Abstract:
An improved ram bore profile for use with a variable bore ram packer designed for use in a standard ram-type blowout preventer used in oil and gas drilling operations is disclosed. The improved ram bore profile in the ram body is a substantially U shaped cutout in the front face of the ram body. The U shaped ram bore profile extends between the upper surface and lower surface of the ram body. The substantially U shape of the improved ram bore profile is further characterized by having an arcuate rear portion with a pair of diverging sides that extend outwardly toward the front face of the ram body to a front throat that intersects perpendicularly the front face of the ram body. The improved ram bore profile is capable of being used with variable bore packers of different configurations.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to an improved ram bore profile for a variable bore packer ram used in a ram-type blowout preventer used for oil and gas drilling operations. The improved ram bore profile allows drill pipe within a given range of sizes to be supported or “hung off” with increased load capacity in comparison to existing designs. Additionally, the current invention ensures the drill pipe weight is in fact supported on the ram body and not on the variable bore packer as in prior art designs. This ensures the variable bore packer is not subjected to unbalanced loads and thereby improves the service life of the packer. Ram-type blowout preventers are part of a pressure control system used in oil and gas drilling operations to control unexpected well bore pressure spikes or “kicks” as they are commonly referred to in the industry. 
     The blowout preventer has a body with a vertical bore and a pair of laterally disposed opposing bonnet assemblies. Each bonnet assembly includes a piston which is laterally moveable within the bonnet assembly by pressurized hydraulic fluid. Replaceable sealing elements called “packers” are mounted on the ends of the pistons which extend into the blowout preventer bore. When these pistons are moved to a closed position, commonly referred to as “closing the blowout preventer” or “closing the rams”, the vertical bore of the blowout preventer is sealed and the “kick” is contained. These “packers” are available in a variety of configurations designed to seal the blowout preventer bore when the opposing pistons are moved to their closed position. 
     One type of packer has ends designed to seal around pipe of a specific size in the blowout preventer bore when the blowout preventer is “closed.” Other packers are configured to seal around a range of pipe sizes. It is the type designed to seal around a range of pipe sizes, called variable bore ram packers, and the ram body in which they are mounted to which the present invention is directed. The ram packers form a pressure tight seal during a kick until the well bore pressure can be controlled. The well bore pressure can reach several thousand pounds per square inch during a “kick.” Each ram packer has a semicircular opening in its front face to form a seal around 180° of the outer periphery of the pipe. When the rams are closed as described above, the opposing ram packers meet and seal the entire 360° periphery of the pipe. 
     During drilling operations, it is sometimes necessary to support the weight of the joints of drill pipe or “drill string” as it is commonly known on the rams of the blowout preventer. This is done by dosing the rams around the straight diameter of the drill pipe and the allowing the drill string to slide downward until an enlarged diameter end, called a tool joint, contacts the top of the ram. Each section or joint of drill pipe has a tool joint formed at each end and the tool joints at opposite ends of a given drill pipe section are threaded with mating male and female threads, respectively. The transition between the straight diameter of the drill pipe and the larger diameter of the tool joint is a tapered shoulder, often referred to as an elevator shoulder. This tapered elevator shoulder contacts the top of the ram and the weight of the drill string is supported by this contact. 
     Prior art variable bore ram designs typically used a semi-circular cutout in the face of ram body. This semicircular cutout had to be sized to accommodate the largest diameter drill pipe that the variable bore ram packer was designed to seal around. This often resulted in little or no contact between the ram body and the tool joint when a smaller diameter drill pipe and its tool joint were used. In this case, when the rams were closed and the drill string lowered into contact with the ram, it was the portion of the variable bore ram packer protruding beyond the face of the ram that supported the weight of the drill string. The variable bore ram packers were not designed or intended for this type of service. As a result, sometimes the drill string was dropped when the variable bore ram packer could not longer support the weight of the drill string. At the very least, the service life of the variable bore packer was greatly compromised when the packer supported the weight of the drill string. The improved ram bore profile for a variable bore packer ram of the current invention offers a substantial improvement by offering a variable bore packer ram body that can support the weight of the drill string for a range of drill pipe sizes. 
