US2606003A - Off-shore drilling - Google Patents

Description

1952 J. M. MCNEILL 2,606,003.

OFF SHORE DRILLING Filed Ail 28. 1948 3 Sheets-Sheet 1 Ll m W14 w I 4770 NE).

Aug. 5, 1952 J. M. MCNEILL OFF'I-SHORE DRILLING 3 Sheets-Sheet 2 Filed Aug. 28. 1948 Wyn/70k.

aim; MAM MA,

A 774 N! y;

Aug. 5, 1952 J. M. M NEILL 2,606,003

- I OFF SHORE DRILLING Filed Aug. 28, 1948 3 Sheets-Sheet 3 l 'atenied Aug. 5, 1952 EJNETE YATES PAT ENT GF'FE C'E 2,606,003 orr snonn' DRILLING James -M. McNe'ill, Placentia, Calif assignor to Union Oil Gompany of California, Los A geles, Calif., a corporation of California Application August 28, 1948, Serial No.46,-573

8 Claims. 1

This invention relates generally to'the drilling of oil and gas wells informations underl-ying deep water. More particularly, this 7 invention I relates to the drilling of wells into formations underlying the ocean or other'rough and deep waters wherein the drilling rig "is-mounted on a floating barge.

In the prior art, wells have been drilled into submarine formations by the construction of solid installations on the floor of the body of water to provide a stationary framework or structure from which a platform is supported which carries the drilling rig and other equipment. Such permanent structures as rock'fill's, piling and caissons have been'employed for this purpose. Other prior art relates to submerging one of several 'kindsof floating barges in the water over the formation to be drilled so that when the hull of the barge and/or-special extensible supports rest onthe bottorn,the superstructure of the barge is supported above the water level. The drilling equipment is carried on a platform supported by the superstructure.

The methods described in the prior art are limited by the'depth of the water in which they can be successfully carriedon -and 'also--by"-the extent of the wave action tending to destroy or upset the installation. The'eoonomics of permanent deep water installations is prohibitive and the size of the submersible barge and other equipment necessary 'for operating in water deeper than 20 to 150 feet renders the equipment unwieldy, and unsafe, especially during rough weather.

It is, therefore, an object of this invention to provide a'method and apparatus for the-drilling of oil and gas wells in rough and/or deep water such as in open seas, large lakes, riverchannels possessing currents and tidal actionand the-like.

It is another object of this invention to provide a rotary drilling method for the drilling of oil or gas wells from a floating barge anchored in the open sea or in rough water.

Another object of this invention is lid-provide a mobile apparatus for drilling wells which is especially suitable for use in rough water ranging from 150 to 400 feet or more in depth.

It is another object of this invention to provide a method and apparatus for supportihg a part of a rotary'drill string onthe'deck of the floating barge such that substantially a 'con stant weight can be maintained on the drill bit and such that continuous contact is maintained between the drill bit and the formation being drilled during the vertical and lateral shifting .2 of the floating barge resulting from wave action.

"It is another object of this invention to *provide a conductor tube communicating. between the floating barge and a point on the-ocean floor which provides for the return ofthe rotary drilling'fluid from the well bore to-thefloatingbarge, and which includes means for icompensatingrfor the vertical and lateral shifting of the barge resulting from surface wave action.

Itis another object: of this invention to provide a method and apparatus ".fori'mountin'g a rotary drilling'table on the "surface of a oating barge whereby the rotary :drilling table is. maintained in substantially a horizontal iplanezduring the vertical and lateral'shifting 'of the zfloating barge resulting from surfacewave action.

It is another object of this invention to -provide an arrangement of equipment onafloat-ing barge to be employed for drilling purposes wherein the arrangement contributes to the maximum stability of the barge during: vertical and lateral shifting occasioned by -'surfacezwave action.

