Rig Substructure And Method Of Moving The Same

Abstract

There is disclosed a substructure for a drilling or workover rig that is particularly adapted to be moved away from a Christmas tree in preparation for transport to a new location. A path of travel is selectively provided for the Christmas tree inside the confines of the substructure. When it is desired to move the substructure away from the tree, the path of travel is cleared and the substructure is forcibly moved while maintaining the Christmas tree within its path of travel.

Description

BACKGROUND OF THE INVENTION

A major item of expense to a drilling contractor that must be passed on to the operator is the cost of moving the drilling rig and necessary equipment from one location to another. This has long been recognized by drilling contractors and drilling rigs have, over the years, become increasingly transportable. A 6,000 foot capacity drilling rig of 15 years ago would typically require two days, 25 trucks and drivers and the three drilling crews to make a short move of, for example, 20 miles. Moving presently available equipment requires about half the expense of that required 15 years ago.

If a well is dry, the surface casing is cut off below ground level and no well equipment extends above the ground. In this circumstance, it is fairly simple to drag the rig substructure away from the location and load it on a truck. On the other hand, if a well has been made, the surface casing and production pipe extend to ground level and a Christmas tree is perched thereon. In this event the rig substructure must have the capability of being moved away from the well site without contacting the Christmas tree. Breaking surface equipment off a well during a move can be an unmitigated disaster.

It will be appreciated by those skilled in the art that the transportability of a small drilling rig, i.e. one having a smaller capacity depth than about 10,000 feet, is more crucial than in larger drilling rigs. Since the smaller drilling rigs drill more wells per year and have to move more than the larger rigs, this fact of life will be readily apparent.

The prior art has taken one of several general approaches in providing rig substructures having the capability of moving away from a Christmas tree without damage thereto. The first and older approach is to provide a two piece rig substructure connected together along a central vertical plane intersecting the Christmas tree. By disconnecting the substructure halves, each half can be moved laterally in opposite directions away from the Christmas tree. This approach is generally not very desirable since each substructure half ends up on a separate truck for transportation thereby requiring two trucks to move the substructure.

A similar approach is disclosed in U.S. Pat. No. 2,922,501 where the substructure is made in two pieces and is pinned together by an interconnecting link. Although the exact mode of moving this substructure away from a Christmas tree is not disclosed, it would appear that the link is first unpinned and then the substructure halves are moved laterally in opposite directions away from the Christmas tree and may then be pinned together for transport on a single truck. The approach disclosed in this patent is somewhat different than the approach mentioned above since the substructure halves are not directly connected during operation. It would appear that the substructure disclosed in this patent would allow differential settling of the substructure halves and may accordingly present some problems during drilling.

A more recent approach has been to construct the substructure such that the rotary table, which determines the location of the Christmas tree, is adjacent the intersection of the substructure and the adjacent draw works unit. In rigs of this type, the draw works unit may be moved away from the Christmas tree in one direction and the substructure moved away therefrom in the opposite direction. This approach has a substantial disadvantage in that the catwalk and pipe racks are normally located in the direction of movement of the substructure. Accordingly, the substructure cannot be moved until the catwalk and pipe racks have been loaded. It is often advantageous or desirable to move the substructure before moving the catwalk and pipe racks for various reasons. For example, if the low boy trailer for the substructure arrives at the old location before the trucks needed to move the catwalk and pipe racks arrive, the low boy and driver must sit and wait. It is normally most convenient to assemble a rig at a new location by placing those rig parts adjacent the site where the well is to be drilled and then spot the rig components spaced therefrom. Accordingly, it is usually desirable to spot the substructure first. In order to spot the substructure first and avoid substantial waiting time, it is usually necessary to move the substructure from the old location first.

By constructing a substructure in accordance with this invention and by moving the same away from the Christmas tree in accordance with this invention, rapid disassembly, transportation and reassembly of a drilling rig is typical. A 10,000 foot capacity drilling rig has been constructed in accordance with this invention. In one typical move, an oil well was completed at one location and the rig released by the operator at 10:00 a.m. The rig was disassembled, moved and reassembled at a new location approximately 2 miles away and began drilling by 8:00 p.m. of the same day. A total of ten truckloads were necessary to move the rig and its associated equipment, excluding drill pipe.

OBJECTS OF THE INVENTION

It is an object of this invention to provide a substructure for a drilling or workover rig which is particularly adapted to be moved away from a Christmas tree.

Another object of the invention is to provide a rig substructure having an elevated floor, means for supporting the floor above an overlying surface and means selectively providing a path of travel of a Christmas tree beneath the floor.

