US3244242A - Drilling equipment - Google Patents

Description

April 5, 1966 P. A. WOLFF 3,244,242

DRILLING EQUIPMENT I Original Filed Dec. 21, 1956 4 Sheets-Sheet l INVENTOR PA L A. WOLFF ATTORNEY April 5, 1966 P. A. WOLFF DRILLING EQUIPMENT 4 Sheets-Sheet 2 Original Filed Dec. 21, 1956 m H TF N 0. 0 m m Wm w Q 1W A L 8 M 5 M U m .x 7/ I: l r ,1, w v mm m 9 w B5 7 April 5, 1966 A. WOLFF I 3,244,242

DRILLING EQUIPMENT Original Filed Dec 21, 1956 4 Sheets-Sheet 5 INVENTOR WOLFF ATTORNEY April 5, 1966 P. A. WOLFF DRILLING EQUIPMENT 4 Sheets-Sheet 4 Original Filed Dec. 21, 1956 INVENTOR WOL FF ATTORNEY W 3 3 5 x m K e k 3; L A Q g 8 P 5 5 6 4 2 3 3 I s 2 k F 2 W a 6 y 7 F EE- v w Y 9 2 B 5 5 .15 3 3 2 v 7 k United States Patent 3,244,242 DRILLING EQUIPMENT Paul A. Wolff, Oklahoma City, Okla., assignor to Kerr- McGee Oil Industries, Inc., a corporation of Delaware Continuation of application Ser. No. 629,961, Dec. 21, 1956. This application Sept. 19, 196i), er. No. 57,066 1 Claim. (Cl. 175-9) This application is a continuation of application Serial Number 629,961, filed December 21, 1956, and now abandoned.

This invention relates to improvements in equipment for forming bore holes in earth formations.

In the art of obtaining valuable deposits in earth formations, such as petroleum deposits, it is frequently desirable to form a multiplicity of bore holes grouped together at one location. The bore holes of the group, except a bore hole having a substantially vertical axis, are of the directionally controlled type so that a single station at the location may function to withdraw deposits from a number of differently located areas about the station. This type of arrangement results in a substantial saving in equipment cost and operating personnel.

In the past, a multiplicity of bore holes have been formed by following one of a number of different methods. According to one method a permanent platform is constructed at the location of the drilling site, whether on dry land or on land underlying a body of water. In the latter case, the platform is ordinarily supported by a plurality of piles driven into the underlying land bottom to locate the platform above the surface of the water. The platform is constructed to at least support a drilling rig including drawworks and power equipment, other equipment required for the drilling operation being supported on the ground adjacent the platform, or on a floating tender or barge in the case of a platform located above submerged land. With an arrangement of this type it is necessary to move the drilling rig relative to the platform in order to drill a multiplicity of bore holes closely grouped together at the site of the platform. The platform may be initially constructed of an adequate size to support the drilling rig when moved to different positions thereon, or the size of the platform must be increased when it is determined that formation of a multiplicity of bore holes is desired. The required movement of the drilling rig is ordinarily accomplished by skidding the drilling rig relative to the platform by means of a tractor when the platform is located on dry land, or by a tug when the platform is located above a body of water. In view of the great mass of the equipment involved such skidding of the drilling rig is a time consuming, tedious operation and great care must be taken to prevent damage to equipment or injury to personnel. In addition, this operation requires relocation of certain equipment and repiping of connections. This method of forming a multiplicity of drill holes is highly uneconomical since expensive equipment is put out of operation for an extended period of time. The latter disadvantage is particularly manifest when the platform is located above water since weather conditions may prevent the use of tugs for skidding the drilling rig at the time this operation is scheduled.

