US3672447A

US3672447A - Marine well drilling method and apparatus

Info

Publication number: US3672447A
Application number: US772888*A
Authority: US
Inventors: David C Kofahl
Original assignee: Richfield Oil Corp
Current assignee: Richfield Oil Corp
Priority date: 1968-09-10
Filing date: 1968-09-10
Publication date: 1972-06-27
Anticipated expiration: 1989-06-27

Abstract

Method and apparatus for drilling an underwater well using subsurface wellhead equipment. A landing base is lowered at the lower end of a conductor pipe toward an underwater bottom. A guide frame is positioned above the landing base. A rotary driven tubular member, passed through the guide base is connected to the conductor pipe to drill the conductor pipe into the underwater bottom after the landing base rests on the bottom. The tubular member is removed after the conductor pipe is cemented and a bit is guided into the conductor pipe to drill hole for a surface casing having a mandrel at its upper end to which blowout preventers may be connected by a hydraulically actuated connector.

Description

United States Patent [151 3,672,447

Koiahl 1 June 27, 1972 1 MARINE WELL DRILLING METHOD 2,808,229 10 1057 Bauer et al ..175/7 AND APPARATUS 2,808,230 10/1957 McNeill et a1. 175/7 2,891,770 6/1959 Bauer et al..,. 175/7 [72] Inventor: David C. Koiahl, Bakersfield, Cal1f. 2,923,531 2/1960 Bauer et 31"" I "175/7 [73] Assignee: Richfield Oil Corporation, Los Angeles, 29509 8/1960 Nfcolsonw Calif. 5, 42 4/1967 Nicolson 166/6 Filed: p 1963 Primary ExaminerMarvin A. Champion Assistant Examiner-Richard E. F avreau [211 App]' 772888 Attorney-Blucher S. Tharp Related U.S. Application Data [57] ABSTRACT [63] Continuation of Ser. No. 628,727, Dec. 17, 1956,

abandoned Method and apparatus for dnllmg an underwater well using subsurface wellhead equipment. A landing base is lowered at 52 U.S. c1 ..l66/.6, 175/7 the end 0f a mducmr Pipe Ward underwater 5] In! CL 7H2 Ezlb 43/01 tom. A guide frame is positioned above the landing base. A ro- [58] Field of Search ..175/5-10; 166/.5, drive" tubular member Passed hmugh the guide base 166/6 connected to the conductor pipe to drill the conductor pipe into the underwater bottom after the landing base rests on the [56] References Cited bottom. The tubular member is removed after the conductor pipe is cemented and a bit is guided into the conductor pipe to N E STATES PATENTS drill hole for a surface casing having a mandrel at its upper end to which blowout preventers may be connected by a hydrauli- 1,4695 74 10/1923 Allan 175/7 X Cally actuated connector. 1,691,715 11/1928 Hansen.... 2,476,309 7/1949 Lang 175/8 8 Claims, 9 Drawing Figures PATENTEDJUNZ'I m2 SHEET 10F 8 R m @W. Z v 4 w w my 1 a E W fil m PATENTEDJIM? I972 3, 572,447

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' SHEET 70F s INVENTOR.

A770F/VEY5 MARINE WELL DRILLING METHOD AND APPARATUS This application is a continuation of application Ser. No. 628,727, filed Dec. 17, 1956, now abandoned.

This invention relates to marine well drilling method and apparatus and is particularly directed to improvements relating to the drilling of wells in relatively deep water. This invention finds particular usefulness in connection with well drilling installations wherein the well head equipment is mounted on the ocean floor and wherein the rotary machine, mast, drawworks and related drilling equipment are mounted on a floating vessel.

It is often necessary or desirable to place a relatively shortlength large-diameter conductor pipe in position on the ocean floor and cement it in place. Similarly, it is often necessary or desirable to extend surface casing down through the interior of this conductor pipe. Drill pipe used for drilling the well to the desired depth passes through the interior of the surface casing. One or more blowout preventers and related shut-off equipment are placed at the ocean floor and connected to the upper end of the surface casing. The blowout preventers are remotely controlled from the floating vessel to shut in the well when necessary to prevent a blowout.

