtain reliable three-dimensional location data for the bottom of the well being drilled. The driller compares this information with the target bottom hole location to determine needed adjustments in the path of the well, and the adjustments to the direction of drilling of the well may be made using the present invention. 
     Prior art surface adjustable bent housings use a complicated series of three connected housings that rotate independently to provide varying configurations from aligned to bent relative to the BHA. These tools require complex schemes for controlling rotational positions of each housing. 
     It is therefore an object of the present invention to provide a downhole adjustable bent housing that can be easily and repeatedly deployed or retracted by controllable changes made at the surface in hydraulic mud pressure in the drillstring. 
     It is a further object of the present invention to provide a downhole adjustable bent housing that can be adjusted without the use of wired or cabled control systems that complicate drilling operations, and that is reliable and simple to deploy and retract. 
     It is a further object of the present invention to provide a downhole adjustable bent housing that, once locked into its deployed position, allows the driller freedom to change the rate of the mud pumps without affecting the deployed condition of the tool. 
     It is a further object of the present invention to provide a downhole adjustable bent housing that provides the driller with reliable detection of the deployed or retracted status of the tool. 
     SUMMARY OF THE INVENTION 
     The above-described objects of the present invention, as well as other objects and advantages, are achieved by a downhole adjustable bent housing that is deployed and retracted by the driller by using the mud pumps located at the surface and used to circulate drilling mud in the well during the drilling process. The present invention does not require wires, cables or cumbersome reciprocation of the entire drillstring to deploy, lock or re-align the downhole adjustable bent housing, and the downhole adjustable bent housing is controllably deployed and realigned without a trip using hydraulic pressure provided by the mud pumps. The present invention provides the driller with readily available information regarding the status of the tool (aligned or deployed, and to what extent), utilizes existing mud pumps as its source of control, and is compatible with existing mud motors and other downhole equipment. The present invention provides reliable deployment and re-alignment of the downhole adjustable bent housing without interfering, with the mechanical transfer of transmission shaft power from a mud motor connected above the tool to a drill bit connected below the tool. 
     The present invention provides a surface-operated downhole adjustable bent housing with a bendable housing and a hydraulically actuated, tubular mandrel that engages and displaces an articulating member which, when actuated by the mandrel, sets or deploys the downhole adjustable bent housing, into its bent, or non-aligned configuration. The downhole adjustable bent housing comprises a mandrel housing  33  and a member housing  34  joined at a knuckle or joint to form a bendable housing. The housings and the knuckle provide a common center passage accommodating a transmission shaft providing power from the mud motor to the drill bit, and provide substantial rigidity to the bendable housing structure in its inactive and deployed configurations. Under the bending force provided by mechanical interaction of the mandrel and the articulating member, the joined sections of the housing are made to angularly deviate one relative to the other to form a slight angle in the downhole adjustable bent housing. 
     The mandrel is reciprocally disposed within a mandrel housing, but protrudes through an opening in the knuckle and into a passage in the articulating member pivotally secured in the member housing. When actuated, the mandrel overcomes a return spring that biases the mandrel towards its inactive position. The mandrel is hydraulically actuated to cycle through a number of predetermined positions to allow drilling with the downhole adjustable bent housing in either the deployed (bent) or inactive (aligned) configurations. For example, the mandrel can be hydraulically actuated from its inactive position (spring force exceeds the mud pressure forces on the mandrel) to an intermediate position (mandrel displaced into contact with the passage of articulating member, but no deployment of the downhole adjustable bent housing), back to the inactive position, and later to its deployed position (mandrel displaced further to enter the passage in the articulating member to deploy the bent housing). 
     The mandrel is actuated towards the articulating member by exposing the mandrel to at least a threshold drilling mud pressure applied through the drillstring by the mud pumps at the surface. When the drilling mud pressure overcomes the opposing return spring force, the mandrel is displaced to the extent allowed by the rotational position of the control collar as it engages a guide finger that is fixed to the housing. The mandrel is locked into its displaced position by the force of the mud pressure on the mandrel until the pressure is reduced below the threshold pressure. The mandrel is said to be “locked” into its intermediate (or deployed) position(s) only in the sense that the mandrel is hydraulically secured into its intermediate (or its deployed) position until the mud pressure drops below the threshold pressure and mud forces on the mandrel are overcome by the force of the return spring. 
