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CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefits under the Patent Laws of U.S. Application Ser. No. 61/189,146 filed Aug. 15, 2008 including claiming priority therefrom and said application is incorporated fully herein by reference for all purposes. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention is directed to drilling oil and gas wellbores in the earth; in certain particular aspects, to drilling and completing such multiple wellbores from a single drilling rig; and, in certain particular aspects, to drilling and completing such multiple wellbores so that they are relatively close to each other. 
     2. Description of Related Art 
     A wide variety of drilling rigs and methods are known for drilling oil and gas wellbores in the earth. In many known systems and methods, a single wellbore is drilled with a drilling rig and then, to drill another wellbore, the drilling rig is moved to a new location, often near the drilled wellbore. By way of example only (and not as a definitive or exhaustive disclosure) the following U.S. Patents and Application disclose drilling rigs and/or methods of the use of rigs (all incorporated fully herein for all purposes): U.S. Pat. Nos. 2,840,198; 4,108,255; 4,616,454; 6,068,069; 6,161,358; 6,443,240; 6,766,860 and Application No. 2007/0251725A1. 
     Many patents and publications illustrate and describe in detail known drilling rigs. By way of example only (and not as a definitive or exhaustive disclosure), U.S. Pat. No. 7,320,374 discloses systems and methods as shown in  FIGS. 1A and 1B  in which a known top drive system TDS 1  in a derrick  140  is suspended from a block becket  18  which is suspended from the derrick  140  in a typical manner. A standard block and hook for hooking a standard becket may be used. An elevator  74  supports a tubular stand  142  which includes two pieces (or three) of drill pipe  143 . The stand  142  has been moved from a monkey board  145  with multiple made-up stands  149  to a position axially aligned with a wellbore  147 . A mouse hole  144  may be used, e.g. to make stands. A driller controls drilling from a driller&#39;s panel  141 . The stands  149  are located at a setback position ST. Optionally, the system includes an emergency brake system and/or an emergency shut down device and, optionally, either or both are controllable from the panel  141 . 
     Also by way of example only, as shown in  FIG. 2  U.S. Pat. No. 5,107,940 discloses a known system TDS 2  which includes a power swivel  30  and guide mechanism  51  mounted on a mast  102  of a conventional portable rotary earth drilling rig generally designated by the numeral  100 . As will hereinafter be more fully explained, the power swivel  30  is pivotally secured through a floating torque arm assembly, called a carriage  70 , to a pair of dollies  75  movable longitudinally on a guide track  51  mounted on the mast  102 . The guide mechanism  51  illustrated in  FIGS. 7-9 , and the carriage  70 , illustrated in  FIGS. 10 and 11  of the drawings, form a torque restraint system. 
     The drilling rig  100  is a conventional 118 foot vehicle-mounted hydraulically telescoping derrick, having an inclined mast  102  with a hook load capacity of, for example 365,000 pounds. The mast  102  is typically inclined at a lean angle  119  of 3½ degrees relative to a vertical axis  125  centered over the well. 
     The mast  102  is pivotally mounted on a trailer  104  and is transported in a horizontal position with the upper mast section  115  telescoped into the lower mast section  110 . When the mast  102  is erected, the telescoped sections  110  and  115  are rotated approximately 90 degrees about a horizontal axis to a vertical position by hydraulically-actuated rams  106 . After legs on the lower mast section  110  engage the ground or other supporting surface, hydraulic fluid is delivered to hydraulically-actuated cylinders which raise the upper mast section  115  to the position illustrated in  FIG. 1 , wherein only the lower end of the upper section  115  extends downwardly into the upper end of the lower section  110 . 
     The trailer-mounted rig includes a single drum drawworks  105  powered by diesel engines  103  through conventional transmissions and a compound box. A fast line  107  extends from drawworks  105  upwardly over a crown block  108 , as illustrated in  FIG. 1 , to provide a number of lines  109  which carry a traveling block  112  connected to the power swivel  30  in the top drive system  20 . A conventional folding substructure  140 , equipped with a V-door  142 , a catwalk  145 , and two sets of pipe racks (not shown), parallel and juxtaposed to the catwalk, are mounted adjacent to the inclined telescoping mast  102 . 
     The stand assembly system consists of a crown cantilevered single joint elevator snatch block  21  mounted directly over the mouse hole, an auxiliary cable  22 , a live swivel assembly  23  and a single joint elevator  148 . The system is permanently installed in the rig for use at any time. 
     The auxiliary cable  22  is designed to quickly attach to existing hydraulic or pneumatically-powered auxiliary tugger lines and is used to hoist a single joint  24 ′ from the pipe ramp to the mouse hole, and to hoist a complete stand  25  from the mouse hole to the fingerboard  136  and set the stand  25  back on the setback SK. 
     The single joint elevator  148  is a specially-designed elevator with, for example, a 2,000 pound hoisting capacity for quick attachment to and release from the drill pipe. It is attached to the auxiliary cable  22  utilizing a live swivel assembly  23  to prevent upspiraling of the cable while shouldering up a stand  25  in the mouse hole. 
     During operation, a stand  25  is attached to or removed from the drill string  150 , utilizing elevator  48 . 
     The guide track  51  is rigid and continuous; it extends longitudinally along mast  102 . The guide track  51  is formed in at least two segments: a lower guide track segment  52 , and an upper guide track segment  54 , secured to the lower mast segment  110  and upper mast segment  120   115 , respectively (see  FIG. 1 ). The guide track  51  shown can be comprised of, for example 3½ inch standard pipe sections, each approximately 20 feet long (for easy handling). However, it should be appreciated that guide track  51  may be formed of members having non-circular cross-sections, such as H-beams, without departing from the basic concept of the torque restraint system. 