When the water depth is such as to permit divers to work on the ocean floor, the various steps in placing the conductor pipe, surface casing and connecting the blowout preventers in place at the well head can be accomplished without serious difficulty. However, when the water depth is too great to permit divers to work at or near the well head on the ocean floor serious problems are presented. It is an important object of this invention to provide a method and apparatus for accomplishing the above named steps in relatively deep water and without the use of divers. Another object is to provide a novel method for installing well head adjacent the ocean floor. Another object is to provide new and improved apparatus for carrying out the method. Related and more detailed objects and advantages will appear hereinafter.

In the drawings:

Steps in the preferred method are shown and the preferred form of the apparatus is disclosed.

FIG. I shows a landing base being lowered into position on a conductor pipe.

FIG. 2 shows a conductor pipe supported from the floating vesselwhile a smaller pipe is connected to its upper end.

FIG. 3 is a view taken in the direction 33 as shown in FIG. 2 illustrating the landing base in position on the ocean floor and showing the guide post assembly suspended on guide cables, with the smaller pipe passing through the center of the guide post assembly.

FIG. 4 shows the conductor pipe, landing base and guide post assembly in final position on the ocean floor.

FIG. 5 shows drilling tools being guided and lowered into the upper end of the conductor pipe, after the conductor pipe has been cemented in place.

FIG. 6 shows surface casing being lowered into place.

FIG. 7 shows the blowout preventers and related'apparatus in operative position adjacent the ocean floor.

FIG. 8 is an enlargement of a portion of FIG. 7.

FIG. 9 is a plan view taken in the direction of the lines 9- -9 as shown in FIG. 3 and illustrating the mounting of the rotary machine on the floating vessel.

Referring to the drawings, the floating vessel or drilling support structure generally designated 10 is provided with a central opening or well 11 through which drilling operations may be carried on. A landing base 12 is lowered through this well opening 11 on the lower end of a conductor pipe 13. The conductor pipe has an enlarged hollow bit 14 at its lower end and the central hub 15 of the landing base 12 rests on the shoulder 16 adjacent this bit 14. An elevator 17 of conventional type is operated by hoisting equipment (not shown) carried on the floating vessel 10. The elevator is clamped about the conductor pipe 13 above the position of the laterally projecting lugs 18 which are mounted on the outer surface of the pipe 13. These lugs 18 are too large to pass through the central opening in the hub 15 of the landing base 12.

As shown in FIG. 2, the conductor pipe 13 is lowered to a position below the floating vessel or drilling support structure 10 and means such as chains 19 are employed to suspend the elevator 17 and conductor pipe 13 and landing base 12, while a tubular member 20 which in effect forms an upper portion of the conductor pipe, is connected to the upper end of the conductor pipe 13. This connection is provided by means of a threaded member 21 engaging left hand threads 22 in the upper end of the conductor pipe 13. While the conductor pipe 13 and tubular member 20 are supported by means of the chains 19, a guide frame generally designated 23 is lowered through the well opening 11 on cables 24. These cables are attached to the upper end of parallel vertical posts 25 which are mounted on the frame 23 and supported from the drilling support structure with conventional hoisting equipment, for example, air winches or counterweights. A central opening 26 on the frame receives the tubular member 20. The lower end of the frame 23 includes a support ring 27. This ring is counterbored at 29 to provide clearance for the lugs 18. The rotary machine 28 and its subframe 31 are then placed in position within the well opening 1 1 in the floating vessel 10.

The tubular member 20 passes through the rotary machine 28 which is supported in a novel manner on the floating vessel 10. As best shown in FIG. 9, this rotary machine 28 is mounted on the subfrarne 31 having axially aligned supporting

trunnions

32 and 33. These trunnions extend in the direction of the longitudinal axis of the floating vessel 10. The rotary machine is positioned centrally over the opening or well 11 which is provided in the vessel 10. The drive shaft 34 of the rotary machine may be driven in any desired manner and as shown in the drawings, this drive shaft extends through the hollow trunnion 32 from a source of power (not shown).