     With a first actuation, the mandrel is displaced to its intermediate position by mud pressure axially displacing the mandrel and an attached rotating position control collar, such as a “J-slot” collar. The reciprocation of the mandrel is controlled by interaction of the control collar and the housing. The leading end, or nose, of the mandrel enters the receiving port of the articulating member and engages the passage therein without rotation of the articulating member or laterally displacing the articulating member. In this intermediate position, the contact between the nose of the mandrel and the articulating member provides additional rigidity to the downhole adjustable bent housing while drilling in a path defined by the tool in its undeployed configuration. The mandrel is unlocked from its intermediate position by reducing the pressure in the drillstring to below the threshold pressure and allowing the force of the return spring to stroke the mandrel back to its original, inactive position. 
     With a second actuation, the mandrel is displaced beyond its intermediate position to its deployed position. Again, the extent of travel of the mandrel is determined by the control collar, but the control collar has a different angular orientation relative to the housing. The controlled angular orientation of the control collar is provided by a series of interconnected grooves in the collar that interface with the guide finger, and the grooves allow further displacement of the mandrel to its deployed position on the second actuation. When actuated to its deployed position, the nose of the mandrel engages and forcibly aligns the passage in the articulating member with the shaft of the mandrel. The articulating member rotates to receive the shaft within the passage and is laterally displaced from its inactive position to its deployed position. 
     The downhole adjustable bent housing is biased towards its inactive (aligned) position by the knuckle or other biasing components that generally urge the mandrel housing and the member housing into axial alignment. More particularly, the space between the mandrel housing and the member housing is beveled on the tool face side to bias the two into axial alignment when the drill string is rotated. Also, beveled lock rings act to prevent bending once a straight position is achieved. The passage in the articulating member is not axially aligned with the mandrel when the downhole adjustable bent housing is in its inactive, aligned configuration. The passage in the articulating member is adapted at its receiving port to receive the nose of the mandrel upon deployment of the downhole adjustable bent housing. The nose of the mandrel and the receiving port of the articulating member are tapered or contoured to rotate the articulating member to generally align the passage for further receiving of the mandrel, thereby directing the end of the mandrel towards the passage. As the mandrel is forced into its deployed position within the passage of the articulating member, a misalignment between the shaft of the mandrel and the wall of the passage causes sliding interference between the mandrel and the articulating member as the mandrel moves to its deployed position. The sliding interference results in a lateral force on the articulating member as the mandrel thrusts into the passage. The forced alignment of the previously axially misaligned passage of the articulating member provides a lateral bending force that is transferred to the member housing through supports pivotally securing the articulating member within the member housing. The transfer of force to the member housing overcomes the biasing alignment of the knuckle or other components tending to align the mandrel housing and the member housing, thereby bending the downhole adjustable bent housing and deploying the tool. 
     The articulating member may be pivotally disposed within the member housing using axle ears located on opposite lateral sides of the articulating member. These axle ears are generally aligned one with the other, and may be pivotally received within recesses on the inside wall of the member housing. The lateral force imparted to the articulating member by the mandrel as it is received into the passage is transferred through the axle ears to the member housing. The lateral force imparted to the member housing causes the downhole adjustable bent housing to bend at the knuckle so that the member housing, and the connected drill bit, are out of alignment with the mandrel housing. This deployed configuration of the downhole adjustable bent housing is used for imparting a curve, or angular deviation, to the well being drilled. As drilling on a curved path progresses with the tool in the deployed configuration, the articulating member and the mandrel remain locked in their deployed position by the force of the drilling mud pressure bearing on the mandrel until the drilling mud pressure is reduced below the threshold pressure. After the mandrel is unlocked from its deployed position, the force of the return spring causes the mandrel to withdraw from the passage and move towards its inactive position. The control collar rotates during each induced angular rotation of the collar to cycle the downhole adjustable bent housing through the inactive, intermediate and deployed positions as needed to deviate the well in the desired path. It should be recognized that other and further actuation cycles can be envisaged, such as a cycles adding a third actuated position achieving partial deployment of the downhole adjustable bent housing. 
    
    
     DESCRIPTION OF DRAWINGS 
     So that the features and advantages of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the embodiments thereof that are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. 
     FIG. 1A is an elevation view of a downhole adjustable bent housing according to the present invention imparting a slight downward angle to the drill bit to drop angle, or turn the well downwardly, from its existing path. 
     FIG. 1B is an elevation view of a downhole adjustable bent housing according to the present invention imparting a slight upward angle to the drill bit to build angle, or turn the well upwardly, from its existing path. 
     FIG. 2A is a detailed, cross-sectional side view of the downhole adjustable bent housing of FIGS. 1A-1B in an inactive, aligned position. 
