WO2017138945A1

WO2017138945A1 - Land-based mobile rig and batch drilling activity process

Info

Publication number: WO2017138945A1
Application number: PCT/US2016/017526
Authority: WO
Inventors: Henry Anthony BERGERON; Anthony TAGLIERI
Original assignee: Chevron U.S.A. Inc.
Priority date: 2016-02-11
Filing date: 2016-02-11
Publication date: 2017-08-17

Abstract

The present disclosure relates generally to land-based mobile rigs and methods of their use, and more specifically to a land-based mobile rig system that is configured to enable batch drilling. Embodiments of the mobile rig of this disclosure comprise a rig where opposing sides of the rig between the legs (508) and the center under the deck are substantially free of structural components, such as bracing, poles, or the like. An embodiment of the method uses wells on multi-well pads, multiple blowout prevention systems and a rig that can skid from one well to the next in a short time period over attached blowout preventers.

Description

LAND-BASED MOBILE RIG AND BATCH DRILLING ACTIVITY PROCESS

TECHNICAL FIELD

[0001] The present disclosure relates generally to land-based mobile rigs and methods of their use, and more specifically to a land-based mobile rig system that is configured to enable batch drilling.

BACKGROUND

[0002] Multi-well pad drilling is where a number of directionally and/or horizontally drilled wells are drilled from a single general area. That is, multiple wells are drilled close to each other, reducing the surface area which contains wellheads. Prior to multi-well pad drilling, an operator would assemble a rig at one drill site, fully drill and cement the well, disassemble the rig, and move it to another well site and reassemble it.

With multi-well pad drilling, multiple wells are drilled close together at one site, thus, reducing the time spent fully disassembling and reassembling the rigs and allowing more wells to be drilled in a given time period. Mobile drilling rigs, also known as walking rigs, further increase the efficiency of multi-well pad drilling, as the rigs slowly "walk" from one well location to the next negating the need to assemble and reassemble the rig at each new drilling location. Multi-well pad well locations are spaced close together, for example from 5-100 feet apart. Most mobile walking drilling rigs move at about 0.5-8 feet per minute making further spacing of wells less efficient, but feasible.

[0003] Using current mobile rigs and processes, the mobile drilling rig is assembled or located at a first well location. Current mobile drilling rigs include a blowout preventer (BOP) below the deck that moves with the rig. Once the rig is assembled, the initial hole is drilled and the BOP is attached to the wellhead and tested.

The well is then fully drilled and cemented with the mobile rig in place. The well can also undergo other actions, such as logging, while the mobile rig is in place. Once the well has been drilled and cemented to total depth, the well is plugged, the BOP is removed, and the rig moves to the next location. At the next location an initial hole is drilled and cemented, the BOP is attached to the new wellhead, the well is fully drilled and cemented, the BOP removed and the rig then moves onto the next location. In some instances this process is repeated until all wells in the multi-well pad have been fully drilled.

[0004] While mobile rigs have increased the productivity and efficiency of drilling multi-well pad wells, time spent by the rig at a specific location not drilling, such as logging or cementing the well, is time not used efficiently drilling by the rig. Thus, a mobile drilling rig and method of using the rig which allows batch processing of multiple types of well drilling activities would allow for increased efficiency in drilling and more wells could be drilled in a specific period of time.

SUMMARY

[0005] Embodiments of the disclosure include methods for batch processing land- based multi-well pads using multiple BOP systems and a mobile drilling rig apparatus that is able to move over well sites with attached BOPs.

[0006] A general embodiment of the disclosure is a method for batch process land- based drilling using a mobile rig, comprising: (a) drilling a first section of a first well with the mobile rig at a first well location; (b) moving the mobile rig to a second well location, wherein when the mobile rig is located at the second well location the first well location is clear of the mobile rig; (c) drilling a first section of a second well with the mobile rig at the second well location; (d) performing offline activities at the first well location while the mobile rig is drilling at the second well; (e) moving the mobile rig back to the first location while a BOP is attached to a wellhead at the first location, and (f) drilling a second section of the first well with the mobile rig at the first well location. The offline activities may be one or more of logging, circulating, cementing, waiting on cement to harden, setting packers, setting plugs, installing a wellhead, testing the wellhead, installing a wellhead wear bushing, attaching a BOP, testing a BOP, attaching a choke manifold, testing a choke manifold and setting a whipstock, for example. In some embodiments, step (d) includes cementing the first section of the first well and attaching a BOP to the first well. In additional embodiments the deck of the mobile drilling rig apparatus does not cover any off-set wells when drilling at the second well location. Additionally, one or more of steps (a), (b), (c), (d), and (f) may be performed while a BOP is attached or being attached to a wellhead on the first well and/or on the second well. A BOP may also be attached or in the process of being attached to a wellhead at the first or second well location offline. In embodiments, two opposing sides of the mobile rig under the deck and the center of the rig under the deck are sufficiently free of permanent structural components such that a BOP can pass fully through the opposing sides of the structure without touching the rig while the rig is moving over the BOP. The sections drilled in steps (a) and (c) may be initial sections, production section, or intermediate sections. Embodiments additionally include (g) performing offline activities at the second well location while the mobile rig is drilling at the first well location. In embodiments, the batch process comprises drilling three or more well sections in series at three well locations. In some embodiments, the offline activities are performed using a crane or a cementing truck.