Briefly, this invention relates 'to'the drilling of oil and gas wells into formations underlying the ocean or other rough and/orrdeep waters floor of the ocean. The barge is equipped with conductor tube which isof relatively'large' diameter relative to thediameter of the ifdrillrstlfin and other tools and is of sufficient length to extend from the barge to an anchoragerinzor' on the submarine formation to. be drilled. The conductor tube is 'fitted'with flexible andzextensible joints in order to accommodate the. usual vertical and horizontalshiftin'g of the-anchored'barge relative to the formation resulting from'surface wave action. lhe lower end of the "conductor tube is anchored to the formation by. any suitable method. Forexample, a connecting-pipe-is hammered or otherwise positioned intheformation surface and'the'conductortube'is coupled to the protruding end of the;1pipe. Alternatively a large block of cement enclosing. a connecting pipe is submerged at the drillingisitesin such :a way that the cementiblock-re'stson thexo'c'ean floor'with the upper end of theipipe extending vertically through the top side of the cement block. The conductor :tube is thenifastened .to the vertical extension of the connecting:- pipe. The drilling tools are thenpassed fromithebarge through the conductor tube to the formation. The drilling operation itself may be effected by any suitable method such as cable tool drilling, sonic vibration actuated tool drilling, rotary drilling and the like.

Among the various drilling methods which may be employed in this invention it is preferable to employ rotary drilling. For this purpose the barge is equipped with a crane, guyed mast equipped with draw works, or other such device for raising, lowering and supporting the drill string; a rotary drilling table; a driving means such as a gasoline engine, electric motor or the like; a pipe storage rack; drilling fluid storage tanks and pumps, and other equipment necessary for rotary drilling. The pipe rack preferably extends below the hull of the barge and provides for the vertical storage of pipe in order that greater stability of the barge may be obtained thereby. The rotary drilling table is suitably mounted on the barge at the top of the conductor tube.

In the preferred method for mounting the drilling table, it is suspended within a torque ring in such a manner that the axis of suspension includes one diameter of the drilling table and one diameter of the torque ring. The torque ring is suspended on a ring gear such that it has free movement about a suspension axis through its diameter which is perpendicular to the suspension axis of the drilling table.

The aforedescribed method of suspension. which is commonly referred to as gimbals, permits the drill string to be rotated through its coupling to the drilling table in a manner which minimizes the excessive bending of the drill string which otherwise occurs when the drilling table must rotate in a fixed plane relative to the deck of the barge and when the barge is then shifted horizontally relative to the bore hole in the formation or when the deck of the barge is inclined to the horizontal plane as a result of wave action. The horizontal shifting of the barge relative to the bore hole bends the drill string above the bore hole and inclines the top of the drill string at varying small angles relative to the vertical. The gimbals allow the drilling table to be rotated in substantially constant planar relationship relative to the formation. The gimbals also permit the drilling table to adjust its rotational planes continuously relative to the movement of the barge to conform to longitudinal axis of the drill string, which is generally -perpendicular or nearly perpendicular to the horizontal plane, during its rotation and during the shifting and pitching of the barge as a result of wave action.

In drilling from the barge by the rotary method a means is inserted into the drill string at a suitable location to maintain the drill bit in substantially constant contact with the formation during the Vertical and lateral shifting of the barge due to wave action. One modification of such means comprises an extensible splined sub which transmits torque at varying positions of extension and contraction. The weight of the upper section of the drill string which is above the splined sub is supported from a crane on the deck of the barge, while the weight of the lower section of the drill string which is below the splined sub rests on the drill bit and provides a constant loading for the drill. The movement of the barge during wave action raises and lowers the guyed mast, or other support, relative to the formation thereby raising and lowering the upper section of drill string. Such movement is, however, without effect on the lower section of drill string.

During rotary drilling a drilling fluid of any suitable type is circulated downwardly through the drill string, out the drill bit and rises through the annular space and into the conductor tube from which it is withdrawn and pumped to the screening and. storage tanks.

Figure 1 shows an overall diagrammatic view of one form of this invention in which rotary drilling equipment is mounted on a floating barge which is anchored over a formation being drilled and wherein the rotary drilling tools are passed from the barge to the formation through an intervening conductor tube having flexible and extensible joints.

Figure 2 shows a cutaway view of the rotary drilling table showing its suspension, mounting, driving means and other related equipment.

Figure 3 shows a slip joint which is one modification of the extensible means by which the conductor tube adjusts its length during the vertical and lateral shifting of the barge.

Figure 4 is a flexible ball and socket type modification of the flexible joint which is employed to provide the conductor tube with flexible means to adjust its shape during the vertical and lateral shifting of the barge.

Figure 5 shows a deck view of the anchored barge.