Another conventional practice, applicable to the formation of a multiplicity of bore holes in earth formations submerged beneath a body' of water, employs a drilling rig non-movably mounted on a mobile platform, such as a barge which may be submersible or non-submersible. 'According to this method the platform is moved to different positions to determine location of the desired bore holes. It is difiicult to perform this operation, whether the mobile platform be of the submersible or non-submersible type, due to wave action. Further difficulties are present when employing a mobile platform of the submersible type in which bottom reaction is utilized to stabilize location of the platform during the drilling operation. Submersible mobile platforms include a base portion which is submerged to the land bottom and is usually sunk into mud or silt overlying the land bottom. Under these circumstances, when the platform is moved slightly to permit the drilling of one of a number of closely positioned bore holes, it frequently happens that the base portion tends to slide on the land bottom toward a depression made by the base portion when in a previous location. Consequently, it is necessary in many cases to fill depressions in the land bottom before movement of the platform to a new location.

Mobile platforms of the submersible or non-submersib-le or floating type are provided with a drilling opening, such as a drilling slot, over which the drilling rig is mounted and through which the drilling operation takes place. The necessity of a drilling opening makes it more difficult to form a multiplicity of closely located bore holes in submerged land since the degree of permissible movement of the platform relative to a formed bore hole or bore holes is materially restricted. Drilling openings present similar operational difficulties when moving the platform to its initial location. Furthermore, the presence of a drilling opening inherently decreases the strength of a mobile platform, whether of the submersible or non-submersible type, and structural problems are presented. Moreover, it is difficult if not impossible in many instances to erect a required production platform after one or a multiplicity of bore holes are drilled without first moving the drilling platform away from the bore hole or holes. It is the usual practice to so move the platform carrying the drilling rig and to employ a barge or floating tender supporting a crane and other equipment required for the construction of a production platform. In addition to the'construction of a production platform, employment of a crane may be desirable or necessary in connection with other phases of all drilling operations, whether performed in non-submerged land or in submerged land from a mobile platform of the submersible or non-submersible type.

The difficulties described above may be overcome in part by employing a multi-well type of derrick. In this type of derrick the transverse dimension at its upper or crown block end are relatively large, with a corresponding increase in the transverse dimension at its base, to permit the crown block to be located on the central longitudinal axis of the derrick and also at a plurality of positions displaced from the central longitudinal axis. Thus by employing a multi-well derrick a plurality of bore holes may be drilled without requiring relative movement between the derrick and a fixed platform or between a mobile platform and the ground. However, multi-well derricks are relatively expensive and it would not be economically feasible to partly overcome the difliculties described above by using multi-well derricks in place of existing single-well derricks or to use only multi-well derricks in future equipment. Also, due to the greater mass of multi-well derricks it is ordinarily more expensive to provide permanent platforms for their support. Moreover, their use in connection with mobile platforms requires a larger drilling opening because of the increased dimension at their base and thus amplifies the structural problems in this type of construction. Furthermore, multi-well derricks do not in any way provide a solution to certain existing problems such as erection of production platforms, for example.

It is therefore an object of the invention to provide a novel combination of novel apparatus and structure which overcomes the problems outlined above.

Another object is to provide a novel drilling apparatus including a single-well drilling rig capable of drilling a multiplicity of bore holes.

Another object is to provide a nove drilling apparatus including a mobile platform supporting a single-well drilling rig capable of drilling a multipi'city of bore hoes in submerged land and without requiring relative movement between the mobile platform and the submerged land.

Still another object is to provide a novel mobile platform for use in performing drilling operations in submerged land which eliminates conventional drilling openings and their attendant disadvantages.

A still further object of the present invention is to provide a novel mobile platform for performing drilling operations in' submerged land which permits the construction of a production platform without requiring movement of the mobile platform andmakes it possible to construct the production platform from the mobile platform.

A still further object is to provide a novel drilling apparatus which eliminates the necessity of" providing an auxiliary crane.

The foregoing and further objects and features of the invention will appear more fully from the following detailed description considered in connection with the accompanying drawings whichdisclose' several embodiments of the invention. It is to be expressly understood, however, that the drawings are designed for purposes" of illustration only and not as a definition of the limits of the invention, reference for the latter purpose being had to the appended claim.

