Abstract:
A process to transport and assemble a drilling or workover rig substructure. The process includes the steps of transporting a driller side substructure section and an off driller side substructure section to a rig site so that the sections are spaced from and parallel to each other. A center substructure section is transported to the rig site. The center substructure section is moved into a space between the driller side and the off driller side sections. The center substructure section is thereafter connected to the driller side and to the off driller side subsections. A floor of the driller side substructure and a floor of the off driller side substructure are raised while both connected to the center substructure section from a transport position to a use position while maintaining the floors parallel to the bases.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a modular drilling or workover rig substructure which may be transported to and from a rig site without entirely dismantling the substructure. In particular, the present invention is directed to a modular drilling rig substructure that may be transported to and from a rig site with various drill floor equipment and hand rails remaining in place and that minimizes liquid discharge by providing an integrated containment and drainage system. 
   2. Prior Art 
   A drilling rig substructure is one important component of a drilling or workover rig. Typically, a drilling rig substructure includes a raised platform or drilling floor which is above the level of a main deck or cellar deck and above the level of a well head, a blowout preventer and other equipment. An upstanding mast is connected to a floor of the rig and is often supported by the substructure. The mast may extend from 30 to 60 meters so that a substantial amount of weight is supported by the substructure. 
   The drilling rig substructure includes certain drilling floor equipment and supports personnel for various operations such as connecting and disconnecting pipe sections. Examples of equipment on the drilling floor include rotary tables, power tong apparatus, pipe handling systems, hydraulic winches, powered hoists and controls operated by personnel. Additionally, a V-door ramp may extend from the floor for movement of tubulars and equipment. 
   It is often necessary to move a drilling or workover rig, including all of its equipment, from one site to another. Traditionally, a rig substructure is assembled or rigged up by assembling the various component pieces of the substructure. For example, a framework is assembled and a plurality of floor panels are put in place to support the equipment and personnel on the drilling floor. While the floor panels are adequate for the purpose of support, they typically do not form a liquid-tight floor section. Accordingly, oil, liquids or debris may run off in the surrounding area. Increasingly, it is desirable to contain any such run-off. 
   Conversely, the drilling rig substructure is typically disassembled or rigged down by disassembling the various component pieces of the substructure. The various components are then transported to an alternate rig site and the entire process is again repeated. 
   In the past, various attempts have been made to place various equipment together in modular arrangements. For example, Bierscheid, Jr. (U.S. Pat. No. 4,899,832) discloses a modular drilling apparatus with a combined mast and drilling platform to facilitate assembly and disassembly of the drilling rig. Bierscheid, Jr. does not, however, provide a modular substructure. 
   It would be advantageous to provide a modular substructure apparatus and method wherein modular components could be moved to and from a rig site by trailer or other vehicle. 
   It would be advantageous to provide a modular substructure apparatus and process wherein various drill floor equipment and hand rails could remain in place during rig up, during rig down and during transportation operations. 
   It would also be desirable to provide a modular substructure apparatus and method to facilitate zero liquid discharge from the drill floor by providing an integrated substructure floor and drainage system. 
   It would be desirable to provide a modular substructure apparatus and method eliminating the requirement of a crane or a gin pole to assemble or rig up and to disassemble or rig down the substructure at a rig site. 
   It would be advantageous to provide a modular substructure apparatus and method wherein various structural, hydraulic and piping connections could be made at ground level prior to raising the drilling floor to its upstanding, use position. 
   It would be advantageous to provide a modular drilling rig substructure wherein component sections are joined by connectors not exposed to hook, rotary or set back live loads. 
   It would be advantageous to provide a modular drilling rig substructure having a drilling floor movable between a lowered, transportation position and an upstanding use position wherein the drilling floor remains parallel to a base at all times. 
   SUMMARY OF THE INVENTION 
   The present invention is directed to a modular drilling rig substructure which is comprised of three discreet, modular components—driller side substructure section, center substructure section and an off driller side substructure section. The center section is juxtaposed and lies between the driller side substructure section and the off driller side substructure section. 