     FIGS. 13-15 of U.S. Pat. No. 5,107,940 describe the procedure for making up a stand 25. FIGS. 16-18 of U.S. Pat. No. 5,107,940 describe how a made-up stand is added to a drilling string. 
     U.S. Pat. No. 4,108,255 discloses an apparatus for drilling concurrently a plurality of wells within a laterally confined area. The confines of the drilling apparatus employ a structure having vertically extending walls rising from a drilling floor. A plurality of wells are drilled, each employing a separate rotary drilling table and a separate draw work assembly mounted in vertical displacement from the drilling table associated there with. Preferably, the individual draw work assemblies associated with separate rotary drilling tables are utilized only to feed drilling pipe assemblies into the well and to aid in the actual drilling operation. To withdraw drilling pipe assemblies, a master draw works is provided and is mounted vertically above the draw work assemblies associated with particular rotary drilling tables. In addition, the draw work assemblies are preferably located on bridges which are rotatably mounted with respect to an upright central support, so that the bridges are rotatable about the upright support and carriages forming part of the draw works are movable along the bridges so that the carriages may be moved both radially and rotationally relative to the upright support. The confining structure of the vertically extending walls renders the well drilling apparatus suitable for construction for use in drilling wells on the floor of a body of water and also for use in drilling a plurality of wells in a highly urbanized areas. This versatility is achieved by constructing the well drilling apparatus with exterior walls of the confining structure in the form of a facade, to resemble a commercial building or in the form of a water resistant cassion that may be lowered into a body of water to extend from the floor to the surface thereof. In one aspect this patent discloses a well drilling apparatus located within a confining structure having cylindrical annular vertically extending walls rising from a drilling floor and enclosing: a plurality of rotary drilling tables laterally displaced from each other proximate to said drilling floor and within the confines of said walls each arranged to accommodate separate drilling assemblies including drilling pipe for drilling separate wells at spatially separated locations at said drilling floor; an upright support extending upward relative to the drilling floor within said confining structure; and separate drilling draw work assemblies associated with and mounted in vertical displacement from each of said rotary drilling tables for manipulating the drilling pipe and other portions of the drilling assembly utilized with the associated rotary table, wherein each of said separate drilling draw work assemblies is mounted on a separate bridge that extends laterally from said upright support and is supported at said vertically extending walls at a distance above the rotary drilling table with which it is associated. 
     In several situations it is desirable to drill wellbores for oil and gas wells relatively near to each other, e.g. within 8 to 12 feet of each other (or more) (platforms are often within 16 to 32 feet of each other). A variety of problems and disadvantages are associated with certain typical ways for drilling wellbores that are close to each other. Often, using rigs designed for drilling one hole and then moving the rig to drill another hole, much of the total time expended to drill multiple holes is not time spent actually drilling. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention discloses, in certain aspects, systems and methods for drilling and completing multiple wellbores, e.g. multiple oil or gas wellbores from a single rig without moving the entire rig. In one particular aspect, such systems and methods include drilling a plurality of wellbores for oil and gas wells which are close to each other. 
     In certain aspects, such systems and methods include, on a single rig machines for drilling an oil or gas wellbore and for completing the wellbores. In certain aspects, machines for completing a wellbore include machines for: drilling a wellbore and/or tripping drill pipe and a drill bit in or out of a drilled wellbore and/or for casing the wellbore; heater installation machines; and/or machines for cementing a cased wellbore; and/or machines for producing an upper portion (sometimes called a “conductor hole”) of a wellbore, e.g., but not limited to, machines previously used to make conductor holes, ratholes and/or mouseholes, e.g., but not limited to, as disclosed in co-owned pending U.S. patent application Ser. No. 12/009,328 filed Jan. 17, 2008, fully incorporated herein for all purposes. 
     In one particular aspect, a drilling machine is moved to a new position on the rig to commence drilling a new hole (without moving the rig) while a tripping machine moves into place over a drilled wellbore and commences tripping out drill pipe and a drill bit used with the drilling machine to drill the drilled wellbore. In another aspect in which two wellbores have been thus drilled, a cementing machine moves over the first drilled wellbore and commences a cementing operation to cement in place casing installed by the tripping machine (or installed by a casing running machine separate from the tripping machine) while the tripping machine moves over a second-drilled wellbore to trip out drilling pipe and a drill bit from the second wellbore as the drilling machine is drilling a third wellbore. Disposable and/or abandonable bits may be used in systems and methods according to the present invention. Also, part of a wellbore can be drilled, e.g., with a drill bit on drill pipe and part using a casing drilling method. 
     In one particular aspect, the drilling machine is a casing drilling machine (with no need for a tripping machine). In certain systems and methods according to the present invention there are multiple (and at least two) casing drilling machines on one rig. 
     In certain aspects, drilling machines, tripping machines, and casing running machines according to the present invention have a pipe racking system, as is traditional, in front of the machine(s) (e.g. as in many known cases in which the hole to be drilled is between the drilling machine and the pipe racking system and setback area); but in other aspects according to the present invention, a pipe racking system is located behind the machine rather then in front of the machine. In certain aspects according to the present invention, a pipe racking system uses the string hoisting mechanism of the rig to operate the pipe racking mechanism. In other aspects, the drill pipe is supported, not by slips, but by two sides of the tool joint. The hoisting mechanism picks up on the other two sides of the tool joint in order to eliminate the need for slips. 
     In certain aspects, multiple machines and multiple wellbore locations are so located that from a single driller&#39;s cabin on the rig all machines and all wellbore locations can be viewed and monitored during stages of drilling, tripping, and cementing on multiple holes. In one particular aspect, a cabin system is provided in which the driller&#39;s cabin is movable to multiple positions on the rig either across the rig or on its periphery. In one particular aspect each of the multiple machines (or only one or two of them) are movable on the rig, either across the rig or on its periphery. In any system according to the present invention, the driller can also move or be moved in a chair around a driller&#39;s cabin, and, in one aspect, he is located in the center of the floor and the chair rotates to view each wellbore. 
