US3741294A

US3741294A - Underwater well completion method and apparatus

Info

Publication number: US3741294A
Application number: US00226348A
Authority: US
Inventors: C Morrill
Original assignee: Courtaulds PLC
Current assignee: Akzo Nobel UK PLC; Cooper Industries LLC
Priority date: 1972-02-14
Filing date: 1972-02-14
Publication date: 1973-06-26
Anticipated expiration: 1990-06-26

Abstract

Extended casing method and apparatus for completing an underwater well whereby complete and continuous pressure control is maintained at the surface drilling platform. A conductor casing is installed in the floor of a body of water with a casing head and riser attached near the floor. Other casing is installed and supported at the water floor by hanger heads and having other risers extending upwardly therefrom. Pressure control equipment is installed at the upper end of one of the risers. A tubing head designed to pass through the pressure control equipment and riser to which it is attached may be lowered to the innermost hangerhead and remotely latched thereto. Orientation apparatus may be lowered into the tubing head and attached thereto. A tubing hanger and tubing may be lowered through the pressure control equipment and latched to the tubing head in an annular position determined by the orientation apparatus. The tubing is plugged, the riser and control equipment removed and a Christmas tree assembly attached to the wellhead in fluidtight flow communication with the tubing string.

Description

United States Patent 11 1 [111 3,741,294

Morrill June 26, 1973 UNDERWATER WELL COMPLETION METHOD AND APPARATUS Primary ExaminerJames A. Leppink [75] Inventor: Charles Donovan Morrill, Bellaire, Attorney-Murray Robinson et 57 ABSTRACT Assigneei coul'mluds Limited, London, Extended casing method and apparatus for completing England an underwater well whereby complete and continuous [22] Filed: 14, 1972 pressure control is maintained at the surface drilling platform. A conductor casing is installed in the floor of PP 226,348 a body of water with a casing head and riser attached Related Application Dam near the floor. Other casing is installed and supported at the water floor by hanger heads and having other ris- [63] Commuamn of Sept 1970 ers extending upwardly therefrom. Pressure control abandoned' equipment is installed at the upper end of one of the ris- 52 us. c1 166/05, 166/89, 166/315 A head designed? Pass "l i l 175/7 sure control equipment and user to which It is attached 51 Int. (:1 E2lb 33/035 may be hangerhead and [58] Field of Search 166/05, 0.6, 89, mmely latched them apparatus may be lowered into the tubing head and attached thereto. A 3, 31 l7 166/31 5 5/7 tubmg hanger and tubmg may be lowered through the [561 Ree'mesci'ed E2i?2312x231ai gifiifi di'illfifiifi bfifilififii UNITED STATES PATENTS tion apparatus. The tubing is plugged, the riser and 3,256,937 6/1966 Haeber Gigi. 166/05 control equi ment removed and a Christmas tree as- 3,414,056 12/1968 166/89 sembly attached to the wellhead in fluidtight flow com- 3,42l,580 1/1969 FOWlCl' et 8].... 166/05 munication the tubing i g 3,424,253 1/1969 Triplett 175/7 3,459,259 8/1969 Mathews 166/05 45 Claims, 16 Drawing Figures I I N i 1, r s f I I 53 r I 1 I w 1 g I i 9 I I H 54 1 1 6 i 1 a I I W 1 v g I 68K ,1 I i 64 /2-\ ,t dz K 42 69 \J 46* i 2, H67- N H 7 P71! 4/ 3| 2:;

fill *4 l, 1 '21,, I} in 5 'llg II '1 i /3 1 gjllll! I i u i I i f -50 1 i I I -ofl 1 I 1 s i W l W h PAIENIEUJUNZB 191s 3.741. 294

saw 010? 15 Arr IVE) PAIENIED HNZ 97 3. 741. 294

saw our 15 ATTORNEY PATENTEDJUHZG ms SHEET 0% 0F W V A zwr' f'f' W Aff NE) (/mr/eJ fl. Mar/f INVENTOR ATTORNEY PATENIEUJUN 2 6 I915 SlEEI I NVEN 70R m nimum ms 3. 741; 294

am 1m 1s A770 Alf) UNDERWATER WELL COMPLETION METHOD AND APPARATUS CROSS-REFERENCE TO RELATED APPLICATION This is a continuation of application Ser. No. 76,664 filed Sept. 30, 1970 now abandoned.

