US2923531A - Drilling - Google Patents

Description

Feb. 2, 1960 Filed April 26. 1956 FIG.

R. F. BAUER L DRILLING 5 Sheets-Sheet 1 INVENTORS' ROBERT E BAUER HAL STRATTON ATTORNEYS Feb. 2, 1960 F, BAUER ml. 2,923,531

DRILLING Filed April 26, 1956 5 Sheets-Sheet 2 FIG. 2.

INVENTORS ROBERT E BAUER t x BY HAL STRATTOIV A TTORNEYS DRILLING 5 Sheets-Sheet 3 Filed April 26, 1956 IN V EN TORS ROBERT E BAUER HAL S TRA T TON ATTORNEYS Feb. 2, 1960 BAUER ErAL 2,923,531

DRILLING Filed April 26, 1956 5 Sheets-Sheet 4 mmem ATTORNEYS Feb. 2, 1960 R. F. BAUER ETAL Filed April 26, 1956 5 Sheets-Sheet 5 DRILLING FIG. 6. m5

/44 I42 I44 F F j/ze fig IN VEN TORS' ROBERT E 8/! U5? HA L S TRA T TON A TTORNEVS United Sttes Patent DRILLING Robert F. Bauer, Whittier, and Hal Stratton, La Habra,

I Califi, assignors to Shell Oil Company and Continental 0i] Company, both of Los Angeles, Calif., both corporations of Delaware, and The Superior Gil Company and Union Oil Company of California, both of Los Angeies, Calif, both corporations of California Application April 26, 1956, Serial No. 580,850

8 Claims. (Cl. 255-25 This invention relates to apparatus for drilling and working on underwater wells.

The apparatus of the invention may be used in connection with wells under any kind of water, whether marine or fresh, but to simplify the explanation of the invention, the apparatus is described as being used in an ocean.

Offshore drilling has heretofore been principally accomplished from stationary platform structures erected at or towed to an offshore location and there rigidly anchored to the underwater formation. Of necessity these structures are massively built and, as a consequence, are cumbersome and costly both in initial fabrication and in transport. Recently techniques of drilling from a floating vessel have been developed to a point where in many circumstances platform drilling can be replaced.

This invention provides an improvement in drilling from a floating vessel.

The principal diificulty in drilling or Working on an underwater well from a floating vessel is withdrawing dri.ling and other equipment from the well and subsequently re-entering the well with such equipment.- Such withdrawal and re entry is usually required many times during the development of a well for changing bits, setting casing, etc. The movement of a floating vessel due-to wind, current, and wave action, which is almost invariably present, makes it diflicult to relocate the well once equipment is removed from it.

Copending application Serial No. 468,214, filed November 12, 1954, now Patent 2,808,229, describes in detail apparatus and methods for drilling underwater wells from a floating vessel to overcome the disadvantage of static structures. That co-pending application discloses flexible guide lines or cables for guiding equipment from a floating vessel to an underwater well. Such apparatus works well under many circumstances but under particularly adverse conditions, such as strong current or wind aCtiOn in relatively deep Water, such guide lines tend to become fouled with each other or with equipment which is to be moved to and from the well; Also, Whenever it might be necessary to move the floating vessel temporarily from the well site, it is necessary to buoy the guide lines and preferably secure them in oppositely extending directions by the use of anchors to prevent fouling of the lines while operation on the well is suspended. This required handling of the lines delays departure from the well site, which must sometimes be on short notice due to a sudden storm. The present invention provides improved apparatus for guiding equipment to an underwater well.

Briefly, this invention provides guiding apparatusfor an underwater well which does not readily become fouled with itself or with equipment being moved to and from the well; The apparatus includes an upwardly extending guide member having its lower end anchored adjacent and laterally spaced from the well. The guide member is of sufiicient strength and buoyancy to maintain itself unsupported in the water in a substantially upri ht position. Such a guide member is more rigid than a flexible wire line, and is more effective in accurately guiding equipment to an underwater well.

Preferably the guide member is hollow so that it has buoyancy and can also be used to conduct fluid to or from the Well. Thus, the guide member can serve a dual function, that 'of guiding equipment to and from the Well, and also of conducting fluid to or from the Well, if desired. In other words, the guide member can be used as a return circulation conduit for drilling mud or as a kill line for the well in the event of a threatened blow-out.