In the diawings, in which similar reference characters denote similar elements throughout the several views:

FIGURE 1 is adiagrammatic Presentation of novel apparatus provided by the present invention, the apparatus being shown with a submersible vessel and in operation to construct a production platform;

FIGURE 2 is a diagrammatic showing of the apparatus of FIGURE 1 in a position to perform a; drilling operation;

FIGURE 3' is an end view of a portion of the apparatus provided'by the present invention;

FIGURE 4 is a plan view of? the apparatus shown in FIGURE 3;

FIGURE 5 is a view in section taken: along the lin 5'--5 of FIGURE 2;

FIGURE 6 is a diagrammatic view illustrating a phase of operation ofa portion of the apparatus provided by the present invention;

FIGURE 7' is a plan view of: another embodiment of the present invention;

FIGURE 8 is a side elevational. view of the: apparatus shown in FIGURE 7; and

FIGURE 9 is a view, partially in section, taken along the line 9"9 of FIGURE 7.

The present invention provides a novel apparatus designed for operations in which drill holes are formed in earth formations, including land or off-shore operations, in which the supporting means for the drilling rig comprises a cantilever type of: platform providing substantially unrestricted space in the region of the platform and a novel arrangement for' mounting a drilling structure, such asa mast or derrick, on the platform for movement in a plurality of different directions to locatethe drilling rig at different positions relative to the platform and sent substantially unrestricted access to the heads'of the.

drill holes and thereby allow the convertible structure to be used as a crane. for erecting a production platform without requiring movement. of' the supporting means.

Although the present invention is described in connection with a mobile platform of the submersible type, it is to be expressly understood that the novel features provided by the present invention may be employed with mobile platforms of the non-submersible or floating and elevatable type, as well as with non-mobile platforms whether erected on dry or submerged land.

As shown in FIGURES 1' and 2 of the drawings, the novel apparatus'provided by the present invention is disclosed in connection with a submersible vessel It designed for use in performing submarine operations. The submersible vessel It may be constructed in a manner disclosed and claimed in application Serial No. 617,127, filed October 19, 1956,. now abandoned for Submersible Vessel for Submarine Operations, and comprises a base 11 including four elongated hollow cylindrical members connectedtogether attheir cornersto form a rectangle, and a platform 13 supported above the base 11 by an openframe structure including four elongated hollow cylindrical stabilizing: members14 located at the corners of the rectangular base 11 and a plurality of supporting columns 15 extending upwardly from each of the cylindrical members 12 The platform 13 includes elongated beams 16 positioned longitudinally and transversely of the vessel and joined'to the upper ends of the stabilizing members 14 and the columns 16 which support a deck 17 and a deck-house 18 providing. housing for equipment and living quarters for operating. personnel. As shown in FIGURE 4, the elongated beams 16 include spaced intermediatebeams 21 extending longitudinally of the vessel between opposite sides of the vessel, one of the latter sides of the vessel being. viewed in FIGURE 1. As fully described in: the .copendingapplication, the submersible vessel 10 may be submergedata desired location of a submarine operation with thebase 1-0 resting on the land bottom 19 and with the platform. 13 spaced above the surface of the water 20 to provide wave clearance asshown in the drawings.