[0007] Another general embodiment of the disclosure is a batch method of land- based drilling with a mobile drilling rig comprising: (a) locating a set of two or more well locations; (b) drilling a well section with the mobile drilling rig at each of the well locations in the set, wherein while the mobile drilling rig is drilling, no off-set well is covered by the mobile drilling rig; (c) performing offline activities at one or more of the well sections drilled in step (b) while the mobile drilling rig is drilling at a different well location in the set; (d) after the well sections have been drilled at each of the well locations of the set, returning the mobile drilling rig to a first well location in the set and drilling a succedent well section, wherein a BOP is attached at the first well location when the mobile drilling rig returns. The method can further comprise repeating steps (b) through (d) until all well sections at each well location in the set are drilled to total depth. The drilled sections can comprise initial, intermediate or production well sections. The method may also further comprise locating a second set of two or more well locations and repeating steps (b)-(d) on the second set of well locations until all well sections at each well location in the second set of well locations are drilled to a total depth. In embodiments the offline activities are logging, circulating, cementing, waiting on cement to harden, setting packers, setting plugs, installing a wellhead, testing the wellhead, installing a wellhead wear bushing, attaching a BOP, testing a BOP, attaching a choke manifold, testing a choke manifold and setting a whipstock, for example. In some embodiments a BOP is installed in at least two well locations in the set and is not removed when the mobile rig is moved a well location with a BOP attached or when moved over a well location with a BOP attached. A BOP may also be attached to a wellhead offline. In embodiments two opposing sides of the mobile drilling rig under the drill floor and the center of the rig under the drill floor are sufficiently free of permanent structural components such that a BOP and any short length of casing above the BOP can pass fully through the opposing sides of the structure without touching the rig while the rig is moving over the BOP. [0008] A general embodiment of the disclosure is a mobile drilling rig apparatus comprising a mast located on a drill floor, and a substructure supporting at least some of the drill floor comprising two legs and two propulsion mechanisms, wherein the area under the drill floor with the mast is substantially free of structural elements along at least one length of the drilling rig apparatus. In embodiments, the mast is located on the drill floor between the two legs. In embodiments the distance between the two legs and the distance between the drill floor and a ground surface are adapted to allow the mobile drilling rig to move fully over a blowout preventer at a surface location. In some embodiments the free area between the legs has a distance between the legs of 8-30 feet. The mobile drilling rig may also comprise removable support structures attached between the legs. Additionally, the mobile drilling rig may also comprise spacers located between each leg and each propulsion mechanism. The free area between the ground surface and the drill floor may have a height of 8-45 feet. In embodiments the drill floor comprises storage for at least one of a pipes. The mast may also be offset on the drill floor. In some embodiments, the mobile drilling rig additionally comprises a quick release mechanism adapted for the quick release of casing pipe underneath the drill floor. The quick release mechanism may be threading, a flange with bolds, or release bolts, for example. In some embodiments, the propulsion mechanism is wheels, hydraulic feet, tracks, or a sliding frame. The apparatus may also comprise a casing weight hang off mechanism configured to allow release of casing weight and/or a casing valve. In some embodiments the mast is located on an overhanging portion of the drill floor. In this embodiment the area under the overhanging portion of the drill floor can be substantially free of structural components in both lengthwise directions. The size and height of the overhanging portion of the drill floor may be adapted to allow the mobile drilling rig to move fully over a blowout preventer at a surface location.

[0009] These and other aspects, objects, features, and embodiments will be apparent from the following description and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The drawings illustrate only example embodiments of methods, systems, and devices for land-based mobile drilling rigs and are therefore not to be considered limiting of its scope, as land-based mobile drilling rigs may admit to other equally effective embodiments. The elements and features shown in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the example embodiments. Additionally, certain dimensions or positionings may be exaggerated to help visually convey such principles. In the drawings, reference numerals designate like or corresponding, but not necessarily identical, elements.

[0011] Fig. 1 illustrates the first step in an example method of batch drilling and completion using a mobile drilling rig. The mobile drilling rig is positioned over a first well location where a first well will be drilled.

[0012] Fig. 2 illustrates the second step in an example method of batch drilling and completion using a mobile drilling rig. The mobile rig has finished drilling a section of the first wellbore and has moved to the site of a second well location. A cementing truck is located at the first well and cementing is completed in the currently drilled section of the first well.

[0013] Fig. 3 illustrates another step in an example method of batch drilling and completion using a mobile drilling rig. The cementing has been completed at the first well location and a BOP is attached. Drilling is ongoing at the second well location.

[0014] Fig. 4 illustrates the further step in an example method of batch drilling and completion using a mobile drilling rig. The mobile drilling rig is now located over the first well location and is drilling a second section of the well. A cementing unit is located at the second well location.

[0015] Fig. 5 illustrates an example mobile drilling rig of the present disclosure.

Two sides and the center area of the mobile rig below the deck are fully open, allowing for the movement of a BOP through each side.

[0016] Fig. 6 illustrates a second example drilling rig of the present disclosure.

The drilling rig has a cantilever design with the area below the deck being fully open.

