Abstract:
Mobile drilling rigs and methods for moving drilling rigs are disclosed which, in one aspect, include wheel assemblies connected to a rig which wheel assemblies are selectively movable from a rig drilling position to a rig movement position. This abstract is provided to comply with the rules requiring an abstract which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure and is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims, 37 C.F.R. 1.72( b ).

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    This invention is directed to drilling rigs with erectable masts and substructures; in certain particular aspects, to such rigs that are mobile; and methods for moving a drilling rig. 
         [0003]    2. Description of Related Art 
         [0004]    The prior art discloses a variety of rigs used in drilling and various wellbore operations, including rigs that are mobile; for example, and not by way of limitation, U.S. Pat. Nos. 3,340,938; 3,807,109; 3,922,825; 3,942,593; 4,269,395; 4,290,495; 4,368,602; 4,489,526; 4,569,168; 4,837,992; 6,634,436; 6,523,319 and the references cited in these patents—all these patents incorporated fully herein for all purposes. 
         [0005]    In many land drilling operations, land rigs are delivered to a site, assembled and then disassembled; including, in many cases, raising a rig mast to a vertical operational position. Often as an oilfield becomes mature, wells are drilled deeper into the earth to obtain production. Oil rigs are getting progressively larger to meet these needs. In the past, a 1500 hp rig was sufficient to handle most drilling. These rigs more recently have been supplanted by larger 2000 hp rigs. Currently, 3000 hp rigs are being made, but are not yet widely used. A 3000 hp rig typically has a 36 to 37 foot high drillfloor, a 156 foot clear height mast, a 1,500,000 pound hookload, a 1,300,000 pound rotary load, and a 1,000,000 pound setback load. Often large drilling rigs, e.g. in the Middle East, are transported between well sites by dismantling the rig into pieces that can be trucked between two well sites which can produce many time-consuming truckloads of rig components resulting in up to four additional weeks of rig downtime (the larger the capacity of the rig, the heavier the loads, and the number of loads also increases); and mounting the drilling module complete with mast on tires. One drawback of a tire-mounted drilling module is tire load capacity and overall&#39; rig height. Often, the largest tires that are used are 40×57 earthmover tires. 
         [0006]    With certain current rig designs, the largest rigs that can be easily moved are 2000 hp rigs of a box style substructure. This style of design is conducive to even tire loading. A typical 3000 hp rig that has an evenly loaded box style substructure will be too tall to move with a 156 foot mast and a 37 foot drillfloor to get under the power line height restriction with current moving systems (e.g. in countries such as Kuwait where a typical maximum clearance for power lines is 161 feet from the ground to the top of the rig being transported). Anything taller than this will produce the potential for electrical arcing between the mast and the power lines if the rig is being towed on its tires. 
         [0007]    Another common style of substructure is the slingshot substructure which is often used in large hookload application. The substructure folds down in order to easily access the drillfloor from the ground level, which aids in rig assembly. Often a substructure of this size is broken down into truck sized loads. Placing a wheeled moving system on certain rigs of this style may not be practical because it is not feasible to easily balance the wheel loads. 
         [0008]    U.S. Pat. No. 3,922,825 discloses a rig with a stationary substructure base and a movable substructure base mounted thereon which is coupled to the stationary base and swings upright into an elevated position on a series of struts that are connected to the stationary base with swivel connections at each end. The movable base is otherwise stationary since neither the stationary base nor the movable base are mobile or repositionable without the use of an auxiliary crane or the like. The movable substructure base and the drill mast are raised with a winch mounted on an auxiliary winch truck. 
         [0009]    U.S. Pat. No. 3,942,593 discloses a mobile well drilling rig apparatus which has a trailerable telescoping mast and a separate sectionable substructure assembly with a rig base, a working floor, and a rail structure. The mast is conveyed to the top of the substructure by rollers and is raised by hydraulic raising apparatus to an upright position. With such a system the the mast assembly can be relatively long when transporting it and the mast can be unstable during raising. This system uses drawlines and winch apparatus to raise the mast onto the working floor. 
