Patent Publication Number: US-10760386-B2

Title: Slant well pumping unit

Description:
BACKGROUND OF THE DISCLOSURE 
     Reciprocating pump systems, such as sucker rod pump systems, extract fluids from a well and employ a downhole pump connected to a driving source at the surface. A rod string connects the surface driving force to the downhole pump in the well. When operated, the driving source cyclically raises and lowers the downhole pump, and with each stroke, the downhole pump lifts well fluids toward the surface. 
     For example,  FIG. 1  shows a sucker rod pump system  10  used to produce fluid from a well. A downhole pump  14  has a barrel  16  with a standing valve  24  located at the bottom. The standing valve  24  allows fluid to enter from the wellbore, but does not allow the fluid to leave. Inside the pump barrel  16 , a plunger  20  has a traveling valve  22  located at the top. The traveling valve  22  allows fluid to move from below the plunger  20  to the production tubing  18  above, but does not allow fluid to return from the tubing  18  to the pump barrel  16  below the plunger  20 . A driving source (e.g., a pump jack or pumping unit  30 ) at the surface connects by a rod string  12  to the plunger  20  and moves the plunger  20  up and down cyclically in upstrokes and downstrokes. 
     During the upstroke, the traveling valve  22  is closed, and any fluid above the plunger  20  in the production tubing  18  is lifted towards the surface. Meanwhile, the standing valve  24  opens and allows fluid to enter the pump barrel  16  from the wellbore. 
     At the top of stroke, the standing valve  24  closes and holds in the fluid that has entered the pump barrel  16 . Furthermore, throughout the upstroke, the weight of the fluid in the production tubing  18  is supported by the traveling valve  22  in the plunger  20  and, therefore, also by the rod string  12 , which causes the rod string  12  to stretch. During the downstroke, the traveling valve opens, which results in a rapid decrease in the load on the rod string  12 . The movement of the plunger  20  from a transfer point to the bottom of stroke is known as the “fluid stroke” and is a measure of the amount of fluid lifted by the pump  14  on each stroke. 
     At the surface, the pump jack  30  is driven by a prime mover  40 , such as an electric motor or internal combustion engine, mounted on a pedestal above a base  32 . Typically, a pump controller  60  monitors, controls, and records the pump unit&#39;s operation. Structurally, a Sampson post  34  on the base  32  provides a fulcrum on which a walking beam  50  is pivotally supported by a saddle bearing assembly  35 . 
     Output from the motor  40  is transmitted to a gearbox  42 , which provides low-speed, high-torque rotation of a crankshaft  43 . Both ends of the crankshaft  43  rotate a crank arm  44  having a counterbalance weight  46 . Each crank arm  44  is pivotally connected to a pitman arm  48  by a crank pin bearing  45 . In turn, the two pitman arms  48  are connected to an equalizer bar  49 , which is pivotally connected to the rear end of the walking beam  50  by an equalizer bearing assembly  55 . 
     A horsehead  52  with an arcuate forward face  54  is mounted to the forward end of the walking beam  50 . As is typical, the face  54  may have tracks or grooves for carrying a flexible wire rope bridle  56 . At its lower end, the bridle  56  terminates with a carrier bar  58 , upon which a polished rod  15  is suspended. The polished rod  15  extends through a packing gland or stuffing box at the wellhead  13 . The rod string  12  of sucker rods hangs from the polished rod  15  within the tubing string  18  located within the well casing and extends to the downhole pump  14 . 
     As is known, pump jack operating characteristics are typically characterized by the American Petroleum Institute (“API”) Specifications, which expresses parameters as a function of the geometry of a pumping unit&#39;s four-bar linkage. Standardized API linkage geometry designates: dimension “A” as the distance from the center of the saddle bearing  35  to the centerline of the polished rod  15 ; dimension “C” as the distance from the center of the saddle bearing  35  to the center of the equalizer bearing  55 ; dimension “P” as the effective length of the pitman arm  48  as measured from the center of the equalizer bearing  55  to the center of the crank pin bearing  45 ; dimension “R” as the distance from the centerline  43  of the crankshaft to the center of the crank pin bearing  45 ; dimension “H” as the height from the center of the saddle bearing  35  to the bottom of the pump jack base  32 ; dimension “I” is the horizontal distance from the center of the saddle bearing  25  to the centerline  43  of the crankshaft; dimension “G” as the height from the centerline  43  of the crankshaft to the bottom of the pump jack base  32 ; and dimension “K” as the distance from the centerline  43  of the crankshaft to the center of the saddle bearing  35 . Dimension “K” may be computed as:
 