Figure 6 shows a splined sub which is inserted in the drill string to allow the drill string to extend and contract as the crane on the barge is raised and lowered relative to the formation whereby the drill bit can be maintained in substantially continuous contact with the formation being drilled during such raising and lowering.

Figure 7 shows a section of the splined sub shown in Figure 6 taken along the line 1-1.

Referring now more particularly to the attached Figures 1 and 5, the floating barge is anchored over the formation by means of lines [2 leading from each of the four corners of the barge to suitable anchorages such as concrete blocks, dolphins, hooks and the like. Suspended counterweights I3 hang from lines i2 and provide additional stability to the anchored barge. Barge I l is equipped with guyed mast l4 and pulley hook I5 or other suitable means for raising, lowering and supporting thedrill string 30, drilling fluid storage tanks [9,drilling fluid pump 19a,drilling fluid line 20, drill pipe storage rack 23, and a gasoline driven engine I! or other power source, drive shaft l8, rotary drilling table 16 andconductor tube 24 which is flexible and extensible and communicates between barge II and connectingpipe 29 lodged in the submarine formation. The conductor tube is of large internal diameter relative to the external diameter of the drill string and may, for example, be from two to ten or more times larger.

The pipe storage rack provides for the vertical storage of the drill pipe and extends below the hull of the barge such that the center of gravity of the pipe being stored is below the center of gravity of the barge as a whole. The mass of the stored pipe helps to stabilize the barge during wave action.

Rotary drilling table 16 is mounted on bearings which permit its surface to remain in substantially a horizontal plane during the vertical and lateral shifting of the barge as is hereinafter described. Rotary table I6 is rotated by gasoline engine I! through shaft l8.

Conductor tube 24 communicates between rotary drilling table l6 and the formation and comprises fiexible joints 2'5 and 21 and extensible 'ter-rubber hose. the ball in socket type described hereinafter,

'joint to provide compensation for the vertical and lateral shifting of the barge relative tothe formation.Flexible joints 25 and 21 shown in Figure 1 comprise sections of heavy large diame- Other flexible joints such as articulated pipe and the like may also be employed. Extensible joint 26 is a large diameter slip joint of the typedescribed hereinafter in detail.Conductor tube 24 is anchored to the formation through large concrete block 28 and connectingpipe 29.Com1ecting pipe 29 is shown as extending a short distance into the formation in order to sealthe well bore and prevent the intrusion of extraneous water and the loss of drilling fluids. If desired, a well casing can be cemented into the well bore below the connecting pipe in order to improve the seal.

Drill string 39 compriseskelly 22 which is supported by means of swivel joint 2! and hook I5 and draw works Ilia from guyed mast l4, drill pipe, asplined sub 32 or other extensible torquetransmitting means which is inserted in the string of drill pipe at some desired point by means of collar joints 3! and 33, anddrill bit 34. The splined sub divides the drill string into two sections. The weight of the upper section is principally supported from the barge by guyed mast l4 through hook l5, swivel joint 2! andkelly 22. The weight of the lower section is rested on thedrill bit 34 at the bottom of bore hole 35 and provides a substantially constant loading of the drill bit. As the floating barge is shifted vertically or horizontally relative to the formation as a result of wave action, the crane l4 raises and lowers the upper section of the drill string relative to the formation and the splined sub expands and contracts to prevent any vertical movement of the lower section of the drill string by the wave action. Torque is continuously transmitted between the upper and lower sections during all positions of extension and contraction of the splined sub.

The rotation of rotary table l3 by power source I! and shaft I8 is transmitted to thekelly 22 by means of Kelly bushings and the entire drill string is rotated thereby. Drilling fluid flows from storage I9 through pump I911 andline 20 into swivel joint 2!, downward through thedrill string 39 to drillbit 34, out ofdrill bit 34 into theannular space 36 between thedrill string 30 and the formation 35, up through the annular space tocasing 29 and throughcasing 29 andconductor tube 24 from which it isremoved through a, line below the top of the conductor tube, screened, and returned to storage [9.

Referring now more particularly to Figure 2,conductor tube 24 is fitted into a, circular hole in the center ofdrilling platform 54. Below thedrilling platform 54 the conductor tube passes throughdeck 49 andhull 59 of the barge and extends downward to the connecting pipe lodged in the formation being drilled. Theconductor tube 24 is tightly sealed in the hull '59 in order to prevent leakage of sea water into the hold of the barge.