The buoyant, self-supporting guide member is readily abandoned, and no special precautions need be taken either to buoy or mark the guide member as long as it is of suflicient length to project slightly above the water. This is an important advantage, since it permits an'oi shore well site to be abandoned quickly if a storm should suddenly develop. Also, dueto its property of maintaining itself upright in the Water and being relatively rigid as compared to a guideline, an individual guide member does not wrap around or tangle with another guide member in the event that a plurality of guide members are used.

Preferably, the self-supporting guide'member has a smooth external surface and is sufliciently flexible to yield, without breaking or becoming permanently deformed, to any forces which may normally be expected to act on it near the surface of the water. In relatively shallow water this flexibility is achieved by anchoring the guide member at its lower end to a pivot. In deeper water, the guide member is of such length that it is sufficiently flexible to withstand any deflections which may occur during the normal course of operations. Thus, a buoyant tubular guide member which is left on a drill site, say during a storm, is not a navigation hazard to seagoing vessels, since, if it is struck, it is simply pushed aside. A wire line, on the other hand, might foul a ships screw, or a buoy required to support the wire line might be sufiiciently large that it would damage a ship,

it rammed.

Another advantage of the guide member of this invention is that it is of such shape as to avoid the accumulation of kelp and debris, which sometimes tends to collect on buoyed guide lines and impart forces sufliciently strong to destroy them. Any kelp or debris which might tend to accumulate on the smooth surfaces of the guide member of this invention simply'slides around the ides of the member or off the upper end of the member as wave or wind forces act to deflect the guide mernber from its normally upright position.

Another advantage of the hollow guide member as provided by this invention, is that if any temporarily used wire line or other equipment does become tangled around the guide member, a new guide member may be slipped down inside the old member, and the old member and the tangled, line can be removed, say by .being.

uncoupled at a back-off joint and slipped up over the new member, leaving the newmember in place of the old and clear of any fouling.

These and other aspects of the invention will be more accordance with the invention being lowered from a floating vessel to a well being drilled in an ocean floor; Fig. 2 is a schematic fragmentary elevation, partially in Section and partially broken away, of the apparatus drilling equipment in and out of the well;

Fig. 3 is a plan view of the apparatus taken on line 3-3 ofFig. 2;

Fig. 4 is an enlarged .view of a back-off joint in one of the guide members taken on line of Fig. 2;. I

Fig. 5 is a schematic fragmentary elevation, partilly in section and partially brokenaway,- of a guidemmber adapted to be used for return circulation of a drilling mud and as a kill line for the well; j i Fig. 6 is a schematic fragmentary elevation .showing how the guide member of Fig. 5 used for drilling mud return circulation is supported from the barge to compensate for the lost buoyancy in'the member; Fig. 7 is a schematic fragmentary elevation showing how a second guide member may be slippedfdown into and anchored at the bottom of a 'first hollo'w guide member, if-the first member should become fouled, for example, by a wire line or a pneumatic or hydraulic control line; and t Fig. 8 is an enlarged view taken on line 8 80f Fig.

7 showing in detail a mechanism for locking the second guide member inside the first. v

' Referring to Fig. 1. a well head base 15 is lowered by a plurality of supporting lines 16 in a body of water 17 from a floating barge 18 toward a -well-19 being drilled from the barge in an underwater formation 20. Each line 16 is looped around a separate'res'pective sheave 21 attached to the top of the well head base. One end of each line is connected to the barge, and the other is connected to a separate respective winch' 22 on the barge, which is anchored over the well by .a'plurality of suitable anchor lines 24 extendng in opposite directions from the barge and connectedto anchors '(not' shown), A draw works 25 and a power unit 26,-which may be of conventional type, are mounted on the barge to operate a hoisting cable 27 carried over;a crown block 28 located at the upper end of a collapsible drilling rig 29, whichis also-mounted on the barge; The travelling end of the hoisting cable carries a travelling block 30 anda hook 31 which supports a swivel joint '32; A Kelly joint 33 extends downwardly from the swivel through a Kelly bushing 34 in' the center of *a rotary table 36 mounted on gimbals (not shown) as-for ex ampl'ein a manner similar to that described inU.S.' Patent No. 2,606,003. i