     In one particular aspect a rig according to the present invention includes a heater installation machine for installing heating devices, apparatuses, tubulars, and/or structure for a wellbore. 
     In certain aspects, systems and methods according to the present invention employ drilling machines in which a drilling device is moved, forced, or pulled down to facilitate drilling of an oil or gas wellbore. In one particular aspect, a cylinder-powered drilling machine according to the present invention includes one, two, or more powered cylinder apparatuses that pull a drilling device down to force it into the earth. 
     In certain aspects, the present invention discloses a center-support drilling machine in which a drilling machine is rotatably mounted on a center support, e.g. a central pillar, so that it is rotatable on the center support for location over multiple wellbore locations. In other aspects, additional machines (tripping, casing running, heater installing, and/or cementing) are also rotatably mounted on the center support. One machine can be mounted above or below another and/or staggered at different levels on a center support. 
     In certain aspects of the present invention a movement apparatus moves individual machines (drilling, tripping, casing running, cementing, and/or heater installing) around a rig and in one aspect the movement apparatus picks up a machine to move it. In one particular aspect, this is a crane, cranes, or a hoisting device. 
     In certain aspects according to the present invention a road module is provided adjacent one multi-hole location or extending by multiple multi-hole locations. In one aspect a crane and/or driller&#39;s cabin is movably positioned on the road module and a multi-function multi-hole rig according to the present invention (or several of them) is located adjacent the road module and movable with respect to the road module from one multi-hole location to another. 
     In certain aspects, the present invention provides systems and methods in which a multi-function multi-hole rig for drilling and completing an oil or gas wellbore includes multiple machines movable on the rig itself to each of several hole locations (without moving the entire rig) by moving the machines around or on the rig&#39;s periphery. In certain particular aspects, such a rig has a rig periphery as viewed from above, which is non-rectangular, e.g., but not limited to, generally circular, elliptical, oval, octagonal, hexagonal, pentagonal, triangular, polygonal or with a curved configuration. Machines can be movable on a track or path around such a periphery or a separate movable support supporting the machines is movable to move the machines around the periphery from one hole location to the next. In one aspect, in such a rig, a driller&#39;s cabin is centrally located while, in another aspect, a driller&#39;s cabin is also movable on the rig&#39;s periphery; or is movable across a rig floor. In one aspect, a driller&#39;s cabin is on the rig&#39;s periphery, but stationary. 
     In one aspect in such rigs with one, two, three, or more machines movable on a rig&#39;s periphery, one, two, three or more machines and/or a driller&#39;s cabin are movable across a portion of a rig floor from one position to another. 
     In one aspect of the present invention, a rig is provided on which a machine or certain machines are movable around a rig&#39;s periphery and a machine or certain machines are movable across a portion of a rig; for example, in a rig according to the present invention a drilling machine and a cementing machine are movable around a rig&#39;s periphery and a tripping machine is movable across a rig from one hole location to another; and, in one aspect, machines other than a drilling machine are movable around a rig&#39;s periphery and a drilling machine is movable across the rig from one hole location to another. 
     Accordingly, the present invention includes features and advantages which are believed to enable it to advance oil and gas wellbore drilling and completion 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. 
     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. 
     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 new, useful, unique, efficient, nonobvious multi-function rigs for drilling and completing multiple adjacent spaced-apart wellbores. 
     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. 
     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 or of the claims in any way. 
     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. 
     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 
       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 legally equivalent embodiments. 
         FIG. 1A  is a side view of a prior art drilling rig. 
         FIG. 1B  is a top view of the rig of  FIG. 1A . 
         FIG. 2  is a side view of a prior art drilling rig. 
         FIG. 3  is a perspective view of a drilling rig for drilling oil and gas wells according to the present invention. 
         FIG. 4  is a perspective view of a drilling rig for drilling oil and gas wells according to the present invention. 
         FIG. 5A  is a perspective view of a drilling rig for drilling oil and gas wells according to the present invention. 
         FIG. 5B  is a side view of the rig of  FIG. 5A . 
         FIG. 5C  is an end view of the rig of  FIG. 5A . 
         FIG. 5D  is a top view of the rig of  FIG. 5A . 
         FIG. 6A  is a perspective view of a drilling system for drilling oil and gas wells according to the present invention. 
         FIG. 6B  is a top view of the system of  FIG. 6A . 
         FIG. 7A  is a top schematic view showing steps in a method according to the present invention using a rig according to the present invention. 
         FIG. 7B  is a top schematic view showing a step in the method of  FIG. 7A . 
         FIG. 8  is a perspective view of a system according to the present invention. 
         FIG. 8A  is a cross-section view of the top of a road module according to the present invention. 
         FIG. 9A  is a top schematic view showing locations for multiple wellbores to be drilled and completed. 
         FIG. 9B  is a top schematic view of a drilling system according to the present invention for drilling at the locations shown in  FIG. 9A . 
         FIG. 9C  is a top schematic view showing steps in drilling and completing wells at the locations of  FIG. 9A . 
         FIG. 10  is a top schematic view of a drilling system according to the present invention. 
         FIG. 11  is a top schematic view of a drilling system according to the present invention. 
         FIG. 12  is a top schematic view of a drilling system according to the present invention. 
         FIG. 13  is a top schematic view of a drilling system according to the present invention. 
         FIG. 14  is a top schematic view of a drilling system according to the present invention. 
         FIG. 15  is a perspective view of a system according to the present invention. 
         FIG. 15A  is a perspective view of a rig floor and shaker pit of the system of  FIG. 15 . 