Kelly 22 is coupled to rotary drilling table 38 by means of Kelly bushings 31. Drilling table 38 is suspended within torque ring 39a by bearof the torque ring. Torque ring 39a is suspended bybearings 49 in journals 4| which provide for the free movement of the torque ring about a suspension axis through journals '4! which includes the diameter of the torque ring which is perpendicular to the suspension axis of drilling table 38 throughbearings 39. Journals 4| are in turn mounted onring gear 43 which is supported ondrilling table platform 54 byroller bearings 45.Ring gear 43 is maintained in continuous contact withbearings 45 by means of bearings which ride in groove 46 cut into the periphery ofring gear 43 and which are held in a fixed axis of rotation relative to thedrilling table platform 54 by means'of rigid anchoringarms 44 which are fastened to the drilling table platform '54.Ring gear 43 is driven by meshing gear 4! on power shaft l8. Shaft I8 is mounted in bearings housed injournal 48 which is secured todrilling table platform 54.Drilling table platform 54 is secured tobarge deck 49.

The rotation of shaft I8 by a suitable power source, such as agasoline engine, rotatesring gear 43 about a fixed axis in a fixed rotational plane which is parallel to the plane ofdeck 49 of the barge ll.Ring gear 43 rides onroller bearings 45 and any forces tending to dislodge the ring gear 43' from its fixed axis and plane of rotation relative tobarge deck 49 are opposed by the peripheral bearings held by anchoringarms 44. The rotation ofringgear 43 is transmitted through journals 4| andbearings 43 to' torque ring 39a. Torque ring 39a is rotated about an axis perpendicular tobarge deck 49 and its surface is inclined at various angles to its plane of rotation which angles are determined by the instantaneous positions of the. barge relative to the drill string. The movement of torque ring 39a in a rotational plane which is generally, but not always, inclined to the surface of the torque ring causes a rotary thrust onbearings 39 which suspend rotary drilling table 38. The rotation of table 38 occurs in a plane which is in general not coincident with the plane of torque ring 39a and is about an axis which is substantially. vertical. The rotation of drilling table 38 in substantially a horizontal plane transmits a torque throughKelly bushings 31 tokelly 22.Kelly 22 is coupled throughcollar coupling 52 to drill string pipe 53, which is in turn fastened by suitable couplings to the remaining components of the drill string.

The shifting of the barge H relative to the submarine formation being drilled as a result of wave action bends the drill string above the formation and in the conductor tube. This bend ing is taken up by the elasticity of the drill string which, in certain cases, may be purposely fabricated from spring steels or from special alloy steels which are highly elastic and have high shear strength. The bending of the drill string tends to incline the longitudinal axis of the kelly at some small angle relative to the vertical. The small inclination of the longitudinal axis of the kelly at the point of coupling to Kelly bushings 31 is accommodated by the sef-adjustment of drilling table 38 and its coupling through bearing 39, torque ring 39a,bearings 43 and journal 4| toringgear 43 whereby the table is inclined and the torque exerted onkelly 22 is substantially about its longitudinal axis and such that the forces tending to rotatekelly 22 about an axis other than its longitudinal axis are thereby minimized or are nullified.

The drilling fluid flows downward throughhollow kelly 22, coupling52, drill pipe 53 through and upward through theannular space 36,

throughconnectingpipe 29 or other form of casing and throughconductor tube 24. The returning drill fluid containing the drill cuttings is removed from theconductor tube 24 through discharge line from which it is pumped to screening for removal of the drill cuttings and thence to drilling fluid storage tanks IQ for re- Referring more particularly to Figure 3,annular ring 59 is integrally and coaxially attached to the lower end of slidingmember 55. Theannular ring 59 moves coaxially within sheath 5'! between the lower limit imposed byconstriction 60 in sheath 5'! and the upper limit imposed byseal ring 58 which is threaded to the upper end of sheath 5! and prevents the complete withdrawal ofannular ring 59 and integrally attached slidingmember 55 fromsheath 51. The annular space between slidingmember 55 andseal ring 58 is sealed by packing gland 5811 which prevents leakage of sea water into the joint and loss of drilling fluid from the joint. The top of slidingmember 55 is threaded through a collar joint to the upper section of the conductor tube adjacent to the slip joint. The lower end of sheath 5'! is internally threaded tomember 56 which is the lower section of the conductor tube adjacent to the slip joint. The entire slip joint is provided with a large diameter longitudinal channel which permits the passage of the drill string through the entire joint.