The tubular member 20 is driven by the rotary machine through a split'drive bushing assembly 35. Thus the tubular member 20 and the bushing assembly 35 constitute means for connecting the conductor pipe to the power means, i.e., the rotary machine 28. Bushing assembly 35 is formed with two duplicate halves clamped around the tubular member 20 by means of threaded fastenings 36 to provide power means for rotating the conductor pipe. The upper end of the tubular member 20 is supported by a swivel (not shown) in the conventional manner.

The tubular member 20 is lowered from the drilling support structure until the landing base 12 rests on bottom as shown in FIG. 3. The split bushing 35 is then installed on the tubular member 20 and the rotary machine is operated to turn the tubular member 20 and conductor pipe 13. In this way the bit 14 is caused to drill into the bottom formation. A fluid such as seawater, may be pumped down the interior of the tubular member 20 and conductor pipe 13 to bring up cuttings by the action of the bit 14. As the hole deepens, drilling operations are interrupted from time to time to readjust the position of the split bushing 35 with respect to the tubular member 20 so that the split drive bushing 35 remains in contact with the driving parts of the rotary machine.

When the lugs 18 on the conductor pipe 13 reach the flange 30 on the hub 15 of the base member 12, the rotary machine 28 is stopped and cement is pumped down the interior of the tubular member 20 and through the interior of the conductor pipe 13. The cement emerges at the bit 14 and returns to the level of the ocean floor 37 through the bore hole 38 formed by bit 14. Overflow from the bore hole 38 may fill in around the landing base 12 and assist in anchoring it to the ocean floor 37.

After an elapse of time to permit the cement to set up," the rotary machine is again caused to supply torque to the upper end of the tubular member 20. Since the conductor pipe 13 is cemented solidly in place, the conductor pipe does not turn and the result is that the left hand threads 22 are disconnected to separate the tubular member 20 from the conductor The tubular member 20 is then withdrawn upwardly through the rotary machine and a drill string 39 is reinserted through the rotary machine 28. The upper end of this drill string is provided with a square kelly 40 which is engaged with the usual kelly bushing (not shown). The lower end of this drill string 39 is provided with a conventional bit 41. A cross head guide 42 is provided in order to guide the bit 41 into the upper end of the conductor pipe 13. This guide includes a pair of laterally spaced tubular elements 43 adapted to slide freely on the cables 24 and posts 25. The guide 42 is provided with a central opening 44 which loosely receives the drill string 39 and during the operation of lowering the guide into position on the post 25, the guide rests on a shoulder 45 provided on the drill string 39 just above the bit 41. The opening 44 is large enough to pass tool joint couplings and rubber protectors on the drill string 39. After the bit 41 has been guided into the conductor pipe 13, the usual rotary drilling operations are carried out to drill out the cement in the interior of the conductor pipe 13 and to form a bore hole extending into the formation below the bit 14. This bore hole 46 does not extend into the production zone but is only deep enough to set surface casing 47. Seawater may conveniently be used for circulating the cuttings out from the bit 41.

After the bore hole 46 has been completed, the surface cas ing 47 is lowered into position using the cross head guide 42 for piloting the lower end of the easing into the conductor pipe 13. The lower end of the casing 47 is then cemented in position by pumping cement down through the interior of the casing and allowing it to fill the annular space between the casing 47 and the bore hole 46.

A mandrel 48 is connected to the casing and forms the upper portion thereof. This mandrel 48 has a downwardly facing shoulder 49 which rests on the upper end of the conductor pipe 13. The upper end of the mandrel is provided with a left hand thread 50 which is disengaged from the upper portion of the casing string after the lower portion of the casing has been cemented in place. The upper portion, not shown, of the easing string is then withdrawn upwardly. The parts are then in a position as shown in FIG. 7. The weight of the casing 47 rests on the conductor pipe 13 and the weight is carried by the lugs 18 resting on the flange 30 ofthe landing base 12.