 K =√{square root over (( H−G ) 2   +I   2 )}
 
     As is typical, the pump jack  30  as in  FIG. 1  operates in conjunction with a vertically aligned wellhead  13 . In some implementations, portions of a wellbore may be inclined or slanted from a vertical angle. In general, the slanted wellbore can penetrate fluid producing strata of a formation along a longer path for more exposure to the producing formation. Therefore, depending on the well&#39;s depth, the wellhead  13  at surface may also be inclined relative to vertical. The range of surface inclination typically varies between 0 and 45 degrees from vertical (i.e., between 90 and 45 degrees relative to the horizontal surface). 
     Apart from all of the complications downhole, the slanted wellhead and wellbore present problems for a traditional pump jack at surface. One configuration of a pump jack  30  for use with a slanted well having an inclined wellhead  13  is shown in  FIG. 2A . (The same reference numerals are used for similar components described in previous figures.) This configuration is similar to that disclosed in U.S. Pat. No. 4,603,592. As shown, the wellhead  13  is inclined at an angle θ relative to the horizontal surface S. To direct the polished rod  15  through the slanted wellhead  13 , the orientation of the walking beam  50  has been tilted. In particular, the pitman arms  48  have a longer length, the Sampson post  34  is tilted forward, and the horsehead  54  may be enlarged so that the pumping unit  30  can address the inclined wellhead  13 . 
     This configuration alters the geometry of the four-bar linkage of the pump jack  30  so that the polished rod  15  can align with the inclined wellhead  13 . Unfortunately, the alteration of the four-bar linkage may have a significant effect on the operating characteristics of the pumping unit  30 , such as changing the allowable polished rod load, changing the shape of the permissible load envelope, altering the length of the pumping stroke, inducing a phase angle shift in the counterbalance, etc. Moreover, the change in operating characteristics at surface may further affect controls, analysis, diagnostics of the downhole rod pump because calculations for these features are typically based on the standard four-bar linkage (K-R-P-C). 
     Another configuration of a pump jack  30  for use with a slanted well having an inclined wellhead  13  is shown in  FIG. 2B . (The same reference numerals are used for similar components described in previous figures.) This configuration is similar to that disclosed in U.S. Pat. No. 8,240,221. Instead of increasing the length of the pitman arms  48 , this configuration has an elbow-shaped walking beam  50  to address the angled wellhead  13 . The elbow shape is formed by a bend or elbow section  53  that defines forward and rearward sections of the beam  50 . The bend  53  is located forward of the centerline of the center bearing  35 . 
     The forward section of walking beam  50  is fabricated so its longitudinal axis is angled to address the inclination of the wellhead  13 . In this way, the radius A from the centerline of the center bearing  35  to the arcuate face  54  of the horsehead  52  is tangent to the inclined polished rod  15 . As disclosed, the non-linear bent walking beam  50  is described as providing a simple and effective means of addressing the angled wellhead  13  while preserving the operating characteristics of a prior art pumping unit. As also disclosed, the beam  50  is fabricated with the bend  53  that closes matches the wellhead angle. As further disclosed, the rearward section of the walking beam  50  from the saddle bearing  35  to the equalizer bearing  55 , and the four-bar linkage system embodied by the pump jack, remains unchanged relative to a prior art pump jack intended for vertical wells. 
     Although slant well pump jacks of the prior art may have some benefits, operators are continually striving to increase the versatility of pump jack systems to meet the challenges of various implementations. The subject matter of the present disclosure is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above. 
     SUMMARY OF THE DISCLOSURE 
     A surface pumping unit disclosed herein is for reciprocating a rod load for a downhole pump in a well. The well has a wellbore axis intersecting at an inclination relative to surface. The unit comprises a frame and a beam. The frame is disposed at the surface and has a fulcrum point. The beam has first and second ends and defines a bend therebetween. The first end is connected to the rod load extending from the well at the inclination. The beam is pivotable at a pivot on the fulcrum point of the frame, and the pivot is disposed between the bend and the first end of the beam. 
     In one further configuration, the frame comprises a base and a post. The base is disposed at the surface, and the post extends from the base to the fulcrum point along an axial line from vertical. The first end of the beam comprises a straight section at the pivot of the fulcrum point, and the straight section is angled to intersect the axial line of the post at an acute forward angle. Orientation of the post, the straight section, and the pivot support a load of the beam with a force along the axial line reducing bending stress on the post. 
     In another further configuration, the unit comprises a head disposed on the first end of the beam. The head has a face circumscribing a segment at a radius relative to the fulcrum point, and the segment is tangential to the angles for the inclination of the wellbore axis. The unit is disposed at one of a plurality horizontal offsets from an intersection of the wellbore axis with the surface, and the face disposed with the base at the horizontal offsets accommodates a plurality of angles for the inclination of the wellbore axis. 
