You are an expert at summarizing long articles. Proceed to summarize the following text:

You are an expert at summarizing long articles. Proceed to summarize the following text: 
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to methods and apparatus for drilling with top drive systems. Particularly, the invention relates to methods and apparatus for adapting a top drive for use with running casing. More particularly still, the invention relates to a torque head for engaging with a tubular and rotating the same. 
   2. Description of the Related Art 
   In well completion operations, a wellbore is formed to access hydrocarbon-bearing formations by the use of drilling. Drilling is accomplished by utilizing a drill bit that is mounted on the end of a drill support member, commonly known as a drill string. To drill within the wellbore to a predetermined depth, the drill string is often rotated by a top drive or rotary table on a surface platform or rig, or by a downhole motor mounted towards the lower end of the drill string. After drilling to a predetermined depth, the drill string and drill bit are removed and a section of casing is lowered into the wellbore. An annular area is thus formed between the string of casing and the formation. The casing string is temporarily hung from the surface of the well. A cementing operation is then conducted in order to fill the annular area with cement. Using apparatus known in the art, the casing string is cemented into the wellbore by circulating cement into the annular area defined between the outer wall of the casing and the borehole. The combination of cement and casing strengthens the wellbore and facilitates the isolation of certain areas of the formation behind the casing for the production of hydrocarbons. 
   It is common to employ more than one string of casing in a wellbore. In this respect, one conventional method to complete a well includes drilling to a first designated depth with a drill bit on a drill string. Then, the drill string is removed and a first string of casing is run into the wellbore and set in the drilled out portion of the wellbore. Cement is circulated into the annulus behind the casing string and allowed to cure. Next, the well is drilled to a second designated depth, and a second string of casing, or liner, is run into the drilled out portion of the wellbore. The second string is set at a depth such that the upper portion of the second string of casing overlaps the lower portion of the first string of casing. The second string is then fixed, or “hung” off of the existing casing by the use of slips which utilize slip members and cones to wedgingly fix the second string of casing in the wellbore. The second casing string is then cemented. This process is typically repeated with additional casing strings until the well has been drilled to a desired depth. Therefore, two run-ins into the wellbore are required per casing string to set the casing into the wellbore. In this manner, wells are typically formed with two or more strings of casing of an ever-decreasing diameter. 
   As more casing strings are set in the wellbore, the casing strings become progressively smaller in diameter in order to fit within the previous casing string. In a drilling operation, the drill bit for drilling to the next predetermined depth must thus become progressively smaller as the diameter of each casing string decreases in order to fit within the previous casing string. Therefore, multiple drill bits of different sizes are ordinarily necessary for drilling in well completion operations. 
   Another method of performing well completion operations involves drilling with casing, as opposed to the first method of drilling and then setting the casing. In this method, the casing string is run into the wellbore along with a drill bit for drilling the subsequent, smaller diameter hole located in the interior of the existing casing string. The drill bit is operated by rotation of the drill string from the surface of the wellbore. Once the borehole is formed, the attached casing string may be cemented in the borehole. The drill bit is either removed or destroyed by the drilling of a subsequent borehole. The subsequent borehole may be drilled by a second working string comprising a second drill bit disposed at the end of a second casing that is of sufficient size to line the wall of the borehole formed. The second drill bit should be smaller than the first drill bit so that it fits within the existing casing string. In this respect, this method requires at least one run-in into the wellbore per casing string that is set into the wellbore. 
   It is known in the industry to use top drive systems to rotate a drill string to form a borehole. Top drive systems are equipped with a motor to provide torque for rotating the drilling string. The quill of the top drive is typically threadedly connected to an upper end of the drill pipe in order to transmit torque to the drill pipe. Top drives may also be used in a drilling with casing operation to rotate the casing. 
   In order to drill with casing, most existing top drives require a threaded crossover adapter to connect to the casing. This is because the quill of the top drives is not sized to connect with the threads of the casing. The crossover adapter is design to alleviate this problem. Typically, one end of the crossover adapter is designed to connect with the quill, while the other end is designed to connect with the casing. 