The preliminary operations for drilling of the main well bore are now complete. A blowout preventer assembly generally designated 52 is then lowered into position as shown in FIG. 7. This assembly 52 includes a remote controlled gate valve 53, double gate valve member 54 and a pair of

blowout preventers

55 and 56. A spool 57 connects the

parts

52 and 53. Assembly 52 also includes a pair of parallel tubular elements 58 which slidably receive the cables 24 and posts 25. Assembly 52 is lowered as a unit until the gate valve member 53 which is a conventional gate valve having sliding elements, rests on the upwardly facing shoulder 59 on the mandrel 48. Horizontally movable elements 60 on the valve member 53 are then closed about the mandrel below the abutment 61. The movement of the ram elements 60 is controlled by means of the hydraulic lines 62 which extend to the floating vessel 10. When the rams 60 are closed, the blowout preventer assembly 52 is latched and sealed with respect to mandrel 48 which forms the upper end of the surface casing 47.

A drill string 63 having a conventional bit 64 on its lower end is then guided by means of the cross head guide 42 into the central opening which extends through the blowout preventer assembly 52. The bit 64 and drill string 63 pass downward through the

blowout preventers

56, 55 and through the

valve member

54 and 53 and downward through the interior of the mandrel 48 and surface casing 47. Sealing pans (not shown) within the

blowout preventers

55 and 56 contact the outer surface of the drill string 63 to form a seal. Accordingly, when fluid is circulated downward through the drill string 63 and out through the bit 64 in the conventional manner, this mud fluid passes upward through the annulus between the drill string 63 and casing 47 and through the interior of the mandrel 48,

gate valve members

53 and 52 and

blowout preventers

55 and 56. The mud fluid then passes outward through the mud return lines 65 which extend to the floating vessel 10. The well is then drilled in the conventional manner using the drill string 63 and operating through the blowout preventer assembly 52. Each time that the drill string 63 is withdrawn to change the bit 64, the cross head guide 42 serves as a pilot for guiding the bit back into the blowout preventer assembly 52. Hydraulic lines in the form of hoses are provided for each of the

members

52, 55 and 56 for the purpose of actuating closure pans therein by remote control from the floating vessel 10.

Having fully described my invention, it is to be understood that I do not wish to be limited to the details herein set forth, but my invention is of the full scope of the appended claims.

What is claimed is:

1. The method of drilling a well in an underwater location from a drilling support structure, comprising the steps of:

lowering a landing base from said support structure by means of a shouldered conductor pipe to rest the landing base on the bottom, the conductor pipe having a bit at its lower end,

drilling a portion of the conductor pipe into the bottom formation from said support structure,

lowering from said support structure an apertured guide frame by means of a pair of cables over the upper end of the conductor pipe to rest on the landing base,

guiding drilling tools from said support structure into the upper end of the conductor pipe extending therethrough into the formation by means of said cables, and

operating the drilling tools from said support structure to form a bore hole therein extending below the lower end of said conductor pipe.

2. The method of drilling a well in an underwater location from a floating vessel, comprising the steps of:

lowering a landing base from the vessel by means of a shouldered conductor pipe to rest the landing base on bottom, the conductor pipe having a bit at its lower end,

drilling a portion of the conductor pipe into the bottom formation by means of a tubular member connected to said conductor pipe and extending from the vessel,

lowering an apertured guide frame by means of a pair of cables extending from the vessel over the tubular member and over the upper end of the conductor pipe to rest on the landing base,

disconnecting said tubular member from said conductor pipe,

guiding drill tools into the upper end of the conductor pipe by means of said cables extending between the vessel and the frame, and

operating the drill tools from the vessel to form a bore hole extending below the lower end of said conductor pipe.

3. The method of drilling a well in an underwater fonnation from a floating vessel, comprising the steps of:

lowering a landing base from the vessel by means ofa shouldered conductor pipe to rest the landing base on bottom. the conductor pipe having a bit at its lower end,

drilling a portion of the conductor pipe into the bottom formation by means of a tubular member extending from the vessel,

cementing said conductor pipe into said formation,

lowering an apertured guide frame by means of a pair of cables extending from the vessel over the tubular member and over the upper end of the conductor pipe to rest on the landing base, disconnecting said tubular member from said conductor guiding drilling tools into the upper end of the conductor pipe by means of said cables extending between the vessel and the frame,

operating the drilling tools from the vessel to form a bore hole,

lowering and guiding casing into the bore hole through said conductor pipe with the upper end of the casing resting upon the conductor pipe and protruding above the frame, lowering a blowout preventer assembly over said cables into position on said frame guide means wherein a member of said assembly encompasses the upper protruding end of the casing,

lowering drilling tools from said vessel through said blowout preventer to said formation, and

operating drilling tools extending through the blowout preventer assembly and casing to deepen the well.