         [0010]    U.S. Pat. No. 6,523,319 discloses a drilling rig base and a lower mast section that are collapsible into a compact transportable position. The base is expandable in the field to support a drilling platform and equipment, and the telescoping mast is also expandable for supporting the crown block and cables of the drawworks. The rig may have a plurality of beams, the outer beams being collapsible to a transportable position for placing on a single truck or trailer, and the A-frame lower mast section which is collapsible to a transportable position for placing on a single truck or trailer. In one aspect, a mobile, collapsible drilling rig base and drilling platform are disclosed which haves: a base having a plurality of parallel beams; the beams being in a horizontal plane and including inner beams and outer beams: the outer beams being collapsible in said horizontal plane to a transportable position; and a drilling platform attached to the base that is elevatable above the base. 
         [0011]    U.S. Pat. No. 6,634,436 discloses a mobile land drilling apparatus and method. The rig has a mobile telescoping substructure box. A lifting apparatus selectively supports the mobile telescoping substructure box unit in a raised position and lowered position. An extension cylinder further extends the mobile telescoping substructure box unit in telescopic extension. A stationary frame member and a telescoping frame member have a plurality of cables attached thereto for supporting the telescoping frame member when extended. A trolley winch allows completion of the rig assembly without an external crane. 
         [0012]    U.S. Pat. No. 7,357,616 discloses oil rig capable of being at least partially disassembled to form at least two portions, such as a top half and bottom half, and an associated structure for transport. An oil rig top portion may be loaded onto a trailer for transport separate from a bottom portion. The trailer includes a bottom frame, a top frame, a structure operably associated with said bottom and top frames for moving the top and bottom frames away from and towards one another, and a moving means attached to the at least bottom frame to allow the trailer to be moved along the support surface. The trailer may be towed by a truck or other vehicle. In one aspect a method is disclosed for transporting an oil rig, including: disassembling the oil rig to form a top portion with a rig floor and a mast and bottom portion with a substructure; transporting the top portion separately from the bottom portion; transporting the rig floor on a trailer; raising a top surface of the trailer to accept the rig floor; and prior to the step of transporting the rig floor on the trailer, lowering the top surface of the trailer. In one aspect, a trailer is disclosed for moving a part of an oil rig along a support surface, the trailer having: a bottom frame; a top frame; a structure operably associated with the bottom and top frames for moving the top and bottom frames away from and towards one another and further operative to temporarily fix the position of the top and bottom frames with respect to one another, the structure having at least one hydraulic piston; an alignment mechanism affixed to one of the top and bottom frame, the alignment mechanism operative to align the top frame with a top surface of the oil rig; an I-beam affixed to the top surface and operative to facilitate loading the part of the oil rig onto the trailer; and a moving means attached to at least the bottom frame to allow the trailer to be moved along the support surface. 
       BRIEF SUMMARY OF THE INVENTION 
       [0013]    The present invention, in certain aspects, discloses a mobile drilling rig with integral wheel assemblies selectively changeable from a drilling mode position to a moving mode position. In the moving mode position, the mobile drilling rig is movable on the wheel assemblies from one location to another. 
         [0014]    In certain aspects, the present invention discloses a system that includes a land rig with an erectable substructure; an erectable mast; and movement apparatus on which the substructure is mounted for moving the rig from one location to another. In one aspect, the present invention discloses a mobile drilling rig with a base box, a plurality of wheel assemblies pivotably connected to the base box, each of the plurality of wheel assemblies selectively pivotable from a first position to a second position, the first position for moving the mobile drilling rig from a first location to a second location. 
         [0015]    Accordingly, the present invention includes features and advantages which are believed to enable it to advance rig movement technology. Characteristics and advantages of the present invention described above and additional features and benefits will be readily apparent to those skilled in the art upon consideration of the following detailed description of preferred embodiments and referring to the accompanying drawings. 
         [0016]    Certain embodiments of this invention are not limited to any particular individual feature disclosed here, but include combinations of them distinguished from the prior art in their structures, functions, and/or results achieved. Features of the invention have been broadly described so that the detailed descriptions that follow may be better understood, and in order that the contributions of this invention to the arts may be better appreciated. There are, of course, additional aspects of the invention described below and which may be included in the subject matter of the claims to this invention. Those skilled in the art who have the benefit of this invention, its teachings, and suggestions will appreciate that the conceptions of this disclosure may be used as a creative basis for designing other structures, methods and systems for carrying out and practicing the present invention. The claims of this invention are to be read to include any legally equivalent devices or methods which do not depart from the spirit and scope of the present invention. 