As mentioned above, the present invention provides a novel apparatus which" may be used to perform a submarine operation such as. a drilling operation, in which case the apparatus may be considered as comprising a drilling rig; or used to perform a lifting operation, in which case the apparatus may be considered as comprising a crane, and a' novel arrangement for mounting the apparatus on a platform, such as the platform 13 of the submersible vessel It in a novel manner for increasing the flexibility and' usefulness of the apparatus when employed for performing a drilling operation or a lifting operation. As shown in FIGURES 2, 3 and 4 of the drawings the supporting columns 15 extendingupwardly from the base member 12 at one; sideof the vessel- 10 support the ends of the elongated beams 21, which may be of I- shap'ed cross-section. Elongated beams ZS'and 26, which may also be of I-shaped' cross-section, each have one end joined to one ofthe supporting columns 15-to which one end of the beams 21 are joined and extend outwardly from one side of the vessel, i.e., the side of the vessel on theright as viewed in FIGURE 1, and terminate a substantial distance therefrom- As shown in the drawings, the elongated beams 25 and 26-not only extend outwardlyfrom one side of the platform- 13 but also project outwardly beyond the base 11 and the open frame structure including the stabilizing members 14 and the supporting columns on the same side of the vessel. The beams 25 and 26 are' each braced by ap-luralityof diagonal tubular members 27, 27 each having their inner ends joined to respective supporting columns 15 of the vessel at a level below the deck 13 andtheir upper ends joined to respective elongated beams 25 and 26 at points spaced from the side of the vessel. The region of the platform 13 to which the elongated beams25 and 26 are joined may be strengthened by diagonal tubular members 28 joined to the supporting columns 15 at points below the deck 13 and extending upwardly and being joined to transverse I-beams 21 and to adjacent supporting columns 15 as shown particularly in FIGURES 2 and 3. For a purpose that will appear more fully below the elongated beams and 26 are not interconnected transversely at any point along their length outboard of the side of the vessel.

The elongated beams 25 and 26 may be considered as comprsing extensions of the beams 21 of the vessel and the upper surfaces of the elongated beams 25 and 26 and of the beams 21 preferably lie in a common plane. Continuous tracks 36 and 31 are mounted on the upper surfaces of elongated beams 25 and 26, respectively, and on or about respective beams 21 of the vessel for slidably supporting a carriage 32 for longitudinal movement relative to the elongated beams 25 and 26 and the platform 13 of the vessel. Stops 33 are located at the outboard ends of the tracks and 31 to limit outward movement of the carriage 32 relative to the elongated beams and stops 34 are located at the inner ends of the tracks 30 and 31 to limit inward movement of the carriage 32 relative to the platform.

The carriage 32 comprises a plurality of openframe trusses 35 each of which may include a lower chord member 36, and upper chord member 37, vertical members 33 and bracing 39. The trusses 35 are positioned transversely of the elongated beams 25 and 26 and connected together in vertically disposed longitudinally spaced relationship by upper and lower longitudinal connecting members and 41 and by diagonal members 42 and vertical members 43. As shown more clearly in FIGURE 5, the lower longitudinal connecting members 41 include a vertical web 44 having an upper edge joined to the lower ends of the vertical members 38 of the trusses 35 and a lower edge joined to a horizontally disposed flange 45. The flanges 45 of the lower longitudinal connecting members 41 are adapted to rest upon the tracks 30 and 31 and slidably support the carriage 32 thereon. The tracks 30 and 31 are similar, and as shown in FIGURE 5 the track 36 may include a bearing surface 46 for sliding contact with the bottom surface of the flange 45 and enclosure members 47 contacting the upper surfaces of the flanges 45 on both sides of the web 44 to prevent upward movement of the carriage relative to the elongated beams 25 and 26 or the deck of the vessel.

A platform 50 is slidably mounted on the carriage 32 for movement transversely of the elongated beams 25 and 26. The platform 56 includes a continuous deck 51 mounted upon transversely disposed longitudinally spaced members 52 interconnected by longitudinal members 53. The top sides of the upper chords 37 of the trusses 35 include a track 54 adapted to slidably support the platform 50 by means of bearing members 56 joined to lower sides of the transverse members 52 of the platform 50. The tracks 54 and the bearing members 56 may be similar to the arrangement shown in FIGURE 5 in which the bearing plates 46 and the enclosing flanges 47 are attached to the top side of the upper chord members 37 and in which the flanges 45 are joined to the lower side of the transverse members 52. If desired, the enclosing flanges 47 may be discontinuous as shown by clamping devices 56 in FIGURE 3. Stops 57 and 58 are located on opposite sides of the carriage to limit transverse movement of the platform 50.