[0017] Fig. 7 is a graph charting depth vs. days for one example of drilling a pad site containing 10 wells using a walking rig and no batch drilling process.

[0018] Fig. 8 is a graph charting depth vs. days for one example of drilling a pad site containing 10 wells using a walking rig and the batch processed described herein.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

Definitions

[0019] Terms such as "first," "second," "end," "inner," "outer," "distal," and

"proximal" are used merely to distinguish one component (or part of a component or state of a component) from another. Such terms are not meant to denote a preference or a particular orientation. Also, the names given to various components described herein are descriptive of one embodiment and are not meant to be limiting in any way. Those of ordinary skill in the art will appreciate that a feature and/or component shown and/or described in one embodiment (e.g., in a figure) herein can be used in another embodiment (e.g., in any other figure) herein, even if not expressly shown and/or described in such other embodiment.

[0020] As used herein, "mobile drilling rig" refers to a land-based drilling rig which is able to move from one well drilling location to another without disassembling the rig or with minimal disassembling. For example, the mobile rig could be on wheels, hydraulic feet, tracks, or a sliding frame. The mobile rig moves on its own power, that is, the mobile rig is self-propelled.

[0021] As used herein, "offline" or "offline activities" refers to activities performed that are not performed while the rig is over the well. Offline activities can include logging, circulating, cementing, waiting on cement hardening, setting packers, setting plugs, installing the wellhead, testing the wellhead, installing the wellhead wear bushing, installing the BOP, testing the BOP, installing the choke manifold, testing the choke manifold and setting whipstocks, for example.

[0022] As used herein, "pad" refers to a land-based drilling site with containing multiple wells. Pads can have 2-100 wells spaced about 5-100 feet apart.

[0023] As used herein, "drilling activities" includes any activity that is performed while a well is being drilled and also includes activities performed between drilling sessions. For example, drilling activities can include drilling, cementing, assembling casing, logging, circulation the hole, installing the BOP, testing the BOP, and so forth.

[0024] As used herein, numerical values recited refer to values equal to the numerical value or values within the standard of error of measuring such values. The term "substantially equal," as used herein, refers to an amount that is within 3% of the value recited.

[0025] As used herein, "offset wells" refer to wells adjacent to a well with a drilling rig.

[0026] As used herein, "total depth" refers to the depth a well is to be drilled. That is, the final depth that well will be drilled to.

[0027] As used herein, "substantially free" refers to at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 98%, or 100% free.

[0028] As used herein, "a" or "an" means "at least one" or "one or more" unless otherwise indicated. A "plurality" refers to two or more.

Method and process of batch drilling with a mobile rig

[0029] Example embodiments of land-based mobile drilling rigs and methods of their use will be described more fully hereinafter with reference to the accompanying drawings, in which example embodiments of land-based mobile drilling rigs are shown. Land-based mobile drilling rigs, may, however, be embodied in many different forms and should not be construed as limited to the example embodiments set forth herein. Rather, these example embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of land-based mobile drilling rigs and methods of their use to those of ordinary skill in the art. Like, but not necessarily the same, elements in the various figures are denoted by like reference numerals for consistency.

[0030] An embodiment of the method uses wells on multi-well pads, multiple blowout prevention systems and a rig that can move from one well to the next in a short time period, such as a mobile drilling rig. The wells are spaced sufficient distance apart to allow offline work to occur on each well when the rig is over an adjacent well. That is, the rig deck floor and all other associated rig components such as the cat walk, pipe slide, dog house etc. only cover one well location at a time. The process is suited for "walking rig" designs but can work with any land rig that can move from one well to another well on the pad without being fully disassembled. The rigs used in this process should be able to move back and forth over a BOP, such that the rig does not touch the BOP while the rig is moving. In this way, the rig is only drilling while it is over a well and not spending time on drilling activities that can be done offline of the rig.

[0031] As illustrated in Fig. 1, in a first step in a method embodiment, the mobile drilling rig 100 is installed or located at a first well location 102. The initial hole section, whether surface or conductor, is drilled to its setting depth and the initial casing is run into the hole. The casing can be set on bottom or hung off on a landing shoulder or such mechanism set in the structural pipe, for example. A valve may or may not be installed in the casing above ground level and below the rig floor. A release mechanism may be installed in the casing above ground level and below the rig floor and above the valve if used. The casing is then released by the mobile drilling rig 100 and the mobile drilling rig 100 is moved to a second well location 202 (Fig. 2). Once moved to a second location 202, the mobile drilling rig 100 does not cover the first well location 102, allowing full overhead access to the first well location 102. The mobile drilling rig 100 then drills the second initial well section and the process is repeated until all desired initial hole sections are drilled. For example, two, three, four, five, six, seven, eight, nine, ten or so on well sections could be drilled in series during this step in the process.

[0032] In a next step in an embodiment of the batch method, also illustrated in Fig.