         [0017]    What follows are some of, but not all, the objects of this invention. In addition to the specific objects stated below for at least certain preferred embodiments of the invention, there are other objects and purposes which will be readily apparent to one of skill in this art who has the benefit of this invention&#39;s teachings and disclosures. It is, therefore, an object of at least certain preferred embodiments of the present invention to provide the embodiments and aspects listed above and: 
         [0018]    New, useful, unique, efficient, non-obvious drilling rigs, systems for moving them, and methods for moving them; and 
         [0019]    Such systems in which a drilling rig has a plurality of wheel assemblies selectively movable into a moving mode to move the drilling rig from one location to another. 
         [0020]    The present invention recognizes and addresses the problems and needs in this area and provides a solution to those problems and a satisfactory meeting of those needs in its various possible embodiments and equivalents thereof. To one of skill in this art who has the benefits of this invention&#39;s realizations, teachings, disclosures, and suggestions, other purposes and advantages will be appreciated from the following description of certain preferred embodiments, given for the purpose of disclosure, when taken in conjunction with the accompanying drawings. The detail in these descriptions is not intended to thwart this patent&#39;s object to claim this invention no matter how others may later attempt to disguise it by variations in form, changes, or additions of further improvements. 
         [0021]    The Abstract that is part hereof is to enable the U.S. Patent and Trademark Office and the public generally, and scientists, engineers, researchers, and practitioners in the art who are not familiar with patent terms or legal terms of phraseology to determine quickly from a cursory inspection or review the nature and general area of the disclosure of this invention. The Abstract is neither intended to define the invention, which is done by the claims, nor is it intended to be limiting of the scope of the invention in any way. 
         [0022]    It will be understood that the various embodiments of the present invention may include one, some, or all of the disclosed, described, and/or enumerated improvements and/or technical advantages and/or elements in claims to this invention. 
         [0023]    Certain aspects, certain embodiments, and certain preferable features of the invention are set out herein. Any combination of aspects or features shown in any aspect or embodiment can be used except where such aspects or features are mutually exclusive. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0024]    A more particular description of embodiments of the invention briefly summarized above may be had by references to the embodiments which are shown in the drawings which form a part of this specification. These drawings illustrate certain preferred embodiments and are not to be used to improperly limit the scope of the invention which may have other equally effective or equivalent embodiments. 
           [0025]      FIG. 1A  is an end view of a drilling rig according to the present invention. 
           [0026]      FIG. 1B  is a side view of the drilling rig of  FIG. 1A . 
           [0027]      FIG. 1C  is a top plan view of a rig floor of the drilling rig of  FIG. 1A . 
           [0028]      FIG. 1D  is a side view of part of the drilling rig of  FIG. 1A . 
           [0029]      FIG. 1E  is a top plan view of wheel assemblies and interconnecting structure of the drilling rig of  FIG. 1A . 
           [0030]      FIG. 1F  is an end view showing the drilling floor of  FIG. 1C  in a raised position. 
           [0031]      FIG. 2A  is a side view of a part of the drilling rig of  FIG. 1A  showing a step in a method according to the present invention. 
           [0032]      FIG. 2B  is a side view of the drilling rig of  FIG. 1A  showing a step after the step shown in  FIG. 2A . 
           [0033]      FIG. 2C  is a side front view of the drilling rig of  FIG. 1A  showing a step after the step shown in  FIG. 2B . 
           [0034]      FIG. 2D  is a side view of the drilling rig of  FIG. 1A  showing a step after the step shown in  FIG. 2C . 
           [0035]      FIG. 2E  is a side view of the drilling rig of  FIG. 1A  showing a step after the step shown in  FIG. 2D . 
           [0036]      FIG. 2F  is a side view of the drilling rig of  FIG. 1A  showing a step after the step shown in  FIG. 2E . 
           [0037]      FIG. 2G  is a side view showing the drilling floor of the drilling rig of  FIG. 1A  raised according to the present invention. 
           [0038]      FIG. 3A  is a top view of a wheel assembly of the drilling rig of  FIG. 1A . 
           [0039]      FIG. 3B  is a side view of the wheel assembly of  FIG. 3A . 