This application is related to and concerns an improvement on the invention disclosed in copending application Ser. No. 792,912 filed on Jan. 22, 1969 now abandoned and in application Ser. No. l03,839 filed on Jan. 4, 1971 as a streamline continuation of co-pending application Ser. No. 792,912, both assigned to the assignee of the present application.

BACKGROUND OF THE INVENTION methods have been developed. Basically, extended cas- 1 ing methods have a well conductor anchored tovthe sea floor which provides support for a special underwater wellhead. The wellhead, in turn, supports a multiple number of casing strings and their respective casing hangers. The drilling platform is thus relieved of much of the structural support responsibilities of other methods. After drilling is completed, the well may be permanently abandoned, temporarily abandoned or immediately completed. For any of these options, the completion equipment may be installed at the sea floor, leaving the drilling platform free for relocation and freeing the underwater wellhead from the hazards of ocean going traffic and structural support problems. One such extended casing method is fully described in-U.S. Pat. No. 3,421,580 issued on Jan. 14, 1969 to J. H. Fowler et al.

In the extended casing methods of the prior art, one or more intermediate casing strings, in addition to the conductor casing and the innermost production casing string, are usually supported in the wellhead. Casing extensions or risers are attached to these strings as they are lowered into place and landed. The extensions are connected at the surface to a blowout preventer for pressure control and also serve as a return for cement circulation. In the past it has been necessary to remove all casing extensions, except possibly the outer conductor riser, for intallation of the tubing head with the collet connector flange for making-connection with the underwater tree, the tubing hanger, and the tubing strings. This requires removal of the surface blowout prevention equipment. In some cases for safety precautions, a bridge plug is set in the production casing prior to removal of the production casing riser. The tubing head is attached to the production casing hanger head and a high pressure riser extended back to the surface for re-attachment of the preventer equipment. The bridge plug is then drilled out or otherwise and the well is then ready to receive tubing. These operations require additional equipment, time and consequently expenses.

Some methods have utilized underwater blowout preventers installed near the underwater wellhead. However, such preventers are very expensive and more complex to operate through than the conventional above water type.

SUMMARY OF THE INVENTION The present invention concerns a method of completing an underwater well comprising the steps of: locating drilling means at an underwater well site; installing conductor casing in the floor of a body of water with a casing head and riser attached thereto at a point near the floor, the conductor riser extending upwardly to the drilling means; drilling holes for, suspending within the conductor casing and cementing in place other casing, each of the other casing being suspended by hanger means above which other risers, extending upwardly to the drilling means, are connected; attaching blowout pressure control equipment to the top of at least one of the other risers; running a tubing head through the pressure control equipment and its riser for attachment to the innermost hanger-head; running a tubing hanger and at least one tubing string, through the control equipment and the riser to which it is attached, into the innermost casing; suspending and latching the tubing hanger and tubing string in the tubing head; and removing the pressure control equipment and the other risers.

This method provides complete and continuous pressure control throughout completion by providing apparatuswhereby the tubing head, tubing hanger and tubing string may be lowered through blowout preventers and a riser to their support positions. After latching the tubing hanger and tubing string in place the tubing is plugged and the riser and pressure control equipment are removed for installation of the Christmas tree assembly.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects and advantages of the invention will become apparent from the description which follows when taken in conjunction with the drawing in which:

FIGS. 1 through 6 are step by step sectional elevation views of an underwater well showing a method and apparatus for completing a dual tubing string well according to a previously developed method,

FIGS. 7 through 10 are step by step sectional elevation views of an underwater well showing a method and apparatus for tubingless completion of a well according to a previously developed method,

FIGS. 11 through 14 are step by step sectional elevation views of an underwater well showing still another method and apparatus for completing a dual tubing string well according to a preferred and improved embodiment of the invention, and

FIGS. 15 and 16 illustrate an exemplary environment in which the present invention may operate.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present'invention is an extended casing completion system for use when drilling from a bottom supported rig with blowout prevention control equipment at the surface. Severaloptions on the method of completion are available, including:

1. Easy permanent abandonment,

2. Temporary abandonment,

3. Completion by extension of casing, risers to a platform,

4. Casing-tubing sub-surface completion with optional diver support or fully remote operation, and

5. Tubingless sub-surface completion with optional diver support or fully remote operation.

The apparatus of the present invention permits installation of one or more tubing stings through blowout prevention control equipment and extended risers, eliminating the necessity of removing the risers and blowout preventers when preparing the well for completion. Because all operations are conducted through the risers and blowout preventers, well pressure control is continuous and remote guidance systems are not necessary when temporarily abandoning the well or preparing it for completion. A guide base may not be installed until a decision is made to complete the well. This allows a selection at that time of either fully remote Christmas tree installation or diver support Christmas tree installation.

Referring now to FIGS. 15 and 16, there is illustrated a bottom supported well drilling and completion apparatus which is entirely conventional except for the tubing hanger-head which is shown in more detail in the other figures. FIG. 15 shows the upper portion of a bottom supported rig 1 with blowout prevention control equipment 2 above the water surface 4 and surmount ing the upper end of

risers

12, 43, 53 and 63 extending from the rig 1 to the well head 5 at the mudline 3.

FIG. 16, in larger scale, shows a downward extension of

risers

12, 43, 53, 63 from the rig l to the mudline 3 beneath the water surface 4, and also shows the well head 5 supporting progressively smaller concentric casing strings 10, 40, 50 and 60 in the well bore. Each sting of casing is cemented in the well bore from the lower ends of the casing strings to a level thereabove as indicated at 6, 7, 8, and 9. Production casing 60 extends from the rig 1 through the ocean floor 3 and water-4 to the production zone 14.

Referring first to FIGS. 1 through 6, a step by step description of casing-tubing sub-surface completion, ac cording to a preferred embodiment of the invention, will be given. The system described will be a 30 X 16 X 34 X 7 inch casing program with two 2 =34; inch tubing stings. However, it is to be understood that the size and number of casing and tubing may vary without departing from the principles of the invention.

First, a 30 inch conductor casing 10, casing head 11, and conductor riser 12 are lowered from the drilling platform 1 and driven or jetted into the sea floor 1 until casing head 11 rests near the floor. If bottom conditions require it, a hole may be drilled for conductor casing 10. Casing head 11 is provided with an upwardly facing stop shoulder 13 for locating the surface casing.

Riser 12 is connected to casing head 11 by an easily disengageable connection 14. One type of easily disengageable joint is shown in FIG. 1A. This type of joint, which we refer to as a breech block joint, reduces drilling costs by eliminating on-site welding, permitting easy recovery of easing risers and reducing rig time during making, running and recovering casing risers. The joint comprises a female member and a male member 30. Segmented threads 21 of a square nonlead profile spaced 30 apart are milled in the female member for engagement with corresponding segmented threads 31 on the male member. Smooth milled out

areas

22, 32 are provided between the

thread'segments

21, 31. For descriptive purposes the

thread segments

21, 31 are referred to as lands and milled out

areas

22, 32 as grooves. Engagement is accomplished by inserting the lands of the male member 30 in the grooves of the female member 20, then rotating the male member 30 degrees in either direction until the lands of each member are in full engagement. A positional stop 33 on the male member cooperates with lugs 35 around the female member to limit rotation to thirty degrees. A pivotable anti-rotation latch 34 may be provided to engage the opposite side of lugs 35 preventing disengagement of the joint.

After the 30 inch conductor casing is set, a hole is drilled for 16 inch surface casing 40, which is lowered into place with surface casing head 41, back-off joint 42 and surface casing riser 43 attached thereto, Backoff joint 42 and head 41 may be connected by a breech block joint 46 similar to that shown in FIG. 1A. Landing lugs 44 are provided on surface casing head 41 cooperating with stop shoulder 13 to locate surface casing 40. The surface casing 40 is then cemented in place. The remainingstrings will be supported by the cement around surface casing 40. Casing head 41 is provided with internal annular recesses to receive hanging latches for the next string.