   The driller side substructure section includes a base having a lower skid suitable to be lowered on, loaded off and transported from a trailer or other vehicle. Parallel to and above the base is a floor frame assembly. Pivotally connected between the base and floor frame assembly are a pair of front legs, a pair of middle legs and a pair of rear legs. The front legs, middle legs and rear legs are each pivotally connected to the base. Likewise, the front legs, the middle legs and the rear legs are pivotally connected to the floor frame assembly of the driller side substructure section. Accordingly, the floor frame assembly, the base, the front legs, and the rear legs form a parallelogram. The floor frame assembly can thus move between an upright, in-use position and a lower position parallel to and adjacent to the base for transportation. 
   The off driller side substructure section operates in the same manner. The off driller side substructure section includes a base, a pair of front legs, middle legs and a pair of rear legs. The front legs, middle legs, and rear legs are each pivotally connected to the base. Likewise, the front legs, middle legs, and rear legs are each pivotally connected to a floor frame assembly of the off driller side substructure section. Accordingly, the floor frame assembly, the base, the front legs and the rear legs together form a parallelogram. In order to assemble a drilling or workover rig substructure, the driller side substructure section and the off driller side substructure section are each transported to a selected rig site in a lowered position. The base of the driller side substructure section is adjacent a drawworks while the base of the off drillers side substructure section is adjacent the drawworks. The driller side substructure section and the off driller side substructure section are parallel to each other and are also spaced apart from each other. Once the off driller side section and the driller side section are in place, the center substructure section is transported and brought to the rig site. The center substructure section is transported on the trailer of a truck with the space between the two side sections being wider than the width of the truck. Accordingly, the truck can back up between the side sections to deposit the center section in place. Thereafter, the center substructure section is pinned to the driller side substructure section and the center section is pinned to the off driller side substructure section. 
   An hydraulic cylinder between the base and floor assembly on the driller side substructure section is utilized to raise the substructure into the upright, use position. Likewise, an hydraulic cylinder between the base and floor assembly of the off driller side substructure section is utilized to raise the substructure to the upright, use position. The center substructure section is connected to the side sections so that it is raised or lowered along with the side sections. The fully assembled substructure forms an integrated floor with a railing surrounding the drill floor. The drill floor forms a zero discharge floor having a perimeter drain system. Located on the drill floor are various pieces of equipment which may remain in place not only in the use position but also during disassembly and while in the transportation position. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1A  is a drillers side elevational view of a modular drilling rig substructure constructed in accordance with the present invention in the use position,  FIG. 1B  is in the lowered position, and  FIGS. 1C and 1D  are in intermediate positions; 
       FIG. 2  is a sectional view of the modular drilling rig substructure in the use position taken along section line  2 — 2  of  FIG. 1  with front legs of the substructure also shown in dashed lines in the lowered position; 
       FIG. 3  is a top view showing the component sections of the drilling rig substructure in the lowered position with portions of the flooring removed for clarity; 
       FIG. 4  is a top view of the assembled rig substructure in the use position with portions of the flooring removed for clarity; 
       FIG. 5  is a front view of the rig substructure in the upright use position; 
       FIG. 6  is a sectional view of the rig substructure taken along section line  6 — 6  of  FIG. 1 ; 
       FIG. 7  is an enlarged view of the portion shown in  FIG. 6 ; 
       FIG. 8  is a top view of the connection shown in  FIG. 7 ; 
       FIG. 9  is an enlarged view of the connection shown in the dashed line circle in  FIG. 1 , 
       FIG. 10  is a top view of the connection shown in  FIG. 9 , and 
       FIG. 11  is a side view of the connection shown in  FIG. 9 ; 
       FIG. 12  is an enlarged view of the connection shown in the dashed line circle in  FIG. 1 , 
       FIG. 13  is a top view of the connection shown in  FIG. 12 , and 
       FIG. 14  is a side view of the connection shown in  FIG. 12 ; and 
       FIG. 15  is a top view of the assembled rig substructure showing various equipment on the drill floor. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The embodiments discussed herein are merely illustrative of specific manners in which to make and use the invention and are not to be interpreted as limiting the scope of the instant invention. 
   While the invention has been described with a certain degree of particularity, it is to be noted that many modifications may be made in the details of the invention&#39;s construction and the arrangement of its components without departing from the spirit and scope of this disclosure. It is understood that the invention is not limited to the embodiments set forth herein for purposes of exemplification. 
   Referring to the drawings in detail,  FIG. 1A  is a side elevational view of a modular drilling rig substructure  10  constructed in accordance with the present invention. As seen in  FIG. 1 , the rig substructure is an upright, in use and fully assembled condition and in place adjacent to a drawworks  12 . A mast (not shown) would be brought to and installed on the rig substructure  10 . 