In accordance with the principles of the present invention the platform 50' is provided with means for supporting apparatus capable of performing a submarine operation or a lifting operation. The apparatus is shown in the form of a convertible drilling mast, although the principles of the present invention may be used in connection with a drilling derrick, which is capable of use as a drilling rig or as a lifting crane. The foregoing means includes transversely spaced standards 66 and 61 mounted on the deck 51 of the platform 50 at medial points along its length, longitudinally and transversely disposed angular braces 62 being provided to stabilize the standards. The standards 60 and 61 carry pivotal supports 64 and 65, respectively, for the lower ends of spaced elongated truss members 66 and 67, respectively, of a drilling mast 68. As shown in FIGURE 1, the other ends of the truss members 66 and 67 are joined together at the upper end of the drilling mast 68 and support a crown block 69. The drilling mast 68 is positioned to perform a drilling operation, as shown in FIGURE 2, by means of gin poles 76 and 71 each having their upper end releasably attached to respective elongated structures 66 and 67 of the drilling mast 68, such as at point 72 of the elongated structure 66, .and their lower ends pivotally connected at 73 and 74 to movable members 75 and 76 of hydraulic cylinders 77 and 78, respectively. The hydraulic cylinders 77 and 78 are mounted on platforms 79 and 8%), respectively, extending from the inboard side of the platform 50 in alignment with respective structural members 66 and 67 of the drilling mast. 'If desired, as shown in FIGURE 2, the carriage 32 may be provided with inwardly extending platform-s 81 located beneath the platforms 79 and to provide support for the latter platforms. The deck 51 of the movable platform 50 also supports drawworks 82 located outboard the standards 60 and 61. The drawworks 82 has a connection to a fast line 83 which passes over the crown block 69 located at the upper end of the drilling mast. The drilling mast may be of the collapsible type and each of the structural members 66 and 67 of the drilling mast may be provided with slots, such as slot 84 shown in FIGURES 1 and 2, for slidably receiving the upper ends of the gin poles 70 and 71 when detached from respective structural members of the mast. Downward inboard movement of the drilling mast about the pivot points 64 and 65 may be controlled by the drawworks 82 through the fast line 83 to lower the drilling mast to a horizontal position as shown in broken lines in FIGURE 1. The platform 50 also includes a rotary drilling table 85 positioned in alignment with the drilling axis of the mast 68 when in drilling position as shown in FIGURE 2.

The provision of the spaced elongated beams, the carriage 32 and the movable platform 50 provides an arrangement permitting the drilling of a multiplicity of bore holes without changing the submerged position of the vessel. With the carriage 32 and the platform 50 relatively positioned with respect to each other and with re spect to the elongated beams 25 and 26 in \the manner shown in FIGURE 4, the rotary table 85 of the drilling apparatus, and hence the center line of the drilling rig, is located intermediate the elongated beams 25 and 26 and outwardly from the side of the vessel. By moving the platform 50 transversely toward either of the beams 25 or 26 and/ or by moving the carriage 32 longitudinally of the elongated beams inwardly and outwardly with respect to the vessel, the rotary table 85 may be moved to a multiplicity of different positions about the posltion shown. The well drilled when the rotary table 35 is centrally positioned with respect to its other possible positions maybe along a substantially vertical axis, while the axis of other wells drilled when the rotary table is at a position displaced from its central position may be deflected outwardly from the axis of the central well to reach deposits in the earth formation located appreciable distances from the vertical aXis of the central well. The platform 50 may be moved relative to the carriage 32 and the carriage 32 may be moved relative to the elongated beams 25 and 26 by means of hydraulic cylinders,

not shown, which may be anchored to a stationary member and positioned to direct forces against the platform or carriage to apply force thereto of the proper direction and a magnitude necessary to provide the desired movement. Also, the platform and carriage may be moved relative to their respective support by means of chains or cables driven by hydraulic motors. It is to be expressly understood that the elongated beam 25 and 26 may be spaced from each other and may extend outwardly from the vessel greater distances than shown in the drawings to increase the permissible relative movement between the carriage and the vessel and to accommodate a carriage 32 of greater width to allow increased transverse movement of the platform 50.