Next a-hole is drilled for the l0 Y4 inch intermediate casing string 50 which is lowered into the hole attached to hanger-head 51, back-off joint 52, and riser 53 and cemented in place. Hanger-head S1 and back-off joint 52 are connected with another breech block'connection 54. Hanger-head 51 is provided with spring biased latches 55 which support the casing string 50 within the well. As the latches 55 engage recesses 45, a locking rib 56 on the hanger-head body locks them into positive engagement. Hanger-head 51 may be provided with internal circulation ducts 57 or the latches 55 may be fluted for cement circulation lntemal latch recess 58 and circulation ducts 59 may be provided for ducting around the next hanger-head. Blowout prevention control equipment is attached to the top of riser 53 at the drilling platform 1.

Next the hole for production casing string 60 is drilled and the production string is landed and cemented in place attached to hanger-head 61, back-off joint 62 and riser 63. Production string hanger-head 61 is similar to hanger-head 51 having spring latches 65,a locking rib 66 and if necessary flow ducts 67. However, it has no internal latch recesses and it is connected to back-off joint 62 by a left hand thread connection 64 rather than a breech block joint. Immediately above the connection 64 two internal tubing hanger hold down recesses 68 are cut. An external key 69'provides orientation for a subsequently installed tubing hanger. Therefore, the production string 60 must be properly oriented while running in place.

The aforementioned drilling is done through the blowout prevention equipment at the drilling platform. At this stage of the drilling, the wellhead equipment would be as shown in FIG. 1. At this time the production string riser 63 is removed by rotating the riser joint and back-off jonit 62 to the right.

Referring specifically now to FIG. 2, an orientation sleeve70 connected by a J-slot arrangement 76 to running tool 71 and running string 72 is run through l0 inch riser 53. A longitudinal slot at the base of sleeve 70 engages hanger-head key 69 and the sleeve comes to rest against hanger-head shoulder 73. An orientation bushing 74 is affixed to the interior of sleeve 70 for automatic guidance of a tubing hanger which is to be installed. It has a dual 180 ramp 75 and a vertical slot 76 communicating with the ramp at its lowermost intersection. Tool 71 is then disconnected from orientation sleeve 70 and removed.

Referring now to FIG. 3, a tubing hanger 80, tubing 90, 91 and annulus access nipple 92 are installed along with test tool 93. Tubing hanger 80 is provided with three vertical bores 81, 82 (one not shown) communicating with annulus access nipple 92 and tubing strings 90, 91. Long tubing handling string 94 is connected to hanger 80 by a handling nipple (not shown) similar to handling nipple 95 connected to short string handling string 79. Both nipples pass through test tool 93. However, nipple 95 is screwed into a landing nipple 96 whereas the long string handling nipple is screwed directly in hanger 80. Both tubing strings 90, 91 are lowered together. However, short string 91 is displaced upwardly a slight amount from the position shown in FIG. 3.

Hanger 80 is provided with a longitudinal key 83 which rides on orientation bushing ramp 75 until it engages orientation slot 76 orienting the tubing hanger 80. The tubing hanger comes to rest on the upper shoulder 85 hanger-head 61. A hold down latch 86 and locking sleeve 87 are mounted in a skirt portion of hanger 80 near its base. In the running position the latch 86 is retracted and locking sleeve 87 is held up against the body of hanger 80 by engagement with landing nipple 96. When the hanger 80 is landed, short tubing string 91 and landing nipple 96 are allowed to move downwardly to the position shown in FIG. 3, where it is supported by shoulder 88, causing locking sleeve 87 to force hold down latch 86 into engagement with hanger-head hold down recesses 68. Up to this point handling nipple 95 and landing nipple 96 are fully made up so that the upper edge of landing nipple 96 is abutting downwardly facing shoulder 97 on handling nipple 95. By rotating handling nipple 95 to the right these shoulders are separated allowing a snap ring 89 in hanger 80 to spring out engaging the upper edge of landing nipple 96 and holding the short tubing string 91 down. At this point all wellhead components appear as shown in FIG. 3.

Next the tubing hanger seals would be tested by pressurizing through short tubing string 91. Pressure would then be applied below the tubing hanger 80 and through annulus access nipple 92 and tubing 90. Testing tool 93 is provided with a vertical port 98 and a horizontal port 99 which communicates with long tubing string 90 through a port in the handling nipple (not shown) attached to handling string 94. Should any of the seals around hanger 80 and landing nipple 96 leak it will be detected in riser 53.