   However, the process of connecting and disconnecting a casing is time consuming. For example, each time a new casing is added, the casing string must be disconnected from the crossover adapter. Thereafter, the crossover must be threaded into the new casing before the casing string may be run. Furthermore, this process also increases the likelihood of damage to the threads, thereby increasing the potential for downtime. 
   There is a need, therefore, for methods and apparatus for coupling a casing to the top drive for drilling with casing operations. There is a further need for methods and apparatus for running casing with a top drive in an efficient manner. There is also a need for methods and apparatus for running casing with reduced damage to the casings. 
   SUMMARY OF THE INVENTION 
   The present invention generally relates to a method and apparatus for drilling with a top drive system. Particularly, the present invention relates to methods and apparatus for handling tubulars using a top drive system. 
   In one aspect, the present invention provides a tubular gripping member for use with a top drive to handle a tubular comprising a housing operatively connected to the top drive and a plurality of gripping elements radially disposed in the housing for engaging the tubular, wherein moving the housing relative the plurality of gripping elements causes the plurality of gripping elements to engage the tubular. 
   In another aspect, the present invention provides a method of handling a tubular comprising providing a top drive operatively connected to a gripping head. The gripping head has a housing, a plurality of gripping elements radially disposed in the housing for engaging the tubular, and a plurality of engagement members movably disposed on each of the plurality of gripping elements. The method further includes disposing the tubular within the plurality of gripping elements, moving the housing relative to the plurality of gripping elements, engaging the tubular, and pivoting the plurality of engagement members. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     So that the manner in which the above recited features of the present invention, and other features contemplated and claimed herein, are attained and can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the embodiments thereof which 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. 1  is a partial view of a rig having a top drive system according to aspects of the present invention. 
       FIG. 2  shows an exemplary torque head according to aspects of the present invention. As shown, the torque head is in a partially actuated position. 
       FIG. 3  is a perspective view of the gripping element of the torque head of  FIG. 2 . 
       FIG. 4  is a perspective view of the torque head of  FIG. 2 . 
       FIG. 5  shows the torque head of  FIG. 2  in an unactuated position. 
       FIG. 6  shows the torque head of  FIG. 2  in an actuated position. 
       FIG. 7  shows another embodiment of a torque head according to aspects of the present invention. 
       FIGS. 8A-B  are two different views of an exemplary gripping element for use with the torque head of  FIG. 7 . 
       FIG. 9  is a cross-sectional view of another embodiment of a gripping element according to aspects of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Aspects of the present invention provide a top drive adapter for gripping a casing for drilling with casing. The top drive adapter includes rotating unit for connection with the top drive to transfer torque. The top drive adapter also has a plurality of gripping elements disposed in a housing. Moving the housing axially relative to the plurality of gripping elements causes the gripping elements to apply an initial gripping pressure on the casing. The gripping elements have engagement members for contacting or gripping the casing. An axial load acting on the engagement members causes the engagement members to pivot axially and support the axial load. 
     FIG. 1  shows a drilling rig  10  applicable to drilling with casing operations or a wellbore operation that involves picking up/laying down tubulars. The drilling rig  10  is located above a formation at a surface of a well. The drilling rig  10  includes a rig floor  20  and a v-door  800 . The rig floor  20  has a hole  55  therethrough, the center of which is termed the well center. A spider  60  is disposed around or within the hole  55  to grippingly engage the casings  30 ,  65  at various stages of the drilling operation. As used herein, each casing  30 ,  65  may include a single casing or a casing string having more than one casing. Furthermore, aspects of the present invention are equally applicable to other types of wellbore tubulars, such as drill pipe. 