     2. Description of Related Art 
     U.S. Pat. No. 4,089,532 to A. I. Kamyshnikov shows a blowout preventer ram assembly with a variable bore ram packer. 
     The blowout preventer shown in U.S. Pat. No. 5,013,005 to J. G. Nance shows a packer capable of sealing around two strings of tubing disposed in the blowout preventer bore. 
     SUMMARY OF THE INVENTION 
     The improved ram bore profile for a variable bore packer ram of the present invention is designed for use in a standard ram-type blowout preventer used in oil and gas drilling operations. The blowout preventer has a body with an axial bore, a pair of opposing bonnet assemblies and a pair of opposing rams laterally moveable within the bonnet assemblies by a pressurized fluid source to control flow of well fluids through the blowout preventer body axial bore. The variable bore ram packer includes a ram body, a top seal, a pair of side packers and a packer member. The packer member is molded of an elastomeric material having a central semi-circular opening sized to fit closely about a tubular member within a given size range. 
     The improved ram bore profile in the ram body is a substantially U shaped cutout in the front face of the ram body. The U shaped ram bore profile extends between the upper ram body and the ram packer cavity of the ram body. The substantially U shape of the improved ram bore profile is further characterized by having an arcuate rear portion with a pair of diverging sides that extend outwardly toward the front face of the ram body to a front throat that intersects perpendicularly the front face of the ram body. The improved ram bore profile is capable of being used with variable bore packers of different configurations as will be shown in the description of the preferred embodiments. 
     A principal object of the present invention is to provide an improved ram bore profile for a variable bore ram packer body that allows supporting a range of drill pipe sizes for which the variable bore packer is sized to seal around. 
     Another object of the present invention is to provide an improved ram bore profile for a variable bore ram packer body that ensures the drill pipe is supported on the ram bore profile and not on the variable bore packer. 
     A final object of the present invention is to provide an improved ram bore profile for a variable bore ram packer body that increases the service life of the variable bore packer. 
     These with other objects and advantages of the present invention are pointed out with specificness in the claims annexed hereto and form a part of this disclosure. A full and complete understanding of the invention may be had by reference to the accompanying drawings and description of the preferred embodiments. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other objects and advantages of the present invention are set forth below and further made clear by reference to the drawings, wherein: 
     FIG. 1 is a perspective view with a cutaway section of a variable bore ram packer with the improved ram bore profile of the present invention installed in a typical ram-type blowout preventer used in oil and gas drilling operations. 
     FIG. 2 is an elevation view in section of a pair of variable bore ram packers suspending 6⅝″ drill pipe utilizing the ram bore profile of the prior art. 
     FIG. 3 is a plan view taken along lines  3 — 3  of FIG.  2 . 
     FIG. 4 is an elevation view in section of a pair of variable bore ram packers suspending 5″ drill pipe utilizing the ram bore profile of the prior art. 
     FIG. 5 is a plan view taken along lines  5 — 5  of FIG.  4 . 
     FIG. 6 is an exploded perspective view of one type of variable bore ram packer assembly utilizing the improved ram bore profile of the present invention. 
     FIG. 7 is an elevation View in section of a pair of variable bore ram packers ysuspending 6⅝″ drill pipe utilizing the improved ram bore profile of the present invention. 
     FIG. 8 is a plan view taken along lines  8 — 8  of FIG.  7 . 
     FIG. 9 is an elevation view in section of a pair of variable bore ram packers suspending 5″ drill pipe utilizing the improved ram bore profile of the present invention. 
     FIG. 10 is a plan view taken along lines  10 — 10  of FIG.  9 . 
     FIG. 11 is an exploded perspective view of a second type of variable bore ram packer assembly utilizing the improved ram bore profile of the present invention. 
     FIG. 12 is an elevation view in section of a pair of variable bore ram packers of the type shown in FIG. 11 suspending 5″ drill pipe utilizing the improved ram bore profile of the present invention. 
     FIG. 13 is a plan view taken along lines  13 — 13  of FIG.  12 . 
     FIG. 14 is an elevation view in section of a pair of variable bore ram packers of the type shown in FIG. 11 suspending 6⅝″ drill pipe utilizing the improved ram bore profile of the present invention. 