Another object of this invention is to provide a rig substructure having incorporated therewith a movable blowout preventer and choke manifold which may be carried by the substructure during moves.

A further object of this invention is to provide a rig substructure having a pipe supporting wing thereon which may be moved between a load supporting position and a collapsed travel position.

SUMMARY OF THE INVENTION

In summary, the rig structure of this invention is particularly adapted to be moved away from a Christmas tree on a well and comprises a floor having means intermediate the sides and ends thereof defining a path of tool movement into the well, support means on opposite ends of the floor supporting the same above an underlying surface and defining therebetween a path of travel for the Christmas tree enabling the substructure to be moved relative to the Christmas tree, and pad means of substantial bearing area including means for rigidly connecting the pad means with the support means for contact with the underlying surface across and blocking the Christmas tree path of travel and for unfastening the pad means from rigid connection with the support means for unblocking the Christmas tree path of travel.

In summary, the method of this invention includes moving a rig substructure from a well having a Christmas tree thereon wherein the rig substructure comprises a floor and spaced apart column means on opposite ends of the Christmas tree elevating the floor above an underlying surface, the method comprising clearing a straight path of travel for the Christmas tree between the support means and applying a force having a substantial horizontal vector in a plane extending along the path of travel for moving the substructure horizontally relative to the Christmas tree while maintaining the Christmas tree in the path of travel thereof until the Christmas tree clears the substructure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view illustrating the layout of many of the rig components and includes a top view of the substructure of this invention;

FIG. 2 is a side elevational view of the rig substructure of this invention as seen from along line 2--2 in FIG. 1 as viewed in the direction indicated by the arrows;

FIG. 3 is a cross sectional view of the rig substructure, taken substantially along line 3-3 of FIG. 2 as viewed in the direction indicated by the arrows;

FIG. 4 is a transverse cross sectional view of the rig substructure of FIG. 2, taken substantially along line 4-4 thereof as viewed in the direction indicated by the arrows;

FIG. 5 is another transverse cross sectional view of the rig substructure of FIG. 2, taken substantially along line 5-5 thereof as viewed in the direction indicated by the arrows;

FIG. 6 is an additional transverse cross sectional view of the rig substructure of FIG. 2, taken substantially along line 6-6 thereof as viewed in the direction indicated by the arrows;

FIG. 7 is a longitudinal cross sectional view of the rig substructure, taken substantially along line 7-7 in FIG. 1 as viewed in the direction indicated by the arrows, illustrating the location of the blowout preventer and choke manifold before installation thereof on the surface casing;

FIG. 8 is a side elevation of a pipe rack wing, as may be viewed from along line 8-8 in FIG. 1;

FIG. 9 is a view similar to FIG. 8 illustrating the wing in the folded or collapsed position; and

FIG. 10 is a view similar to FIG. 8 illustrating another embodiment of the pipe rack wing of this invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, there is illustrated a major part of a drilling or workover rig 10 having as major components a rig substructure 12 having a pipe rack 14 thereon and a V-door ramp 16 leading to a catwalk 18 from which extend a plurality of pipe racks 20 having a plurality of pipe joints 22 horizontally supported thereon. The rig 10 is also illustrated as comprising a ramp 24 for receiving a drawworks unit 26, a tool house 28 and a shale shaker 30. Not illustrated for reasons of clarity is the derrick or mast which may conveniently be supported from the ramp 24 in a conventional manner. Also not illustrated are other conventional equipment typically provided on a drilling rig, such as mud pumps, mud tanks and/or mud pits, a tool pusher's house and water supply equipment.

Referring to FIGS. 1-7, the substructure 12 comprises a floor 32 having thereon a rotary table 34 defining a path of tool movement 36 into the well or borehole. The floor 32 conveniently comprises metal plate and is elevated above an underlying ground surface 38 by support means 40. The rig substructure 12 is rectangular in plan with the edges thereof parallel to the long dimension being denominated as sides and the edges thereof parallel to the short dimension being denominated as ends.

The support means 40 comprises a ground engaging section including a pair of elongate beams 42, 44 extending along the sides of the substructure 12 and pad means 46, 48 interconnected between the beams 42, 44. The pad means 46 comprise a plurality of transverse beams 50 permanently affixed to the beams 42, 44 and a pad plate 52 secured, as by welding or the like, to the underside of the beams 50. As will be noted most particularly in FIG. 3, the fixed pad means 46 reside between one end 54 of the substructure 12 and the path of movement 36.