           [0040]      FIG. 3C  is a front view of the wheel assembly of  FIG. 3A . 
           [0041]      FIG. 4A  is a front view of part of the rig of  FIG. 1A . 
           [0042]      FIG. 4B  is a front view of a bearing pad of the rig of  FIG. 1A . 
           [0043]      FIG. 4C  is a front view of the bearing pad of  FIG. 4B . 
       
    
    
       [0044]    Presently preferred embodiments of the invention are shown in the above-identified figures and described in detail below. Various aspects and features of embodiments of the invention are described below and some are set out in the dependent claims. Any combination of aspects and/or features described below or shown in the dependent claims can be used except where such aspects and/or features are mutually exclusive. It should be understood that the appended drawings and description herein are of preferred embodiments and are not intended to limit the invention or the appended claims. On the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the invention as defined by the appended claims. In showing and describing the preferred embodiments, like or identical reference numerals are used to identify common or similar elements. The figures are not necessarily to scale and certain features and certain views of the figures may be shown exaggerated in scale or in schematic in the interest of clarity and conciseness. 
         [0045]    As used herein and throughout all the various portions (and headings) of this patent, the terms “invention”, “present invention” and variations thereof mean one or more embodiment, and are not intended to mean the claimed invention of any particular appended claim(s) or all of the appended claims. Accordingly, the subject or topic of each such reference is not automatically or necessarily part of, or required by, any particular claim(s) merely because of such reference. So long as they are not mutually exclusive or contradictory any aspect or feature or combination of aspects or features of any embodiment disclosed herein may be used in any other embodiment disclosed herein. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0046]    The present invention provides mobile drilling rigs, systems and methods for rig erection; and systems and methods for moving a drilling rig. This invention&#39;s teachings are applicable, inter alia, to any rig which has an erectable substructure. 
         [0047]      FIGS. 1A and 1B  show a system  10  according to the present invention which includes a drilling rig  12  with a mast  14 , a substructure  16 , and movement apparatus  20  supporting the substructure  16 , the mast  14 , and related equipment and structure. The mast  14  may be, as shown, a tilt top mast, or it may be any suitable known mast. The substructure  16  is erectable from a lowered position as shown in  FIG. 1B  to a raised position as shown in  FIGS. 1A and 1D . The system  10  includes typical rig equipment and, apparatuses, e.g., but not limited to, a drawworks  1 , a rotary table  2  (see  FIG. 1C ), a driller cabin/doghouse  3 , a setback floor  4 , a BOP stack  5 , a drill line spooler  6 , and hydraulic catheads  8 . 
         [0048]    The movement apparatuses  20  (see, FIG.  FIGS. 2G ,  3 A- 3 C) include four wheel assemblies  30  which are pivotably mounted to a base box  18  at pivot points  19 . Each wheel assembly  30  has two wheels  35  each with a tire  36  and has a lug  31  selectively secured with a removable pin  17   a  to a lug  17  projecting from the base box  18 . Stop members  15  abut top beams  32  of the wheel assemblies  30  when the wheel assemblies  30  pivot at the pivot points  19  to prevent further movement of the top beams  32  toward the substructure  16 . 
         [0049]    Axles  33  which rotate in trunnions  32  of the wheel assemblies  30  have wheels  35  secured thereto. Each wheel  35  has a tire  36  (e.g., but not limited to 40×57, 76 ply tires). Optionally there is only one wheel for each wheel assembly each with one tire thereon at each of the four corners of a rig. A trunnion support  34  of each wheel assembly is rotatably secured at a wheel pivot  34   a  to a trunnion load beam  37  which is secured to the base box  18 . 
         [0050]    Each wheel assembly  30  has a towbar linkage  42  and one steering cylinder  41  for steering each wheel assembly. The steering cylinders  41  are connected to steering links  38  connected to the wheel pivots  34   a.  The steering cylinders  41  are controlled by a portable hydraulic power unit system PHP (shown schematically,  FIG. 1B ). 
         [0051]    The base box  18  includes base box spreaders  18   a  (beams that interconnect boxes on each side of the rig) and roller tracks  18   c  for scissors rollers (described below). Frame connection braces  18   b  are secured between pairs of base box spreaders  18   a.  Removable trunnion beam spreaders  37   a  are connected between pairs of trunnion load beams  37 . 