Next, the downhole tubing packer is set, usually by hydraulic means, a back pressure valve is installed in long string 90 and the packer pressure tested. Pressure is applied through short string 91. If the packer leaks the test fluid passes through annulus access nipple 92 and through test tool ports 98, 99 into handling string 94 for detection.

If all tests are positive, the tubing handling strings 94, 79, their respective handling nipples, and test tool 93 are removed from the hole by rotating the handling strings to the right. The orientation sleeve 70 and orientation bushing 74 are removed using the running tool 71. The tubing strings 90, 91 and annulus access nipple 92 are plugged. It will be noticed that throughout running and setting of the tubing hanger and tubing strings complete pressure control is maintained at the surface by blow-out prevention equipment connected to 10 inch riser 53. 1

Next, the pressure control equipment, 10 54 inch rise 53 and 16 inch riser 43 are removed by 30 rotation to the right for disengagement of

breech block connections

54 and 46. At this stage, the wellhead will appear as shown in FIGS. 4 with conductor extension 12 being the only remaining riser.

Referring now to FIG. 5, a tubular Christmas tree adapter 100 is run on drill pipe 120 using a combination running testing tool 130. The external midportion of adapter 100 is provided with the male part of a breech block connection 101 for engagement with the female part of the connection 101 in the 10 9'4 inch head 51. Rotatably connected by ball bearings 102 to the lower part of adapter 100 is an annular packoff assembly comprising a resilient seal member 104 sandwiched between upper and

lower retainer members

103, 105. Lower retainer 105 is stopped against hanger-head shoulder 106 and as the breech block connection 101 is engaged upper retainer ring 103 presses against seal member 104 causing it to sealingly engage the walls of hanger-

heads

51 and 61. A port 131 connects the bore 132 of tool 130 with the annular space between adapter 100 and tubing hanger 80. This space is sealed at 133, 134 by 0-rings, allowing adapter seals 104, 108, 109 and tubing hanger seals 110 to be tested.

Christmas tree adapter 100 has an upper flange member 11] and internal connection threads 112 to which tool is connected. Christmas tree adapter 100 also has stop lugs 113 which cooperate with stop lugs 114 on the top of hanger-head 51 when the breech-block connection is made to stop rotation at full engagement. To prevent disengagement, a locking ring 115 with depending lugs 116, is mounted around adapter 100 and held upwardly thereon as shown by radial pins 117 which ride in an L-slot in sleeve skirt 136 of tool 130. A shear pin 137 is sheared on further right handrotation of tool 130. This allows skirt 136 to rotate to a position where pins 117 drop out of the L-slot allowing the locking ring 115 to drop downwardly so that its lugs 116 fall between the back of adapter lugs 113 and the next closest hanger-head lug 114. This prevents rotation of adapter 100 in either direction thus locking it in position. Further rotation of tool 130, to the right, releases it for removal from the well.

If it is decided to temporarily abandon the well, rather than immediately complete it, a corrosion cap (not shown) may be run on drill pipe using a J-type running tool. It would be connected to the internal threads 112 of tubing head adapter 100. The corrosion cap could be provided with a port for spotting oil within the wellhead to prevent corrosion. This port would, of course, be plugged after the oil was injected. After installation of the corrosion cap, conductor riser 12 would be removed by rotating 30 to the right. A corrosion cap top could be installed by a diver and the well could be temporarily abandoned.

Alternatively, if it is desired to immediately complete the well, rather than install a corrosion cap, the Christmas tree would be installed. To do this, conductor riser 12 would be removed. Now referring also to FIG. 6, a small guide base 140 with two guide posts 141 would be clamped around the lower part of adapter 100 or hanger-head 51 by a diver. The guide base would be oriented by a tool with two pins adapted to engage tubing

hanger receiving pockets

118, 119.