An important part of this invention resides in the movable pad means 48 which comprise a plurality of beams 56 extending transversely between the beams 42, 44 on the opposite side of the path of tool movement 36, as shown in FIGS. 3-5. A pad plate 58 is conveniently secured to the beams 56 in any suitable manner, as by welding. The pad means 48 may be disconnected from the beams 42, 44 to clear a path of Christmas tree movement from the path of tool movement 36 through the other end 60 of the substructure 12 as will be more fully apparent hereinafter. Toward this end, the beams 56 may conveniently be pivoted, as by a plurality of pins 62 cooperating with ears 64 affixed to the beam 42, to allow upward pivotal movement of the pad means 48 about an axis 66. Suitable pins 68 and ears 70 are conveniently provided to secure the free ends of the beams 56 to the beam 44 as shown in FIGS. 3-5.

Extending vertically from the respective beams 42, 44 are a plurality of columns 72, 74 along with suitable diagonal struts 76, 78. A pair of longitudinally extending beams 80, 82 overlie and are secured to the members 72, 76 and the members 74, 78 respectively. A plurality of transverse beams 84 are secured, as by welding or the like, between the beams 80, 82 and act to reinforce the floor 32. As seen in FIGS. 5 and 7-10, suitable permanent bracing elements 86 may be provided as desired so long as the elements 86 do not interfere or cross the path of travel of the Christmas tree through the substructure 12 toward the end 60.

It is highly desirable to provide additional bracing elements to avoid racking of the substructure 12. Such additional bracing elements should, of course, not impede moving the substructure 12 away from a Christmas tree. Toward this end there is provided one or more movable bracing elements 88 extending diagonally across the substructure 12 as may be seen in FIGS. 4 and 6. The movable bracing element 88 may be affixed in any suitable manner, as by the provision of pins 90. The movable bracing element 88 conveniently comprises telescoping members 92, 94 which are connected by pins 96, 98.

When the well is being drilled or when the floor 32 is otherwise loaded, the movable pad means 48 are in the solid line position shown in FIGS. 4 and 5 to provide a substantial bearing surface with the ground 38 and the movable bracing elements 88 are as shown in FIG. 4. When it is desired to move the substructure 12 away from a Christmas tree, the movable bracing elements 88 are collapsed, as by removing the uppermost pin 90, the pins 96, 98, and pivoting the same against the column 72. The movable pad means 48 are then folded upwardly, as by removing the pins 68, against the column 72. As shown in FIG. 4, a path of Christmas tree movement 100 is thus cleared between the path of tool movement 36 and the end 60 of the substructure 12. With the path 100 cleared, the substructure 12 may be dragged horizontally away from the Christmas tree, in the direction of the arrow in FIG. 1, merely by attaching a line thereto from a winch truck. In the alternative, the loading truck may exert an inclined force to the substructure 12 to tilt the same for immediate loading onto a low boy trailer.

Referring to FIGS. 1, 8 and 9, the pipe rack 14 is illustrated as comprising flooring 102 supported by a beam latticework 104. The latticework 104 is pivotally mounted by a suitable bracket 106 to a support 108 secured to the columns 74 while a diagonal brace 110 supports the free end of the pipe rack 14. The diagonal brace 110 may conveniently be similar to the diagonal brace 88 and comprise telescoping members secured together by suitable pins 112 and secured to the substructure 12 and the pipe rack 14 by additional pins 114. It will be apparent that removal of the pins 112 allows the pipe rack 14 to be pivoted into a generally vertical position as shown in FIG. 9. Suitable chains or the like may be used to lash the pipe rack 14 to the substructure 12 in the collapsed position of FIG. 9 for transport.

Referring to FIG. 10, the pipe rack 14 may be modified to include a ground engaging pad means 116 and a support 118 to provide additional stability when it is heavily loaded. The pad means of 116 includes a plurality of beams 120 pivotally connected to the substructure 12 by suitable ears 122 and pins 124. A pad plate 126 is conveniently welded to the underside of the beams 120 to provide a substantial bearing area with the ground 38. The support 118 is releasably connected to the pad means 116 and to the latticework 114 by suitable pins 128. It will be apparent that the support 118 may be removed and the pad means 116 folded upwardly against the columns 74 for transport in much the same manner that the pipe rack of FIGS. 8 and 9.

Referring to FIGS. 1 and 2, the shale shaker 30 is arranged to receive mud returns from the well during the drilling thereof and may be of any suitable type. The shale shaker 30 is mounted on a platform 130 comprising a pair of beams 132 pivoted respectively to one of the columns 72, 74 by a suitable pin connection 134. The beams 132 incline downwardly toward the end 60 of the substructure 12 and are connected by a pair of brackets 136, 138 for receiving the shale shaker 30. The free end of each of the beams 132 is supported by a diagonal bracing element 140 which may conveniently comprise telescoping members 142, 144 pinned respectively to the beams 132 and the substructure 12 by pins 146, 148. The telescoping members 142, 144 are releasably connected by suitable pins 150, 152,.

