US 3125171 A
Abstract available in
Claims available in
Description (OCR text may contain errors)
March 17, 1964 w. N. STEWART in 3,125,171
OFFSHORE DRILLING EQUIPMENT Filed Oct. 27, 1958 4 Sheets-Sheet 1 VV////am A o/on Jfewarzjfl INVENTOR.
aflzm awwf/ March 17, 1964 Filed Oct. 27, 1958 W. N. STEWART Ill OFFSHORE DRILLING EQUIPMENT 4 Sheets-Sheet 2 W/ ///O'/77 lVo/a/z Jfewarl, ZZ'
ATTORNEY March 17, 1964 w. N. STEWART m OFFSHORE DRILLING EQUIPMENT 4 Sheets-Sheet 3 Filed 001'.- 27, 1958 W////c7/77 /V0/a/2 Jfe war/,2?
ATTORNEY March 17, 1964 w. N. STEWART m OFFSHORE DRILLING EQUIPMENT Filed Oct. 27, 1958 u a /l- 4 Sheets-Sheet 4 INVENTOR.
QMZZWU/K United States Patent 3,125,171 ()FFSHORE DRILLING EQUWMENT William Nolan Stewart 111, Houston, Tex., assiguor to Zapata (DE-Shore Company, Houston, Tex., a corporation of Delaware Filed Get. 2.7, 1958, Ser. No. 769,791 2 Claims. (Cl. 175-5) This invention relates to the drilling and servicing of submerged wells and consists particularly in novel apparatus and method for stably mounting and supporting the well casing, including wellhead instrumentalities, upon the water bottom and drilling the well by the use of power means carried on a free floating vessel brought to the immediate vicinity of the well casing.
Heretofore, offshore or submerged wells, particularly oil wells, have been drilled either from elaborate, massive, permanent or semi-permanent installations, actually artificial islands, built upon the water bottom and extending to a platform above the surface of the water, or from free floating vessels which have been connected to the wells by complicated, flexible elements which are diflicult to disassociate from the well or the vessel in case it is necessary for the vessel to leave the scene, as in case of an impending storm. The permanent platform method is very expensive and often may not be justified in view of the uncertainties in oil well exploration. Furthermore, such permanent structures must be very strongly built so as to withstand the bulfeting forces of wind and water as well as colliding vessels. Attempts to drill submerged wells from freely floating vessels, also, have necessitated very substantial expenditures in special equipment in an eifort to accommodate the drilling equipment to motion due to waves, wind, and tide while permitting ready location of the well in case it is necessary for the vessel to leave the vicinity.
In some recent instances, submerged wells have been drilled with the use of submerged wellhead and drill powering equipment which have obvious disadvantages. On the other hand, it has not been practical heretofore to mount a conventional drill powering means on a free floating vessel and connect the power means to the well by a simple drill string, as is used in ordinary land drilling.
Accordingly, the main object of the present invention is to provide novel means and method for drilling a submerged well, particularly an oil or gas well, with the use of powering equipment carried wholly on and by a free floating vessel and without the need of special flexible drill strings and casings.
Another object is to provide novel means for supporting and protecting an oil well drilled into a submerged formation.
Another object is to provide a novel well support frame which, while of relatively light and inexpensive construction, is capable of supporting and protecting the usual well head instrumentalities.
. Another object is to provide guard and support structure for a submerged well, including a platform above the surface of the water for mounting workover instrumentalities.
Still another object is to provide vessel mounted power equipment and a submerged well casing construction which are adapted to manipulate and receive a powered drill string with suflicient lateral play to accommodate the relative motion of the vessel, without unduly straining any of the parts.
Briefly, the present invention consists in a power swivel which is mounted for vertical and limited swivelling motions on an upright trolley rigidly carried by the vessel. The usual draw works are provided for controlling the vertical motion of the swivel and the drill string connected thereto. The string extends over the side of the vessel 'of vertical leg 25 as a protective bumper.
and into a hollow leg of the novel well support and guard frame, which leg serves as the upper portion of the well casing. A longitudinally-extensible coupling is provided in the drill string and swivelling is provided between the power swivel and the mounting trolley so that, together with a certain amount of lateral play provided between the drill string and casing, the rocking and swaying of the vessel due to wind, wave, and tidal action is accommodated without undue straining of the drill string or casing.