     FIG. 2B is a detailed, cross-sectional side view of the downhole adjustable bent housing of FIGS. 1A-1B as the mandrel enters the receiving port of the articulating member. 
     FIG. 2C is a detailed, cross-sectional side view of the downhole adjustable bent housing of FIGS. 1A-1B in its intermediate position as the nose of the mandrel contacts the inside wall of the passage in the articulating member. 
     FIG. 2D is a detailed, cross-sectional side view of the downhole adjustable bent housing of FIGS. 1A-1B in the deployed position. 
     FIG. 3 is a side view of a four-stroke rotating position control collar. 
     FIGS. 4A through 4D are a sequential series of side views showing a cycle of a control collar and its interaction with the guide finger. 
     FIG. 5 is a perspective view of an articulating member according to a preferred embodiment of the present invention. 
     FIG. 6 is a cross-sectional side view of the articulating member in its inactive and deployed (phantom lines) positions. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1A shows a downhole adjustable bent housing  10  connected between a mud motor and a drill bit in accordance with the present invention. The downhole adjustable bent housing  10  in this configuration is set to have a slight downward angular deviation, thereby influencing the drill bit to drop angle, or turn downwardly, from its existing path. FIG. 1B shows how the downhole adjustable bent housing  10  may impart an upward angular deviation to the BHA that affects the angle of attack of the bit against the bore wall. The angular deviation imparted by the downhole adjustable bent housing  10  is a slight upward angular deviation thereby influencing the drill bit to build angle, or turn upwardly, from its existing path. 
     FIG. 2A shows the general configuration of a preferred embodiment of the downhole adjustable bent housing  10 , in its inactive position. The downhole adjustable bent housing  10  has a mandrel housing  33  and a member housing  34  pivotally joined at a knuckle  35 . The knuckle  35  can be any of several pivoting connections including a ball and socket connection or a flexible sleeve connection. The knuckle  35  shown in FIGS. 2A through 2D comprises a ball portion  135  extending from the mandrel housing  33  into a socket portion  235  formed in the member housing  34 . The mandrel housing has a threaded proximal connection  22  disposed at the end of the mandrel housing  33  opposite the knuckle  35  for connection to a drillstring  30  (See FIGS. 1A,  1 B). The member housing  34  has a threaded distal connection  24  disposed at the end of the member housing  34  opposite the knuckle  35  for connection to the drill bit  80  (See FIGS. 1A,  1 B). When the downhole adjustable bent housing  10  is in its inactive, aligned position, the centers of the proximal connection  22  and the distal connection  24  generally define a common axis  26 . 
     An articulating member  140 , shown in greater detail in FIG. 5, has a pair of axle ears  141  for engaging the member housing  34  at mating pivot points (not shown) on the inside wall of the member housing  34 . The centers of the axle ears  141  of the articulating member  140  form an axis  143 , indicated in FIG. 6, that lies perpendicular to the axis  26  of the mandrel housing  33 . The articulating member  140  pivots about the axis  143  as dictated by the engagement with the mandrel  40 . 
     FIG. 2A shows the mandrel  40 , the articulating member  140  and the downhole adjustable bent housing  10  all in their inactive and aligned positions. FIG. 2B shows the mandrel  40  moved into a first portion of the passage in the articulating member, the receiving port  142 , but the nose of the mandrel  40  has not yet engaged the articulating member  140 . FIG. 2C shows the mandrel  40  distally displaced against the force of the return spring  36  to its intermediate position, the articulating member  140  remaining in its inactive position, and the downhole adjustable bent housing  10  still in its aligned position. In its intermediate position shown in FIG. 2C, the mandrel  40  is fully received into the first portion of the passage, the receiving port  142 , but has not yet entered into the second portion of the passage, receiving port  144 , to deploy the tool. FIG. 2D shows the mandrel  40 , the articulating member  140  and the downhole adjustable bent housing  10  all in their active and deployed positions (upward build angle). In its active, deployed position, the mandrel  40  is fully received into the second portion of the passage, port  144 , after the articulating member  140  has rotated to align port  144  with the shaft of the incoming mandrel  40 . 
     FIGS. 2A through 2D show the mandrel  40  with the rotating position control collar  42  rotatably received thereon, with both the mandrel  40  and the control collar  42  disposed within a chamber in the mandrel housing  33 . The mandrel  40  has an axis  26  and an annular drillstring pressure sensing surface  48 . The mandrel  40  and the control collar  42  axially reciprocate together within the chamber of the mandrel housing  33  along their axis  26 . 