The rotary table is supported on a platform 37 directly over a cellar 38 which may be located in the center of the barge as illustrated. Power is supplied to the rotary table through a shaft 39 turned by a rotary table power unit 40. r A string of drill pipe 41 is connected to the lower end of the kellyand, extends down through the. cellar, the water, a vertical conductor pipe 42 mounted in the well head base, and'down'into the well. A drill collar 43. and an under reamer drill bit 44 are attached to the lower end ofthe drill pipe for boring the well to a diameter slightly larger than, the outside diameter, of the conductor pipe 42 which is welded to. the well head base to project upwardly a relatively short distance above and downwardly a relatively great distance from the well head base. i

The wellheadbase may be positionjedinthe well by any one of several suitable means, 'for example, it may be suspended by lines 16 underneaththe.pcellar of the barge while the drill pipe is extendeddown through the well conduitto drill the well in the formation, After the well is drilled to a'sufiicient depth toreceive the conductor pipe, the well head base is lowered from the barge so that 'the conductor pipe slides down the drill ductor .pipe maybe firmly anchored in the well by pumping cement down the drill pipe to fill the annular space between the conductor pipe and the well. The under reamer may then be retracted and the drill pipe,

a drill collar and drill bit removed from the well bore, t

or drilling may be continued without removing the drill bit from the well until somelater period of the drilling operation.

V The well head base may take manyforms, and the t details of a suitable well head base are shown most clearly in Figs. 2 and 3. The well head base -is a relatively flat and wide structure which is hexagonal in shape as viewed in plan. well head base is made upof six sections 46 of I-beams of equal length welded together end to end to .form a hexagon. A separate vertical brace 47 is welded to the junctions of the ends of each of the l-beam sections 46 and connects the bottom of the well head base to the top of the well head base, whichis also formedin six sections 48 of I-beams welded together end to end to form a hexagon identical in size and shape to the bottom of the well head base.

The upper end 49 of the conductor pipe 42 extends a short distance, about two or three. feet, above the upper surfaceof the well head base. The conductor pipe extends below the bottom of the well head base for any suitable length, say twenty, to a hundred feet. An upper set of horizontal and radially extending braces 50 (see Fig. 3) are welded at their outer ends to respective joints of theends of the peripheral sections of the top of the well head base, and are-weldedat their inner ends to the outside of the conductor pipe. A lower set of horizontal radially extending braces 51 are welded at their outer ends'to the joints of theends of the peripheral sections of the=bottomofthe well head base and are welded at their inner ends to the "conductor pipe in the plane of the bottom of the wellhead base.

Referring to Fig. 2. a set of six diagonal'braces 52 extending upwardly and inwardly from the joints of the ends of the peripheral sections of the bottom of the well head base are welded at their lower ends to the base bottom and at their upper ends to the conductor I pipe just below the inner'ends of respective upper radial braces 50. a I l A plurality of separate water tight compartments 53 are attached to the interior of the wellhead base so that it maybe floated and towed to any desired location. A pad-eye 54 welded to one of the radial sections in the top of the well head base provides a conpipe and into the well, the bottom of the wellhead base venient means for attaching a tow line .(not shown).

An annular circular plate 55 having a central open ing 56 equal in diameterto the outside diameter of the" upper end of the conductor pipe is welded to ;the top surface of the radially extending braces in the top of the Well head base. The outer diameter of the plate is approximately one half the maximum dimension of the well head base top.

A pair of upwardly extending tubular guide members. 58 are attached at their lower ends to the periphery of the plate in diametrically opposed locations. Each of the guide members is made up of a pluralityof joints 60 of pipe, each joint being threaded at each end to. permit it to be coupled to another joint. Thethreaded joints are made sothat when coupled together, they present smooth external and internal surfaces. Each guide member is .of sufiicient length .to extendqabove the water surface and into the cellar of the barge.

, The guide member on-the right hand (as 'viewed in Fig. 2) side of the well is welded at its lowerend to the circular platesoqthat'it is rigidly attached to the wellhead base, but because of its. length, it is; flexible enough to accommodate, without breaking or permanent deformation, any normal movement imparted to it at the. surface by the floating barge, wave, 1 current and wind action, etc.

The periphery of the bottom of the The left hand guide member is pivotally connected to the circular plate bya pair of interlocking U-shaped links 62, one link being welded to the circular plate and the other to a closure 63 welded to the bottom of the guide member. a

The guide members may both be either pivotally or rigidly connected to the well head base, the rigid connection being preferred for deep water and the flexible connection being preferred for shallow water.