Referring now more particularly to attached Figure 4,members 63 and 64 comprise two machined concentric spherical Sections which are threaded topipes 62 and 65 respectively. The movement of innerspherical member 63 relative to and in concentric relationship to outerspherical member 64permits pipe 62 which is attached to innerspherical member 63 to be inclined relative topipe 65 which is attached to outerspherical member 64. The varying inclination ofpipes 62 and 65 which comprise sections of the conductor tube respectively provides the conductor tube with flexibility about the joint.

Referring more particularly to Figures 6 and 7, drill string member 10 is threaded to the top of the splined sub 61 by means of collarjoint coupling 69. Sheath 68 is internally splined withlongitudinal splines 14 which engage the longitudinal splines of annular ring '13 which ring is integrally attached to the upper end of slidingmember 15. Splined annular ring [3 slides lengthwise in engagingspline 14 on the inside of sheath 68 between the upper limit imposed by the fiat machined constriction II of collarjoint coupling 69 and theseating 72 at the lower end of engagingsplines 14. The lower section of sliding member extends through the lower end of sheath 68 and seal ring 18, the latter being threaded to the lower end of the sheath. The annular contact between seal ring 18 and slidingmember 15 is sealed by packing gland 16 which prevents loss or gain of drilling fluid from or to the sub. The lower end of slidingmember 15 is threaded to adjacent drill string member 11 through collar joint coupling 16. The slidingmember 15 and splinedannular ring 13 in engagement withsplines 14 of sheath 68 permits the sub to be extended and contracted within the limits hereinbefore described and under conditions which maintain the sliding member and sheath in aligned coaxial relationship. A torque applied to the upper section of the joint is transmitted through sheath 68 andsplines 14 tosplines 13 and slidingmember 15 which in turn trans- 8 mits the torque to the lower section or the drill string under varying positions of extension and contraction.

In the drilling of a well by rotary methods ac cording to the process of this invention, a barge is stocked with the essential items of equipment hereinbefore described and is floated to the location of the formation to be drilled. A concrete block which encloses a large diameter connecting pipe is submerged at the locationand is positioned on the floor of the sea over the drilling site. Alternatively, a section of well casing is forced into the formation to be drilled by hammering, hydraulic drilling, twisting or the like.

The barge is then anchored by lines from each of its four corners to anchorages secured to the ocean floor, such as concrete blocks, dolphins, hooks and the like and counterweights are suspended along the mid-section of the lines to increase the stability of the anchorage as hereinbefore described. The lower end of the conductor tube is fastened or coupled to the connecting pipe extending into the large cement block and/0r into the formation. Such coupling can be effected by employing long connecting pipes which extend upward from the floor of the ocean to shallower water to which a diver can be dispatched to complete the attachment. Alternatively, purely mechanical, remote control methods may be employed to eifect the coupling,

Following the communication of the conductor tube between the barge and the connecting pipe extending upward from the ocean floor by any suitable method, the drill string is assembled and inserted into the conductor tube by means or a crane mounted on the barge. The drill string comprises, in general, a drill bit, a section of drill pipe, a splined sub of the type hereinbefore described, an additional section of drill pipe and a kelly from which the remaining members of the drill string are supported. The Kelly bushings are wedged in the drilling table around th kelly in order to couple the drill string to the drilling table. The circulation of drilling fluid into the kelly down through the drill string and upward through the pipe and conductor tube is begun.

The drill string is lowered in the conductor tube until its entire weight rests on the drill bit in contact with the formation or the cement block in the bottom of the connecting pipe, in which condition the splined sub is completely contracted. The guyed mast and draw works are then employed to raise the upper section of the drill string a distance which is somewhat greater that its maximum rise and fall resulting from wave action on the barge. Under these conditions the splined sub is never fully contracted as a result of wave action. The vertical component of the movement of the barge relative to the formation as a result of wave action i taken up by the extension and contraction of the s lined sub and the drill bit is maintained in continuous contact with the formation during such movement of the barge.