     The mandrel  40  controllably and cyclically moves between three positions as determined by the angular orientation of the control collar  42  relative to the mandrel housing  33 . In the four-cycle embodiment described in this example, the positions of the mandrel  40  are the inactive position (FIG.  2 A), the intermediate position (FIG.  2 C), back to the inactive position (FIG.  2 A), and the deployed position (FIG.  2 D), in that order. In its deployed position shown in FIG. 2D, the mandrel  40  axially engages the articulating member  140  causing it to rotate the passage therein to receive the nose of the mandrel  40 . The mandrel  40  is not normally aligned with the second portion of the passage, port  144 , in the articulating member  140 , and the resulting interference causes a lateral force on the articulating member  140  as the mandrel is received into the passage. The mandrel  40  forcibly aligns port  144 , rotating the articulating member  140  as it is forced into its deployed position. The forced alignment of passage or port  144  with the mandrel  40  rotates articulating member  140  from position  140   a  to position  140   b , shown in FIG. 6, and laterally displaces the articulating member  140  and the member housing  34  in which the articulating member  140  is secured by an amount equal to the difference between lengths “a” and “b” in FIG.  6 . 
     The responsiveness of the mandrel  40  can be enhanced through strategic placement of circumferential seals and equalization ports to provide a net differential force on the mandrel. FIGS. 2A through 2D show a proximal mandrel seal  38  and a distal mandrel seal  39  disposed in sliding contact with the mandrel  40 . A proximal portion of the chamber of the mandrel housing  33  is in fluid communication with the drilling mud pressure in the drillstring  30 . The portion of the chamber of the mandrel housing  33  between the proximal mandrel seal  38  and the distal mandrel seal  39  is isolated from the drilling mud pressure in the drillstring  30 , but is in fluid communication with the annular mud pressure outside the housing through equalization port  173 . The pressure in the drillstring  30 , the pressure in the annulus, the force of the return spring  36 , along with friction of the seals  38  and  39 , all combine to influence the net axial force acting on the mandrel  40 . The pressure in the drillstring  30  results from drilling mud being forcefully pumped down the drillstring  30  from the discharge of the mud pumps at the surface and the restriction at the bit nozzles. The mud pressure in the drillstring bears on the annular pressure sensing surface  48  of the mandrel  40  and urges the mandrel  40  from its inactive position towards either its intermediate or its deployed positions, depending on the orientation of the control collar  42  relative to the downhole adjustable bent housing  10 . 
     The return spring  36  is disposed in contact with the mandrel housing  33  at a first circumferential spring shoulder  13  and with the mandrel  40  at a first circumferential ridge  15 . The return spring  36  is placed under compression to urge the mandrel  40  towards its inactive position shown in FIG.  2 A. The mandrel spring  36  is designed to elastically compress when the pressure in the drillstring  30  exceeds the threshold actuation pressure. The downhole adjustable bent housing  10  is secured in the desired intermediate (aligned) or deployed (bent) configuration during normal drilling operations as long as the drillstring pressure is above the threshold pressure necessary to overcome and compress the return spring  36 . For example, the threshold actuation pressure may be any pressure that is great enough to compress the return spring  36 . It should be recognized that the threshold actuation pressure is primarily determined by the amount of resistance in the return spring  36  and the net surface area of the annular pressure sensing surface  48 , but is also influenced by the shape of the mandrel  40  and the annular pressure outside the downhole adjustable bent housing  10  adjacent to the equalization port  173 . 
     As shown in FIG. 3, the control collar  42  has a proximal end  41  disposed toward the proximal end of the downhole adjustable bent housing  10  and a distal end  43  disposed toward the articulating member  140  and the distal connection  24  of the downhole adjustable bent housing  10 . The control collar  42  is the device that enables the driller to controllably deploy and re-align the downhole adjustable bent housing  10  by varying the pressure in the drillstring  30  to reciprocate the mandrel  40 . A series of interconnected grooves are machined into the radially outward surface of the control collar  42 . In a simple four-stroke design, these grooves comprise two return grooves  50  (not shown) and  52  and two rotation grooves  51  and  53 . The control collar  42  is axially fixed to the mandrel  40  and reciprocates within the mandrel housing  33  with the mandrel  40 , but it is free to rotate about the axis  26  as guided by a protruding guide finger  55  in a fixed relationship to the mandrel housing  33 . Throughout the four-position inactive-to-intermediate-to-inactive-to-deployed cycle of the mandrel  40 , the guide finger  55  is maintained in rolling or sliding contact with the grooves in the control collar  42 . As the control collar  42  and the mandrel  40  reciprocate within the housing  12 , the guide finger  55  traverses the grooves in a path as dictated by the intersections of the grooves  50 ,  51 ,  52  and  53  and the reciprocation of the mandrel  40  within the mandrel housing  33 . 