   The drilling rig  10  includes a traveling block  35  suspended by cables  75  above the rig floor  20 . The traveling block  35  holds the top drive  50  above the rig floor  20  and may be caused to move the top drive  50  axially. The top drive  50  includes a motor  80  which is used to rotate the casing  30 ,  65  at various stages of the operation, such as during drilling with casing or while making up or breaking out a connection between the casings  30 ,  65 . A railing system (not shown) is coupled to the top drive  50  to guide the axial movement of the top drive  50  and to prevent the top drive  50  from rotational movement during rotation of the casings  30 ,  65 . 
   Disposed below the top drive  50  is a tubular gripping member such as a torque head  40 . The torque head  40  may be utilized to grip an upper portion of the casing  30  and impart torque from the top drive to the casing  30 . The torque head  40  may be coupled to an elevator  70  using one or more bails  85  to facilitate the movement of the casing  30  above the rig floor  20 . Additionally, the rig  10  may include a pipe handling arm  100  to assist in aligning the tubulars  30 ,  65  for connection. 
     FIG. 2  illustrates a cross-sectional view of an exemplary torque head  40  according to aspects of the present invention. Because the torque head  40  is adapted to couple the top drive  50  to the casing  30  the torque head  40  includes a mandrel  103  coupled to a rotary unit  109  for connection to the top drive  50 . In this respect, the top drive  50  may rotate, raise, or lower the torque head  40  for drilling with casing. The mandrel  103  includes a load collar  113  for coupling one or more gripping elements  105  to the mandrel  103 . As shown in  FIG. 2 , an upper portion of the gripping element  105  includes a recess  114  for engagement with the load collar  113  of the mandrel  103 . The gripping elements  105  are circumferentially disposed around the mandrel  103 . 
   A housing  104  surrounds the gripping elements  105  and ensures the gripping elements  105  remain coupled to the mandrel  103 . The housing  104  is actuatable by a hydraulic cylinder  110  disposed on the mandrel  103 . Particularly, an upper portion of the housing  104  is coupled to the piston  111  of the hydraulic cylinder  110 . Actuation of the piston  111  causes the housing  104  to move axially relative to the mandrel  103 . 
   The gripping elements  105  are adapted to engage and retain the casing  30  once the casing  30  is inserted into the housing  104 . As shown in  FIG. 3 , the gripping elements  105  include an upper end having a recess  114  for coupling to the mandrel  103  and a lower end having one or more engagement members  106 . A width of the gripping elements  105  may be arcuate in shape such that the gripping elements  105  may be circumferentially disposed to form a substantially tubular structure to engage a tubular such as a casing or a pipe.  FIG. 4  is a perspective view of the torque head  40  showing the gripping elements  105  circumferentially disposed inside the housing  104 . 
   Referring again to  FIG. 3 , the gripping elements  105  include an arcuate interior surface  131  for engaging the tubular and an arcuate exterior surface  132  for engaging the housing  104 . In one embodiment, the interior surface  131  includes one or more slots  115  for receiving one or more engagement members  106 . Preferably, the engagement members  106  are pivotable within the slots  115 . Initially, the engagement members  106  are disposed at an upward angle in a direction towards the upper portion of the mandrel  103 . In other words, the distal end  161  of the engagement members  106  is higher than the proximal end  162 . More preferably, each engagement member  106  is set at the same angle. When the engagement members engage the casing string, the load of the casing string will cause the engagement members  106  to pivot in the slots  115  thereby carrying the casing string load. It is believed that this arrangement allows the engagement members  106  to carry an equal, partial load of the casing  30 . The engagement members  106  may be designed with any suitable contact surface as is known to a person of ordinary skill in the art. For example, the contact surface may be a smooth surface or a tooth structure to increase the load carrying capacity. 
   The exterior surface  132  of the gripping elements  105  is adapted to interface with the interior surface of the housing  104  to move the gripping elements  105  radially relative to the housing  104 . In one embodiment, the gripping elements  105  may interface with the housing  104  using a complementary key and groove system. As shown in  FIGS. 3 and 4 , the lower, exterior portion of the gripping elements  105  includes one or more keys  108  formed thereon. The keys  108  are adapted to fit in a complementary groove  116  formed on the inner surface of the housing  104  when the torque head  40  is in the unactuated or “unlocked” position, as illustrated in  FIG. 5 . Referring to  FIG. 2 , the housing  104  includes one or more keys  117  formed between the grooves  116 . The keys  117  of the housing  104  reside between the keys  108  of the gripping elements  105  when the torque head  40  is in the unlocked position. 