     FIG. 15 is a plan view taken along lines  15 — 15  of FIG.  14 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to the drawings, and particularly to FIG. 1, an isometric view with a cutaway section of a ram type blowout preventer  10  used in oil and gas drilling operations is shown. The ram type blowout preventer  10  includes a body or housing  12  with a vertical bore  14  and laterally disposed ram guideways  16 . Bonnet assemblies  18  are mounted to the body  12  with suitable securing means such as studs or bolts  20  and aligned with laterally disposed guideways  16 . Each bonnet assembly  18  includes an actuation means  22 , including a piston  24  and connecting rod  26 . While only one guideway  16  and actuation means  22  is shown, it is understood by those of ordinary skill in the art that there is a pair of opposed guideways  16  and actuation means  22 . Each connecting rod  26  is connected to a ram  28  with variable bore ram packer assembly  30  positioned therein. Actuation means  22  allows ram  28  and variable bore ram packer assembly  30  to be reciprocated within guideways  16  or “opening and closing the rams” as it is referred to in the industry. 
     FIGS. 2 and 3 show a pair of rams  28  with one type of variable bore ram packer  30  positioned within ram bodies  32 . Variable bore ram packer  30  is of the type shown and claimed in U.S. Pat. No. 5,005,802 issued Apr. 9, 1991 and is incorporated herein by reference. Ram bodies  32  include prior art ram bore profile  34  with a substantially half circle cross section. Positioned within rams  28  is 6⅝″ O. D. drill pipe  36  with tool joint  38  attached at its upper end by suitable means as cold forging or welding. Tool joint  38  will typically have an 8″ O. D., as is well known in the art. Elevator shoulder  40  of tool joint  38  allows prior art ram bore profile  34  to support the weight of tool joint  36 . As seen in FIG. 3, prior art ram bore profile  34  is sized to fit around the 6⅝″ outside diameter of tool joint  36  while prior art ram bore profile  34  engages elevator shoulder  40 . 
     FIGS. 4 and 5 show the pair of rams  28  with variable bore ram packer  30  positioned within ram bodies  32  with prior art ram bore profile  34  and 5″ O. D. drill pipe  42  positioned within rams  28 . 5″ O. D. drill pipe  42  has 6⅝″ O. D. tool joint  44  attached at its upper end by suitable means as cold forging or welding. Elevator shoulder  46  of tool joint  44  functions as before. The problem with such a design is that prior art ram bore profile  34  is sized for the 6⅝″ O. D. drill pipe  36  with  8 ″ O. D. tool joint  38 . When 6⅝″ O. D. tool joint  44  is supported on prior art ram bore profile  34  only a very thin shoulder is present to support the weight of drill pipe  42  as seen in FIG.  5 . The present invention solves this problem by providing a new and unique ram bore profile that accommodates different diameter tool joints and provides greatly increased load capacity. 
     With reference to FIG. 6, variable bore ram packer assembly  100  includes ram body  102 , top seal  104  and variable bore packer  106 . Ram body  102  is a generally rectangular parallelepiped shape with rounded sides  108  that fit in laterally disposed ram guideways  16 . Ram body  102  includes upper body  110  and lower body  112  connected by front face  114  and defining ram packer cavity  115  therebetween. Formed within front face  114  of upper body  110  is ram bore profile  116 . Ram bore profile  116  is substantially U shaped and extends vertically through upper body  110  to ram packer cavity  115 . Ram bore profile  116  is further characterized by rear portion  118 , diverging sides  120  and front throat  122 . Rear portion  118  is an arcuate segment connected to front throat  122  by diverging sides  120 . Front throat  122  intersects front face  114  at a substantially perpendicular angle. Arcuate sections  124  connect diverging sides  120 . Area  126  adjacent ram bore profile  116  is hardened by suitable means as weld inlay or thermal treatment to increase the load carrying capacity of ram bore profile  116 . 