A conduit 64 connects the lower end of the right hand guide member to the conductor pipe just be.ow the top of the well head base. A check valve 65 in the conduit 64 permits fluid to flow in the conduit only in the direction from the guide member to the well bore.

With the exception of the bottom joints in the guide members, all of the joints have right hand threads at each end. The joints attached to the well head base have left hand threads at their upper ends to form backoff joints 66 with the next joint, which has a left hand thread at its lower end only. The back-off joints permit the guide members to be uncoupled near the well head base during a later stage of the drilling operation which is described below. Fig. 4 is an enlarged fragmentary view of a back-off joint showing in detail how the individual joints couple together to present a smooth and flush exterior and interior.

A drilling operation as illustrated in Fig. l is conducted as follows:

The well head base is towed to the desired location, and the drilling barge is firmly anchored over the well site. The supporting lines 16 are connected to the well head base, only the lowest joints of the guide members being in place at this time, and the tow line is disconnected. The buoyant compartments in the well head base are then flooded either by puncturing the wall of the compartments or by opening valves (not shown).

The upper ends of the supporting lines being controlled from the drilling barge, the well head base is allowed to sink and swing under the cellar in the barge, where it is held by the lines at a shallow depth below the cellar. The drill bit, drill collar and drill pipe are then made up on the barge and lowered through the conductor pipe in the well head base to the ocean floor.

A pump 67 on the barge picks up sea water from an inlet (not shown) and forces it through a flexible drilling mud hose 68 into the swivel, down through the kelly, drill pipe and out the under reamer bit. The pressure of the water forces the under reamer blades out into the position shown in Fig. 1, and the drill pipe is rotated by the rotary table turning the Kelly joint so that the Well is drilled. The bit is lowered by controlling the hoisting cable, and cuttings are washed out of the well by the sea water flowing from the bit up the annular space between the drill pipe and the well bore, no attempt being made to obtain return circulation of a drilling fluid at this time.

The drilling operation proceeds as described above until a suflicient depth is reached to permit the conductor pipe to be lowered into the well and allow the bottom of the well head base to rest on the ocean floor. Before the base is lowered the guide member joints with the left hand threads are screwed into the joints attached to the base, and additional joints are coupled to these with right hand thread connections until each guide member extends up into the cellar above the water line. The base is then slowly lowered with the winches 22 to the position shown in Fig. 2, additional guide member joints being coupled during the lowering operation so that each guide member projects above water level when the base rests firmly on the ocean bottom. The ends of the lines attached to the barge are then released and the lines are withdrawn from their respective sheaves.

The drill bit and drill pipe are left in the well while the base is lowered so that the conductor pipe is readily c ient diameter to permit the drill collars,

removed immediately or drilling may proceed to what- .ever depth it becomes necessary to replace the bit or provide for return circulation of drillingmud. -At this point it is necessary-to have apparatus which will permit equipment to be guided accurately to the well bore. One suitable form of such apparatus is shown in Fig. 2.

Referring to Fig. 2, a guide assembly 70 is adapted to slide up anddown the guide members. The guide assembly includes a left hand (as viewed in Fig. 2) sleeve 71 adapted to slide up and down the lefthand guide member. A hollow truncated cone 72 is' welded to the lower end of the left hand sleeve and adapted to nest over a matching truncated hollow cone 73 welded to the plate 55 and coaxially disposed around the point of anchoring of the left hand guide member.

A right hand sleeve 74, slightly longer than the left hand sleeve, is adapted to slide up and down the right hand guide member, the bottom of the right hand sleeve resting on the top of plate 55 around the bottom of the right hand guide member when the guide assembly is in its lowest position.

A circulating'head 75 is carried between the two sleeves by radially extending first and second brackets 76, 77 which are welded at their outer ends to the right and left sleeves, respectively, and at their inner ends to the circulating head.

The circulating head includes an upright cylindrical body' 78 having'a relatively large first vertical bore 79 beginning in the bottom of the body and extending almost half way into the body. The first bore is stepped down to a second vertical bore 80 which joins a horizontal bore 81, which opens out the left side of the body. A nipple 82 is screwed into the horizontal bore, and a flexible drilling mud return line 83 is connected to the nipple and extends up to the barge. A downwardly opening annular channel 84 is provided in the shoulder formed between the first and second vertical bores.