         [0052]    Four bearing pad apparatuses  40  are secured to the base box  18  in a raised position by pins  40   a.  When the rig  12  is in a drilling mode (e.g. see  FIGS. 1A and 2G ), the bearing pads  40  rest on the ground G. The bearing pads  40  have a limited travel length (e.g., see  FIGS. 2B ,  2 C). The bearing pads  40  are movable by cylinder apparatuses  70  (described below). 
         [0053]    The substructure  16  supports a drillfloor  50  which includes a drillfloor skid  51  with ends  51   a  and  51   b  supported by drill floor skid supports  56 ;, a driller&#39;s side floor box  52 ; a central drill floor  53 ; and an off driller&#39;s side floor box  54 . The drillfloor boxes  52 ,  54  include roller tracks  55  for scissors rollers (described below). Drawworks support spreaders  57  extend between the drill floor boxes  52 ,  54 . 
         [0054]    The substructure  16  has four scissors apparatuses  60 , two front and two rear. Each front scissors apparatus has a two outer scissors  61  and two inner scissors  62 . Each rear scissors has two outer scissors  63  and two inner scissors  64 . The front and rear scissors parts are secured together with center pipe connections  65 . Rollers  66  are rotatably mounted at certain ends of the beams of the scissors  61 - 64  for movement in the tracks  55  (top rollers) or the tracks  18   c  (bottom rollers). Top ends of the beams of the scissors  61 - 64  without rollers are pivotably secured to the drill floor boxes  52  and  54  at pivot points  59  and bottom ends of the beams of the scissors  61 - 64  without rollers are pivotably secured to the base box  18  at pivot points  18   p.    
         [0055]    The substructure  16  is raised and lowered by hydraulic cylinder apparatuses  70  (one, two, three, four or more at each end; eight shown, two pairs at each corner) which are connected at their tops to lugs  58  on the drill floor boxes  52 ,  54  and at their bottoms to connections  48  of the bearing pads  40 . 
         [0056]      FIGS. 2A-2G  illustrate a method according to the present invention for raising a drilling rig according to the present invention from a transport position to a drilling position. 
         [0057]    As shown in  FIG. 2A , the system  10   a,  like the system  10  described above and like numerals indicate like parts, has been moved on its wheel assemblies  30  from an original location to the new location shown in  FIG. 2A  (e.g. towed by a truck or trucks with tow bars attached to the tow bar linkages  42 ). The substructure  16  (system  10   a  shown partially; may include some or all of the structures and apparatuses shown in  FIGS. 1A ,  1 C and/or  1 D) is located over a proposed well site W. As shown, the substructure  16  has not yet been raised. 
         [0058]    As shown in  FIG. 2B , following removal of the pins  40   a,  the bearing pads  40  are lowered using the hydraulic cylinders  70 . As shown in  FIG. 2C  the hydraulic cylinders  70  are extended to lift the substructure  16 , supported on the bearing pads  40  on the ground D. The pins  17   a  are then removed to permit disconnecting the lugs  31  from the lugs  17  to free the wheel assemblies  30  for pivoting. 
         [0059]    As shown in  FIG. 2D , the substructure  16  (and whatever, not shown, is on the substructure  16 ) is lowered using the hydraulic cylinders  70 . The wheel assemblies pivot at wheel pivots  19 . As shown in  FIG. 2E , the substructure  16  is lowered until it rests on the ground D (or rig mats if they are used), with the wheel assemblies pivoted sufficiently to permit the substructure  16  to rest on the ground D. At this point, if the mast is not already mounted on the drill floor boxes  52 ,  54 , the mast may be placed in a horizontal position on the drill floor and raised to a vertical position. (i.e., the mast can be moved as a separate load). Pins  15   a  which selectively secure the drill floor  50  and the base box  18  are removed so that the substructure  16  can be raised. 
         [0060]    As shown in  FIG. 2F , the substructure  16  and the drillfloor  50  (and whatever is on the drillfloor  50 ) are raised using the cylinders  70 . The scissors apparatuses  60  are moving with their rollers in tracks from the collapsed positions of  FIG. 2E  to the contracting positions of  FIG. 2F . 