         FIG. 15B  is a perspective view of a driller&#39;s cabin on the floor of  FIG. 15A . 
         FIG. 15C  is a perspective view of a crane on the floor of  FIG. 15A . 
         FIG. 15D  is a perspective view of the system parts of  FIG. 15B  with an active mud system. 
         FIG. 16A  is a perspective view showing a step in the erection of the rig floor of  FIG. 15A . 
         FIG. 16B  is a perspective view showing a step in the erection of the rig floor of  FIG. 15A . 
         FIG. 16C  is a perspective view showing a step in the erection of the rig floor of  FIG. 15A . 
         FIG. 17A  is a perspective view showing a step in the method according to the present invention using the system of  FIG. 15 . 
         FIG. 17B  is a perspective view showing a step in the method according to the present invention using the system of  FIG. 15 . 
         FIG. 17C  is a perspective view showing a step in the method according to the present invention using the system of  FIG. 15 . 
         FIG. 17D  is a perspective view showing a step in the method according to the present invention using the system of  FIG. 15 . 
         FIG. 17E  is a perspective view showing a step in the method according to the present invention using the system of  FIG. 15 . 
         FIG. 17F  is a perspective view showing a step in the method according to the present invention using the system of  FIG. 15 . 
         FIG. 17G  is a perspective view showing a step in the method according to the present invention using the system of  FIG. 15 . 
         FIG. 17H  is a perspective view showing a step in the method according to the present invention using the system of  FIG. 15 . 
         FIG. 17I  is a perspective view showing a step in the method according to the present invention using the system of  FIG. 15 . 
         FIG. 17J  is a perspective view showing a step in the method according to the present invention using the system of  FIG. 15 . 
         FIG. 17K  is a perspective view showing a step in the method according to the present invention using the system of  FIG. 15 . 
         FIG. 17L  is a perspective view showing a step in the method according to the present invention using the system of  FIG. 15 . 
         FIG. 17M  is a perspective view showing a step in the method according to the present invention using the system of  FIG. 15 . 
         FIG. 17N  is a perspective view showing a step in the method according to the present invention using the system of  FIG. 15 . 
         FIG. 17O  is a perspective view showing a step in the method according to the present invention using the system of  FIG. 15 . 
         FIG. 17P  is a perspective view showing a step in the method according to the present invention using the system of  FIG. 15 . 
         FIG. 17Q  is a perspective view showing a step in the method according to the present invention using the system of  FIG. 15 . 
         FIG. 17R  is a perspective view showing a step in the method according to the present invention using the system of  FIG. 15 . 
         FIG. 17S  is a perspective view showing a step in the method according to the present invention using the system of  FIG. 15 . 
         FIG. 18  is a perspective view of a system according to the present invention. 
         FIG. 19  is a perspective view of a system according to the present invention. 
         FIG. 20A  is a perspective view of a system according to the present invention. 
         FIG. 20B  is a perspective view of the system of  FIG. 20A . 
         FIG. 20C  is a top view of the system of  FIG. 20A . 
     
    
    
     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. 
     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 
       FIG. 3  shows a system  10  according to the present invention which has a base or rig floor  12  with supports  14  to which is secured an upright pillar  20 . An optional shroud  16  (sides shown in dotted lines), e.g. for use in harsh weather environments, encompasses the majority of the rig floor  12  and has a top  17  A crane  18  is rotatably mounted on a top  21  of the pillar  20 . A platform  13  projects from the rig floor  12 . 
     Six holes  15  extend through rig floor  12 , each hole corresponding to and above a location on the ground below the rig floor  12  where a wellbore is to be drilled and completed. Any desired number of such holes can be provided (for any desired number of wellbores). 
     A drilling machine  30  is movably mounted for up and down movement on a beam  31  which is part of a support  32  which is rotatably mounted on the pillar  20 . Crossbeams  33  are connected to rings  34  which encompass and rotate on the pillar  20 . A drawworks  40  is mounted on the lower crossbeam  33 . A beam  35  connected to the lower crossbeam  33  extends down to the top of the rig floor  12 . 
     A cartridge  50  with tubulars  52  therein (e.g. drill pipe) is supported on the rig floor  12 . The cartridge  50 , in one aspect, is movable around the rig floor  12  so it is adjacent a desired machine. As shown in  FIG. 3 , the cartridge  50  is adjacent the drilling machine  30 . Any suitable and desirable rig equipment and apparatuses may be located on the rig floor  12 ; e.g., but not limited to, an iron roughneck  58 . 
     Optional air treatment equipment  56  on the rig floor  12  provides heated or cooled air to the system  10 . Optionally, the equipment  56  is located near the system  10 , but not on the rig floor  12 . Any system according to the present invention disclosed herein may have equipment like the equipment  56 . A bucket B collects mud circulated from the wellbore. 
       FIG. 4  illustrates a system  10   a , like the system  10 ,  FIG. 3 , and like numerals indicate like parts. An additional support  32   a  supports an additional machine  30   a  (shown schematically). The machine  30   a  may be a drilling machine, tripping machine, a cementing machine, a casing machine, a heater installation machine or any other machine used or useful on a drilling rig. 
     A machine  30   a  may be on the same ring  34  as a machine  30  or there may be separate rings for the support  32   a  for the machine  30   a  and its drawworks. 
     Optionally, an additional machine (not shown) on an additional support (not shown) is rotatably mounted on the pillar  20 . 
       FIGS. 5A-5D  show a system  100  according to the present invention which has a rig floor  102  on four supports  104  (three shown). Optionally, the system  100  is mobile (as may be the system  10 ) and is mounted on wheels  106  (shown schematically in dotted line; tracks may be used instead of wheels). The rig floor  102  has six holes  108  therethrough. Each of the six holes  108  is located above a location on the ground G at which it is desired to drill and complete an oil and gas wellbore A drilling machine  120  is located adjacent one of the holes  108  and is drilling a wellbore  110  with a bit  114  on a drill string  112 . 