     The face can have a top end and a bottom end. At least seventy-percent or greater of the face from the top end can tangentially intersect the rod load along the wellbore axis for a largest of the angles of the inclination; and at least seventy-percent or greater of the face from the bottom end can tangentially intersect the rod load along the wellbore axis for a smallest of the angles of the inclination. 
     In various arrangements, the fulcrum point is disposed at a first vertical height (H) above the surface and is disposed at a horizontal offset from an intersection of the wellbore axis with the surface. The pivot can comprise a saddle bearing. The first end of the beam can comprise a first straight section having a first length, the second end of the beam can comprises a second straight section having a second length, and the bend can define an angle between the first and second straight sections and inclining the first straight section downward toward the frame. 
     In further configurations, the unit further comprises a prime mover, a crank arm, and a pitman arm. The prime mover is disposed adjacent the frame, and the crank arm connected to the prime mover is rotatable thereby about a crank point. The crank point is disposed at a first (K) dimension relative to the fulcrum point. The pitman arm has a second (P) dimension and connected between a first bearing point on the crank arm and a second bearing point on the second end of the beam. The first bearing point is disposed at a third (R) dimension from the crank point, and the second bearing point is disposed at a fourth (C) dimension relative to the fulcrum point. Therefore, the crank arm rotated by the prime mover about the crank point translates the pitman arm to oscillate the beam on the fulcrum point and reciprocates the rod load along the wellbore axis. In fact, the unit can have a pair of crank arms and pitman arms, and the pitman arms can connect with an equalizer bar at the second bearing point. 
     In various arrangements, the first bearing point comprises a crank pin bearing, and the second bearing point comprises an equalizer bearing. The crank arm comprises a counterweight disposed thereon, and the first bearing point is disposed between the counterweight and the crank point. 
     In the further configuration, the unit can be disposed at one of a plurality horizontal offsets from an intersection of the wellbore axis with the surface. In this way, the unit keeping the first, second, third, and fourth dimensions and disposed at the horizontal offsets can accommodate a plurality of angles for the inclination of the wellbore axis. 
     In the further configuration, the unit having the first, second, third, and fourth dimensions can operate at the inclination of the wellbore axis inclined from the surface comparable to a pumping unit having the first, second, third, and fourth dimensions that operates at a vertical wellbore axis. 
     According to the present disclosure, a surface pumping unit reciprocates a rod load for a downhole pump in a well. Again, the well has a wellbore axis intersecting at an inclination relative to surface. The unit comprises a base, a post, a beam, and a head. The base is disposed at the surface at one of a plurality horizontal offsets from an intersection of the wellbore axis with the surface. The post extends from the base to a fulcrum point along an axial line from vertical. 
     The beam has first and second ends and defines a bend therebetween. The beam is pivotable at a pivot on the fulcrum point of the frame. The pivot is disposed between the bend and the first end of the beam. The first end of the beam has a straight section at the pivot of the fulcrum point. The straight section is angled to intersect the axial line of the post at an acute forward angle; and 
     The head is disposed on the first end of the beam and is connected to the rod load extending from the well at the inclination. The head has a face circumscribing a segment at a radius relative to the fulcrum point. The segment is tangential to the angles for the inclination of the wellbore axis. The face disposed with the base at the horizontal offsets accommodates a plurality of angles for the inclination of the wellbore axis. 
     The present disclosure disclosed a reciprocating pump system for a well having a wellbore axis intersecting at an inclination relative to surface. The system comprises a downhole pump disposed in the well and comprises a pumping unit disposed at the surface and coupled to the downhole pump by a rod string. The unit can include any of the various configurations outlined herein. 
     The foregoing summary is not intended to summarize each potential embodiment or every aspect of the present disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates an example of a reciprocating rod pump system known in the art. 
         FIG. 2A  illustrates one type of reciprocating rod pump system of the prior art for use with a slanted well. 
         FIG. 2B  illustrates another type of reciprocating rod pump system of the prior art for use with a slanted well. 
         FIG. 3A  illustrates an elevational view of a reciprocating rod pump system of the present disclosure for use with a slanted well. 
         FIG. 3B  illustrates a perspective view of the reciprocating rod pump system of the present disclosure. 
         FIGS. 4A-4B  illustrate the geometry of the disclosed reciprocating rod pump system. 
         FIG. 5A  illustrates the geometry of the horsehead of the disclosed reciprocating rod pump system. 
         FIG. 5B  illustrates a perspective view of elements of the horsehead of the disclosed reciprocating rod pump system. 
     