Next, Christmas tree 150 would be lowered to the wellhead. It would be provided with guide arms 151 and bell bottom sleeves 152 which would engage guide posts 141 to assist a diver in installing the tree 150. The base of tree 150 carries three

long nipples

153, 154, the one for tubing 90 not shown, which sealingly engage the corresponding receiving

sockets

118, 119, the one for tubing 90 not shown, in hanger 80. The base of tree 150 would come to rest against the upper face of adapter 100. An annular seal ring 155 would be provided at the joint. The tree 150 is then clamped to Christmas tree adapter 100 by a standard type clamp 160. A remote hydraulic connector could be used as an option eliminating the need for a diver to torque up clamp bolts. Thus, as shown in FIG. 6, the well is ready for production.

Should it be necessary at a future date to perform workover operations, tubing strings 90, 91 would be plugged and the Christmas tree 150 removed. Then a workover riser with a built in orientation sleeve and bushing similar to sleeve 70 and bushing 74 in FIGS. 2 and 3 would be attached to tree adapter 100. The orientation bushing would have a slot to engage key 83 of tubing hanger 80. in this manner, after the tubing hanger 80 is re-installed, following workover operations, it is landed in the same position as it was before workover operations.

I If a tubingless sub-surface completion is desired, instead of a casing-tubing sub-surface completion, a somewhat different procedure is followed. However, with reference to FIG. 7, the first steps are the same as in the casing-tubing sub-surface completion just described, A 30 inch conductor casing 210, casing head 211, and conductor riser 212 connected by breechblock joint 214 are installed. A 16 inch surface casing 240, casing head 241, back-off joint 242, and riser 243 are installed. Next, the inch casing string 250, hanger-head 251, back-off-joint 252, and riser 253 are installed as in the conventional completion.

There is a slight difference in hanger-head 251 and back-off joint 252. Hanger-head 251 is provided with an internal vertical slot 259 immediately above the hanging recesses 258. Orientation in this method will be obtained by orienting the 10 34 inch hanger-head 251 rather than the 7 inch hanger-head in the aforedescribed casing-tubing sub-surface completion. Backoff joint 252 is provided with an orientating bushing 260 which has a double ramp orienting slot 261 cut on a 45 angle. A vertical slot 262 is cut at the bottom or ramp 261 for alignment with hanger head slot 259. A

In the next step, two strings of

tubing

270, 271 are clamped together and run in the well tied by shear pins 273 to a tubing hanger assembly 280. Tubing hanger 280 is provided with outwardly biased hanging latches 281 and inwardly biased tubing latches 282 around

openings

284, 285 through which tubing strings 270, 271 pass. An offset opening (not shown) through the hanger 280 provides access to the annulus between the

tubing string

270, 271 and 10 inch casing 250. This allows both cementing circulation and limited gas lift production.

Also provided on hanger 280 is an external spring loaded dog 290. Referring also to FIG. 7A dog 290 is beveled-at the top 291 and bottom 292 so that it is cammed inwardly by any horizontal shoulder it encounters as the hanger is lowered into the well. However, looking at the face of dog 290, its bottom 292 is V-shaped providing 45 angle edges 293, 294. If these angle edges 293, 294 encounter a matching 45 angle shoulder such as orienting ramp 261, the dog 290 will not be cammed inwardly but will ride down the ramp causing the tubing hanger 380 to rotate therewith. Thus, as the tubing stings 270, 271 and hanger 280 are lowered into the well, dog 290 engages ramp slot 261 rotating the hanger 280 until dog 290 falls through ver tical slot 262 and into slot 259 as shown. Latches 281 engage hanging recesses 258 in a proper orientation. Attached to the upper end of

tubing strings

270, 271 are

tubing hanging nipples

275, 276 which are provided with external hanging grooves 277, 278. One of the nippies, in this case 275, is longer than the other for reasons to be described subsequently. Running tools 286, 287 connect the hanging

nipples

275, 276 to running strings 296,297.

After the tubing hanger 280 is in place as shown in FIG. 7, the weight of

tubing

270, 271 shear pins 273. Both

strings

270, 271 are then run to bottom and tubing latches 282 engage the latch grooves 277, 278 in hanging

nipples

275, 276, supporting the tubing strings as shown in FIG. 8. Both strings can then be cemented and handling

strings

296, 297 and running tools 286, 287 removed by rotation to the right. At this stage of completion the wellhead equipment appears as in FIG. 8.