4. Marine well drilling apparatus including a drill string and power means comprising, in combination:

a landing base having an opening and being adapted to rest on the ocean floor,

a conductor pipe slidably mounted within the landing base opening and having stop means on the outer surface thereof resting on the landing base,

a bit on the lower end of the conductor pipe for drilling the conductor pipe into the formation,

means for connecting said conductor pipe to said power means,

a frame with laterally spaced vertical guide posts associated therewith resting on the landing base and having a central opening into which the upper end of the conductor pipe extends,

an upwardly extending guide cable connected to each of said guide posts,

means for supporting the cables, and

means slidably engaging the cables for guiding said drill string into the upper end of the conductor pipe.

5. Marine well drilling apparatus including power means comprising, in combination:

a landing base having an opening and being adapted to rest on the ocean floor,

a conductor pipe slidably mounted within the landing base and having stop means on the outer surface thereof resting on the landing base,

means for connecting said conductor pipe to said power means,

a surface casing extending through the conductor pipe and having a mandrel at the upper end thereof, the mandrel having a first shoulder resting upon the upper end of the conductor pipe and at least one axially spaced shoulder above said first shoulder, said conductor pipe being affixed to said formation,

an upwardly extending guide cable connected to each of said guide posts,

means for supporting the cables, and

a blowout preventer assembly having laterally spaced elements associated therewith, said elements slidably receiving the guide cables and guide posts,

laterally guided movable parts provided in said blowout preventer assembly, said movable parts being adapted to encompass the upper end of the mandrel.

6. Marine well drilling apparatus including power means comprising, in combination:

a landing base having an opening and being adapted to rest on the ocean floor,

means for connecting said conductor pipe to said power means,

a frame with laterally spaced vertical guide posts resting on the landing base and having a central opening into which the upper end of the conductor pipe extends,

a surface casing extending through the conductor pipe and having a mandrel at the upper end thereof, the mandrel having a first shoulder resting upon the upper end of the conductor pipe, and at least one axially spaced shoulder above said first shoulder, said conductor pipe being affixed to said formation,

an upwardly extending guide cable connected to each said guide posts,

means for supporting the cables,

laterally guided movable parts provided in said blowout preventer assembly, said movable parts being adapted to encompass the upper end of the mandrel, and

fluid operated laterally guided movable latch means on said member engageable with said mandrel.

7. Marine well drilling apparatus including power means comprising, in combination:

a landing base having an opening and being adapted to rest on the ocean floor,

means for connecting said conductor pipe to said power means,

an upwardly extending guide cable connected to each of said guide posts,

means for supporting said cables,

a blowout preventer assembly with laterally spaced elements associated therewith, said elements slidably receiving the guide posts,

fluid operated laterally guided movable parts provided in said blowout preventer assembly, said movable parts being adapted to latch said blowout preventer assembly onto the upper end of the mandrel.

8. A method of preparing a well in a formation underwater for well working operations, said method comprising:

lowering conduit means from support means downwardly through the water and positioning said conduit means at least partially within an opening extending downwardly into an underwater formation with an upper end of said conduit means submerged beneath water;

from said support means, conveying cementitious material to a zone exterior of said conduit means and within said opening;

sealingly cementing at least a portion of said conduit means to wall means of the opening in said formation;

guiding a wellhead assembly having a well apparatus passageway extending therethrough from said support means toward said conduit means by lowering said wellhead assembly in slidable engagement with flexible guide means extending downwardly from said support means;

prior to said guiding of said wellhead assembly, providing said flexible guide means supported by said support means and extending to the general vicinity of said submerged upper end of said conduit means, with said upper end of said conduit means being exposed;

axially converging and engaging portions of said wellhead assembly and said exposed upper end of said conduit means;

interconnecting said wellhead assembly with said upper end of said conduit means to establish said well apparatus passageway in sealed communication with the interior of said conduit means and to mechanically prevent disconslidable engagement with said flexible guide means; and

controlling the well apparatus passageway of said wellhead assembly from said support means whereby said well apparatus passageway may be selectively closed off or opened.