   The rig substructure  10  includes a safety railing  16  surrounding a drill floor  18 . An opening in the railing  16  accommodates a personnel trailer, driller&#39;s cabin, or “dog house” for drilling rig personnel. The driller&#39;s cabin may be supported by the drill floor of the substructure or may have its own support assembly depending on the particular arrangement. Accordingly, the view in  FIG. 1A  is from the drillers side view. The opposite side is known as and will be described herein as the off driller side. 
   The drawworks  12  itself may be modular and reside on a skid to be moved to and from a rig site. The substructure is comprised of three discreet, modular components—a driller side substructure section  20  visible in  FIGS. 1A , B, C and D, a center substructure section  22  partially visible in  FIG. 1A , and an off driller side substructure section  24  (not visible in  FIGS. 1A , B, C and D). The center section  22  is juxtaposed and lies between the driller side substructure section  20  and the off driller side substructure section  24 . 
   As seen in  FIG. 1A , the driller side substructure section  20  includes a base  30  having a lower skid suitable to be loaded on, loaded off and transported on a trailer or other vehicle. Parallel to and spaced above the base  30  is a floor frame assembly  32 . Pivotally connected between the base  30  and floor frame assembly  32  are a pair of front legs  34 , a pair of middle legs  36  and a pair of rear legs  38 . The front legs  34 , middle legs  36  and rear legs  38  are each pivotally connected to the base  30 . Likewise, the front legs  34 , middle legs  36 , and rear legs  38  are each pivotally connected to the floor frame assembly  32  of the driller side substructure section  20 . Accordingly, the floor frame assembly  32 , the base  30 , the front legs  34  and rear legs  38  form a parallelogram. The floor frame assembly  32  is capable of moving between an upright, in-use position shown in  FIG. 1A and a  lower position parallel and adjacent to the base for transportation shown in FIG.  1 B.  FIGS. 1C and 1D  illustrate intermediate positions between the lowered position in  1 B and upright position in FIG.  1 A. 
   The off driller side substructure section  24  operates in the same manner. 
     FIG. 2  is a sectional view taken along section line  2 — 2  of FIG.  1 A. As seen in  FIG. 2 , the driller side substructure section  20  and the off driller side substructure section  24  are parallel to each other and also spaced apart from each other. The space therebetween receives the center substructure section  22  which has been removed for clarity and is not seen in FIG.  2 . Driller side substructure section  20  includes rear legs  38 , middle legs  36  and front legs  34 . When the substructure  10  is rotated from the upright, use position shown in  FIGS. 1A and 2  to the lowered transportation position show in  FIG. 1B , the front legs  34  will move and rotate so that they are in the position shown in dashed lines  34 ′. 
   Likewise, the off driller side substructure section  24  includes a base  42 , a pair of front legs  48 , middle legs  46  and a pair of rear legs  44 . The front legs  48 , middle legs  46 , and rear legs  44  are pivotally connected to the base  42 . When the substructure  10  is rotated from the upright, use position shown in  FIGS. 1A and 2  to the lowered position shown in  FIG. 1B , the front legs  48  will move and rotate so that they are in the position shown in dashed lines  48 ′. 
   A base brace  50  between the base  30  of the driller side substructure section and the base  42  of the off driller side substructure section is visible. The brace  50  is pivotally connected to the base  42  of the off driller side substructure section  24  and moves radially. A diagonal brace  52  between the front legs  34  and  48  and a diagonal brace  54  between the rear legs  38  and  44  may be provided for stabilization. 
   In order to assemble a drilling rig or workover rig substructure  10 , the driller side substructure section  20  and the off driller side substructure section  24  are each transported to a selected rig site in a lowered position as shown in FIG.  3 . The base  30  of the driller side substructure section is adjacent the drawworks  12  while the base  42  of the off driller side substructure section is adjacent the drawworks  12 . Once the off driller side section  24  and the driller side section  20  are in place, the center substructure section  22  is ready for installation. In one arrangement shown in  FIG. 3 , the center substructure section  22  is transported on a trailer of a truck with the space between the two side sections being wider than the width of the truck. Accordingly, the truck can back up between the drillers and off driller side sections to deposit the center substructure section in place. 