    
    
     DETAILED DESCRIPTION OF THE DISCLOSURE 
     Referring now to  FIGS. 3A-3B , a surface pumping unit  100  according to the present disclosure is used for reciprocating a rod string for a downhole pump in a well where the rod string extends at an angle or inclination A at an intersection relative to the horizontal surface S. In other words, a polished rod connected to the rod string reciprocates along a wellbore axis WA through a slanted or inclined wellhead at the surface S. Details of the well, slanted wellhead, polished rod, rope bridle, carrier bar, downhole pump, and the like are not shown here for simplicity, but have been discussed previously. 
     The pumping unit  100  includes a frame having a base  110  and a Sampson post  112 . An actuator  120  is disposed on the base  110 , a crank assembly is connected to the actuator  120 , and a walking beam  150  is connected to the crank assembly and is supported by the Sampson posts  112  on the base  110 . Structurally, the Sampson posts  112  on the base  110  provide a fulcrum point on which the walking beam  150  is pivotally supported by a saddle bearing assembly  116 . In addition to the Sampson posts  112 , the frame on the base  110  may include one or more back posts  114  joined together forming an A-frame to support the walking beam  150 . 
     The pumping unit  100  is driven by a prime mover  122 , such as an electric motor or internal combustion engine, mounted on a pedestal above the base  110 . A pump controller  125  monitors, controls, and records the pump unit&#39;s operation. Output from the motor  122  is transmitted to a gearbox  124 , which provides low-speed, high-torque rotation of a crankshaft  132 . Both ends of the crankshaft  132  rotate a crank arm  130  about the crankshaft&#39;s centerline. Disposed away from the crankshaft  132 , the crank arms  132  each have a counterbalance weight  136 . Each crank arm  130  is pivotally connected to a pitman arm  140  by a crank pin bearing  134 . In turn, the two pitman arms  140  are connected to an equalizer bar or beam  142 , which is pivotally connected to the rear end  151   b  of the walking beam  150  by an equalizer bearing assembly  156 . 
     A horsehead  152  with an arcuate forward face  154  is mounted to the forward end  151   a  of the walking beam  150 . As is typical, the face  154  may have tracks or grooves for carrying a flexible wire rope bridle (not shown). At its lower end, the bridle (not shown) terminates with a carrier bar (not shown), upon which a polished rod (not shown) for a reciprocating rod system is suspended. As before, the polished rod typically extends through a packing gland or stuffing box at an inclined wellhead for connection to downhole sucker rods and pump. 
     As is typical and best shown in  FIG. 3B , the pumping unit  100  may have two pitman arms  140  joined by an equalizer beam  142 , which is connected to the walking beam  150  by the equalizer bearing assembly  156 . Each pitman arm  140  is pivotably connected to one of the crank arms  130  by a crank pin assembly  134 , also called a wrist pin. 
     As the actuator  120  rotates the crank arms  130 , the walking beam  150  seesaws on the frame&#39;s bearing  116  so the polished rod reciprocates the rod system and downhole pump in the well. During operation, for example, the motor  122  and gearbox  124  rotates the crank arms  130 , which causes the rearward end  151   b  of the walking beam  150  to move up and down through the pitman arms  140 . Up and down movement of the rearward end  151   b  causes the walking beam  150  to pivot about the bearing assembly  116  resulting in downstrokes and upstrokes of the horsehead  152  on the forward end  151   a.    
     During an upstroke, for example, the motor  122  and gearbox  124  aided by the counterbalance weights  136  overcomes the weight and load on the horsehead  152  and pulls the polished rod string up from the wellbore, which reciprocates the rod string and downhole pump in the well to lift fluid. During a downstroke, the motor  122  aided by the weight and load on the horsehead  154  rotates the crank arms  130  to raise the counterbalance weights  136 . 