     The position of the mandrel  40  is controlled by manipulation of pressure in the drillstring  30 . As shown in FIG. 2A-2C, when the pressure of the drilling mud in the drillstring  30  overcomes the opposing spring and friction forces urging the mandrel  40  towards the inactive position, the mandrel  40  is axially displaced towards its intermediate position. Following an intervening low mud pressure that allows the mandrel  40  to return to its inactive position as shown in FIG. 2A (each return to this position being indicated by the pressure drop resulting from upset  70  closely fitting within pressure sensing surface  48 ), the pressure of the drilling mud in the drillstring  30  is again increased to overcome the opposing forces urging the mandrel  40  towards its inactive position, and the mandrel  40  is displaced towards the deployed position shown in FIG.  2 D. Although it is preferred that the pressure sensing surface  48  be disposed at the proximal end of the mandrel  40  adjacent to the proximal connection  22  to the drillstring  30 , the pressure sensing surface  48  can be located at the distal end of the mandrel  40  or, using a proper arrangement of seals, at any point therebetween. It should also be recognized that by strategic placement of seals, fluid communication passages and the pressure sensing surface, the mandrel  40  may actuate in either the proximal or the distal (uphole or downhole) directions. 
     The control collar  42  rotationally cycles through multiple positions as the mandrel  40  reciprocates within the downhole adjustable bent housing  40 . The description that follows assumes that the control collar  42  is a four-stroke collar. The invention may be used with a two-stroke, six-stroke, eight-stroke or higher number of cycles, and the explanation of the four-stroke cycle does not limit the applicability or adaptability of the invention. For purposes of illustration, the control collar  42  is shown in FIGS. 3 and 4A through  4 D in a cutaway perspective view to improve visualization of the interconnected grooves  50 ,  51 ,  52  and  53 . 
     When the downhole adjustable bent housing  10  is in its inactive position shown in FIG. 2A, the guide finger  55  is in rolling or sliding contact in the first actuation groove  50  near the distal end  43  of the collar  42  shown in FIG.  4 A. The mandrel  40  begins its four-stroke cycle from its inactive position shown in FIG.  2 A. From the inactive position, the mandrel  40  is actuated against the mandrel spring  36 , by exposure of the pressure sensing surface  48  to a threshold pressure, beyond the position shown in FIG. 2B to its intermediate position shown in FIG.  2 C. As this first actuation stroke of the mandrel  40  begins, the control collar  42  moves distally relative to the guide finger  55 . The guide finger  55  initially rolls or slides toward the proximal end  41  of the control collar  42  within the second leg  253  of the second actuation groove  53  to the intersection of the second actuation groove  53  and the first leg  150  of the first actuation groove  50 . When the guide finger  55  reaches that intersection, it slides or rolls into the first leg  150  of the first actuation groove  50  toward the intersection of the first actuation groove  50  and the first leg  151  of the first return groove  51 . The first leg  150  of the first actuation groove  50  is not aligned with the axis  26  of the control collar  42 , and the sliding or rolling contact between the guide finger  55  and the first leg  150  imparts a moment causing the control collar  42  to rotate about its axis  26 . The second leg  250  (not shown) is not aligned with the first leg  150  and is generally aligned with the axis  26 . When the guide finger  55  leaves the first leg  150  and enters the second leg  250 , the guide finger  55  slides or rolls within the second leg  250  to a point near the proximal end  41  of the control collar  42 . At this position, the downhole adjustable bent housing  10  is in the intermediate position shown in FIG.  2 C. Since the second leg  250  is generally aligned with the axis  26  of the control collar  42 , there is little or no rotation of the collar  42  as the guide finger  55  slides within the second leg  250 . 
     At the intermediate position shown in FIG. 2C, the protruding collar spacers  74  distally extending from the distal end  43  of the control collar  42  engage the second circumferential shoulder  75  on the inside wall of the mandrel housing  33  as shown in FIG.  4 B. The spacers  74  thereby limit the movement of the control collar  42  and the rotatably attached mandrel  40  from actuating beyond the intermediate position. 