2, while the mobile drilling rig 100 is on the second well location 202, a cementing unit 204 is connected to the casing 206 of the first well 208 and a cement job is performed. Hole conditioning consisting of fluid circulation may or may not occur prior to pumping the cement. Fluid returns can be taken into a steel mud pit or cellar and pumped to the rig for re-use or disposal. After sufficient time has passed to allow the cement to set, the casing 206 is prepared and the initial wellhead or multi-bowl wellhead is installed and tested. Then a first blowout preventer 302 is installed and tested while the second well 304 is being drilled (Fig. 3). The blowout preventer 302 may consist of the blowout preventer stack, the choke manifold and accumulator power unit, for example. A wellhead wear bushing could also be installed at this point. A crane, for example, or other such lifting equipment such as a pulling unit can aid in this process since the mobile drilling rig 100 footprint is not covering the first well. The cementing process is started on the second well as the mobile drilling rig 100 moves back to the first well location 102 over the currently installed BOP 302 on the first well 208 (Fig. 4) or the mobile drilling rig 100 could move on to a third well (not shown).

[0033] The mobile drilling rig 100, after finishing drilling all desired initial hole sections on the multi-well pad, moves back onto the first well location 102 which received its BOP 302 (Fig. 4). Controls for the BOP 302 are connected to the mobile drilling rig 100. The mobile drilling rig 100 then drills the next deeper hole section whether intermediate or production to the desired depth. Depending on if electric line well logs are desired the rig could move to the next well and begin drilling the second well's next hole section while electric line well logs are run on the first well. Otherwise the mobile drilling rig 100 runs intermediate or production casing to its setting depth and the casing 206 hung off in the wellhead. The casing 206 is then released by the mobile drilling rig 100 and the mobile drilling rig 100 moves to the second well location 202 and repeats this process until all desired intermediate or production hole sections are drilled in the wells of a batch. The casing 206 may be hung on casing hangers in the well head or a load ring above the BOP 302 while the rig is moving off of the well site. A valve may or may not be installed in the casing 206 above the BOP 203 and below the rig floor. A release mechanism may be installed in the casing 206 above the BOP 203 and below the rig floor and above the valve if used. The casing 206 is then released by the mobile drilling rig 100 and the mobile drilling rig 100 is moved to where the next well is to be located.

[0034] While a batch process using two wells is illustrated in the figures, it should be understood that three wells or more wells could be drilled and cemented in the batch process disclosed herein. That is, instead of moving back to the first well after completing drilling the initial section of the second well, the rig could move on to a third well location and start the initial drilling on a third well location while the first and second well locations undergo offline activities such as cementing, logging, and installation of their BOPs. Additionally, four, five, six, seven, eight, nine, or ten wells could be batch processed. The amount of wells used in the batch process described herein depends on the types of wells needed, the depth of the wells, time to drill the wells, business objectives and the materials used among others. Example batch drilling processes using a mobile drilling rig, as described above, can complete a plurality of wells in parallel. For example, two, three, four, five, six, seven, eight, nine or ten wells could be drilled, cemented, logged, and completed in parallel.

[0035] Further, the amount of wells used in the batch process can vary depending on the section of the wells to be drilled. For example, the batch process could include four wells while drilling the initial section, and then include two wells while drilling intermediate or production sections. That is, the first four well sections could be drilled in series. While a fifth well is being drilled, the first four wells are then cemented and have the wellhead and BOPs attached. The rig would then go back and address drilling additional sections of two of the first four wells in series. Once those two wells are fully drilled and cemented, the rig could move on to the next two of the first four wells, for example. Depending on the specifics of the pad, this combined batch process could be more efficient, as cementing the initial holes, attaching the wellhead, attaching the BOP, and testing the BOP could take more time than cementing intermediate hole sections, for example. The number of wells used in batch drilling each hole section can be optimized to reduce the total time it takes to drill all of the wells in the pad. For example, offline activities that use more time would include more wells per batch, while offline activities that use less time could include less wells per batch. The batch process can also be optimized by maximizing the time the mobile drilling rig is drilling and minimizing the time the drilling rig is not drilling, i.e. walking or retooling.

[0036] Embodiments of the disclosure can use multiple BOP systems. For example, two, three, four, five, six, seven, eight, nine, or ten or more BOP systems are installed on a single pad at multiple wells. However, not all wells at the pad site need to have BOPs attached, nor do the BOPs need to be attached at neighboring wells. For example, every other well may have a BOP attached, every third well, every forth well and so forth. Another example is that the time for the drilling rig to drill its next hole section is sufficiently long and the time to perform all necessary offline activity on the previous sufficiently short such that the previous well's BOP could be removed and then installed on the next well the drilling rig is planned to drill resulting in only two BOPs being used although the pad has three or more wells. BOP systems can be installed offline of the mobile drilling rig or can also be installed while the mobile drilling rig 100 is located over the well. The BOP systems can also be tested offline of the mobile drilling rig. BOPs systems can comprise rams, annular preventer, spools, valves, rotating head, choke manifold, kill manifold, accumulator unit, and a power system, for example. The BOP can include multiple rams, for example 2, 3, 4, or more. Each additional ram will increase the height of the BOP, and therefore, the height of the drill floor of the mobile drilling rig.