If the Christmas tree installed on the well being drilled is of moderate height, it will clear the underside of the platform 130 without upward pivoting thereof. On the other hand, if the Christmas tree is of unusual height, the platform 130 may be pivoted upwardly about the axis of the pin connection 134. This may be readily accomplished by attaching a sling from the traveling block to the free end of the platform 130, pulling upwardly thereon and releasing the telescoping members 142, 144 for relative movement. The diagonal bracing element 140 may conveniently be provided with additional pin connections for holding the platform 130 in its upwardly pivoted position.

Referring to FIG. 7, the typical approach in drilling a well is to drill a few hundred feet and cement in the bore hole a string of surface casing 154 having a flange 156 thereon. While the cement is setting up, it is customary practice to attach a blowout preventer to the flange 156, hook up a choke manifold to the blowout preventer and make the necessary connections between a control unit and the blowout preventer to remotely operate the same. With substructures typically used in the industry, this can be an arduous task. In contrast, the substructure 12 of this invention conveniently provides means for expediting the installation of a blowout preventer.

As shown in FIGS. 3 and 7, the substructure 12 includes track means 158 and a dolly 160 to position a blowout preventer 162 on the flange 156. The track means 158 comprises a first pair of permanent tracks 164, a second pair of permanent tracks 166 and a pair of removable tracks 168 providing a path of movement for the dolly 160 between a position overlying the path of tool movement 36 and a position adjacent the end 54 of the substructure 12. The permanent tracks 164, 168 are conveniently welded to the beams 50, 56 respectively while the removable tracks 168 may be pinned or otherwise placed across the innermost beams 50, 56 as shown in FIG. 3.

When not in use or during transport of the substructure 12, the dolly 160, blowout preventer 162 and movable tracks 168 are positioned adjacent the end 54 of the substructure 12 and lashed in place. During the drilling of the surface hole, the movable bracing elements 88 are in place as shown in FIGS. 4 and 6. After the surface pipe 154 is cemented in the bore hole, the movable bracing elements 88 blocking the path of travel of the blowout preventer 162 (FIG. 6) are folded against the columns 72, the removable tracks 168 are positioned as shown in FIGS. 3 and 7 and the dolly 160 is moved along the track means 158 until the blowout preventer 162 is disposed adjacent the path of tool movement 36. A sling suspended from the traveling block is then passed through the rotary table 34 and tied to the blowout preventer 162. The blowout preventer 162 is then raised slightly and the dolly 160 is moved away from the flange 156 toward the right in FIG. 7. The blowout preventer 162 is then lowered so that the flange 170 thereof may be bolted to the flange 156.

It will be noted that the overall height of the blowout preventer 162 and the Hydril unit 172 thereon is less than the transverse beams 174 which support the rotary table 34. It will also be noted that the choke manifold 176 remains attached to the blowout preventer 162 at all times thereby obviating connecting and disconnecting the choke manifold 176 during assembly and disassembly of the blowout preventer 162. In this regard, it will be seen that the choke manifold 176 is shorter than the distance between the path of tool movement 36 and the rightmost position of the dolly 160 so that the manifold 176 does not interfere with drilling or other operations conducted along the path of tool movement 36 when the blowout preventer 162 is not in use.

After the blowout preventer 162 is attached to the flange 156, the choke manifold 176 is connected to an articulated flow line 178 (FIG. 1) by the use of suitable quick-disconnect couplings. The blowout preventer 162 is then connected to a suitable control unit 180 by suitable flexible air lines or the like for remotely controlling the blowout preventer 162 in a conventional manner. After the blowout preventer 162 is in place, the diagonal bracing elements 88, which were moved out of the way to allow passage thereof, are moved into load supporting position as shown in FIG. 6. The remainder of the well may then be drilled in a customary manner.

If the well is non-productive, the blowout preventer 162 is unbolted from the flange 156, elevated by the traveling block so that the dolly 160 may be moved thereunder, placed on the dolly 160, rolled toward the end 54 of the substructure 12 and then lashed in place. The surface pipe 154 is cut off below ground level and the substructure 12 may be moved merely by dragging it in the direction shown by the arrow in FIG. 1. Since no well equipment extends above the ground 38, there is no necessity to move the pad means 48, the removable struts 88 or the shale shaker 30.