         [0061]      FIG. 2G  illustrates the substructure  16  raised to a desired height. The top roller ends of the beams of the scissors  61 - 64  are pinned with pins  67  to the drill floor boxes  52 ,  54  and the base box  18  with pins  67  (e.g. hydraulic pins may be used). 
         [0062]    It is within the scope of the present invention for the scissors apparatuses  60  to be folded up with the drillfloor pinned to the base box in the moving mode. Optionally the BOP stack or stacks can be removed for transport (e.g. at a 5 mph speed) using a known skidding-type BOP handling system or traditional BOP hoists to remove the stacks. At a 2.5 mph speed the BOP stack(s) may, optionally, stay onboard the rig in such a position to complement the tire loading at the four corners. The cylinders used to lift up the substructure may be the same cylinders used to raise the substructure base. 
         [0063]    In one aspect four pairs of cylinders  70  are multistage power cylinder apparatus used with two cylinders located under each of four rig corners to raise the drillfloor and mast (if present) as one unit. The cylinders, optionally, are failsafe in that the safety factor of the hydraulics and cylinders is such that if one cylinder loses pressure, the system can still safely run with another cylinder holding the load in the same corner. If both cylinders in one corner lose pressure, then the structure, in one aspect, may still be safely lowered to the base box because the hydraulics and the cylinders have enough support ability built into them to prevent a catastrophic failure. 
         [0064]    In one aspect the scissors apparatuses  60  are additional lifting apparatus for the BOP stacks in a cellar CR. The cellar CR can also, optionally, have spreaders with rails built in for the stack handler to roll onto from the truck bed. 
         [0065]    The scissors apparatuses  60  are pinned at a drilling height (e.g. as in  FIG. 2G ) using hydraulic latch pins  67  which secure the scissor apparatuses to the guide tracks  18   c  and  55 . In one drilling position, the rig is typically raised to a maximum height, but, in one aspect, the inherent design of the scissors apparatuses  60  allow this substructure to operate over a much larger range of heights, e.g. from 28-29 feet to 36-37 feet, although a larger design according to the present invention can provide a maximum height to over 40 feet. For example, a smaller design of the scissors apparatuses  60  may be used to create a range of 15 feet to 25 feet for an operating height. 
         [0066]    In certain aspects, for any sized rig according to the present invention, a mast can have its top section lay down to clear the power lines. This rig may include a top drive and torque track in place. Depending on the size of the rig selected, the transport height can be much lower for a smaller rig. For example, in one aspect, a shorter portable drilling rig provided according to the present invention still has a complete drilling module. The mast may also be removed completely and shipped separately in order for the system  10   a  to achieve an even smaller minimum road height. 
         [0067]    The scissors apparatuses  60  may be used in conjunction with any other sized drillfloor, large or small, tall or short, and other sized mast, in order to achieve a minimum road height and to help with clearance and stability for all families of scissor-type substructure drilling rigs. In cases where the BOP stack or other wellhead equipment is left on the well when the drilling rig (e.g. a rig  10 ) is ready for transport, the rig can be towed clear of the stack and then lowered to the transport height. 
         [0068]    Systems according to the present invention, in certain aspects, aid in keeping the center of gravity of a rig in a horizontal plane at the same location in both drilling and transport modes (e.g. see  FIGS. 1D and 1B ;  FIGS. 2G and 2A ). This allows for quicker and easier rig moves with less down time for the operator, and a more evenly loaded and compact moving system design. The system, in certain aspects, also incorporates a relatively shorter wheelbase providing a more maneuverable drilling rig with a tighter turning radius, allowing for much easier transportation and location on well sites than certain current designs allow. 