The second bore is stepped down to a third vertical bore 85 which extends for a relatively short distance and is then stepped up to a fourth vertical bore 86, which opens out the top of the body. An upwardly opening annular channel 87 is formed in the shoulder between the third. and fourth vertical bores.

An annular bottom closure 88 is secured by bolts 89 to the bottom of the main body of the circulating head.

The central opening 90 in the bottom closure is of slightly larger diameter than the outside diameter of the conductor pipe 42 so that the circulating head may he slipped over the upper end of the conductor pipe, as shown in Fig. 2. An annular upwardly turned lip 91 on the inner periphery of the bottom closure forms an annular channel 92 with the lower end of the first vertical bore. heavy flexible rubber sleeve into annular channels 84 and 92, and forms a well conduit seal. "A horizontal well conduit seal bore 94 in the body permits fluid pressure to be applied to the outer surface of the sleeve 93 from a line 95 extending to the floating barge.

.An annular upper closure 96 is secured by bolts 97 to the upper end of the main body of the circulating head. The central opening 98 in the upper closure is of suflibut not the drill bit, to pass'through it. An annular downwardly extending lip 99 on the inner periphery of the upper closure forms a downwardly opening channel 100 with the upper end of the fourth vertical bore. A heavy flexible rubber sleeve 10l ismolded at. each end into annular grooves 87 and 100 to form a drill pipe seal. A horizontal drill pipe seal bore 102 permits fluid pressure to be applied to the .outside of the drill pipe seal through a line 103 connected to the floating barge.

As can be seen in Fig. 2,'the circulating head is adapted to permit the drill pipe and drill collars to pass through 93 is molded at each end it, but the bore 85 is smaller than maximum diameter 'of the drill bit (shown only in phantom line) so that the drill bit,.whi ch is screwed onto the lower end of the 'drill pipe, engages the shoulder formed between the second and third vertical bores to provide means for raising and lowering the circulating head with the drill pipe.

When it is necessary toobtain return circulation, the

circulating head is lowered by means of the drill pipe, the circulating head resting on the drill bit during the lowering operation, and the sleeves slide down the guide each guide'member in a, right hand direction to cause the left handed threads of the back off -joints to unscrew. The

The right handguide sleeve slips securely down to the bottom end of the right hand guide member which is vertical even though its upper end may beinclined due to some force exerted on the surface. a

Fluid pressure is applied'to the circulating 'head through line 95 to seal the circulating head to theupper end of the conductor pipe. Once the circulating-head is sealed as shown in Fig. 2, the drill pipe is lowered further so that it enters the conductor pipe and finally reaches the bottom of the well. pressured through line 103 to permit the drill pipe to rotate within the seal and yet prevent excessive leakage of drilling 'mud, some leakage being desirable for lubrication between the drill pipe and the drill pipe seal.

With the return circulation equipment properly sealed to the conductor pipe as shown in Fig. 2, a closed circuit is provided for circulating drilling mud from a mud pit 105 on the barge, through the mud pump 67 the flexible drilling hose 68, the swivel 32, down the center of the Kelly joint and drill pipe, out the end'of the drillbit, up

the annulus between the drill pipe and the well bore, and back to the floating barge through the drilling mud return line 83 connected to the circulating head.

For relatively deep water, where the length of the mud column returning to the surface-might placea dangerous back pressure on the formation being drilled'so as to possibly rupture the formation and create a problem .of lost circulation of the drilling mud, air is pumped'down theiright hand guide member, through conduit 64 and into the upper end .of the conductor pipe. The air-is entrained by the return drilling mud, and serves as an air lift, reducing the back pressure on the formation.

When the drill-bit is to be withdrawn from the well,

pressure is released from the drill pipe seal and conductor pipe seal, and the drill pipe is raised until the drill bit engages the shoulder formed between the second and third vertical bores in the circulating head. The circulating head and guide sleevesare raised 'to the barge up the guide members by further withdrawal of the drill bit.

Drilling may be resumed as described above.

As drilling proceeds to increasing depths, it is necessary to set a string of casing 69 inside the conductor pipe (see Fig. 5) to support the walls of thewell and to permit amore positive control of the well in the event of a threatened blow-out, i.e., encountering a formation under sufiicientpressure to blow the drilling .fluid out of the wellbore.