The present invention provides novel means associated with the drilling apparatus described above for converting the drilling mast 68 into a crane for use in performing a liftingoperation. As shown in FIGURES l, 2 and 4, the foregoing means comprises the hydraulic cylinders 77 and 78 having movable members 75 and 76 pivotally connected to the lower ends of the gin poles '70 and 71, respectively. When the drilling mast is in drilling position as shown in FIGURE 2 the movable members 75' and 76 are fully contracted within respective cylinders and locked in that position by any suitable means to form a rigid triangular structure including the gin poles- 70 and '71, the lower portions of the elongated structures 66 and 67 of the mast and the platform 50; When it is desired to convert the drilling mast into a crane, the gin poles 70 and 71 are extended upon application of fluid under pressure to the hydraulic cylinders to effect outward movement of their movable members and thereby rotate the drilling mast in a clockwise direction about the pivot points 64 and 65' of the elongated structures 66 and 67, the stroke of the movable members is suflicient to rotate the drilling mast in a clockwise direction to a position in which its center of gravity is located outboard a vertical plane passing through the axes of the pivots 64 and 65. When rotated to this position the drilling Inast remains rigidly supported by the triangular structure including the gin poles 7t) and 71. In FIGURE 6 the hydraulic cylinder 77 is shown with its movable member 75 moved outwardly to extend the gin pole 70'. Supports 9t) and 91, each including inclined hearing plates 92 and 93', respectively, are positioned on the deck 51 of the platform 50 in the region of respective gin poles to stabilize the movable members of the hydraulic cylinders when in extended position. The bearing plates 92 and 3 are inclined at an angle corresponding to the angle of inclination of the movable members and are positioned to contact the inside of the movable members as they move upwardly upon energization of the hydraulic cylinders. After the drilling mast is rotated to a position in which its centerof gravity is outboard a vertical plane passing through the pivots 64 and 65,.further clockwise rotation of the drilling mast is controlled by a cable 100 passing over a block 101 located at the upper end of the drilling mast on its inboard side and having one of its ends 102 fixed to the vessel and its other end attached to a power driven drum apparatus 103 the cable 100 being located on the inboard side of the drilling mast. Before the drilling mast is supported by the cable 100, and before further clockwise rotation is possible, the upper ends of the gin poles are disconncted from the mast. The gin poles may remain disconnected from the mast when supported by the cable 1% or auxiliary slots may be provided on the elongated structures 66 and 67 for slidably receiving the upper ends of the gin poles. As shown inFIGURE 2 a guide member 164, secured to the elongated structure 66, provides a slot 105 for slidably receiving the upper end of the gin pole 70. In FIGURE 1 the drilling mast is shown rotated clockwise to a position beyond the position determined by the stroke of the hydraulic cylinders in which the upper end of the gin pole 7% lies in the slot 105. The provision of auxiliary slots adds lateral stability to the structure when employed to perform a lifting operation. As shown in FIGURE 1, when the apparatus is converted to perform a lifting operation, an article to be lifted, such as a section 1% of a production platform, is attached to a travelling block 167 carried by the fast line 83 under control of the drawworks 82;. Thus,

by operating the drum apparatus 103 and the drawworks 82 the travelling block 1%7 may be moved to different vertical and horizontal positions outwardly from one side of the vessel as determined for the most part by the angle of the drilling mast.