[0037] The mobile drilling rig is able to move onto or off of a well that has a BOP already attached. The two opposing sides of the mobile rig under the mast and the center of the rig under the mast are sufficiently free of permanent structural components such that the installed BOP and any short length of casing above the BOP can pass fully through the opposing sides of the mobile drilling rig without touching the rig while the mobile drilling rig is moving over the BOP. The deck, also called the drill floor, must also be of sufficient height such that the BOP system can pass underneath the deck. Additional spacers can be added between the propulsion apparatus on the bottom of the rig and the substructure in order to increase the height of a rig such that it can pass over a BOP system. Additionally, temporary structural supports can be added while the mobile drilling rig is positioned over a well site between open sides of the substructure of the mobile drilling rig. These temporary structural supports can then be removed when the rig is moved in order to let the BOP pass under the mobile drilling rig.

[0038] Standard equipment can be used for offline processes. For example, a crane or other such lifting equipment can be used for performing electric line well logs after the rig has moved off the well if desired. Other such operations that could be performed at this point are setting packers, plugs or whipstocks using wireline units or coil tubing units. A cementing unit can also be connected to the casing and a cement job performed which includes hole conditioning by fluid circulation. Fluid returns can be taken into a pit and pumped to the mobile drilling rig for reuse or disposal. Plugs could also be set offline with coil tubing or wire line, for example. Wellheads and associated components including wear bushings could be installed and tested. It should also be understood that the processes described as offline activities could still be accomplished from the mobile drilling rig, if needed.

[0039] In embodiments of the method, wells are spaced apart such that offset wells are clear of the rig. That is, the mobile drilling rig deck or any part of the rig structure is clear of any offset well. Given a specific mobile drilling rig, the wells will need to be spaced apart such that the mobile drilling rig substructure does not overlay an offset well. For example, if the mobile drilling rig is 10 feet across between sides of the rig which are clear in the substructure, the wells will need to be spaced farther apart than 5 ft. Wells can be between 5 ft to 100 ft apart, for example, wells can be about 5, 10, 15, 20, 30, 40, 50, 60, 70, 80, 90 or 100 feet apart. Given a specific well spacing, the size of the mobile drilling rig will need to be smaller than half of the distance between wells. Between open sides, the sides that the BOP passes through, a mobile drilling rig can be between 8-40 feet long, for example, 8, 9, 10, 12, 14, 16, 18, 20, 25, 30, 35, 40 feet long. Structures that extend off of the rig, not including a deck with a mast, such as stairs or pipe ramp should be located away from offset wells, for example, on perpendicular sides of the rig from the clear sides. Distance between the sides of the rig perpendicular to the open sides is irrelevant to well spacing. Additional structures can be added to the perpendicular sides, such as pipe storage, pipe ramps, mud management equipment, stairs, mud pumps, engines, and so forth. Additionally, the wells do not need to be located in a straight line, as some walking rigs are capable of changing direction.

[0040] The batch method described herein enables safe operation of offline drilling activities. This batch process decreases well cost, lowers drilling time, increases well production time, and more wells can be drilled in the same time period. Additionally, with the batch method described here, the rig does not need to be retooled every time it moves saving additional time and expense. For example, in a three well batch process, three surface holes could be drilled at three well locations. The mobile drilling rig could then be retooled to drill intermediate holes and three intermediate holes could be drilled down from the three initial holes. The mobile drilling rig could then be retooled to drill production holes, and the production holes can be drilled down from the intermediate holes.

[0041] Mobile drilling rig apparatus and system

[0042] The batch process described herein requires structural changes to the current designs for mobile drilling rigs. Current mobile rigs have all four mobile drilling rig substructure sides under the mast or derrick taken up with structural elements. These current designs would not allow a mobile drilling rig to move off of and back to a well having a BOP already installed. Embodiments of the mobile rig of this disclosure comprise a rig where opposing sides of the rig underneath the mast, such as between the legs and the center under the deck are substantially free of structural components, such as bracing, poles, or the like. In this way, a BOP and any short length of casing above the BOP can move completely though and under the mast of a mobile drilling rig while the rig is moving, without touching any part of the rig. This allows the rig to move both onto and off of a well with a BOP attached.

[0043] Fig. 5 illustrates the side view of an embodiment of a mobile drilling rig

500 apparatus. The mobile drilling rig 500 comprises a mast 502, a drill floor 504, and a substructure 506 comprising two legs 508 and two propulsion mechanisms 510. The center under the drill floor 504 where the mast 502 is located and the two sides between the legs 508 are substantially free of structural components, such that a BOP and any short length of casing above the BOP can move completely under the drill floor 504 without touching any part of the mobile drilling rig 500 as the mobile drilling rig 500 is moving. In embodiments of the disclosure, each leg 508 of the apparatus may be a single support structure or may comprise multiple support structures (multiple legs or structural elements supporting the drill floor).

[0044] In an embodiment of the disclosure, the height 512 of the opening under the drill floor 504 where the mast 502 is must be high enough to clear a standard BOP height and any short length of casing above the BOP. In some embodiments, the height of the opening 512 must be high enough to clear a tall BOP with multiple rams, such as 2 rams, 3 rams, 4 rams or 5 rams. In some embodiments, the height of the opening 512 can be 8-50 feet off of the surface. For example, the drill floor can be 8, 9, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, or 30 feet and higher from the surface 514. If the drill floor 504 including elements hanging off of the drill floor 504 are not tall enough, a spacer can be added between the propulsion mechanism 510 and the legs 508 to increase the height of the drill floor 504, such that a BOP and any short length of casing above the BOP can completely fit underneath the mast 502 area below the drill floor 504 without touching any part of the mobile drilling rig 500.