     The drilling machine  120  is movable up and down on a track  122 . A pipe rack  130  behind the drilling machine  120  holds drill pipe  132  (or, if desired, tubing or casing) for use in the drill string  112 . Optionally, as shown in dotted line in  FIG. 5C , the system  100  has a harsh weather shroud  136  and an optional air treatment system  138  (shown schematically) to heat or cool air. 
     The drill machine  120  may be a pull-down drilling machine, a cylinder rig, or a drawworks-driven machine. 
     A tripping machine  140  ( FIG. 5B ) on the rig floor  102  is adjacent a hole  108  through which a wellbore  109  has already been drilled with the drilling machine  120 . The tripping machine  140  is removing the drill pipe  132  used by the drilling machine  120  from the wellbore  109 . In certain aspects, this tripping machine can hang off the drill pipe on the tool joint upset at the rig floor instead of using slips. The hoisting mechanism is on either side of the hang off point. 
     A cementing machine  150  (shown schematically in  FIG. 5A ) is positioned for cementing a wellbore  111  which was previously drilled by the drilling machine  120  and from which, previously, the drill pipe was removed from the wellbore  111  by the tripping machine  140  (or for cementing when casing drilling was used, casing having been run by a tripping machine or by a casing running machine). 
     A driller&#39;s cabin  160  is located on the rig floor  102 . Personnel in the driller&#39;s cabin, e.g. a driller, can see each hole  108  and each machine located adjacent a hole. 
     A pathway  128  indicates movement options for each of the machines  120 ,  140 ,  150 . Any suitable movement paths may be used and any suitable movement apparatus for moving the machines may be used. 
     The machine  140  has a pipe rack system  142  adjacent thereto and the machine  150  has a pipe rack system  152  adjacent thereto. As viewed in  FIG. 5B , e.g., the pipe rack  130  is behind the drilling machine  120 . This is the opposite of known pipe rack systems which are in front of a drilling system and in which the hole through which a well is drilled is between a drilling system and a pipe rack system. Locating the pipe rack system behind the drilling machine (or behind another machine) has several advantages, e.g., saving space and allowing an unobstructed view of multiple operations and/or multiple wells. Also, in certain aspects of the present invention, a hoisting system is part of a pipe rack system. 
     In one particular aspect the drilling machine  120  is a pull-down cylinder-powered rig as shown, e.g., in  FIG. 5B . Power cylinders  127  have rods  129  connected to a plate  133  that moves on tracks  137 . The power cylinders  127  are connected to a drilling apparatus  120   a . Extension of the rods  129  upwardly results in pushing up of the sheaves that then pull up a top drive or tripping machine. Retracting of the rods  129  results in pulling down on other sheaves that then pull down on the top drive or on the tripping machine. Power cylinders can be advantageous, e.g., as compared to a typical top drive rig, in saving space in ease of control, and in the ability to keep a top drive from colliding with the rig floor or into the crown. In one particular aspect, the drilling machine  120  has a 50-to-75 ton top drive or power swivel. In other aspects, for any system according to the present invention, the drilling machine is a 50-to-1250 ton top drive system. 
       FIG. 6A  shows a system  200  according to the present invention which includes multiple systems  100  (any desired number; two shown at a location  201 ) adjacent a road module  300  according to the present invention. Multiple wellbores  210  are being drilled and completed by the systems  100 . 
     The road module  300  includes connected road sections  302  supported by supports  304 . In one aspect, the supports  304  extend down to bedrock at the location  201  (e.g., but not limited to, through top soil, tundra, muskeg, peat, sand, unstable soil or material and/or ice). Optionally, a crane  310  is semi-permanently or movably mounted on the road sections  302  for use in operations of any of the systems  100 . 
     Each system  100  can have all the machines needed to drill and complete multiple wellbores or, optionally, each system  100  can have only machines with certain functions. For example, and not by way of limitation, the machine  100  to the right in  FIG. 6A  can have a drilling machine  120   b  and its associated pipe racking system  120   c  and a tripping machine  140   b  with its associated pipe racking system  140   c  while the drilling machine to the left in  FIG. 6A  (to be moved from left-to-right following the drilling machine  100  to the right in  FIG. 6A ) has a casing machine  150   c  (with its rack system  150   e ) and a cementing machine  150   d  (with its rack system  150   f ). The first drilling system  100  (the one to the right in  FIG. 6A ) drills the wellbores and trips out the drill pipe while a second machine cases the wellbores and/or cements the casing in place. In one aspect, each rig is capable of performing all the operations to produce an entire well. Once the well is drilled, casing is run immediately. According to the present invention, a single rig can drill, etc. an entire well or one rig can drill one section of a hole case and cement it, then another (the next) rig comes in and drills the next section of that hole, etc. Each system  100  can have all the necessary machines to drill and complete a well and, optionally, a heater installation machine to install heaters in a wellbore. 
       FIGS. 7A and 7B  illustrate one option for a drilling machine  100  in a system for progressive work on multiple wells. As shown in  FIG. 7A , there are sixteen wells to be drilled ( 1 - 8  in line A and  1 - 8  in line B). As illustrated in  FIG. 7A , a system  100  drills all the wells below holes  1 - 4 , line A and  1 - 4 , line B, and completes (or trips pipe out of) hole  1 A and  1 B (or only some of them). In one aspect the system  100  completes wells on lines  1 - 3  and partially completes wells on line  4 . Then the system  100  is moved so that it is above wellbore locations  4 - 7 , line A and  4 - 7 , line B. Thus while various machines are working on the already-drilled holes, the drilling machine can drill the wellbores at locations  5 A and  5 B; and so on for all sixteen wellbores. 