Claims

1. The method of drilling a well in an underwater location from a drilling support structure, comprising the steps of: lowering a landing base from said support structure by means of a shouldered conductor pipe to rest the landing base on the bottom, the conductor pipe having a bit at its lower end, drilling a portion of the conductor pipe into the bottom formation from said support structure, lowering from said support structure an apertured guide frame by means of a pair of cables over the upper end of the conductor pipe to rest on the landing base, guiding drilling tools from said support structure into the upper end of the conductor pipe extending therethrough into the formation by means of said cables, and operating the drilling tools from said support structure to form a bore hole therein extending below the lower end of said conductor pipe.

2. The method of drilling a well in an underwater location from a floating vessel, comprising the steps of: lowering a landing Base from the vessel by means of a shouldered conductor pipe to rest the landing base on bottom, the conductor pipe having a bit at its lower end, drilling a portion of the conductor pipe into the bottom formation by means of a tubular member connected to said conductor pipe and extending from the vessel, lowering an apertured guide frame by means of a pair of cables extending from the vessel over the tubular member and over the upper end of the conductor pipe to rest on the landing base, disconnecting said tubular member from said conductor pipe, guiding drill tools into the upper end of the conductor pipe by means of said cables extending between the vessel and the frame, and operating the drill tools from the vessel to form a bore hole extending below the lower end of said conductor pipe.

3. The method of drilling a well in an underwater formation from a floating vessel, comprising the steps of: lowering a landing base from the vessel by means of a shouldered conductor pipe to rest the landing base on bottom, the conductor pipe having a bit at its lower end, drilling a portion of the conductor pipe into the bottom formation by means of a tubular member extending from the vessel, cementing said conductor pipe into said formation, lowering an apertured guide frame by means of a pair of cables extending from the vessel over the tubular member and over the upper end of the conductor pipe to rest on the landing base, disconnecting said tubular member from said conductor pipe, guiding drilling tools into the upper end of the conductor pipe by means of said cables extending between the vessel and the frame, operating the drilling tools from the vessel to form a bore hole, lowering and guiding casing into the bore hole through said conductor pipe with the upper end of the casing resting upon the conductor pipe and protruding above the frame, lowering a blowout preventer assembly over said cables into position on said frame guide means wherein a member of said assembly encompasses the upper protruding end of the casing, lowering drilling tools from said vessel through said blowout preventer to said formation, and operating drilling tools extending through the blowout preventer assembly and casing to deepen the well.

4. Marine well drilling apparatus including a drill string and power means comprising, in combination: a landing base having an opening and being adapted to rest on the ocean floor, a conductor pipe slidably mounted within the landing base opening and having stop means on the outer surface thereof resting on the landing base, a bit on the lower end of the conductor pipe for drilling the conductor pipe into the formation, means for connecting said conductor pipe to said power means, a frame with laterally spaced vertical guide posts associated therewith resting on the landing base and having a central opening into which the upper end of the conductor pipe extends, an upwardly extending guide cable connected to each of said guide posts, means for supporting the cables, and means slidably engaging the cables for guiding said drill string into the upper end of the conductor pipe.