[0045] In an embodiment of the disclosure, the width of the opening 516 between the area under the drill floor 504 where the mast 502 is located of the mobile drilling rig 500 must be wide enough such that a BOP can pass safely under the drill floor 504. In some embodiments, the width of the opening 516 can be between 8-30 feet apart with that distance defining an opening underneath the mast 502 area on the drill floor 504. For example, the width of the opening 516 can be 8, 9, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, or 30 feet apart.

[0046] In a specific embodiment, the width of the opening 516 is the distance between the legs 508. In this embodiment, once the mobile drilling rig 500 is set in place over a well, additional removable supports can be added between the legs. These removable supports would be removed prior to moving the mobile drilling rig to another site so that a BOP attached at a wellhead could move between the legs of the mobile drilling unit. Non-removable structural supports could also be added between the legs of the mobile unit as long as long as they do not interfere with a BOP moving between the legs. For example, an arch support could be added between the legs such that it does not cover a substantial portion of the opening but provides additional bracing to support the weight on the drill floor above.

[0047] In embodiments of the apparatus, additional storage and structures can be located perpendicular to the sides of the rig that are open. For example, pipe ramp 518, stairs or a storage deck can be located perpendicular to the open sides, thus, allowing for extra storage and functionality, while still minimizing the distance between open sides such that no off-set wells are covered by a rig structure. Additional storage areas on the deck can include storage space for mud systems and extra storage of casing pipe and drill pipe. In embodiments of the apparatus, the mast 502 can be offset on the mobile drilling rig.

[0048] The mobile drilling rig 500 may also contain standard rig equipment plus additional equipment and extra storage space not illustrated in the figures. For example, the mobile drilling rig can include one or more of a mud tank, shale shakers, suction line, mud pump, motors, vibrating hose, draw-works, standpipe, kelly hose, goose-neck, traveling block, drill line, crown block, derrick, monkey board, pipe stand, pipe rack, top drive, kelly, kelly bushing, master bushing, mouse hole, rathole, backup tongs, makeup tongs, iron roughneck, driller's console, rotary house, accumulator unit, mud return line, choke manifold, water storage, catline boom, hoist line, kelly drive, rotary table, bell nipple, drill string, flow line, dog house, hook, swivel, elevators and engines.

[0049] In an embodiment of the apparatus, there is a release mechanism 520 below the drill floor 504 that allows for the release of casing after a run. For example, the casing may need to be easily disconnected from the mobile drilling rig 500 so that the mobile drilling rig 500 can move off of the well location. The release mechanism 520 may be located above the hang off structure and below the drill floor and no higher than can be cleared by a BOP attached to a well the mobile drilling rig 500 is moving off or over. The release mechanism 520 may be a quick release mechanism. For example, the release mechanism may be a threaded connection, a flange with bolds, release bolts, or the like.

[0050] In the embodiment of the disclosure, the casing weight may need to be hung off on a structure separate from the mobile drilling rig 500 so that the mobile drilling rig 500 can move off of the well location. This structure may be the wellhead in which a casing hanger is used, the BOP in which an appropriate sized ram is closed on the casing just below a casing collar or a load ring located on top the BOP on which a mandrel or clamp can land to hold the casing weight among others. In the embodiment of the disclosure, a valve may need to be installed in the casing string above the mechanism to hold the casing weight when released by the mobile drilling rig 500 and below the release mechanism 520.

[0051] In embodiments of the disclosure, the propulsion mechanism 510 is located beneath the legs 508 on either side of the mobile drilling rig 500. In embodiments, any propulsion mechanism 510 known in the art is compatible with the mobile drilling rig 500 apparatus. For example, the propulsion mechanism 520 may be wheels, hydraulic feet, tracks, or a sliding frame.

[0052] Fig. 6 illustrates another embodiment of a mobile drilling rig 600 with a deck or cantilever design. The mast 602 in this embodiment is located on an overhang 604 on the drill floor 606, forming a deck like structure. The area underneath the overhang is substantially free of structural elements in both length directions of the overhang such that the mobile drilling rig 600 can move fully over a blowout preventer and any short lengths of casing. The weigh on the drill floor 606 not on the overhang may be increased in order to provide a counter weight to the mast 602. For example, the drill floor 606 may comprise additional casing storage to increase the weight on the non-overhang part of the drill floor. The height 608 of the overhang 604 defines the height of the opening 512.

[0053] Example embodiments of the disclosure allow for more efficient drilling, logging, and cementing. Example embodiments can be used to systematically and in a targeted fashion perform, in parallel, drilling, logging, and cementing. Thus, using embodiments of the disclosure can provide significant time savings, costs savings, easier installation, safer installation, the installation of more wells than could be completed otherwise, and easier maintenance. For example, the described process results in improved safety, ability to performed multiple offline activities from the rig and reduced time leading to cost savings.