     When the pressure in the drillstring  30  is reduced to below the threshold pressure, the mandrel  40  reverses direction and moves in the direction of the force applied by the return spring  36 . This reversal begins the first return stroke of the control collar  42 . As the return spring  36  returns the mandrel  40  to or near its inactive position, the guide finger  55  slides or rolls within the second leg  250  toward the intersection of the first actuation groove  50  and the first leg  151  of the first return groove  51 . The first leg  151  of the first return groove  51  is not aligned with the axis  26  of the mandrel  40 , and sliding or rolling contact between the fixed guide finger  55  in the first leg  151  causes the control collar  42  to further rotate about the axis  26 . The rotation of the control collar  42  during the first return stroke is in the same angular direction as the rotation caused by the guide finger  55  sliding or rolling within the first leg  150  during the first actuation stroke. The intersection of the first actuation groove  50  and the first leg  151  of the first return groove  51  directs the guide finger  55  from the second leg  250  of the first actuation groove into the first leg  151  of the first return groove  51 . As the mandrel  40  is displaced by the force of the mandrel spring  36  toward its inactive position, the guide finger  55  slides or rolls within the first leg  151  of the first return groove  51  towards the intersection of the first return groove  51  and the first leg  152  of the second actuation groove  52 . The second leg  251  of the first return groove  51  is generally aligned with the axis  26  of the mandrel  40  and, as the guide finger  55  moves from the first leg  151  to the second leg  251 , there is little or no rotation of the control collar  42 . As the mandrel  40  returns to its inactive position under the force of the return spring  36 , the guide finger  55  slides or rolls within the second leg  251  of the first return groove  51  to a point near the distal end  43  of the control collar  42  as shown in FIG.  4 C. As the mandrel  40  returns to or near its inactive position, the rotational moment imparted to the control collar  42  by interaction with the tracking guide finger  55  causes the control collar  42  to rotate into the position shown in FIG.  4 C. This inactive position occurs between the intermediate position shown in FIG.  2 C and the deployed position shown in FIG. 2D, and the rotation of the control collar  42  has rotatably aligned the spacers  74  to be received within the recesses  75  when the tool is next actuated. 
     When the pressure in the drillstring  30  is again raised above the threshold pressure necessary to overcome the return spring  36 , the mandrel  40  is distally displaced to begin the second actuation stroke to deploy the downhole adjustable bent housing  10 . The second actuation stroke begins as the axial movement of the control collar  42  reverses and the guide finger  55  slides or rolls within the second leg  251  of the first return groove  51  toward the proximal end  41  of the control collar  42 . The second leg  251  intersects the first leg  152  of the second actuation groove  52 . The first leg  152  is not aligned with the axis  26  of the control collar  42 , and as the guide finger  55  passes into the first leg  152  of the second actuation groove  52 , it contacts and slides along the edge of the first leg  152  that is disposed towards the proximal end  41  of the control collar  42 . The first leg  152  is not aligned with the axis of the mandrel  40 , and as the guide finger  55  slides or rolls within the first leg  152 , the control collar  42  rotates about its axis  26 . The rotation of the control collar  42  during the second actuation stroke in the same angular direction as its previous rotations during the first actuation stroke and the first return stroke. The rotation of the control collar  42  as the guide finger  55  slides or rolls within the first leg  152  causes the spacers  74  to become rotatively aligned with, and received into, the recesses  77  in the second circumferential shoulder  75  on the inside wall of the mandrel housing  33 . The guide finger  55  enters the intersection of the first leg  152  and the second leg  252  of the second actuation groove  52  and the first leg  153  of the second return groove  53 . The motion of the mandrel  40  towards the distal end of the mandrel housing  33  causes the guide finger  55  to enter into the second leg  252  of the second actuation groove  52  of the control collar  42 . The second leg  252  of the second actuation groove  52  is generally aligned with the axis  26  of the mandrel  40 , and there is little or no rotation of the control collar  42  as the guide finger  55  slides within the second leg  252  to the point near the proximal end  41  of the control collar  42  shown in FIG.  4 D. 
     At the end of this second actuation stroke the spacers  74  extending from the distal end  43  of the collar  42  are received within the recesses  77  in the second circumferential shoulder  75  of the mandrel housing  33 . The alignment of the spacers  74  and the recesses  77  allow the control collar  42  and the mandrel  40  to actuate beyond the intermediate position shown in FIG. 2C to the deployed position shown in FIG.  2 D. The position of the control collar  42  and the mandrel  40  shown in FIG. 4D correspond to the deployed position of the stabilizer shown in FIG.  2 D. As the spacers  74  are received into the recesses  77 , the mandrel  40  engages and displaces the articulating member  140 . As the mandrel  40  engages the articulating member  140 , the bending force needed to deploy the downhole adjustable bent housing  10  is transferred from the mandrel  40  to the member housing  34  through the articulating member  140  and its axle ears  141 . 