5. Marine well drilling apparatus including power means comprising, in combination: a landing base having an opening and being adapted to rest on the ocean floor, a conductor pipe slidably mounted within the landing base and having stop means on the outer surface thereof resting on the landing base, a bit on the lower end of the conductor pipe for drilling the conductor pipe into the formation, means for connecting said conductor pipe to said power means, a frame with laterally spaced vertical guide posts associated therewith resting on the landing base and having a central opening into which the upper end of the conductor pipe extends, a surface casing extending through the conductor pipe and having a mandrel at the upper end thereof, the mAndrel having a first shoulder resting upon the upper end of the conductor pipe and at least one axially spaced shoulder above said first shoulder, said conductor pipe being affixed to said formation, an upwardly extending guide cable connected to each of said guide posts, means for supporting the cables, and a blowout preventer assembly having laterally spaced elements associated therewith, said elements slidably receiving the guide cables and guide posts, laterally guided movable parts provided in said blowout preventer assembly, said movable parts being adapted to encompass the upper end of the mandrel. 6. Marine well drilling apparatus including power means comprising, in combination: a landing base having an opening and being adapted to rest on the ocean floor, a conductor pipe slidably mounted within the landing base opening and having stop means on the outer surface thereof resting on the landing base, a bit on the lower end of the conductor pipe for drilling the conductor pipe into the formation, means for connecting said conductor pipe to said power means, a frame with laterally spaced vertical guide posts resting on the landing base and having a central opening into which the upper end of the conductor pipe extends, a surface casing extending through the conductor pipe and having a mandrel at the upper end thereof, the mandrel having a first shoulder resting upon the upper end of the conductor pipe, and at least one axially spaced shoulder above said first shoulder, said conductor pipe being affixed to said formation, an upwardly extending guide cable connected to each said guide posts, means for supporting the cables, a blowout preventer assembly having laterally spaced elements associated therewith, said elements slidably receiving the guide cables and guide posts, laterally guided movable parts provided in said blowout preventer assembly, said movable parts being adapted to encompass the upper end of the mandrel, and fluid operated laterally guided movable latch means on said member engageable with said mandrel.

7. Marine well drilling apparatus including power means comprising, in combination: a landing base having an opening and being adapted to rest on the ocean floor, a conductor pipe slidably mounted within the landing base opening and having stop means on the outer surface thereof resting on the landing base, a bit on the lower end of the conductor pipe for drilling the conductor pipe into the formation, means for connecting said conductor pipe to said power means, a frame with laterally spaced vertical guide posts resting on the landing base and having a central opening into which the upper end of the conductor pipe extends, a surface casing extending through the conductor pipe and having a mandrel at the upper end thereof, the mandrel having a first shoulder resting upon the upper end of the conductor pipe, and at least one axially spaced shoulder above said first shoulder, said conductor pipe being affixed to said formation, an upwardly extending guide cable connected to each of said guide posts, means for supporting said cables, a blowout preventer assembly with laterally spaced elements associated therewith, said elements slidably receiving the guide posts, fluid operated laterally guided movable parts provided in said blowout preventer assembly, said movable parts being adapted to latch said blowout preventer assembly onto the upper end of the mandrel.

8. A method of preparing a well in a formation underwater for well working operations, said method comprising: lowering conduit means from support means downwardly through the water and positioning said conduit means at least partially within an opening extending downwardly into an underwater formation with an upper end of said conduit means submerged beneath water; from said support means, conveying cementitious material to a zone exterior of said conDuit means and within said opening; sealingly cementing at least a portion of said conduit means to wall means of the opening in said formation; guiding a wellhead assembly having a well apparatus passageway extending therethrough from said support means toward said conduit means by lowering said wellhead assembly in slidable engagement with flexible guide means extending downwardly from said support means; prior to said guiding of said wellhead assembly, providing said flexible guide means supported by said support means and extending to the general vicinity of said submerged upper end of said conduit means, with said upper end of said conduit means being exposed; axially converging and engaging portions of said wellhead assembly and said exposed upper end of said conduit means; interconnecting said wellhead assembly with said upper end of said conduit means to establish said well apparatus passageway in sealed communication with the interior of said conduit means and to mechanically prevent disconnection of said wellhead assembly and said upper end of said conduit means; mechanically and selectively maintaining said interlocking of said wellhead assembly with said upper end of said conduit means, with said interlocking being selectively maintainable until said wellhead assembly is to be disconnected from said end of said conduit means and raised in slidable engagement with said flexible guide means; and controlling the well apparatus passageway of said wellhead assembly from said support means whereby said well apparatus passageway may be selectively closed off or opened.