EXAMPLES

Example 1

[0054] A pad well site was drilled using a walking rig without the batch method described herein. That is, each well was fully drilled and completed before moving onto the next well site. The pad contained 10 wells including sidetracks. The wells were drilled using a walking rig which moved 0.25 ft/min. The walking rig traversed wells spaced 40 feet apart in 10 minutes and could move 1 mile per day. The 10 wells were drilled in 259 days at a non-fixed cost of 34 million dollars. Fig. 7 shows a chart for the measured depth vs. the days for drilling the 10 wells.

Example 2

[0055] A pad well site such as that given in Example 1 is drilled using a walking rig with the batch process described herein. Four wells are drilled to an initial depth and cemented in the first batch process. Two wells each are drilled to an intermediate depth in the second batch process. Two wells each are then drilled to total depth in a third batch process. While the rig is drilling at one well location in the batch, offline activities are occurring at the other wells in the batch. Using this batch process, operations could cut 51 days off drilling the ten wells, resulting in a 20% reduction in rig time. This reduction in time would result in 4.8 million dollars in savings, nearly sufficient for 2 additional wells to be drilled in both time and cost. Fig. 8 shows a chart for the measured depth vs. the days for drilling the 10 wells using the batch process. PARTICULAR EXAMPLE EMBODIMENTS

[0056] The following numbered paragraphs (1 to 39) define particular example embodiments of the present disclosure:

1. A method for batch process land-based drilling using a mobile rig, comprising: (a) drilling a first section of a first well with the mobile rig at a first well location; (b) moving the mobile rig to a second well location, wherein when the mobile rig is located at the second well location the first well location is clear of the mobile rig; (c) drilling a first section of a second well with the mobile rig at the second well location; (d) performing offline activities at the first well location while the mobile rig is drilling at the second well; (e) moving the mobile rig back to the first location while a BOP is attached to a wellhead at the first location, and (f) drilling a second section of the first well with the mobile rig at the first well location.

2. The method of claim 1, wherein the offline activities are one or more of logging, circulating, cementing, waiting on cement to harden, setting packers, setting plugs, installing a wellhead, testing the wellhead, installing a wellhead wear bushing, attaching a BOP, testing a BOP, attaching a choke manifold, testing a choke manifold and setting a whipstock.

3. The method of any one of claims 1-2, wherein step (d) includes cementing the first section of the first well and attaching a BOP to the first well.

4. The method of any one of claims 1-3, wherein the mobile rig apparatus does not cover any off-set wells when drilling at the second well location.

5. The method of any one of claims 1-4, wherein one or more of steps (a), (b), (c), (d), and (f) are performed while a BOP is attached or being attached to a wellhead on the first well.

6. The method of any one of claims 1-4, wherein one or more of steps (a), (b), (c), (d), (e) and (f) are performed while a BOP is attached or being attached to a wellhead on the second well.

7. The method of any one of claims 1-6, wherein a BOP is attached or being attached to a wellhead at the first or second well location offline.

8. The method of any one of claims 1-7, wherein two opposing sides of the mobile rig under a mast on the mobile rig and the center of the rig under the mast are sufficiently free of permanent structural components such that a BOP can pass fully under the mast without touching the rig while the rig is moving over the BOP. 9. The method of any one of claims 1-8, wherein the sections drilled in steps (a) and (c) are initial sections.

10. The method of any one of claims 1-8, wherein the sections drilled in steps (a) and (c) are production sections.

11. The method of any one of claims 1-8, wherein the sections drilled in steps (a) and (e) are intermediate sections.

12. The method of any one of claims 1-11, additionally comprising

(g) performing offline activities at the second well location while the mobile rig is drilling at the first well location.

13. The method of any one of claims 1-12, wherein the batch process comprises drilling three or more well sections in series at three well locations.

14. The method of claim 13, wherein the offline activities are performed using a crane or a cementing truck.

15. A batch method of land-based drilling with a mobile drilling rig comprising, (a) locating a set of two or more well locations; (b) drilling a well section with the mobile drilling rig at each of the well locations in the set, wherein while the mobile drilling rig is drilling, no off-set well is covered by the mobile drilling rig; (c) performing offline activities at one or more of the well sections drilled in step (b) while the mobile drilling rig is drilling at a different well location in the set; (d) after the well sections have been drilled at each of the well locations of the set, returning the mobile drilling rig to a first well location in the set and drilling a succedent well section, wherein a BOP is attached at the first well location when the mobile drilling rig returns.

16. The method of claim 15, further comprising repeating steps (b) through (d) until all well sections at each well location in the set are drilled to total depth.

17. The method of claim 16, wherein the drilled sections comprise at least one intermediate well section.

18. The method of claim 16, wherein the drilled sections comprise at least one production well section.

19. The method of any one of claims 15-18, further comprising locating a second set of two or more well locations and repeating steps (b)-(d) on the second set of well locations until all well sections at each well location in the second set of well locations are drilled to a total depth.

20. The method of any one of claims 15-19, wherein the offline activities are logging, circulating, cementing, waiting on cement to harden, setting packers, setting plugs, installing a wellhead, testing the wellhead, installing a wellhead wear bushing, attaching a BOP, testing a BOP, attaching a choke manifold, testing a choke manifold and setting a whipstock. The method of any one of claims 15-20, wherein a BOP is installed in at least two well locations in the set and is not removed when the mobile rig is moved a well location with a BOP attached or when moved over a well location with a BOP attached.