     The mandrel  40 , the articulating member  140  and the downhole adjustable bent housing  10  all remain in their deployed positions shown in FIG. 2D as drilling in the deviated direction progresses. Pressurized drilling mud flows into the mandrel housing  33  at the proximal connection  22 , through the knuckle  35  and exits the member housing  34  at the distal connection  24 . Drilling mud flows through the downhole adjustable bent housing  10  through a series of passages (not shown) running the length of the tool or through the tubular interior of the mandrel  40  and the articulating member  140 , or some combination thereof. One or more of these drilling mud passages may be closed or restricted when the downhole adjustable bent housing  10  is in its deployed configuration, thereby providing a backpressure detectable at the surface for determining the position (intermediate or deployed) of the tool. 
     When the pressure in the drillstring  30  is again reduced below the threshold pressure, this begins the second return stroke, the final stroke of the cycle. At the onset of the second return stroke, the mandrel  40  again reverses direction and returns to its original inactive position shown in FIG.  2 A. 
     On the second return stroke, the guide finger  55  slides or rolls within the second leg  252  of the second actuation groove  52  toward the distal end  43  of the control collar  42  toward the intersection of the second actuation groove  52  and the first leg  153  of the second return groove  53 .The guide finger  55  passes from the second leg  252  of the second actuation groove  52  into the first leg  153  of the second return groove  53 . The first leg  153  is not aligned with the axis  26  of the mandrel  40 , and as the control collar  42  and mandrel  40  are axially displaced relative to the guide finger  55 , the guide finger  55  slides or rolls along the edge of the first leg  153  disposed towards the distal end  43  of the control collar  42 . As the guide finger  55  slides or rolls within the first leg  153 , the control collar  42  angularly rotates in the same angular direction as its previous rotations during the first actuation stroke, the first return stroke and the second actuation stroke. As the guide finger  55  passes through the intersection of the second return groove  53  and the first leg  150  of the first return groove  50 , the guide finger  55  enters the second leg  253  of the second return stroke  53 . The second leg  253  is generally aligned with the axis  44  of the mandrel  40 , and little or no rotation of the control collar  42  as the guide finger  55  slides or rolls within the second leg  253  to a point near the distal end  43  of the control collar  42  shown in FIG.  4 A. This completes the four cycles of the control collar  42  selected for this example. 
     The articulating member  140  pivots within and relative to the member housing  34  about a pivot axis  143  defined by the axle ears  141 . When port  144  is forcibly aligned with the mandrel axis  26  by insertion of the mandrel  40 , the pivot axis  143  is laterally displaced relative to the mandrel axis  26 . The lateral force applied to the articulating member  140  by the mandrel  40  is transferred through the axle ears  141  to the member housing  34 , causing the downhole adjustable bent housing  10  to bend at the knuckle  35 . The extent of the bend is determined by the physical dimensions of the housing, mandrel and articulating member, but is generally in the range up to 10 degrees, but most preferably in the range up to 2 degrees. 
     When the mandrel  40  is in its inactive position, port  144  of the articulating member  140  remains pivotally misaligned with the axis of the mandrel  40 , but sufficiently positioned for non-interference with the transmission shaft  57  providing power from the mud motor  90  to the drill bit  80 . When the downhole adjustable bent housing  10  is in the intermediate position shown in FIG. 2C, the transmission shaft  57  turns on its axis within the passage defined by the annular pressure sensing surface  48 , the tubular interior of the mandrel  40 , the passage  142  of the articulating member  140 , and a port in the slotted support disk  136 . 