In accordance with another feature of the present in vention the tracks 3d and 31 provided on the upper sides of the elongated beams 25 and 26 are extended inwardly along the deck 17 of the vessel a sufficient distance to allow inward movement of the carriage 32 to a osition in which its outer side lies inboard of the side of the vessel to which the elongated beams are attached. This position of the carriage 32 is shown in FIGURE 1. This arrangmen-t permits the drilling mast, when converted to function as a crane, to operate in the region between the elongated beams 25 and 26, that is, directly above the well or wells that may have been drilled by the apparatus when functioning as a drilling rig in the manner described above. This feature together with the provision of spaced elongated beams 2-5 and 26 permits the erection of a production platform without requiring movement of the vessel although a plurality of Wells may have been drilled. In FIGURE 1 the apparatus is illustrated operating as a crane and ositioning the section 1% of a production plat-form onto a previously positioned section 108. The absence of transverse connecting members between the elongated beams 25 and 26 permits unobstructed erection of the production platform and overcomes the prior necessity of moving the vessel after completing the drilling operation and before a production platform could be erected.

In the embodiment of the invention shown in FIG- URES 7, 8 and 9 of the drawings, the transversely movable platform 50 rotatably supports a table having a continuous deck 121 upon which the standards do and 61 for the drilling mast 63, the draw-works 82 and the rotatable table 35 are mounted. The deck 121 of the table 120 is supported by an annular member 122 depending downwardly from the underside of the deck 121 and including an enlarged lower portion 123- presenting a fiat annular bearing surface 124 on its bottom side, as viewed in FIGURE 9, and an external circumferential shoulder 125 An annular member 126, of U-shaped cross-section, is attached to the deck 51 of the platform 50 and is shaped to receive in sliding engagement the enlarged portion 123 and the circumferential shoulder 125 of the member 122 to allow relative rotational movement between the platform 59' and the table 120 and to securely attach the table to the platform. An annular gear 127 may be formed on the internal surface of the annular member 122 for effecting rotation of the table 129 relative to the platform 50 upon rotation of pinion 123 driven by shaft 129. With this arrangement the table 120 is maintained stationary relative to the platform 59 during drilling operations while the platform 50 and the carriage 32 may be moved relative to each other and to the elongated beams 25 and 26 in the manner discussed above, however, during phases of operation in which the drilling mast is converted for use as a crane, the table 12%) may be rotated relative to the platform 5i) to thereby rotate the converted drilling mast about a vertical axis. In order to allow the latter rotation, the block 161 is universally mounted at the upper end of the drilling mast. If desired, the power driven drum 103 and the fixed end 192 of the cable 100 may be movable transversely of the vessel to allow extended horizontal rotation of the converted drilling mast.