     The counterbalance weight  136  is selected based on the weight and load of the reciprocating rod system (i.e., the force required to lift the reciprocating rod and fluid above the downhole pump in the wellbore). In one embodiment, the counterbalance weight  136  may be selected so that one or more components of the pumping unit  100  have substantially symmetrical acceleration and/or velocity during upstrokes and downstrokes. The component may be any moving part of the pumping unit  100 , such as the pitman arm  140 , the wrist pin assembly  134 , the crank arm  130 , the equalizer beam  142 , the walking beam  150 , the horsehead  152 , etc. 
     As can be seen in  FIGS. 3A-3B , the walking beam  150  defines a bend  153  between the forward and rearward ends  151   a - b . The bend  153  is situated between the rearward end  151   b  and the bearing  116  at the fulcrum point of the frame&#39;s Sampson posts  112  about which the beam  150  pivots. 
     As can best be see in  FIG. 3A , the position of the bend  153  behind the saddle bearing  116  offers structural advantages to the pumping unit  100 . In particular, the bearing  116  engages the beam  150  at an angle more tangential to the straight section at the forward end  151   a . This allows the bearing  116  to support the loads more directly and allows the loads from the bearing  116  to be supported more in line with the Sampson post  112 . In this way, the Sampson posts  112  of the frame support compressive loads and are less subject to bending stresses in direct contrast to the Sampson posts  34  in the prior art arrangement of  FIG. 2B . 
     The geometric arrangement of the unit  100  is schematically depicted in  FIG. 4A . In this depiction, the frame, actuator, arms, and the like are not shown. Instead, the fulcrum point for the walking beam  150  is represented as a pivot point for the bearing assembly  116 , and the bend  153  of the beam  150  is depicted reward of the pivot point  116  and on the opposite side thereof from the face  154  of the horsehead ( 152 ). 
     The face  154  connects to the polished rod extending along the wellbore axis WA from the wellhead at an inclination angle θ. The prime mover is not shown, but the crank arm  130  is connected to the prime mover at a crank point of the crank pin  132  and is connected to the pitman arm  140  at a first bearing point for the wrist pin  134 . The pitman arm  140  is connected between the first bearing point  134  and a second bearing point  157  for the equalizer bearing assembly  156  on the walking beam  150 . 
     The crank point  132  is disposed at a first dimension (K) relative to the fulcrum point  116  (i.e., the distance from the centerline of the crankshaft to the center of the saddle bearing), and the pitman arm  130  has a length of a second dimension (P) (i.e., the effective length of the pitman arm  130  as measured from the center of the equalizer bearing assembly  156  to the center of the crank pin bearing  134 ). The first bearing point  134  is disposed at a third dimension (R) from the crank point  132  (i.e., the distance from the centerline  132  of the crankshaft to the center of the crank pin bearing  134 ), and the second bearing point  157  is disposed at a fourth dimension (C) relative to the fulcrum point  116  (i.e., the distance from the center of the saddle bearing  116  to the center of the equalizer bearing  156 ). This completes the four-bar linkage of the unit  100 . 