     As best seen in FIGS. 7-10, the unique ability of ram bore profile  116  to support different diameter tapered tubular members such as tool joints is shown. FIGS. 7 and 8 show a pair of rams  128  with variable bore ram packer  106  positioned within ram bodies  102 . Positioned within rams  128  is 5″ O. D. drill pipe  130  with tool joint  132  attached at its upper end and elevator shoulder  134  connecting therebetween. Tool joint  132  will typically have an 6⅝″ O. D., as previously described. Improved ram bore profile  116  allows rear portion  118  to closely fit about drill pipe  130  while supporting tool joint  132  on elevator shoulder  134  to provide increased support. Similarly, FIGS. 9 and 10 show a pair of rams  128  with variable bore ram packer  106  positioned within ram bodies  102 . Positioned within rams  128  is 6⅝″ O. D. drill pipe  136  with tool joint  138  attached at its upper end and elevator shoulder  140  connecting therebetween. Tool joint  138  will typically have an 8″ O. D., as previously described. Improved ram bore profile  116  allows rear portion  118  to closely fit about drill pipe  136  while supporting tool joint  138  on elevator shoulder  140  to provide increased support, particularly in the area of front throat  122 . This provides increases support to drill pipe  136 . Thus it is seen ram bore profile  116  accommodates a range of drill pipe sizes and their associated tool joints to allow increase load supporting capabilities and preventing damage the variable bore packer within. 
     FIG. 11 shows the unique ram bore profile of the present invention in another type of variable bore ram packer assembly. This variable bore ram packer assembly  200  is of the type shown and claimed in pending U.S. application Ser. No. 09/550,403 filed Apr. 14, 2000 and is incorporated herein by reference. Those items which are the same as in the first embodiment retain the same numerical designations. Variable bore ram packer assembly  200  includes ram body  202 , top seal  204  and variable bore packer  206 . Ram body  202  is a generally rectangular parallelepiped shape with rounded sides  208  that fit in laterally disposed ram guideways  16 . Ram body  202  includes upper body  210  and lower body  212  connected by front face  214  and defining ram packer cavity  215  therebetween. Formed within front face  214  is ram bore profile  116  as in the previous embodiment. Ram bore profile  116  is substantially U shaped and extends vertically through upper body  210  to ram packer cavity  215 . Ram bore profile  116  is further characterized by rear portion  118 , diverging sides  120  and front throat  122 . Rear portion  118  is an arcuate segment connected to front throat  122  by diverging sides  120 . Front throat  122  intersects front face  114  at a substantially perpendicular angle. Arcuate sections  124  connect diverging sides  120 . Area  126  adjacent ram bore profile  116  is hardened by suitable means as weld inlay or thermal treatment to increase the load carrying capacity of ram bore profile  116 . 
     As best seen in FIGS. 12-15, the unique ability of ram bore profile  116  to support different diameter tapered tubular members such as tool joints is again shown with the alternate variable bore packer  206 . As before, FIGS. 12 and 13 show a pair of rams  216  with variable bore ram packer  206  positioned within ram bodies  202 . Positioned within rams  216  is 5″ O. D. drill pipe  130  with tool joint  132  attached at its upper end and elevator shoulder  134  connecting therebetween. Tool joint  132  will typically have an 6⅝″ O. D., as previously described. Improved ram bore profile  116  allows rear portion  118  to closely fit about drill pipe  130  while supporting tool joint  132  on elevator shoulder  134  to provide increased support. Similarly, FIGS. 14 and 15 show a pair of rams  216  with variable bore ram packer  206  positioned within ram bodies  202 . Positioned within rams  216  is 6⅝″ O. D. drill pipe  136  with tool joint  138  attached at its upper end and elevator shoulder  140  connecting therebetween. Tool joint  138  will typically have an 8″ O. D., as previously described. Improved ram bore profile  118  allows rear portion  118  to closely fit about drill pipe  136  while supporting tool joint  138  on elevator shoulder  140  to provide increased support, particularly in the area of front throat  122 . This provides increases support to drill pipe  136 . Thus it is seen ram bore profile  116  accommodates a range of drill pipe sizes and their associated tool joints to allow increase load supporting capabilities and will work with different types of variable bore packer designs. 
     The construction of my improved ram bore profile for a variable bore packer ram in a ram type blowout preventer variable bore ram packer will be readily understood from the foregoing description and it will be seen that I have provided an improved ram bore profile to accommodate a range of tubular member diameters. Furthermore, while the invention has been shown and described with respect to certain preferred embodiments, it is obvious that equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of the specification. The present invention includes all such equivalent alterations and modifications, and is limited only by the scope of the appended claims