One suitable type of apparatus to meet this problem is shown in Fig. 5. With the circulating head removed from the conductor pipe, the casing 69 is located in the conductor pipe (as shown in Fig. 5) by either guiding it down with the first set of guide members 58 or by stripping it down over the drill pipe or other member disposed in the well. The casing is then cemented in place uncoupled at their respective back-ofi joints by rotating The drill pipe seal is then tion, if required.

guide members 58 arethen raisedto the barge and saved for starting another well: A second set ofguide members (described 'below) are landed with the casing and replace the removed guide members.

Casing 69 has a first external flange just below its upper end whicli'rests on the upper end of the conductor pipe 42. An outwardly turned second flange 111 on the casing is connected by bolts 112 to an outwardly turned flange 113 provided on the lower end .of a blow-out preventer 114, which may be of a conventional type such as a Hydrill type MSP-20 0. The blow-out preventer is actuated from the surface though a line 115 either to close when the drill pipe is out of the well, or to close around the drill pipe in the well. I

A well conduit 116 is connected by bolts 117 and an outwardly turned flange 118 on its lower end to a matching outwardly turned flange 1 19 on'the upper end of the blow-out preventer. A pairof horizontal and radially outwardly extending arms 120, say short sections of I- beams,- are welded at their inner ends to the blow-out preventer on diametrically opposed sides. A separate upwardly extending tubular guide member 122 is welded at its lower end to the upper side and outer end of each of the arms 120. Each of the guide members is made up of threaded joints as described for guide members 58 of Fig. 2,.and each has a back-off joint 124 at its lower end. The lower end of the left hand (as viewed in Fig. 5) guide member is connected through a conduit 126 to the upper end of the blow-out preventer. A check valve 127 in the conduit 12 6 prevents the flow of any fluidin the conduit from the guide member toward the well, but permits flow in the opposite direction. A conduit 128 is connected at one end to the casing 69 below the blow-out preventer and at the other end to the conduit 126 between the left hand guide member and the check flow in the conduit from the well toward the left hand guide member, but permits flow in the opposite direc- A circulating head-130, similar to that described with respect to Fig. 2,.except that the horizontalbore for return circulation of'drilling mud is omitted, is adapted to be carried up and down the guide members by a pair of radially extending brackets 131 welded at their inner ends to the circulating head and at their outer ends to right and left hand guide sleeves 132 disposed around the right and left hand guide members, respectively.

The left hand guide sleeve has a vertical notch 134 in its lower end which. fits around the conduit 126 and permits theleft hand sleeve to seat on the top .of the left arm 120. The right hand guide sleeve has a vertical notch 136 in its lower end which fits over a conduit 137 connected to the lower end of the right. hand guide member and to the casing below the blow-out preventer. A

' check valve 138 in the conduit 137. prevents the flow of member just above the back-off joint is controlled by a a pneumatic line "141'which extends upwardly inside the guide member to the barge. A rupturable diaphragm 142 is sealed across the lower end of the right hand guide member to insure the water-tight integrity of the guide member. a 1

With the apparatus of Fig. 5, drilling is conducted as follows: a i The circulating head is lowered by means: of the drill pipe to the position shown in Fig. 5, and sealed towell conduit 116. The drill bit is lowered and drilling operations are resumedas described for'the apparatus of Fig. 2, only with the arrangement of Fig. 5, drilling mud now returns up the well annulus, through conduit 126, into the lower end of the left hand guide member, and up to the mud pit on the barge. When the left hand guide member is filledwith returning drilling mud, the member loses its buoyancy, and is supported from the barge as shown schematically in Fig. 6 by a wire line 142', one end of which is connected to the upper end of the member, and the other end of which is connected to a counter weight 143. The wire line is hung over pulleys 144 carried by the barge and kept under a constant tension by the counter weight which is arranged to hang down from the pulleys.

Drilling continues in this fashion until it is desired to withdraw the drill bit, say to replace it, at which time valve 140 in the lower end of the left hand guide member is closed by pneumatic line 141 to prevent the loss of drilling fluid from the member, and the pressure is released from control lines 95 and 103 connected to the circulating head so that the circulating head may be raised from the well conduit 116 by the drill bit.