In the accompanying drawings which illustrate the invention, FIG. 1 is a side view of the novel well support and guard structure and a drilling barge anchored alongside the same.
FIG. 2 is a top view of the well guard and support structure.
FIGS. 3 and 4 are side views of the well guard and support structure. (Taken at to each other.)
FIG. 5 is a somewhat schematic representation of the top portion of the well guard and support structure, showing the casing and wellhead equipment and also indicating the position of the barge during the drilling operation, parts being broken away and sectioned.
FIG. 6 is a schematic front view showing the upper parts of the well guard and support structure and the vertical trolley with travelling block and power swivel mounted thereon and connected to a drill string with an expansible joint, parts being sectioned.
FIG. 7 is a side view of the parts in FIG. 6, but showing the travelling trolley and its appendages inclined, as during rolling of the barge, parts being sectioned.
FIG. 8 is a detail horizontal section taken substantially on line 8-8 of FIG. 7.
' FIG. 9 is a side view of the upper portion of the well guard and support structure showing workover apparatus mounted thereon.
The novel drilling apparatus consists broadly in a free floating vessel or barge 1d having suitable anchors attached by means of chains 11 for stabilizing the barge at the drilling site. Mounted on the barge are a crane, generally indicated at 12, and other necessary drilling equipment 13, including the usual draw works and pumps, storage equipment and handling machinery for casing and tubing, and storage facilities for drilling fluid, as well as living quarters for the crew. Projecting sidewardly from the deck of the barge is a cantilever platform 14 upon which is mounted a derrick 15 having the usual pipe mounting racks 16 and crown block (not shown) at the top. Rigidly mounted at the center of the derrick is a fabricated I-beam guide or trolley 17 which mounts for longitudinal movements therealong (FIGS. 6-8) the travelling block 18 and a power swivel hydraulic motor mechanism 19. The power swivel, represented externally, is a commercially-obtainable hydraulic unit.
Stably mounted on the bottom of the body of water beneath cantilever platform 14 is a rigid, welded well guard and support structure 20 of general tripod form, including hollow legs 25, 26 and 27, leg 25 being vertical and legs 26 and 27 being tilted with respect to leg 25 and to each other, as shown in FIGS. 3 and 4. The three legs are mutually secured together and braced by transverse strut members 28. At the bottom of the tripod structure, is a mud pad 29 consisting of a horizontal platform secured to the tripod legs near the bottom extremities thereof.
At the top of the tripod structure, is a combination bumper and platform mounting frame, including relatively short, vertical posts 30 and 31 extending, respectively, along the upper parts of legs 26 and 27 and secured thereto by short cross pieces 32 and 33, and welded at their lower ends to the legs. A network of vertical legs 34 and horizontal brace pieces 35 extends around the outer side Horizontal pieces 35 are secured directly to pipe 25 by radial struts 36. Topmost horizontal piece 35 is continued to legs 26 and 27, as at 37 and 37a and a piece 33 completes the uppermost bumper framing. intermediate and lower horizontal bumper pieces 35 are extended to legs 26 and 27 by pieces 35 and 49. Directly connecting vertical leg 25 and tilted legs 26 and 27 at the top are diverging horizontal pieces 41 aligned horizontally with previouslymentioned element 35 of the bumper. A platform 42 is provided on uppermost horizontal braces 38 and 41 and guard rail structure 43, 4-4 projects above the bumper framing, its legs 43 being respectively aligned with previously-mentioned vertical bumper elements 3t and the center one of elements 34. Guard rail 44 extends entirely around the upper part of the tripod and has curved corners of rather large radii.