21. The method of any one of claims 15-21, wherein a BOP is attached to a wellhead offline.

22. The method of any one of claims 15-22, wherein two opposing sides of the mobile drilling rig under a mast on the mobile drilling rig and the directly under the mast are sufficiently free of permanent structural components such that a BOP and any short length of casing above the BOP can pass under the mast without touching the rig while the rig is moving over the BOP.

23. A mobile drilling rig apparatus comprising a mast located on a drill floor, and a substructure supporting at least some of the drill floor comprising two legs and two propulsion mechanisms, wherein the area under the drill floor with the mast is substantially free of structural elements along one length of the drilling rig apparatus.

24. The apparatus of claim 23, wherein the mast is located on the drill floor between the two legs.

25. The apparatus of claim 24, wherein the distance between the two legs and the distance between the drill floor and a ground surface are adapted to allow the mobile drilling rig to move over a blowout preventer at a surface location.

26. The apparatus of claim 25, wherein the free area between the legs has a distance between the legs of 8-30 feet.

27. The apparatus of any one of claims 23-25, further comprising removable support structures attached between the legs.

28. The apparatus of any one of claims 23-26, further comprising spacers located between each leg and each propulsion mechanism.

29. The apparatus of any one of claims 23-28, wherein the free area between the ground surface and the drill floor has a height of 8-45 feet.

30. The apparatus of any one of claims 23-29, wherein the drill floor comprises storage for casing. 31. The apparatus of any one of claims 23-30, wherein the mast is offset on the drill floor.

32. The apparatus of any one of claims 23-31, wherein the mobile drilling rig additionally comprises a quick release mechanism adapted for the quick release of casing pipe underneath the drill floor.

33. The apparatus of claim 32, wherein the quick release mechanism is threading, a flange with bolds, or release bolts.

34. The apparatus of any one of claims 23-33, wherein the propulsion mechanism is wheels, hydraulic feet, tracks, or a sliding frame.

35. The apparatus of any one of claims 23-34, further comprising a casing weight hang off mechanism configured to allow release of casing weight.

36. The apparatus of any one of claims 23-35, further comprising a casing valve.

37. The apparatus of any one of claims 23 and 27-36, wherein the mast is located on an overhanging portion of the drill floor.

38. The apparatus of claim 37, wherein the area under the overhanging portion of the drill floor is substantially free of structural components in both lengthwise directions.

39. The apparatus of any one of claims 37 and 38, wherein the size and height of the overhanging portion of the drill floor is adapted to allow the mobile drilling rig to move over a blowout preventer at a surface location.

[0057] Although embodiments described herein are made with reference to example embodiments, it should be appreciated by those skilled in the art that various modifications are well within the scope and spirit of this disclosure. Those skilled in the art will appreciate that the example embodiments described herein are not limited to any specifically discussed application and that the embodiments described herein are illustrative and not restrictive. From the description of the example embodiments, equivalents of the elements shown therein will suggest themselves to those skilled in the art, and ways of constructing other embodiments using the present disclosure will suggest themselves to practitioners of the art. Therefore, the scope of the example embodiments is not limited herein.

Claims

CLAIMS What is claimed is:

1. A mobile drilling rig apparatus comprising a mast located on a drill floor, and a substructure supporting at least some of the drill floor comprising two legs and two propulsion mechanisms, wherein the area under the drill floor were the mast is located is substantially free of structural elements along at least one length of the drilling rig apparatus.

2. The apparatus of claim 1, wherein the mast is located on the drill floor between the two legs.

3. The apparatus of claim 2, wherein the distance between the two legs and the distance between the drill floor and a ground surface are adapted to allow the mobile drilling rig to move over a blowout preventer at a surface location.

4. The apparatus of claim 3, wherein the free area between the legs has a distance between the legs of 8-30 feet.

5. The apparatus of claim 1, further comprising removable support structures attached between the legs.

6. The apparatus of claim 1, further comprising spacers located between each leg and each propulsion mechanism.

7. The apparatus of claim 1, wherein the free area between the ground surface and the drill floor has a height of 8-45 feet.

8. The apparatus of claim 1, wherein the drill floor comprises storage for at least one of a pipes.

9. The apparatus of claim 1, wherein the mast is offset on the drill floor.

10. The apparatus of claim 1, wherein the mobile drilling rig additionally comprises a quick release mechanism adapted for the quick release of casing pipe underneath the drill floor.

11. The apparatus of claim 10, wherein the quick release mechanism is threading, a flange with bolds, or release bolts.

12. The apparatus of claim 1, wherein the propulsion mechanism is wheels, hydraulic feet, tracks, or a sliding frame.

13. The apparatus of claim 1, further comprising a casing weight hang off mechanism configured to allow release of casing weight.

14. The apparatus of claim 1, further comprising a casing valve.

15. The apparatus of claim 1, wherein the mast is located on an overhanging portion of the drill floor.

16. The apparatus of claim 15, wherein the area under the overhanging portion of the drill floor is substantially free of structural components in both lengthwise directions.

17. The apparatus of claim 16, wherein the size and height of the overhanging portion of the drill floor is adapted to allow the mobile drilling rig to move over a blowout preventer at a surface location.