     When the mandrel  40  is moved from the inactive position shown in FIG. 2A to the intermediate position shown in FIG. 2C, and then returned to the inactive position shown in FIG. 2A, the four stroke control collar  42  angularly rotates about one-half of a revolution. As further angular rotation of the control collar  42  occurs, the spacers  74  extending from the distal end  43  of the collar  42  are rotatively aligned with recesses  77  in the circumferential shoulder  75  on the inside wall of the mandrel housing  33 . The alignment of these recesses  77  allow the mandrel  40 , displaced by the drilling mud pressure bearing on the pressure sensing surface  48 , to move beyond its intermediate position to its deployed position. As shown in FIGS. 2D and 4D, upon second actuation of the mandrel  40  from its inactive position, the mandrel  40  engages and laterally displaces the articulating member  140  and the member housing  34  toward their deployed positions. FIG. 3 shows a four-stroke rotating collar having two actuation grooves, a first actuation groove  50  (not shown) and a second actuation groove  52 , and two return grooves, a first return groove  51  and a second return groove  53 . This configuration is referred to as a four-stroke collar  42  because of the total number of interconnected grooves being four. By its nature as a cylindrical shape, the outside surface of the collar  42  into which the grooves are machined provides 360 degrees of angular rotation. Equal spacing of the four distinct strokes provides about 90 degrees per stroke. For a four stroke configuration described above, it is preferable to angularly space the first actuation groove and the first return groove within about 180 degrees of the outside angular surface of the collar and the second actuation groove and the second return groove within the remaining 180 degrees. In a four stroke configuration, the collar  42  “toggles” the mandrel  40  between the two actuated mandrel positions, the intermediate position shown in FIG.  2 C and the deployed position shown in FIG.  2 D. 
     The downhole adjustable bent housing  10  may be modified to include a higher number of positions in the cycle. For example, the control collar  42  could be modified to operate in six cycles by including a third actuation groove immediately followed by a third rotation groove angularly inserted between the second return groove  53  and the first actuation groove  50 . In this six cycle configuration, each actuation groove and return groove pair will comprise approximately 120 degrees of the outside angular surface of the control collar  42  so that the control collar  42  accommodates three actuated mandrel positions instead of only two. The six-cycle collar would accommodate a second set of spacers corresponding to the second deployed position extending from the distal end of the collar and angularly spaced from the first set of spacers  74  corresponding to the first deployed position. The second set of spacers may be longer or shorter than the first set of spacers  74  to make the bend in the downhole adjustable bent housing  10  corresponding to the second deployed position different from the bend in the downhole adjustable bent housing  10  corresponding to the first deployed position. Conversely, a second set of recesses of different depth than the first set of recesses  77  in the second circumferential shoulder  75  may receive a second set of spacers in order to make the corresponding second deployed position impart a different angular bend from the first deployed position. Additional deployment positions and angular bends can be created by inclusion of additional spacers, actuation grooves and return grooves in correspondingly smaller angular portions of the collar. 
     By further “compressing” the pairs of actuation grooves and return grooves into angularly smaller portions of the collar, the control collar can be modified to provide more than one cycle of the stabilizer per revolution of the collar. For example, an eight stroke control collar wherein each pair of actuation grooves and return grooves are disposed within 45 degrees of the angular rotation of the collar may provide strokes  5  through  8  as a mirror image of strokes  1  through  4 . That is, the control collar may be designed such that the first actuation stroke and the third actuation stroke displace the mandrel to identical intermediate positions, and the second actuation stroke and the fourth actuation stroke displace the mandrel to identical deployed positions. The design of the control collar, i.e. the number of deployed positions and the number of cycles per revolution, should take into consideration several factors affecting the operation of the rotating position control collar. These factors include, but are not limited to, the diameter of the control collar, the thickness of the grooves, the friction between the guide finger and non-aligned portions of the grooves and the overall displacement of the reciprocation of the mandrel within the housing. 
     The meaning of “groove”, as that term is used herein, includes, but is not limited to, a groove, slot, ridge, key and other mechanical means of maintaining two parts moving relative one another in a fixed rotational, axial or aligned relationship. Further, the meaning of “mandrel”, as that term is used herein, includes, but is not limited to, mandrels, pistons, posts, push rods, tubular shafts, discs and other mechanical devices designed for reciprocating movement within a defined space. The term “gauge” means diameter, thickness, girth, breadth and extension. The term “collar” means collars, rims, sleeves, caps and other mechanical devices rotating about an axis and axially fixed relative to the mandrel. “Slender” means little width relative to length. An “appendage” is a part that is joined or attached to a principal object. The term “port” means a passageway, slot, hole, channel, tunnel or opening. The term “finger” means a protruding or recessed guide member that allows rolling or sliding engagement between the housing  12  and the control collar  43  that maintains the housing  12  and the control collar  42  within a desired orientation one to the other, and includes a key and groove and rolling ball and socket. 
     While the foregoing is directed to the preferred embodiment of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims which follow.

Technology Classification (CPC): 4