   In one aspect, the housing  104  may be actuated to move the keys  108  of the housing  104  and the keys  117  of the gripping element  105  into an actuated or locking position.  FIG. 2  shows the keys  108 ,  117  in a partially locked position. To this end, the keys  108  of the gripping elements  105  include an upper surface  121  and an abutment surface  123 . The upper surface  121  of the keys  108  may be inclined downward to facilitate the movement of the keys  108  of the gripping elements  105  out of the grooves  116  of the housing  104 . Similarly, the keys  117  of the housing  104  include a lower surface  122  and an abutment surface  124 . The lower surface  122  is adapted to engage the upper surface of the key  108  of the gripping element  105  as the housing  104  is lowered. Due to the incline of the upper surface  121 , the gripping elements  105  move radially inward to engage the casing  30  while the housing  104  is lowered. 
   The abutment surfaces  123 ,  124  are adapted to provide a self locking function. In one embodiment, the abutment surface  123  of the gripping elements  105  is inclined slightly downward, and the abutment surface  124  of the housing  104  has a complementary incline. When the two abutment surfaces  123 ,  124  engage, the incline causes the gripping elements  105  to move radially toward the axial center to establish its grip on the casing  30 . Preferably, the abutment surface  122  of the gripping elements  105  is angled at about ten degrees or less relative to a vertical axis. More preferably, the abutment surface  122  of the gripping elements  105  is inclined at about seven degrees or less relative to a vertical axis. 
   Referring to  FIG. 1 , a casing  30  is shown as it is being brought up to the rig  10  for connection with a casing string  65 . The casing string  65 , which was previously drilled into the formation (not shown) to form the wellbore (not shown), is shown disposed within the hole  55  in the rig floor  20 . The casing string  65  may include one or more joints or sections of casing threadedly connected to one another. The casing string  65  is shown engaged by the spider  60 . The spider  60  supports the casing string  65  in the wellbore and prevents the axial and rotational movement of the casing string  65  relative to the rig floor  20 . As shown, a threaded connection of the casing string  65 , or the box, is accessible from the rig floor  20 . 
   In  FIG. 1 , the top drive  50 , the torque head  40 , and the elevator  70  are shown positioned proximate the rig floor  20 . The casing  30  may initially be disposed on the rack  25 , which may include a pick up/lay down machine. The lower portion of the casing  30  includes a threaded connection, or the pin, which may mate with the box of the casing string  65 . The elevator  70  is shown engaging an upper portion of the casing  30  and ready to be hoisted by the cables  75  suspending the traveling block  35 . The elevator  70  may be used to transport the casing  30  from a rack  25  or a pickup/lay down machine to the well center. The elevator  70  may include any suitable elevator known to a person of ordinary skill in the art. The elevator defines a central opening to accommodate the casing  30 . The bails  85  interconnect the elevator  70  to the torque head  40  and are pivotable relative to the torque head  40 . 
   While the casing is moved towards the well center, the pipe handling arm  100  is actuated to guide and align the casing  30  with the casing string  65  for connection therewith. A suitable pipe handling arm is disclosed in U.S. Pat. No. 6,591,471 issued to Hollingsworth on Jul. 15, 2003, assigned to the assignee of the present invention and incorporated by reference herein in its entirety. Another suitable pipe handling arm is disclosed in U.S. patent application Ser. No. 10/382,353, filed on Mar. 5, 2003, entitled “Positioning and Spinning Device,” which application is assigned to the same assignee of the present invention and incorporated by reference herein in its entirety. An exemplary pipe handling arm  100  includes a gripping member for engaging the casing  30  during operation. The pipe handling arm  100  is adapted and designed to move in a plane substantially parallel to the rig floor  20  to guide the casing  30  into alignment with the casing  65  in the spider  60 . 