         [0069]    The present invention, therefore, provides in some, but not in necessarily all, embodiments a mobile drilling rig including: a base box, a plurality of wheel assemblies pivotably connected to the base box, each of the plurality of wheel assemblies selectively pivotable from a first position to a second position, the first position for moving the mobile drilling rig from a first location to a second location. Such a system may include one or some, in any possible combination, of the following: a substructure connected to the base box; the substructure raisable above the base box; a raising system connected to the substructure and to the base box for raising the substructure above the base box; the raising system includes a plurality of powered cylinder apparatuses for raising and lowering the substructure; wherein the raising system includes a plurality of scissors apparatuses for bracing the substructure, the scissors apparatuses each with top ends connected to the substructure and bottom ends connected to the base box; the scissors apparatuses positionable in a collapsed configuration with the substructure lowered and in an extended configuration with the substructure raised; and the scissors apparatuses releasably securable in the collapsed configuration and in the extended configuration; wherein the plurality of scissors apparatuses includes four spaced-apart scissors apparatuses, each with two centrally connected scissors members; wherein the substructure has top roller tracks; the base box has bottom roller tracks; and each scissors apparatus has a first scissors member with a top roller movable in a top roller track and a second scissors member with a bottom roller movable in a bottom roller track; a plurality of bearing pads connected to the base box, each bearing pad of the plurality of bearing pads selectively movable down from the base box to contact ground therebeneath; the bearing pads movable by the powered cylinder apparatuses; each wheel assembly including a steering apparatus for steering the wheel assembly; a drill floor on the substructure; a mast on the drill floor; wherein the mast is selectively erectable with respect to the drill floor; wherein the mobile drilling rig has four corners; and the plurality of powered cylinder apparatuses includes four pairs of two powered cylinder apparatuses each; a pair of powered cylinder apparatuses at each corner of the rig; wherein a substructure is connected to the base box, the substructure raisable above the base box and wherein one powered cylinder apparatus alone of each pair can be used to raise and lower the substructure; and/or wherein the mobile drilling rig has a center of gravity maintainable in a horizontal plane during drilling and during rig movement. 
         [0070]    The present invention, therefore, provides in some, but not in necessarily all, embodiments a mobile drilling rig including a base box, a plurality of wheel assemblies pivotably connected to the base box, each of the plurality of wheel assemblies selectively pivotable from a first position to a second position, the first position for moving the mobile drilling rig from a first location to a second location, a substructure connected to the base box, the substructure raisable above the base box, a raising system connected to the substructure and to the base box for raising the substructure above the base box, the raising system includes a plurality of powered cylinder apparatuses for raising and lowering the substructure, and a plurality of scissors apparatuses for bracing the substructure, the scissors apparatuses each with top ends connected to the substructure and bottom ends connected to the base box, the scissors apparatuses positionable in a collapsed configuration with the substructure lowered and in an extended configuration with the substructure raised, the scissors apparatuses releasably securable in the collapsed configuration and in the extended configuration, the plurality of scissors apparatuses including four spaced-apart scissors apparatuses, each with two centrally connected scissors members, a plurality of bearing pads connected to the base box, each bearing pad of the plurality of bearing pads selectively movable down from the base box to contact ground therebeneath, the bearing pads movable by the powered cylinder apparatuses, each wheel assembly movably connected to the base box and including a steering apparatus for steering the wheel assembly, a drill floor on the substructure, a mast on the drill floor, and wherein the mast is selectively erectable with respect to the drill floor. 
         [0071]    The present invention provides, therefore, in at least certain, but not necessarily all, embodiments a mobile drilling rig with a base box, a substructure connected to the base box, the substructure raisable above the base box, a raising system connected to the substructure and to the base box for raising the substructure above the base box, the raising system includes a plurality of powered cylinder apparatuses for raising and lowering the substructure, the raising system includes a plurality of scissors apparatuses for bracing the substructure, the scissors apparatuses each with top ends connected to the substructure and bottom ends connected to the base box, the scissors apparatuses positionable in a collapsed configuration with the substructure lowered and in an extended configuration with the substructure raised, and the scissors apparatuses releasably securable in the collapsed configuration and in the extended configuration. Such a rig may have one or some, in any possible combination, of the following: wherein the plurality of scissors apparatuses includes four spaced-apart scissors apparatuses, each with two centrally connected scissors members; wherein the substructure has top roller tracks, the base box has bottom roller tracks, and each scissors apparatus has a first scissors member with a top roller movable in a top roller track and a second scissors member with a bottom roller movable in a bottom roller track; a drill floor on the substructure, a mast on the drill floor, and wherein the mast is selectively erectable with respect to the drill floor. 