The drilling operation is begun by applying power to the rotary drilling table. The rotation of the drill string in conjunction with the weight of the lower section of the drill string on the drill bit causes the drill bit to pass downwardly through the successive strata. During the drilling operation the vertical component of the movement or the barge as a result of the wave action .is continuously absorbed in the extension and contraction of the splined sub. As the drill bit continues its downward path through the forma- 94 tion. the splined sub is gradually extended to maintain such motion relative to the variable position of the barge with respect to the formation.

After the bore holehas been drilled a depth equivalent to a drill stand, the drill. string is raised by the draw works and guyed mast and is blocked into a supporting position by bushings on the rotary drilling table. The kelly is then detached and an additional stand of drill pipe is attachedto the drill string. The kelly isattached; the drill string is lowered until its entire weight is on the drill bit. The draw works and guyed mast are then employed to raise the drill string the calculated distance which will prevent complete contraction of the splined sub as a, result of a downward thrust-of the barge due to wave action as has been described before. The Kelly bushings are replaced, the drilling table is rotated and the drilling is then resumed in the manner described above for the first drill string;

After the drilling has progressed some distance into the formation, such asfor example 200 to 1,000 feet or more, it is desirable to relocate the splined sub in the drill string at a new position which willgive an increased and more optimum loadingon the drill bit. For this purpose the drill string is progressively raised by the guyed mast and draw works and disassembled until the splined sub is reached and removed. Drill pipe is then added to the drill string and lowered into the conductor tube and well bore until an amount has been added such that the drill string-in the conductor tube and bore hole corresponds in weight to the desired loading of the drill bit. The splined sub is reinserted and additional drill pipe is added above the splined sub until the drill bit approaches the bottom of the well bore. The kelly is attached to the drill string and the drill string is lowered until it is supported on the drill bit. The drill string is raised a distance which will prevent complete contraction of the splined sub as a result of the downward movement of the barge during wave action and is coupled to the drilling table by Kelly bushings. The drilling is then resumed according to the methods described hereinbefore.

Following the completion of the well to the i desired depth, the well bore is completed in any desirable fashion. The floating barge; is. uncoupled from the connecting pipe or other form of well casing and is moved to a new location for the drilling of additional wells,

Although the foregoingdescripticn of this inventionhas pertained specifically to its application to rotary drilling, it is apparent that the broad scope of this invention comprises the method of drilling an oil or gas well from a heating barge wherein there is connected between the well bore and the barge a conductor tube having both flexible and extensible means to compensate for the movement of the barge relative to the formation during wave action.

In one modification of'this invention the well bore is drilled with cable tools or other percussion-type drilling tools. The conductor tube is coupled between the barge and the underlying formation in the manner described hereinbefore for the case of rotary drilling. A cable tool drilling string comprising, for example, a swivel, a set of jars, a sinker bar and a drill bit is lowered on the end of a cable into the conductor tube and connecting pipe until it rests at the bottom of the hole. The drillstring is alter: nately raisedby any suitable power source such.

ing is conducted in extremely rough Waters. 3 The movement of the barge relative to the formation is. compensated for in the conductor tube by the flexibleand extensible means described herein:- before.

The vertical component of the movement of the-barge whichraises and lowers the cable tool:

relative to theformation causes no serious prob.-

lems and in general no, special means is provided to compensatelfor. such-movement. The raising and'falling of the drill string is generally. adjust.-

edso that. when the barge. is approximately at its mean height above the formation the cutting. of the formation is greatest- When the barge. isat its. minimum height during the wave. cycle;

the vertical stroke ofthe cable tool is shortened and the drillingtool may even rest on the floor of the-bore hole As. the barge risesto its maximum height during the wave cycle the vertical.

stroke of the cabletoolisiincreased and-thedrill bit may .evenbe temporarily lifted completely. from contact with the bottom-of the borehole. Under these-conditions the. drilling takes. place mostly during those periods. of. the, wave cycle.

that the barge-is near or. is passing through the. mean elevation. This discontinuity of the drill: ingpresents no serious problem andin extremely rough'water is justified-by.thesimplicity of. the equipment and itsrelative-freedom from mechanical failure. i