In operation, after the submersible vessel 10 is submerged to the underlying land bottom at the site of a desired drilling operation, the drilling mast 68 is moved to its drilling position and locked in that position by means of the gin poles 7d and 71, as shown in FIGURE 2. The first bore hole may be formed with its axis vertically disposed, and the platform 54) and the carriage 32 may be positioned relative to each other and to the elongated beams 25 and 26 to locate the vertical axis of the first bore hole at the approximate center of the open area defined by the spaced elongated beams. After completion of the first bore hole the carriage may be moved inwardly or outwardly with respect to the vessel and/or the platform may be moved transversely relative to the carriage 32 to locate the drilling table 85 in spaced relation with respect to the first bore hole. Thereafter a second bore hole may be formed directionally and deflected outwardly from the axis of the first bore hole. By moving the carriage 32 and the platform 50 to different positions additional directional bore holes may be formed without requiring movement of the vessel. The drilling rig is operated in a conventional manner when employed to form bore holes, the deck of the vessel being provided with a pipe rack 110 and a skid board 111 for this purpose; the skid board being preferably supported by the platform to follow movements of the drilling mast. After the desired number of bore holes are completed, the carriage 32 is moved inwardly along the tracks 30 and 31 to a position inboard the side of the vessel from which the beams 25 and 26 extend, as shown in FIG- URE 1. The drilling mast may then be converted into a crane by energizing the hydraulic cylinders 77 and 78 to extend the gin poles 70 and 71 and rotate the mast in a clockwise direction to a position in which its center of gravity lies outboard a vertical plane passing through the pivot points 64 and 65 at the lower end of the mast. The upper ends of the gin poles are then slidably connected to the mast and the cable 100 and the drum apparatus 103 supports the mast and controls further clockwise rotation. The converted mast may then be utilized to erect a production platform over the group of bore holes or wells without requiring movement of the vessel 10. In this operation the converted mast may be employed to lift sections of a production platform from an adjacent barge by utilizing the travelling block 167 as a lifting means and for positioning the production platform sections over the group of Wells and lowering the sections to the land bottom in the manner shown in FIGURE 1. This performance is possible since the carriage 32 is moved inboard of the elongated beams 25 and 26 leaving an open space, between the beams 25 and 26, above the bore holes. In the embodiment of the invention shown in FIGURES 7, 8 and 9 the converted drilling mast has greater utility as a crane inasmuch as it may be rotated to the right or to the left of the longitudinal axis of the vessel and its movement is not restricted to one plane as is the arrangement shown in FIGURE 1. It is to be understood that the drilling mast may be converted for use as a crane and so operated with the carriage 32 located at any position along the tracks 30 and 31. In the erection of a production platform the feature of moving the carriage inboard the side of the vessel permits operation of the crane directly above a bore hole or group of bore holes; however, for other lifting operations location of the carriage may be immaterial while in still other operations it may be advantageous or necessary to move the carriage to its extreme outboard position.

Although several embodiments of the invention have been disclosed and described herein, it is to be expressly understood that various changes and substitutions may be made Without departing from the spirit of the invention. For example, the principles of the present invention are applicable to forms of drilling rigs in addition to the mast type, While the feature of providing apparatus operable as a drilling rig or a crane and the feature or providing drilling equipment longitudinally and transversely mounted relative to its base have general utility and are not restricted in use with a submersible vessel but may be employed with non-submersible vessels or with non-mobile platforms erected over dry or submerged land. Furthermore, the feature of providing a cantilever platform may be employed for supporting well work-over rigs, and it is to be expressly understood that the term submarine operation used in the specification and the claim describes drilling rigs as well as work-over rigs. Reference therefore will be had to the appended claim for a definition of the limits of the invention.

What is claimed is: Offshore drilling structure comprising: submersible base means; open frame supporting structure supported entirely by and extending upwardly from the base means; deck means supported by the open frame structure above the base means; platform means, joined to the deck means and receiving support entirely from the base means, the platform means extending outboard of the deck means, the open frame structure and perimeter of the base means and providing a drilling opening outboard of the deck means, the open frame structure and perimeter of the base means; continuous track means supported by the deck means and the platform means; carriage means mounted for movement along the continuous track means onto the platform means; movable deck means mounted on the carriage means; means for moving the movable deck means transversely relative to the continuous track means; and drilling apparatus, including a drilling table, mounted on the movable deck means capable of being supported over the drilling opening provided by the platform means.

References Cited by the Examiner UNITED STATES PATENTS 1,829,304 10/ 1931 Schroeder.

2,399,656 5/1946 Armstrong 6l46.5 X 2,592,448 4/ 1952 McMenimen 6l46.5 2,628,818 2/1953 Graham 6l46.5 X 2,699,042 1/ 1955 Hayward 6l46.5 2,975,601 3/1961 Thorson 6l46.5 3,001,592 9/1961 Lucas 6l46.5 X 3,001,593 9/1961 Suderow 6l46.5 X 3,001,594 9/1961 Suderow 6l46.5 X 3,081,600 3/1963 Davidon 6l46.5

EARL J. WITMER, Primary Examiner. ILLIAM L MU HA xaminer.

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