When drilling operations are to be resumed, the circulating head and drill pipe are returned to the position shown in Fig. and sealed in place as previously described. Valve 140 is opened and drilling operations are resumed.

In the event of a threatened storm, requiring a quick temporary abandonment of the well site, the circulating head and drill pipe are removed from the well, and the valve 140 in the lower end of the left hand guide member is left open to permit drilling fluid to drain from the member through conduits 126, 128 and out the upper end of the well conduit to a level which balances the ocean hydrostatic head acting on the well head, the mud being replaced by air admitted at the upper end of the guide member. If additional buoyancy of the left hand guide member is desired, air is pumped down the membeer from a source (not shown) on the barge to fill the member with the required amount of air. The valve 140 is then closed to maintain the buoyancy of the guide member.

The upper ends of both guide members are then sealed by threaded caps (not shown), the pneumatic line in the left hand guide member first being disconnected, sealed, and suitably fastened in the upper end of the member.

The blow-out preventer is closed by line 115 which is then disconnected from the barge, sealed, and tautly secured to the upper end of one of the guide members to prevent its subsequent fouling.

The barge is then ready to hoist its anchors and move to shelter, leaving guide members to mark the well site. Once the weather is again favorable, the barge is relocated and drilling is resumed by reversing the foregoing procedure.

In the event of a threatened blow-out during drilling operations, the blow-out preventer may be closed either with the drill pipe in the well or with the drill pipe out of the well to prevent drilling fluid from being blown out of the well. Valve 140 is also closed. Check valve 129 also prevents the drilling mud from blowing mud out of the Well through conduit 128 before valve 140 can be closed. To bring the well under control, heavy drilling fluid is pumped down the left hand guide member, through conduits 126 and 128, through the check valve 129 and into the string of casing 69 to provide a hydrostatic head sufficient to control the pressure in the formation threatening to cause the blow-out. Thus the left hand guide member serves as a kill line to control blowouts, as well as a return circulation conduit.

If desired, conduit 128 and check valve 129 may be omitted, and the right hand guide member used as a kill line to control a blow-out. In such a case, the diaphragm is ruptured, say by fluid pressure of the control mud being pumped down the right band member, and mud is pumped into the well through conduit 137 for blow-out control.

A unique advantage of using hollow guide members is shown most clearly in Fig. 7, which shows how a first "10 tubular guide member welded at its lower end to a well head base- 146 may become fouled with a piece of equipment, say a pneumatic control line 147 for a blowout preventer, so that the trouble cannot be cleared from the surface. In such a case, a second tubular guide membar 148 having an outside diameter slightly less than the inside diameter of the first guide member is slipped down into the first guide member and anchored in the bottom of the guide memberso that the outer guide member may then be uncoupled at a back-off joint 149, permitting the outside guide member and the fouled line to be slipped up together overthe new or second guide member, leaving the new guide member free of any fouling and in condition to guide equipment to and from the well as the first guide member did originally.

The second guide member may be secured inside the lower end of the first guide member by any of several suitable devices. Fig. 8 ilustrates in detail one arrangement in which a first mushroom-shaped spear 150 is welded in the bottom of the first guide member so that the second guide member may be slipped down over it and be locked to it by a pawl 151 pivoted at its lower end to the second guide member and urged by a spring 152 to engage the under side of the spear. The shaft of the spear may be fluted or splined so that the pawl will lock the second guide member against rotation about its longitudinal axis, and thus permit it to be uncoupled at a back-01f joint 153, if subsequently required.

A second spear 154 inside the lower end of the second guide member permits a third guide member (not shown) to he slipped inside the second in the event the second member also becomes fouled.

We claim:

1. Apparatus for guiding equipment to a hole in an underwater formation and for carrying out operations such as drilling and working in the hole, the apparatus comprising a floating vessel, a laterally flexible and selfsupporting elongated and hollow guide member extending from the vessel toward the formation, means firmly anchoring the lower end of the guide member to the formation, equipment supported from the vessel exteriorly of the guide member, connecting means attached to the equipment and to the guide member to be slidable on the guide member, means for constraining the connecting means as it slides down the guide member so the equipment registers with the upper end of the hole, and conduit means connecting the guide member to the hole to permit fluid to flow between the guide member and the hole.