   For clarity, drilling floor panels  56  have been partially cut away in order to view the framework for the floor frame assembly  32  of the driller side substructure and the floor of the off driller side section. 
     FIG. 4  illustrates a subsequent sequence in the process whereby the center subsection  22  has been brought into place and secured to the drillers side and off drillers side sections, as will be described herein. 
   Intersecting dashed lines  58  depict the center line of the wellhead over which the substructure  10  is installed. 
   As seen in  FIG. 4 , the center substructure section  22  includes a frame forming a skid  60  to be received on a trailer for transportation. In one arrangement to assemble, a tandem-type trailer will move the center section  22  between the side sections and, with a rolling tail board, tip the center section to set the center section in place. 
     FIG. 5  illustrates a front view of the substructure  10  while  FIG. 6  illustrates a rear view of the substructure in the upright, use position. In  FIG. 5 , the pair of front legs  34  of the driller side subsection and the pair of front legs  48  of the off driller side subsection are visible. Cross bracing  64  between the pairs of front legs may be utilized. An hydraulic cylinder  70  between the base  30  and floor assembly  32  of the driller side substructure section  20  is utilized to raise the drill floor into the upright, use position. Likewise, an hydraulic cylinder  72  between the base  42  and the floor assembly of the off driller side section  24  is utilized to raise the floor to the upright, use position. The cylinders  70  and  72  are powered by the hydraulic power system of the rig. The center section is connected to the side sections so that it is raised or lowered along with side sections. 
   The pair of rear legs  38  of the drillers side substructure section and the pair of rear legs  44  of the off driller side substructure section are visible in FIG.  6 . 
     FIG. 7  illustrates the connection between center section  22  and the side substructure sections, an enlarged view of the portion shown in the dashed line circle in  FIGS. 5 and 6 . The center section  22  includes a protrusion in the form of a tube  74  which extends along each side of the center section  22 . The side substructure section includes an L-shaped shelf  76 . The tube  74  and, in turn, the center section  22  rests upon the shelf. Accordingly, the center section  22  is supported on the shelves of the driller and off driller side substructure sections. 
     FIG. 8  is a top view of the connection shown in  FIG. 7. A  set of pins  78  extends through the tube  74  and through the shelf  76  in order to secure the center section to the side sections. While  FIGS. 7 and 8  illustrate the connection between the center section and the off driller side subsection, a similar arrangement is provided to connect the center section with the drillers side section. 
     FIG. 9  illustrates an enlarged view of the pivotal connection between the base  30  of the drillers side section and the rear leg or legs  38 . A stop  80  extending from the base  30  restricts the rear leg  38  from moving past the vertical position. The rear legs  38  move about a hinge  82  between the upright position shown in  FIGS. 9 ,  10  and  11  and a lower position. It will be observed that the pin does not carry any of the load of the substructure while in the upright use position. 
     FIG. 12  shows an enlarged view of the pivotal connection between the base  30  of the drillers side subsection and the front legs  34 . 
     FIG. 13  is a top view of the pivotal connection shown in  FIG. 12  while  FIG. 14  is a side view of the connection shown in FIG.  12 . The front legs  34  moves about hinge  90  so that the front legs  34  move between the upright position shown in  FIGS. 12 ,  13  and  14  and a lowered, transportation position illustrated by the dashed lines in FIG.  12 . The front legs terminate in a shear block which provides a contact with a base box pin plate on the base  30  to provide a significant mating area. It will be observed that the pin does not carry any of the load of the substructure while in the upright position. 
     FIG. 15  illustrates a top view of the fully assembled substructure with a railing  16  surrounding the entire drill floor  18 . As the substructure sections have integrated floors, which are not dismantled during rig up or rig down, the drill floor  18  forms a zero discharge floor having a perimeter drain system. On the drill floor are various pieces of equipment which remain in place not only in the use position but also while in the transportation position. For example, winches  92 , stand pipe manifold  94 , rotary table  96 , wire line unit  98  and shoes  100  and  102  for the mast are visible. 
   Hydraulic and electric connections can be made while the substructure  10  is in the lowered, transportation position prior to extending the hydraulic cylinders and prior to raising the substructure to the upstanding, in use position. 
   Whereas, the present invention has been described in relation to the drawings attached hereto, it should be understood that other and further modifications, apart from those shown or suggested herein, may be made within the spirit and scope of this invention.