       FIG. 8  shows a system  260  with systems  10   a  according to the present invention and a road module system  300 . The systems  10   a  move down a location  301  (left-to-right in  FIG. 8 ) drilling and completing multiple wellbores corresponding to multiple holes  261 ,  262 ,  263 , etc. (six holes for each set of multiple holes, six shown for hole location  263 , five shown for hole location  261 ; but it is within the scope of the present invention to have as many holes as desired, including, but not limited to, two holes, three holes, four holes, five holes, seven holes or eight holes). As illustrated, a system  10   a  can be any desired height sufficient to achieve wellbores of desired depth.  FIG. 8A  shows in cross-section one embodiment of a road module according to the present invention supported by pillars P. A lite duty road top LD, supported directly by the pillars P, supports a heavy duty road top HD. The heavy duty road top HD is optional, or, if present, is selectively removable. Alternatively, the lite duty road top LD is, selectively, removed or eliminated. 
       FIG. 9A  shows a site  401  with multiple wellbore sites W 1 , W 2 , W 3 , and W 4 . It is within the scope of the present invention for there to be any desired number of wellbore sites at a location (e.g. two, fifty, two hundred, etc.). In many instances they will be 10 feet apart; but smaller (and larger) spacings are within the scope of the present invention. 
       FIG. 9B  shows a system  400  according to the present invention which includes a driller&#39;s cabin  402  on a base  404  from which personnel, e.g. a driller, can view at all times multiple machines located at the system&#39;s periphery. A drilling machine  410 , a tripping machine  420 , and a cementing machine  430  (which may also perform casing functions; or a separate casing machine may be used). Each machine may be mounted for movement in a pathway  406  (e.g. a track, groove, or a rail system); or the base  404  can have the pathway  406  rotatably mounted therearound and the entire pathway  406 , supporting the machines, can rotate with respect to the base  404 . Optionally, the base  404  rotates. Also, as described above, a driller chair can rotate. 
     Optionally, and this is true for any system disclosed herein according to the present invention, including but not limited to the systems of  FIGS. 3-8 , the system  400  can include a heater running machine  440  for installing a heater function in or near any wellbore drilled with the system  400  (or with any system according to the present invention). The machine  440  can install heaters in an already-drilled wellbore. 
       FIG. 9C  illustrates the system  400  in use with the drilling machine  410  drilling the wellbore W 1 , the tripping machine  420  tripping drill pipe from the already-drilled wellbore W 4 , and the cementing machine  430  cementing in place casing (installed previously either by the cementing machine which includes casing installation apparatus, etc. or by a separate casing apparatus  450  (optional for the system  400 , shown in  FIG. 9C ). The next wellbore to be drilled will be the wellbore W 2 . 
     In another embodiment, in a system  500  according to the present invention as shown in  FIG. 10 , a drilling machine  510  is on a pathway  506  (like the pathway  406 ); and both a tripping machine  520  and a cementing machine  530  (and a heater installer if present) move on a base  504  (like the base  404 ). Optionally the heater installer is also on the pathway  506 . A pipe racking system  508  is behind the drilling machine  510  (either connected to the pathway  506  or to another adjacent structure). Alternatively, a crane or hoist is used. 
     As shown in  FIG. 11 , optionally, in a system  560  according to the present invention, a drilling machine  562  is movable across a base  564 ; and a tripping machine  566  and a cementing machine  568  have a pathway  569 . Optionally (as is true for any system according to the present invention) a casing machine may be used with any of the systems of  FIGS. 9A-13 ). 
     As shown in  FIG. 12 , a driller&#39;s cabin can be in a fixed position connected to a base of a system or to some other structure adjacent thereto. In one aspect, the driller&#39;s cabin is located so personnel therein can view all operating machines and/or all well locations simultaneously. In one aspect viewing is possible via direct line of sight, camera(s), and/or rotating a drill chair to a desired position for viewing. 
       FIG. 13  shows an optional disposition of a driller&#39;s cabin  403 . The driller&#39;s cabin  403  is on the pathway  406  (and may be located anywhere on the pathway  406 ) and is movable with respect to the base  404  as are any of the machines. A crane or other apparatus can move the driller&#39;s cabin  403  to any desired location on the pathway  406 . Optionally, as shown in  FIG. 14 , a driller&#39;s cabin  403   a  has its own dedicated pathway  406   a  which, in one aspect, moves around both a pathway  406  and a base  404 . 
       FIG. 15  shows a system  600  according to the present invention which includes an erectable rig structure  602  with a floor  604  under which are a plurality of shale shakers  606  with a mud pit  606   p  (see, e.g.,  FIG. 15A ), optionally as shown in  FIG. 15A  with an auger apparatus  606   a  for moving material in and from the mud pit  606   p . The shakers and the mud pit are located between the wellbore locations  611 - 614  and are movable thereinto and therefrom as desired. For each well location, there may be pressure control equipment (e.g., a flowline; a blowout preventer apparatus; and/or diverter apparatus—indicated by the numeral  608 ). As shown, multiple blowout preventer stacks  608  are each located over a wellbore location  611 - 614 . In certain particular aspects wells to be drilled at locations  611 - 614  are at least eight feet apart and at most twenty five feet apart, but any desired spacing is within the scope of the present invention. In one particular aspect, the wells are about fifteen feet apart. The shaker apparatuses  606  are supported by the structure  602 . 