If for any reason tubing strings 270, 271 should be come stuck after tubing hanger 280 is latched in, and cannot be freed, both strings would be cemented in. Then a standard outside tubing cutter would be run over one of the tubing strings. The cutter would be modified slightly to support tubing slips at its bottom. These tubing slips (not shown) would be lowered to engage tapered receiving bowls 288, 289 in the top of the hanger 280. The slips would be set and then the tubing string would be cut off at a distance from hanger 280 equal to the height of hanging

nipples

275, 276, one longer than the other. After one tubing is set and cut the same procedure would be followed for the other tubing string.

Next, tubing strings 270, 271 are plugged and

risers

253 and 243 are removed by 30 rotational disengagement of breech-

block connections

246, 254 as in the casing-tubing sub-surface completion previously discussed. This leaves only the 30 riser 212.

As now shown in FIG. 9, a Christmas tree adapter 300, similar to the adapter (FIGS. 5 and 6), is lowered through riser 212 on drill pipe 320 and combination running and testing tool 330. The external midpor-

Claims

1. A method of completing an underwater well comprising the steps of: locating drilling means at an underwater well site; installing conductor casing in the floor of a body of water with a casing head and riser attached thereto at a point near said floor, said riser extending upwardly to said drilling means; drilling holes for, suspending within said conductor casing and cementing in place other casing, each of said other casing being suspended near said floor by hanger means above which other risers, extending upwardly to said drilling means are connected; attaching blowout pressure control equipment to the top of at least one of said other risers at said drilling means prior to removal of any of said other risers; removing through said pressure control equipment any of said other risers which are surrounded by the riser to which said pressure control equipment is attached; running a tubing head means through said pressure control equipment and said riser to which it is attached; running a tubing hanger and at least one tubing string, through said control equipment and the riser to which it is attached, into the innermost casing; suspending and latching said tubing hanger and tubing string in said tuBing head means; and removing said pressure control equipment and the remainder of said other risers.

2. A method of completing an underwater well as set forth in claim 1, characterized in that prior to running said tubing-hanger means, first orientation means is run through said pressure control equipment, and said riser to which it is attached, and is latched to said tubing head means, said tubing hanger being provided with second orientation means engageable with said first orientation means on said running of said tubing hanger to automatically align said tubing hanger and tubing-string in a predetermined orientation.

3. A method of completing an underwater well as set forth in claim 2, characterized in that prior to said removing of said pressure control equipment, at least a portion of said first orientation means is removed and after said removing of said pressure control equipment and said other risers an underwater wellhead is attached to said well around said tubing head and said tubing hanger.

4. A method of completing an underwater well as set forth in claim 3, characterized by the further steps of: packing off an annular space between said tubing head and said wellhead and attaching a Christmas tree to said wellhead.

5. A method of completing an underwater well as set forth in claim 1, characterized by the further steps of: attaching a wellhead to one of said hanger means with an annular space between said wellhead and said tubing head; packing off said annular space; and attaching a Christmas tree to said wellhead.

6. Underwater well completion apparatus comprising: a first casing string penetrating the floor of a body of water; first hanger-head means connected to the upper end of said first casing string near the floor of said body of water; riser means connected to said first hanger-head means extending upwardly through said body of water to the surface of said body of water; pressure control means connected to the upper end of said riser means; a second casing string, lowerable through said pressure control means and said riser means, supported by second hanger-head means on said first hanger-head means; tubing head means lowerable through said pressure control means and said riser means and connected to said second hanger-head means; tubing hanger means lowerable through said pressure control means and said riser means to a position within said tubing head means to be supported thereby; and at least one tubing string supported by said tubing hanger means and lowerable through said pressure control means and said riser means.

7. Underwater well completion apparatus as set forth in claim 6 characterized by first orientation means lowerable through said pressure control means and said riser means connected to said tubing head means and second orientation means on said tubing hanger means to position said tubing hanger means within said tubing head means in a predetermined angular orientation relative thereto.

8. Underwater well completion apparatus as set forth in claim 7 characterized in that said first orientation means comprises a helically generated upwardly facing surface.

9. Underwater well completion apparatus as set forth in claim 7 characterized in that said riser means and at least a portion of said first orientation means are removable and reengageable with said tubing head means to permit subsequent removal and replacement of said tubing hanger means in the same said predetermined angular orientation.