The tripod structure just described constitutes a guiding jacket for tubular piles 45, 46 and 4-7, snugly received in legs 25, 25 and 27 and driven securely into the formation 43 at the bottom of the water. The jacket structure is designed to extend from the water bottom slightly above the maximum water level for maintaining the conventional wellhead instrumentalities, generally designated at 49 (FIG. above the Water. All of the upper parts of legs 25, 26 and 27, the upper bracing members 28 and the bumper elements are jacketed, as indicated at 5G, by a suitable non-corrodible material, such as Monel metal. Pile 45 extending through vertical leg 25 constitutes the upper element of the well casing structure, as will be mentioned hereafter. An inner casing member is shown at 51. A drill fluid return line is provided at 52.
As best shown in FTGS. 6 and 7, travelling block 18 has lateral arms 53, having rollers 54, running in the side channel of I-beam 17. As shown in detailed FIG. 8, the rollers loosely fit the I-beam channels, being merely generally guided thereby. The power swivel, having hydraulic pressure and exhaust lines 55, and drilling fluid line 56 attached thereto, also has lateral arms 57 mounting rollers 58, similar to rollers 54, running along the I- beam channels. Play is provided between rollers 53 and the I-beam channels to permit a certain amount of tilting of the power swivel with respect to the trolley. Arms 57 have pivoting connections 59 with the power swivel casing which is supported from block 18 by means of a hook 60 and pivoted loop 61.
The power swivel has a depending drive shaft 62 which is threadedly secured to the end of drill string 63. FIG. 7 shows the power swivel much closer to the wellhead than would be the case in practice. The tilting of the power swivel and resultant flexing of the drill string to accommodate the tilting of the trolley is correspondingly exaggerated, for clearer illustration. Mounted in the drill string within the well is a longitudinally extensible coupling or slip joint 64, such as a bumper sub (FIG. 5), which accommodates relative vertical motions of the drill barge and well.
In the operation of my novel offshore drilling apparatus, the well guard and support apparatus is first transported to the site and placed upon the water bottom, as with the use of crane 12, shown in FIG. 1. It is feasible to use this type of well guard and support structure in water up to 150' deep, when the structure is of steel and in even deeper water when the structure is formed of light metal such as aluminum, the limitations being in the ability of the crane to handle the jacket structure. After the tripod structure is mounted on the water bottom, with mud pad 25 resting on the mud, hollow pipe piles are driven through the jacket legs into the submerged structure for firmly anchoring the well guard device. Vertical leg 25 is, of course, positioned directly over the point of drilling and pile 45 extending therethrough serves as the upper well casing member. As the drilling proceeds, an inner, reduced casing member 51 is run and appropriately cemented in the well known manner.
FIG. 7 shows trolley member 17 tilted to illustrate how the novel drilling apparatus accommodates rocking of the barge and the resultant relative motion between derrick 16 and trolley 17 and the stationary well casings and wellhead structure. Wellhead instrumentalities 49, such as a blowout preventer and master valve, are of such types as to permit a certain amount of lateral play of drill string 63 therein. This play, together with permissible flexing of the drill string itself, is sufficient to accommodate rocking of the barge without undue straining of the drill string. Such rocking motion, longitudinally as well as laterally, is further facilitated by the non-rigid mounting of power swivel 19 relative to trolley 17 and travelling block 13. The opening 7 it in platform 14 is adequate to accommodate all lateral play of the drill stem incident to rocking of the barge. Relative vertical motion between the casings and wellhead and the barge are accommodated by slipjoint 64 provided in the drill string at a suitable point within the casing. Such a slipjoint positioned at a fixed point above the bit, insures the maintenance of a substantially uniform load on the bit, irrespective of vertical movements of the barge and drilling equipment mounted thereon.
FIG. 9 shows the novel well guard and support struc ture utilized as a workover platform, thus dispensing with the necessity of maintaining a special drill barge at the location. A somewhat extended platform is provided at 65 and mounted thereon is a portable tower 66 and an engine 67 and winch 68. Wellhead instrumentalities are shown at 69.