     A variety of machines can be used with the system  600  including, but not limited to, any machine in any system of  FIGS. 3-20A . In one aspect two drilling machines DM 1  and DM 2  are connected to or are adjacent the rig structure  602 , and a tripping machine TM 1  is connected to or adjacent the rig structure  602 . Any machine is movable to a position above any well location. Optionally, and selectively, the machines may be supported by the pressure control equipment and/or by a frame around any such equipment (e.g., a frame  608   f  as shown in  FIG. 15 , part of which encompasses a wellhead  608   w ). In such cases, drilling loads (the loads of a drilling machine and/or a tubular string connected to the drilling machine and/or equipment connected to the tubular string) are supported by the pressure control equipment (e.g., but not limited to, by a blowout preventer stack and/or by a frame therearound). Optionally, e.g. as shown in  FIG. 17N , machines are supported by the equipment  608  and are out of the way of a driller&#39;s cabin  616  if it moves on the structure  602 . 
     A driller&#39;s cabin  616  is connected to the rig structure  602  and another cabin  618  (or an extension of the cabin  616 ) is connected to erection structure  622  above an active rig mud system  620  (which may include mud pit structure). The erection structure  622  includes position locking apparatuses  621  and powered erection apparatuses  623 ,  624  (e.g., but not limited to, power cylinder apparatuses, lead screw apparatuses, and/or motorized apparatuses). Optionally, the cabin  616  is movable from one end of the structure to the other. 
     As shown in  FIG. 15B , the driller&#39;s cabin  616  has been placed on and connected to the floor  604  of the rig structure  602 . As shown in  FIG. 15C  a crane  630  has been placed on and connected to rails  604   r  of the floor  604 . The crane  630  on a base  630   b  has roller apparatuses  632  which move on the rails  604   r .  FIG. 15D  illustrates the position of the active rig mud system  620  and its connection to the rig structure  602  (with the rig structure  602  fully erected). 
       FIGS. 16A-16C  illustrate steps in the erection of the rig structure  602 . Powered cylinder apparatuses  624  connected between a top  602   a  and a bottom  602   b  of the rig structure  602 . As shown in  FIG. 16A , the apparatuses  624  are energized and the rig structure  602  begins to rise. As shown in  FIG. 16B , the rig structure  602  continues to rise. As shown in  FIG. 16C  the rig structure  602  has reached its full height and is locked in place with locking apparatuses  625   
     The rig structure  602  has four multi-part lets  605  each with a base  605   a , a pivotably connected mid-section  605   b , and an upper part  605   c.    
       FIGS. 17A-17S  illustrate steps in a method according to the present invention using the system  600 . 
     As shown in  FIG. 17A  a blowout preventer stack  608  is lifted by lifting apparatus, e.g., by the crane  630 , and placed in position over the well location  613 . 
     A drilling machine DM 1  is moved adjacent an end of the rig structure  602  and the crane  630  proceeds to begin lifting of the drilling machine DM 1  ( FIG. 17B ).  FIG. 17C  shows the crane  630  lifting the drilling machine DM 1  and  FIG. 17D  illustrates the crane  630  holding the drilling machine DM 1  upright at the end of the rig structure  602 . 
       FIG. 17E  shows the crane  620  moving in the rails  604   r  of the floor  604  while supporting the drilling machine DM 1 .  FIG. 17F  shows the drilling machine DM 1  in position above the stack  608  while the drilling machine DM 1  is still connected to the crane  630 . 
       FIG. 17G  illustrates a pipe erector apparatus  640  with tubulars for tripping operations which has been moved adjacent the well location  613 , e.g., to supply pipe for drilling by the drilling machine DM 1  or tubulars, e.g., casing, for tripping operations. 
     As shown in  FIG. 17H , the crane  630  has placed another blowout preventer stack in position over the well location  614 . The crane  630  connects to and raises a second drilling machine DM 2  ( FIG. 17I ) and moves it into place above the well location  614  ( FIG. 17J ). Meanwhile, the drilling machine DM 1  is drilling a wellbore at the well location  613  ( FIGS. 17I-17K ). 
     As shown in  FIG. 17K , a pipe erector apparatus  640  has been placed adjacent the well location  614  to supply drill pipe for drilling by the drilling machine DM 2  and the crane  630  has moved to the end of the rig floor  604  opposite the end with the driller&#39;s cabin  616 . 
     While drilling commences with the drilling machines DM 1  and DM 2 , the crane  630  has positioned another blowout preventer stack  608  above the well location  611  ( FIG. 17L ) and another pipe erector apparatus  640  has been positioned adjacent the well location  611 . 
     After the wellbore has been drilled at the well location  613 , the drilling machine DM 1  is moved by the crane  630  above the stack  608  at the well location  611  ( FIG. 17M ) while drilling with the drilling machine DM 2  proceeds. 
     As shown in  FIG. 17N , the crane  630  has moved a tripping machine TM 1  into place at the well location  613  and the tripping machine has commenced a tripping operation, e.g. to trip out drill pipe and or to trip in casing to case a wellbore at the well location  613 ; and drilling proceeds with the drilling machine DM 1  (well location  611 ) and with the drilling machine DM 2  (well location)  614 . 
     The crane  630  moves a blowout preventer stack  608  (or other pressure control equipment if it is used) into position at the well location  612  and a pipe erector apparatus  640  is positioned at this well location ( FIG. 17O ). Meanwhile, the machines DM 1 , DM 2  and TM 1  continue their operations. 
       FIG. 17P  illustrates movement of the drilling machine DM 2  by the crane  630  toward the well location  612  after the crane  630  has moved the tripping machine to the well location  614 . Meanwhile, the machine DM 1  continues operation as does the tripping machine TM 1  and a cementing machine CM 1  (previously moved into place by the crane) is cementing casing in place in the wellbore  613 . 
     As shown in  FIG. 17Q  the drilling machine DM 2  has commenced drilling a wellbore at the well location  612  while the machines DM 1 , CM 1 , and TM 1  continue operations. 