There is=ageneraldanger of blowouts in.drill-, ing high pressure formationsby the cabletool method and especially in those cases .where :the bore hole contained littleor. no'water seepage. or. added wash liquid. Insuch casestheconductor tube is suitablymachined and fabricated to withstand the formation pressure and the top of the conductor tube is cappedwith suitable fitting-to permit thevertical stroke of they cable and at the same time: provide a-seal ,to retain the formation pressure By employing"the conductor tube as a part of the sealing means; the wellbore can bedrilled, by' cable tools through high-pressure formations.-

The present-'apparatusmay' also be-usedin drilling off-shore oil'wells by means, of percussion tools which are placed: in contact withthe formation and are actuated by sonici vibrations which serve to shatter and disintegrate the rock formation in contact with the drill bit.

Having fully described and illustrated the principles of my invention I wish to claim the following:

1. An apparatus for drilling a well in a formation underlying deep water which is subject to wave action, which apparatus comprises a floating barge, a conductor tube communicating between said fioating barge and said formation and providing a fiuid tight path therebetween, said conductor tube comprising a series of tubular sections joined together by at least two flexible joints and at least one extensible joint, said flexible joints and extensible joint being positioned in the conductor tube between the barge and the produced by wave action, means for anchoring said, conductor tube to said formation, a drill bit and a drill string, the outer diameters of which are substantially less than the inner diameter of said conductor tube, and means for driving said drill bit and drill string.

, 2. An apparatus according toclaim 1 wherein said extensible joint is a slip joint.

3. Anapparatus according toclaim 1 wherein a pipe storage container is mounted within and extends below said floating barge to providefor the substantially vertical storage of drill pipe and wherein the mounting of the pipe storage container places said contained pipe principally below the deck of the barge thereby lowering the center of gravity ofthe barge and tending to stabilize said barge under wave action.

4. An apparatus for drilling a well in a formation underlying deep water which is subject to wave action, which apparatus comprises a floating barge, a conductor tube communicating between said floating barge and said formation and providing a fluid tight path therebetween, said conductor tube comprising a series of tubular sections joined together by at least two flexible joints and at least one extensible joint, said flexible joints and extensible joint being positioned in the conductor tube between the barge andthe formation and cooperating to provide compensation for the vertical and horizontal movement of said floating barge relative to said formation produced by wave action, means for anchoring said conductor tube to said formation, a drill bit and a drill string, the outer diameters of which are substantially less than the inner diameters of said conductor tube, means for rotating said drill string, means for pumping a drilling fluid downwardly through a central cavity in the drill string to the bottom of the bore hole, thence upwardly through the annular space between said drill string and said formation, and thence upwardly through the annular space between said drill string and said conductor tube. 5. An apparatus according to claim 4 wherein said drill string comprises an upper section and a lower section, said upper and lower sections being joined by an extensible joint for transmitting torque at varying positions of extension.

6. An apparatus for drilling a well in a formation underlying deep water which is subject to wave action, which apparatus comprises a floating barge, a conductor tube communicating between said floating barge and said formation and providing a fluid tightpath therebetween, said conductor tube comprising a series of tubular sections joined together by at least two flexible joints and at least one extensible joint, said flexible joints and said extensible joint being positioned in the conductor tube between the barge and the formation and cooperating to provide compensation for the vertical and horizontal movement of said barge relative to said formation produced by wave action, means for anchoring said conductor tube to said formation, a drill bit and a drill string, the outer diameters of which are substantially less than the inner diameters of said conductor tube, a driving means mounted on said barge and coupled to said drill string through gimbals, means for pumping a drilling fluid downwardly through a central cavity in the drilling string to the bottom of the bore hole, thence upwardly through the annular space between said drill string and said formation, and thence upwardly through the annular space between said drill string and said conductor tube.

7. An apparatus according to claim 6 wherein said drill string comprises an upper section and a lower section, said upper and lower sections being jointed by an extensible joint for transmitting torque at varying positions of extension.

8. An apparatus according to claim 6 wherein said drill string comprises an upper section and a lower section being joined by an extensible joint for transmitting torque at varying positions of extension, and wherein a support attached to said barge principally supports the weight of said upper section of said drilling string while allowing the weight of said lower section of said drill string to rest principally on a drilling foot at the bottom of the well bore.

JAMES M. McNEILL.

REFERENCES CITED The following references are of record in the file of this'patent:

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