   After the casing is guided into alignment by the pipe handling arm  100 , the torque head  40  is lowered relative to the casing  30  and positioned around the upper portion of the casing  30 . As the casing  30  is inserted into the torque head  40 , the coupling  32  of the casing  30  forces the gripping elements  105  to expand radially. In this respect, the keys  108  of the gripping elements  105  move into the grooves  116  of the housing  104 .  FIG. 5  shows the casing  30  inserted into the torque head  40 . It can be seen that coupling  32  is located above the gripping elements  105 . 
   To grip the casing  30 , the hydraulic cylinder  110  is actuated to move the piston  111  downward. In turn, the housing  104  is lowered relative to the gripping elements  105 . Initially, the lower surface  122  of the housing  104  encounters the upper surface  121  of the gripping elements  105 . The incline of the upper and lower surfaces  121 ,  122  facilitate the movement of the gripping elements  105  out of the groove  116  and the lowering of the housing  104 . Additionally, the incline also causes the gripping elements  105  to move radially to apply a gripping force on the casing  30 . As shown in  FIG. 2 , the housing  104  has been lowered relative to the gripping elements  105 . Additionally, the keys  108  of the gripping elements  105  have moved out of the groove  116 . The housing  104  is lowered until the abutment surfaces  123 ,  124  of the keys  108 ,  117  substantially engage each other, as shown in  FIG. 6 . It can be seen in  FIG. 6  that the piston  111  is fully actuated. 
   During drilling operation, the casing string load will pull the casing  30  down. Due to this movement, the engagement members  106  will pivot in the slot  115  of the gripping elements  105  to clamp the casing  30 . In this respect, the engagement members  106  will work as an axial free running drive. Moreover, because the engagement members  106  are all set at the same angle, each of the engagement members  106  carries an equal amount of the casing string weight. Additionally, the radial clamping force will be balanced by the housing  104 . In one embodiment, when the key angle between the key  117  of the housing  104  and the key  108  of the gripping element  105  is less than seven degrees, the radial force will be distributed across the housing  104 . 
   When the casing string load is removed, such as actuating the spider  60  to retain the casing string, the engagement members  106  will immediately release the radial force exerted on the casing  30 . Thereafter, the piston is deactuated to raise the housing  104  relative to the gripping elements  105 . The casing  30  may be removed when the keys  108  of the gripping elements  105  return to their respective grooves  116 . 
   In another aspect, the torque head  40  may be used to transfer torque. In this respect, an appropriate hydraulic cylinder may be selected to apply a sufficient force to clamp the casing  30 . 
     FIG. 7  presents another embodiment of a torque head  240  according to aspects of the present invention. The torque head  240  includes a rotary unit  209  for connection with the top drive  50  and transmitting torque. A mandrel  203  extends below the rotary unit  209  and is coupled to an upper end of a tubular body  235  using a spline and groove connection  237 . The spline and groove connection  237  allows the body  235  to move axially relative to the mandrel  203  while still allowing torque to be transmitted to rotate the body  235 . The lower portion of the body  235  includes one or more windows  240  formed through a wall of the body  235 . The windows  240  are adapted to contain a gripping element  205 . Preferably, eight windows  240  are formed to contain eight gripping elements  205 . 
   The outer surface of the body  235  includes a flange  242 . One or more compensating cylinders  245  connect the flange  242  to the rotary unit. In this respect, the compensating cylinders  245  control the axial movement of the body  235 . The compensating cylinder  245  is particularly useful during makeup or breakout of tubulars. For example, the compensating cylinder  245  may allow the body  235  to move axially to accommodate the change in axial distance between the tubulars as the threads are made. An exemplary compensating cylinder is a piston and cylinder assembly. The piston and cylinder assembly may be actuated hydraulically, pneumatically, or by any other manner known to a person of ordinary skill in the art. A suitable alternate compensating cylinder is disclosed in U.S. Pat. No. 6,056,060, which patent is herein incorporated by reference in its entirety and is assigned to the same assignee of the present invention. 