       FIG. 17R  shows the tripping machine TM 1  (after movement by the crane  630 ) proceeding with a tripping operation at the well location  611  while the drilling machine DM 2  continues drilling a wellbore at the well location  612 . Meanwhile the crane  630  is moving the drilling machine DM 1  to a new well location  615  (after moving a stack  608  there and after a pipe erector apparatus  640  has been installed there). The cementing machine CM 1 , after being moved to the well location  614 , is cementing casing in the wellbore  614 . 
     As shown in  FIG. 17S , the drilling machine DM 1  has commenced drilling a wellbore at the well location  615 ; the drilling machine DM 2  is finishing a drilling operation at the well location  612 ; and the cementing machine CM 1  is finishing the cementing job for the wellbore  614 . 
     Optionally, at any well location in  FIGS. 17A-17S , a cementing machine is used as desired. At this time wellbores at the well locations  611  and  613  are drilled and cased with casing. 
       FIG. 18  shows a system  700  according to the present invention with a rig structure  702  (like the rig structure  602 ) and a driller&#39;s cabin  716  (like the driller&#39;s cabin  616 ). The driller&#39;s cabin  716  is mounted on a base  720  which is movable on a floor  704  of the structure  702 . The base  720  has a plurality of roller apparatuses  722  (four present, two on each side; two shown) to facilitate movement of the base  720  on the floor  704 . 
     Any system disclosed herein according to the present invention may have a movable driller&#39;s cabin (e.g. like that of the system  700 ). 
       FIG. 19  illustrates a system  730  according to the present invention which has a rig structure  732  (like the rig structures  602  or  702 ) with a floor  734  under which, optionally, is a series of shale shakers  736 . Two cranes  731 ,  733  are movably mounted on the floor  734 . Each crane has a base  735  and roller apparatuses  738 . 
     The system  730  may have a driller&#39;s cabin as in any system disclosed herein (e.g., but not limited to, the systems of  FIGS. 15A and 18 ) or it may have a driller&#39;s cabin  739  spaced-apart from the rig structure  732 , but positioned for viewing of the entire rig structure  732  and operations conducted therewith (as may any system according to the present invention have a driller&#39;s cabin  739  instead of the cabin disclosed above for any such system). 
     Any system disclosed herein according to the present invention may have multiple movable cranes (e.g. like the system  730 ). 
       FIGS. 20A-20C  disclose a system  750  according to the present invention which has a rig structure  752  with a floor  754  and an optional roof  756 . The system  750  may be completely enclosed as described for systems herein above. Multiple well operations machines are movably mounted on the structure  752 , including any machine or machines described for any system according to the present invention described above. As shown in  FIG. 20C , the system  750  has drilling machines  760 , a tripping machine  762 , and cementing machines  764 . A superstructure  758  supports a movable crane  770  which is movable to move any of the machines to a desired location. The system  750  is located over multiple well locations, one well location corresponding to each of the six machines as shown in  FIG. 20C . A driller&#39;s cabin  772  is like any driller&#39;s cabin described above; and, in one aspect, with the machines moved out of the way, is movable down the floor  754 . 
     The present invention, therefore, provides multi-function rigs for producing multiple spaced-apart wellbores from the multi-function rig, the multi-function rig in certain aspects including: a base, the base overlying multiple wellbore locations; multiple machines on the base; each machine of the multiple machines for accomplishing a task related to producing a wellbore; each machine movable on and with respect to the base to positions adjacent a plurality of the wellbore locations for operation thereat so that multiple wellbores are producible without moving the rig from wellbore location to wellbore location; and movement apparatus movably mounted on the base for moving the machines with respect to the base. Such a rig may have one or some, in any possible combination, of the following: the multiple machines including multiple drilling machines and at least one tripping machine and/or at least one cementing machine and/or at least one auxiliary drilling machine for drilling a conductor portion of the wellbores; the multiple machines including at least one heater installation machine; the multiple machines including at least one casing drilling machine; the multiple machines including at least one casing machine; the multiple machines including at least one cementing machine; the multiple machines including at least one pipe racker apparatus, the at least one pipe racker apparatus located behind (not between a machine and a well location) a machine of the multiple machines; a driller&#39;s cabin from which a person can view all machines of the multiple machines in operation; wherein the driller&#39;s cabin is movable on the base to view the rig and/or multiple machines in operation; wherein the base is generally rectangular or not; wherein each of the wellbores as produced is a cased cemented wellbore; pressure control equipment operatively positioned at each wellbore location; wherein the pressure control equipment is one of flowline apparatus, blowout preventer apparatus, and diverter; wherein the pressure control equipment supports drilling loads (e.g., the loads are supported by a blowout preventer apparatus, a frame therearound, and/or a wellhead); wherein the multiple machines are capable of conducting multiple operations simultaneously at least two well locations; pipe racker apparatus which is a pipe racker with generally vertically oriented tubulars or a pipe racker with generally non-vertically oriented tubulars; auxiliary drilling apparatus for drilling an upper portion of the wellbores; control system apparatus for selectively controlling the multiple machines; and/or wherein the control system apparatus controls the multiple machines to automatically operate to perform their functions; and/or shaker apparatuses and a mud pit or pits within the rig structure and selectively movable out therefrom, and, in one aspect, the shaker apparatuses and the mud pit(s) movable away from the base independently of any pressure control apparatuses and/or BOP&#39;s at each well location. 
     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. The inventors may rely on the Doctrine of Equivalents to determine and assess the scope of their 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.

Summary:
A multi-function multi-hole rig is disclosed which, in certain aspects, includes multiple machines for accomplishing rig functions, e.g. drilling machine(s), tripping machine(s), casing machine(s), and/or cementing machine(s), for producing multiple usable wellbores one after the other. 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).