     Other geometric measures include the dimension (A), heights (H) and (G), and separation (I). The dimension (A) is the distance from the center of the saddle bearing  116  to the centerline of the polished rod represented by the wellbore axis WA and defines the radius at which the face  154  arcs along (circumscribes) a segment SG. As shown in  FIG. 4A , the dimension (A)—as the radius of the segment SG—is perpendicular to the segment SG and extends along a first line (L 1 ) from the segment SG to the fulcrum point  116 . As also shown in  FIG. 4A , the dimension (C)—as the distance from the center of the saddle bearing  116  to the center of the equalizer bearing  156  (i.e., second bearing point  157 )—extends along a second line (L 2 ), which is at an acute angle (δ) relative to the first line (L 1 ). The height (H) is the fixed elevation of the fulcrum point  116  from the surface S on which the base  110  is supported, and the height (G) is the fixed elevation of the crank point  134  from the surface S. Finally, the separation (I) is the fixed vertical distance between the fulcrum point  116  and the crank point  132 . 
     As noted, the unit  100  operates as a kinematic four-bar linkage (KPRC), in which each of four rigid links (KPRC) is pivotally connected to two other of the four links (KPRC) to form a closed polygon. In the mechanism, the link (K) is fixed as the ground link. The two links (C, R) connected to the ground link (K) are referred to as grounded links, and the remaining link (P) not directly connected to the fixed ground link (K) is referred to as the coupler link. The grounded link (R) rotated by the prime mover about the crank point  132  translates the coupler link (P) arm to oscillate the grounded link (C) for the beam  150  on the fulcrum point  116 . This in turn oscillates the radius (A) at which the face  154  arcs along (circumscribes) the segment SG. 
     In general, the unit  100  may have dimensions (C) and (A) that are increased compared to a comparable vertical well pumping unit. The head  152  also has a face  154  that may be longer compared to a comparable vertical well pumping unit. However, various dimensions are adjusted proportionally so that the unit  100  can operate comparably to the kinematic four-bar linkage (KPRC) used for a vertical well pumping unit. In this way, the disclosed unit  100  can use many of the same or similar components (i.e., motor  122 , gearbox  124 , crank arms  130 , counterweights  136 , pitman arms  140 , control unit  125 , and the like) as used for a comparable vertical well pumping unit. Even the saddle bearing  116  and the equalizer bearing  156  can be the same or similar. This provides the unit  100  with flexibility to meet the needs of various pumping implementations. 
     The forward section  151   a  of the beam  150  comprises a first straight section having a first length, and the rearward section  151   b  of the beam  150  comprises a second straight section having a second length. In one example, the bend  153  defines a bend angle α □  of about 46-degrees between the first and second straight sections  151   a - b , although the bend angle α can vary. The bend angle α can define the minimum inclination θ min  of the pumping unit  100 . In general, the first length of the forward section  151   a  is longer than the second length of the rearward section  151   b.    
     Because the walking beam  150  defines the bend  153  between rearward and forward portions  151   a - b  and because the forward section  151   a  has the head  152 , the beam  150  defines a center of gravity that is more forward heavy. The center of gravity location can vary, however, based on the mass of the beam  150  and how that mass is distributed along its length following from the head  152 , the forward portion  151   a , the bend  153 , and the rearward portion  151   b.    
     The unit  100  with the same dimensions (K, P, R, C &amp; A) outlined above can be disposed at a range of horizontal offsets (O) to accommodate a range of inclination angles θ relative to the vertical surface S. In general, the offset (O) could be measured from the edge  111  of the base  110 , or it can be measured from the vertical location of the fulcrum point  116  or from some other given point. 
     The chart below provides example inclination angles θ at offsets (O) measured from the edge  111  of the base  110 . 
     