Accordingly, there is provided means for drilling a submerged well, utilizing, substantially simpler apparatus than has heretofore been provided for the purpose, while permitting the mounting of all of the drilling apparatus on the barge itself for transport from place to place. The casing support and guard structure is substantially simpler than is required where such structure must support the complete drilling equipment. Yet, the structure is adequate for protecting the casing against wave and wind action as well as impact from floating objects such as barges. In a practical embodiment, vertical leg 25 of the jacket frame is made of 33 inch O.D. pipe, while tilted legs 26 and 27 are made of 24 inch O.D. pipe. The vertical pile is 30 inch O.D. pipe while the tilted piles are 20 inch O.D. pipe. Braces 28 are made of 10%" OD. pipe, as are horizontal bumper pieces 36, 38, 39, and 4t) and vertical pieces 30. All of the legs and brace structures are firmly welded together in a rigid structure. I have found that this type of well guard and support structure will withstand an impact of a freely-floating 300 ton barge travelling at 2 knots.
The full guard rail 44 is of particular importance in permitting the drilling barge to be positioned about the well as desired, for instance, with its nose into the wind to reduce the pull on the anchors. In case the wind should shift, or, if for other reason it is desirable to do so, the vessel can be swung around the tripod without departure from the protecting bumper rail.
The flexing and vertical and lateral play provided for the drill string and its powering means are adequate for the purpose, so that the gimbal-mounted rotary, as previously mounted on the drill barge, and the complications incident to the mounting of the drilling equipment in or above the water upon a permanent or semi-permanent in stallation are avoided. The invention may be modified in various respects as will occur to those skilled in the art and the exclusive use of all modifications as come within the scope of the appended claims is contemplated.
1. Olf shore drilling apparatus comprising a hollow casing projecting from the water bottom to the vicinity of the surface of the water, a hollow pile received within said casing and firmly embedded in the water bottom, a floating vessel anchored alongside and independently of said casing, a platform projecting beyond the edge of said vessel and subject to rocking action relative thereto, drill powering means mounted on said platform above said casing and pile, well head instrumentalities mounted on the upper portions of said casing and pile, and a torque transmitting, longitudinally flexible drill string extending from said powering means through said platform and said instrumentalities and said hollow pile, said casing and instrumentalities terminating substantially below said platform and said powering means to expose a substantial length of said string for flexing during rocking of said vessel, there being substantial clearance between said string and said instrumentalities and upper portions of said casing and pile permitting lateral play of said string to accommodate flexing thereof.
2. Apparatus for use in performing work in a well in a submerged formation comprising a hollow pipe extending from the water bottom to the vicinity of the surface of the water, a hollow pile received in said pipe and firmly driven into the water bottom to form a well casing, a floating vessel anchored alongside said pipe but structurally disconnected therefrom, a platform projecting from said vessel over said casing, drill powering equipment carried by said platform and constrained for rocking action therewith about the center of gravity of the vessel and a drill string extending from said powering equipment into said casing for operating a well tool, there being a substantial unrestrained length of said string between said powering equipment and said casing to accommodate the flexing of said string due to rocking of said vessel.
References Cited in the file of this patent UNITED STATES PATENTS Re. 24,083 McNeill Nov. 1, 1955 89,794 Rowland May 4, 1869 285,628 Jones et al Sept. 25, 1883 496,729 Fairchild May 2, 1893 525,795 Palmer Sept. 11, 1894 1,175,725 Dunbar Mar. 14, 1916 1,829,304 Schroeder Oct. 27, 1931 2,001,576 Johnson May 14, 1935 2,026,879 Ferguson Jan. 7, 1936 2,515,540 Willey et a1 July 18, 1950 2,637,978 Evans et a1 May 12, 1953 2,699,321 Nelson Jan. 11, 1955 2,854,215 Cox et a1 Sept. 30, 1958 2,906,500 Knapp et a1 Sept. 29, 1959 3,004,612 Kofahl Oct. 17, 1961 UNITED STATES PATENT OFFICE CERTHHCATE OF CORRECTHIN Patent N0. 3,l25,l7l March 17, 1964 William Nolan Stewart III It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.
Column 3, line 9, for "element" read elements line 34, for "channel" read channels e-;-column 4, line 75, before the comma insert and subject to rocking action relative thereto column 5 line 1 strike out "and subject to rocking action relative thereto Signed and sealed this 14th day of July 1964 @EAL) Attest:
ESTON G. JOHNSON EDWARD J. BRENNER Attesting Officer Commissioner of Patents