         [0072]    The present invention, therefore, provides in some, but not in necessarily all, embodiments a method for moving a mobile drilling rig, the method including: pivoting wheel assemblies pivotably connected to a base box of a rig from a drilling position to a movement position, the rig comprising a base box, a plurality of wheel assemblies pivotably connected to the base box, each of the plurality of wheel assemblies selectively pivotable from a first position to a second position, the first position for moving the mobile drilling rig from a first location to a second location; securing the wheel assemblies in the movement position, and moving the mobile drilling rig on the wheel assemblies. Such a method may include one or some, in any possible combination, of the following: a substructure connected to the base box, the substructure raisable above the base box, a raising system connected to the substructure and to the base box for raising the substructure above the base box, the method including raising with the raising system the substructure above the base box; wherein the raising system includes a plurality of powered cylinder apparatuses for raising and lowering the substructure; wherein the raising system includes a plurality of scissors apparatuses for bracing the substructure, the scissors apparatuses each with top ends connected to the substructure and bottom ends connected to the base box, the scissors apparatuses positionable in a collapsed configuration with the substructure lowered and in an extended configuration with the substructure raised, and the scissors apparatuses releasably securable in the collapsed configuration and in the extended configuration, the method including moving the scissors apparatuses from the collapsed configuration to the extended configuration as the substructure is raised; wherein the substructure has top roller tracks, the base box has bottom roller tracks, and each scissors apparatus has a first scissors member with a top roller movable in a top roller track and a second scissors member with a bottom roller movable in a bottom roller track, the method including moving the top rollers in the top roller tracks, and moving the bottom rollers in the bottom roller tracks; wherein a plurality of bearing pads are connected to the base box, each bearing pad of the plurality of bearing pads selectively movable with respect to the base box, the bearing pads in contact with ground during drilling and movable by the powered cylinder apparatuses, the method including raising the bearing pads above the ground to facilitate movement of the mobile drilling rig; wherein each wheel assembly including a steering apparatus for steering the wheel assembly, the method including steering each wheel assembly with its corresponding steering apparatus; wherein there is a drill floor on the substructure, a mast on the drill floor, and wherein the mast is selectively erectable and lowerable with respect to the drill floor, the method including lowering the mast to facilitate movement of the mobile drilling rig; wherein the raising system includes a plurality of powered cylinder apparatuses for raising and lowering the substructure, the mobile drilling rig has four corners, and the plurality of powered cylinder apparatuses includes four pairs of two powered cylinder apparatuses each, a pair of powered cylinder apparatuses at each corner of the rig, and wherein a substructure is connected to the base box, the substructure raisable above the base box and wherein one powered cylinder apparatus alone of each pair can be used to raise and lower the substructure, the method including operating only one powered cylinder apparatus of one pair of powered cylinder apparatuses during raising or lowering of the substructure; and/or wherein the mobile drilling rig has a center of gravity maintainable in a horizontal plane during drilling and during rig movement, the method including maintaining the center of gravity of the mobile drilling rig in a horizontal plane during drilling and during rig movement. 
         [0073]    In conclusion, therefore, it is seen that the present invention and the embodiments disclosed herein and those covered by the appended claims are well adapted to carry out the objectives and obtain the ends set forth. Certain changes can be made in the subject matter without departing from the spirit and the scope of this invention. It is realized that changes are possible within the scope of this invention and it is further intended that each element or step recited in any of the following claims is to be understood as referring to the step literally and/or to all equivalent elements or steps. The following claims are intended to cover the invention as broadly as legally possible in whatever form it may be utilized. The invention claimed herein is new and novel in accordance with 35 U.S.C. §102 and satisfies the conditions for patentability in §102. The invention claimed herein is not obvious in accordance with 35 U.S.C. §103 and satisfies the conditions for patentability in §103. This specification and the claims that follow are in accordance with all of the requirements of 35 U.S.C. §112. The inventor may rely on the Doctrine of Equivalents to determine and assess the scope of the invention and of the claims that follow as they may pertain to apparatus not materially departing from, but outside of, the literal scope of the invention as set forth in the following claims. All patents and applications identified herein are incorporated fully herein for all purposes. It is the express intention of the applicant not to invoke 35 U.S.C. §112, paragraph 6 for any limitations of any of the claims herein, except for those in which the claim expressly uses the words ‘means for’ together with an associated function. In this patent document, the word “comprising” is used in its non-limiting sense to mean that items following the word are included, but items not specifically mentioned are not excluded. A reference to an element by the indefinite article “a” does not exclude the possibility that more than one of the element is present, unless the context clearly requires that there be one and only one of the elements.