If the well being drilled is productive, a string of production casing 182 (FIG. 2) is cemented in the bore hole and the blowout preventer 162 is removed from the flange 156 as previously mentioned. During the completion of the well, a Christmas tree 184 is assembled on the flange 156. The Christmas tree 184 provides communication between the production pipe extending into the well and the surface and includes suitable valves and other pressure control equipment as is conventional. Since the Christmas tree 184 extends above the ground 38, it will be readily apparent that the substructure 12 cannot merely be dragged away therefrom. The pad means 48, the diagonal bracing element 88 of FIG. 4 and the shale shaker 30 are moved to clear the path of Christmas tree movement 100. The substructure 12 may then be moved laterally in the direction shown by the arrow in FIG. 1 and loaded onto a truck.

If the substructure 12 is being used on a workover rig, it must be capable of being moved over an existing Christmas tree. This may readily be accomplished by positioning the substructure 12 laterally of the existing Christmas tree, positioning the various elements out of the Christmas tree path of travel and then dragging the substructure 12 toward the Christmas tree so that the path of tool movement 36 becomes concentric with the Christmas tree.

Claims

I claim:

1. A rig substructure comprising

a floor having means intermediate the confines thereof defining a path of vertical tool movement into a bore hole;

means for supporting the floor above an underlying surface and defining a path of travel for a Christmas tree from the path of movement to the periphery of the substructure, the support means including spaced rows of generally vertical columns on opposite sides of the path of travel and generally horizontal beam means rigid with the column rows above the path of travel; and

pad means rigidly connected with the support means providing bearing contact with the underlying surface across and blocking the path of travel including means for unfastening the pad means from rigid connection with the support means for movement relative thereto for unblocking the path of travel.

2. The rig substructure of claim 1 wherein the last mentioned means includes means hingeably mounting the pad means relative to the support means.

3. The rig substructure of claim 2 wherein the hingeably mounting means comprises hinge means on one side of the path of travel supporting the pad means for movement from a first position parallel with the underlying surface and a second generally upright position out of the path of travel and means for releasably securing the pad means in the first and second positions.

4. The rig substructure of claim 1 wherein the last mentioned means includes means for disconnecting the pad means from the support means.

5. The rig substructure of claim 1 wherein the Christmas tree path of travel extends from a location intermediate the sides and ends of the substructure through a first end thereof.

6. The rig substructure of claim 5 further comprising a shale shaker attached to the first end of the substructure and extending into the Christmas tree path of travel and including means mounting the shale shaker for movement to a location out of the Christmas tree path of travel.

7. The rig substructure of claim 5 wherein the support means comprises means on opposite sides of the floor defining therebetween a path of travel of a blowout preventer from the location intermediate the sides and end of the substructure toward the second end of the substructure and further comprising

a blowout preventer; and

means mounting the blowout preventer on the substructure between the column means for movement between the location intermediate the sides and ends of the substructure to a second location adjacent a second end of the substructure.

8. The rig substructure of claim 7 further comprising a choke manifold connected to the blowout preventer extending therefrom toward the first end of the rig substructure and wherein the length of the choke manifold is less than the distance between the second location and the location intermediate the sides and ends of the substructure.

9. The rig substructure of claim 7 further comprising strut means including means for rigidly connecting the strut means diagonally across and blocking the blowout preventer path of travel and for unfastening the strut means from rigid connection with the support means for unblocking the blowout preventer path of travel.

10. The rig substructure of claim 1 wherein the support means further comprises strut means including means for rigidly connecting the strut means diagonally across the substructure blocking the Christmas tree path of travel and for unfastening the strut means for rigid connection with the substructure for unblocking the Christmas tree path of travel.

11. The rig substructure of claim 1 further comprising pipe supporting means for supporting the lower ends of pipe joints racked on the substructure comprising pipe support means, means mounting the pipe support means on one side of the substructure for movement between a first position generally parallel to the floor for supporting the pipe joints and a second position depending from the floor.

12. The rig substructure of claim 11 wherein the pipe supporting means comprises strut means extending from adjacent the underlying surface to the pipe support means and means for disconnecting the strut means from supporting engagement with the pipe support means.

13. The rig substructure of claim 12 wherein the strut means extend diagonally from adjacent the free end of the pipe support means to the support means adjacent the underlying surface.

14. The rig substructure of claim 12 wherein the strut means depend from adjacent the free end of the pipe support means and include pad means on the lower end thereof.

15. The rig substructure of claim 14 wherein the last mentioned pad means include means hingeably connecting the same to the support means.

16. A method of moving a rig from a well having a Christmas tree thereon, the rig being of the type having a drawworks units, a substructure including means intermediate the sides and ends thereof defining a path of tool movement into the well, and a catwalk, defining together an alignment axis, the method comprising

moving the substructure, as a unit, in a direction transverse to the alignment axis.