   A housing  204  is disposed around the windows  240  of the body  235 . The housing  204  is coupled to the flange  242  using a one or more actuating cylinders  210 . In this respect, the housing  204  may be raised or lowered relative to the body  235 . The interior of the housing  204  includes a key and groove configuration for interfacing with the gripping element  205 . In one embodiment, the key  217  includes an inclined abutment surface  224  and an inclined lower surface  222 . Preferably, the transition between the lower surface  222  and the abutment surface  224  is curved to facilitate lowering of the housing  204  relative to the body  235 . 
   A gripping element  205  is disposed in each of the windows  240  in the body  235 . In one embodiment, the gripping element  205  has an exterior surface adapted to interface with the key and groove configuration of the housing  204 , as shown in  FIGS. 7 and 8 . Particularly, keys  208  are formed on the exterior surface and between the keys  208  are grooves that may accommodate the key  217  of the housing  204 . The keys  208  of the gripping element  205  include an upper surface  221  and an abutment surface  223 . The upper surface  221  is inclined downward to facilitate movement of the keys  217  of the housing  204 . The abutment surface  223  has an incline complementary to the abutment surface  224  of the housing  204 . A collar  250  extends from the upper and lower ends of the exterior surface of the gripping elements  205 . The collars  250  engage the outer surface of the body  235  to limit the inward radial movement of the gripping elements  205 . Preferably, a biasing member  255  is disposed between the collar and the body  235  to bias the gripping element  205  away from the body  235 . In one embodiment, the biasing member  255  may be a spring. 
   The interior surface of the gripping element  205  includes one or more engagement members  206 . In one embodiment, each engagement member  206  is disposed in a slot  215  formed in the interior surface of the gripping element  205 . Preferably, the engagement members  206  are pivotable in the slot  215 . The portion of the engagement member  206  disposed in the interior of the slot  215  may be arcuate in shape to facilitate the pivoting motion. The tubular contact surface of the engagement members  257  may be smooth or rough, or have teeth formed thereon. 
   In another aspect, the gripping element  205  may include a retracting mechanism to control movement of the engagement members  206 . In one embodiment, an axial bore  260  is formed adjacent the interior surface of the gripping element  205 . An actuating rod  265  is disposed in the bore  260  and through a recess  267  of the engagement members  206 . The actuating rod  265  includes one or more supports  270  having an outer diameter larger than the recess  267  of the engagement members  206 . A support  270  is positioned on the actuating rod  265  at a level below each engagement member  206  such that the engagement members  206  rest on their respective support  270 . 
   A biasing member  275  coupled to the actuating rod  265  is disposed at an upper end of the bore  260 . In the relaxed position, the biasing member  275  biases the actuating rod  265  in the upward position. In this respect, the actuating rod  265  places the engagement members  206  in the retracted position, or pivoted upward position, as shown in  FIGS. 8A-B . When the biasing member  275  is compressed, the actuating rod  265  is placed in the downward position. In this respect, the engagement members  206  are in the engaged position, or pivoted downward such that it is relatively closer to a horizontal axis than the retracted position. 
   In operation, the casing  230  is inserted into the body  235  of the torque head  240 . At this point, the keys  208  of the gripping element  205  are disposed in their respective groove  216  in the housing  204 . Additionally, the actuating rod  265  is in the upward position, thereby placing the engagement members  206  in the retracted position. As the casing  230  is inserted into the torque head  240 , the coupling moves across the gripping elements  205  and forces the gripping elements  205  to move radially outward. After the coupling moves past the gripping elements  205 , the biasing members  255  bias the gripping elements  205  to maintain engagement with the casing  30 . 