2. Apparatus for guiding equipment to a hole in an underwater formation and for carrying out operations such as drilling and working in the hole, the apparatus comprising a floating vessel, a self-supporting elongated guide member extending from the vessel toward the formation, means firmly and pivotally anchoring the lower end of the guide member to the formation to permit .lateral displacement of the vessel during drilling, equipment supported from the vessel exteriorly of the guide member, connecting means attached to the equipment and to the guide member to be slidable on the guide member, and means for constraining the connecting means as it slides down the guide member so the equipment registers with the upper end of the hole.

3. Apparatus for guiding equipment to a hole in an underwater formation and for carrying out operations such as drilling and working in the hole, the apparatus comprising a floating vessel, a laterally displaceable and self-supporting elongated and hollow guide member extending from the vessel toward the formation, means firmly anchoring the lower end of the guide means to the formation, equipment supported from the vessel exteriorly of the guide member, connecting means attached to the equipment and to the guide member to be slidable on the guide member. means for constraining the connecting means as it slides down the guide member so the 11 7 equipment registers with the upper end of'the hole, blowout preventer means connected in the hole for closing the hole, and conduit means connecting the hollow guide member to the hole below the blowout preventer means so that fluid may be introduced to the hole from the guide member when the blowout preventer is closed.

4. Apparatus for guiding equipment to a hole in an underwater formation and for carrying out operations such as drilling and working in the hole, the apparatus comprising a floating vessel, a pair of laterally displaceable and self-supporting, elongated and hollow guide members extending from the vessel toward the formation, means firmly anchoring the lower endsof the guide members to the formation on opposite sides of. the hole, equipment supported from'the vessel exteriorly of the guide members, connecting means interconnecting the equipment and the guide members so that as the equipment is lowered it isconstrained by the guide members to register with the upper end of' the hole, and conduit means connecting each of the hollow guide members to the hole so fluid may be flowed down one and up the other.

5. Apparatus for guiding equipment to a hole in an underwater formation and for carrying out operations such as ,drilling and working in the hole, the apparatus comprising a floating vessel, a pair of laterally displaceable and self-supporting, elongated and hollow guide members extending from the vessel toward the formation, means firmly anchoring the lower end of the guide members to the formation on opposite sides of the hole, equipment supported from the vessel exteriorly of the guide members, connecting means interconnecting the equipment and the guide members so that as the equipment is lowered it is constrained by the guide members i to register with the upper end of the hole, blowout preventer means connected in the hole, first conduit means connectingone of the hollow guide members to the hole above the blowout preventer means, and second conduit means connecting the other hollow guide member to the hole below the blowout preventer means.

6. Apparatus for guiding equipment to a hole in an underwater formation and for carrying out operations such as drilling and working in the hole, the apparatus comprising a floating vessel, a laterally displaceable and self-supporting elongated and hollow guide member extending from the vessel toward the formation, means firmly anchoring the lower end of the guide member to the formation, equipment supported from the vessel exteriorly of the guide member, connecting means attached to the equiprne'nt and to guidernember to be slidable on the guide memben'r neans for constraining the connecting means as it slides down the guide member so the equip ment registers with the upper end of'the hole, blowout preventer means connected to the hole, a first conduit connecting the guide member interior to the hole above the blowout preventer means, and a second conduit connecting the guide member interior to the hole below the blowout preventer.

7. Apparatus according toclaim 6 which includes a first check valve in the first conduit to prevent fluid flow through the first conduit from the guide member toward the hole, and a second check valve in the second conduit to prevent fluid flow through the second conduit from the hole toward the guide member.

8. Apparatus for guiding equipment to a hole in an underwater formation and for carrying out operations such as drilling and working inthe hole, the apparatus comprising a floating vessel, a first laterally displaceable and self-supporting elongated and hollow guidemember extending from the vessel toward the formation, means firmly and releasably anchoring the lower. end of the first guide member to the formation, equipment supported from the vessel 'exteriorly of the guide member, connecting means attached to the equipment and to the guide member to be slidable on the guide member, means for constraining the connecting means as it slides down the guide member so the equipment registers with the upper end of the hole, a second guide member adapted .to fit inside the first guide member, means for anchoring the second guide member to theformation inside the first gmide' member, and means for unanchoring the first guide member from the formationand sliding it 'up over the second guide member.

References Cited in the file of this patent UNITED STATES PATENTS McNeill et al Oct. 1, 1957

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