       
         
           
               
               
               
             
               
                   
                   
               
               
                   
                 Inclination Angles (deg) 
                 Offset (mm) 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 46 
                 457 
               
               
                   
                 47 
                 563 
               
               
                   
                 48 
                 668 
               
               
                   
                 49 
                 770 
               
               
                   
                 50 
                 872 
               
               
                   
                 51 
                 972 
               
               
                   
                 52 
                 1071 
               
               
                   
                 53 
                 1169 
               
               
                   
                 54 
                 1267 
               
               
                   
                 55 
                 1367 
               
               
                   
                 56 
                 1459 
               
               
                   
                   
               
            
           
         
       
     
     As shown in  FIG. 4B , the base  110  of the frame is shown disposed at the surface S, and the Sampson post  112  extends from the base  110  to the fulcrum point  116  along an axial line from vertical. Various orthogonal rotations of the crank arm  130  with dimension (R) are shown translating the pitman arm  140  with dimension (P) and pivoting the links (C) and (A) of the beam  150 . As disclosed herein, the first end  151   a  of the beam  150  includes a straight section  151   a  at the pivot of the fulcrum point  116 . As the beam  150  reciprocates, the straight section  151   a  remains angled to intersect the axial line of the post  112  at an acute forward angle β (i.e., the angle situated forward of the saddle bearing  116  and defined at the intersection of the straight section  151   a  and the post  112 ). Accordingly, the orientation of the post  112 , the straight section  151   a , and the pivot of the fulcrum point  116  support a load of the beam  150  with a force F along the axial line. This tends to reduce bending stress on the post  112 . 
     Turning now to  FIGS. 5A-5B , details of the horsehead  152  are discussed. To accommodate the various inclination angles θ, the horsehead  152  preferably includes a runner on its face  154  long enough and positioned so that a stroke for the smaller inclination angles θ min  runs on the bottom half of the head&#39;s face  154  whereas a stroke for the larger inclination angles θ max  runs on the upper half of the head&#39;s face  154 . As shown in  FIG. 5A , a maximum run area  160  on the face  154  is depicted for the greatest and smallest angles of inclination θ max , θ min  of the wellbore axis. Run area refers to the surface area of the face  154  at which the rope bridles make intersecting contact with the face as the head strokes. During at least part of the strokes, some of the bridles rest against the face, but successive tangential points along the lengths of the bridles lift and lay with changing engagement on the surface  154  as the horsehead  152  moves. 
     Line  161  shows a line that extends between the pivot  116  and a point on the face  154  at which the inclined line  163  of the greatest inclination angle θ max  is tangent, whereas line  164  shows another line that extends between the pivot  116  and another point on the face  154  at which the inclined line  165  of the smallest inclination angle θ min  is tangent. In general, the run area for the greatest inclination angle θ max  preferably encompasses an arc  162  on the upper face  152  of at least 70% or greater (preferably about 80% or greater) of the total run area  160 . Similarly, the run area for the smallest inclination angle θ min  encompasses an arc  165  of at least 70% or greater (preferably about 80% or greater) of the total run area  160 . 
     In the particular example shown, line  161  is perpendicular to the tangent for the largest inclination angle θ max  of 56-degress, and line  164  is perpendicular to the tangent for the smallest inclination angle θ min  of 46-degress. These two lines  161 ,  164  therefore define an arc of 10-degrees on the face  154  of the horsehead  152 , each line  161 ,  164  being on either side of the first line (L 1 ) noted above. Overall, the maximum run area  160  of the horsehead can define the arc  160  of about 51.4-degrees. Therefore, the run area for the largest inclination angle θ max  encompasses the arc  162  of about 41.1-degrees—i.e., 20.7-degrees on either side of this point of tangency. Similarly, the run area for the smallest inclination angle θ min  encompasses the arc  165  of about 41.1-degrees—i.e., 20.7-degrees on either side of the point of tangency. 
     Typically, as shown in  FIG. 5B , the face  154  of the horsehead  152  has rope bridles  56  affixing with a fixture  57  at the top end of the head  152 . The rope bridles  56  flexibly run along and lift from the face  154  as the head  152  moves, and they connect to the polished rod  15  with a carrier bar  58 . The changing engagement of the rope bridles  56  with the head  152  runs along the bottom 80% of the face  154  for the smallest inclination angle θ min , runs along the top 80% of the face  154  for the largest inclination angle, and runs along intermediate arcs for intermediate inclination angles θ max . This can provide better support and control of the reciprocation of the rod  15 . 
     The foregoing description of preferred and other embodiments is not intended to limit or restrict the scope or applicability of the inventive concepts conceived of by the Applicants. It will be appreciated with the benefit of the present disclosure that features described above in accordance with any embodiment or aspect of the disclosed subject matter can be utilized, either alone or in combination, with any other described feature, in any other embodiment or aspect of the disclosed subject matter. 
     In exchange for disclosing the inventive concepts contained herein, the Applicants desire all patent rights afforded by the appended claims. Therefore, it is intended that the appended claims include all modifications and alterations to the full extent that they come within the scope of the following claims or the equivalents thereof.