   Once the casing  230  is received in the torque head  240 , the actuating cylinder  210  is activated to lower the housing  204  relative to the body  235 . Initially, the lower surface  222  of the housing  204  encounters the upper surface  221  of the gripping elements  205 . The incline of the upper and lower surfaces  221 ,  222  facilitate the movement of the gripping elements  205  out of the groove  216  and the lowering of the housing  204 . Additionally, the incline also causes the gripping elements  205  to move radially to apply a gripping force on the casing  30 . Preferably, the gripping elements  205  move radially in a direction substantially perpendicular to the vertical axis of the casing  30 . The housing  204  continues to be lowered until the abutment surfaces  223 ,  224  of the keys  208 ,  217  substantially engage each other, as shown in  FIG. 7 . During the movement of the housing  204 , the biasing members  255  between the collars  250  and the body  235  are compressed. Additionally, the weight of the casing  30  may force the engagement members  205  to pivot slightly downward, which, in turn, causes the actuating rod  265  to compress the biasing member  275 . In this respect, a radial clamping force is applied to support the axial load of the casing  30 . 
   To makeup the casing  230  to the casing string  65 , the top drive  50  may be operated to provide torque to rotate the casing  230  relative to the casing string  65 . During makeup, the compensating cylinder  245  is activated to compensate for the change in axial distance as a result of the threaded engagement. In this respect, the body  235  is allowed to move axially relative to the mandrel  203  using the spline and groove connection  237 . 
   During drilling operation, the entire casing string load is supported by the torque head  240 . Particularly, the heavier casing string load further pivots the engagement members  206  in the slot  215  of the gripping elements  205 . In this respect, the casing string load is distributed among the engagement members  206 , thereby allowing the torque head  240  to work as an axial free running drive. Moreover, because the engagement members  206  are all set the same angle, each of the engagement members  206  carries an equal amount of the casing string weight. Additionally, the radial clamping force will be balanced by the housing  204 . In one embodiment, when the angle between the key  217  of the housing  204  and the key  208  of the gripping element  205  is less than seven degrees, the radial force will be distributed across the housing  204 . In this manner, the torque head according to aspects of the present invention may be used to connect tubulars and generally used to perform tubular handling operations. 
   In another embodiment, the gripping element  305  may include a collar  350  on either side, instead of the upper or lower end. As shown in  FIG. 9 , a biasing member  355  is disposed between two adjacent gripping elements  305 . Additionally, the biasing member  355  is between the side collars  350  and the body  335 . In this respect, the biasing member  355  may be used to control the position of the gripping elements  305 . In one embodiment, the biasing member  355  may comprise one or more retracting blade springs. 
   In another aspect, the torque head  40  may optionally employ a circulating tool  280  to supply fluid to fill up the casing  30  and circulate the fluid. The circulating tool  220  may be connected to a lower portion of the mandrel  203  and at least partially disposed in the body  235 . The circulating tool  280  includes a first end and a second end. The first end is coupled to the mandrel  203  and fluidly communicates with the top drive  50 . The second end is inserted into the casing  30 . A cup seal  285  is disposed on the second end interior to the casing  30 . The cup seal  285  sealingly engages the inner surface of the casing  30  during operation. Particularly, fluid in the casing  30  expands the cup seal  285  into contact with the casing  30 . The circulating tool  280  may also include a nozzle  288  to inject fluid into the casing  30 . The nozzle  288  may also act as a mud saver adapter for connecting a mud saver valve (not shown) to the circulating tool  280 . 
   It addition to casing, aspects of the present invention are equally suited to handle tubulars such as drill pipe, tubing, and other types of tubulars known to a person of ordinary skill in the art. Moreover, the tubular handling operations contemplated herein may include connection and disconnection of tubulars as well as running in or pulling out tubulars from the well. 
   While the foregoing is directed to embodiments 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 that follow.

Summary:
Methods and apparatus for drilling with a top drive system. In one aspect, the apparatus provides a tubular gripping member for use with a top drive to handle a tubular comprising a housing operatively connected to the top drive and a plurality of gripping elements radially disposed in the housing for engaging the tubular, wherein moving the housing relative to the plurality of gripping elements causes the plurality of gripping elements to engage the tubular.