10. Underwater well completion apparatus as set forth in claim 6 characterized in that said tubing hanger means is provided with remotely actuable latch means to lock said tubing hanger means to said tubing head means.

11. Underwater well completion apparatus comprising: conductor casing means penetrating the floor of a body of water; casing head means affixed to said conductor casing means near said floor; other casing means concentrically disPosed within said conductor casing means; hanger means connected to said other casing means, said hanger means being provided with support means engageable with other support means surrounding said hanger means to limit longitudinal movement of said other casing means and said other hanger means; riser means connected to at least one of said hanger-head means extending upwardly therefrom to drilling means above the surface of said body of water; pressure control means connected to the upper end of at least one of said riser means; tubing head means lowerable through said pressure control means and the riser means to which it is attached and connected to the innermost of said hanger means; tubing hanger means lowerable through said pressure control means and said riser means to a supported position within said tubing head means; at least one tubing string connected to said tubing hanger means and lowerable therewith through said pressure control means and said riser means to said supported position; and characterized in that said tubing hanger means is provided with latch means engageable with said tubing head means on longitudinal movement of said string relative to said tubing hanger means to said tubing head means.

12. Underwater well completion apparatus as set forth in claim 11 characterized by first orientation means lowerable through said pressure control means and connected to said tubing head means and second orientation means on said tubing hanger means cooperable with each other to automatically orient said tubing hanger means in a predetermined angular position relative to said tubing head means.

13. Underwater well completion apparatus as set forth in claim 12, characterized in that said first orientation means comprises an upwardly facing helical surface terminating at a longitudinal slot means and said second orientation means comprises key means engageable with said helical surface and slidable thereon to rotate said tubing hanger means to allow said key means to engage said slot means.

14. Underwater well completion apparatus as set forth in claim 12 characterized in that at least a portion of said first orientation means is removable from said tubing head and subsequently reengageable therewith in the same orientation as before removable.

15. Underwater well completion apparatus comprising: conductor casing means penetrating the floor of a body of water; casing head means attached to said conductor casing means near said floor; other casing means concentrically disposed with said conductor casing means; hanger means connected to said other casing means, said hanger means being provided with support means engageable with other support means surrounding said hanger means to limit longitudinal movement of said other casing means and said other hanger means; tubing head means connected above said hanger means in internal fluid flow communication with the innermost of said other casing means and having a maximum diameter no greater than the inside diameter of the casing means adjacent said innermost casing means; tubing hanger means supported on said tubing head means; at least one tubing string supported by said tubing hanger means; tubular wellhead means connected to one of said hanger means above and in communication with said adjacent casing means, an annular space being left between said wellhead and said tubing head; a Christmas tree assembly connected above said wellhead means, said Christmas tree assembly being provided with at least one flow bore; and nipple means between said tubing hanger means and said Christmas tree assembly providing fluidtight flow communication between said tubing string and said Christmas tree assembly flow bore.

16. Underwater well completion apparatus as set forth in claim 15, characterized by packoff means installed in said annular space to prevent fluid passage therethrough.

17. Underwater well completion appaRatus as set forth in claim 15, characterized in that said tubing head means and said tubing hanger means are provided with orientation means for positioning said tubing hanger means within said tubing head means in a predetermined angular orientation relative thereto.

18. A method of completing an underwater well comprising the steps of: locating drilling means at an underwater well site; installing conductor casing in the floor of a body of water with a casing hanger and riser attached thereto at a point near said floor, said riser extending upwardly to said drilling means; drilling holes for, suspending within said conductor casing and cementing in place other casing, each of said other casing being suspended near said floor by hanger head means above which other risers, extending upwardly to said drilling means are connected; attaching blowout pressure control equipment to the top of at least one of said other risers at said drilling means prior to removal of any of said other risers; installing an innermost casing hanger suspending an innermost string of casing from the hanger head means of the previously installed casing; removing through said pressure control equipment any risers which are surrounded by the riser to which said pressure control equipment is attached; running a tubing head into the well; attaching said tubing head to said innermost casing hanger; running a tubing hanger and at least one tubing string, through said pressure control equipment and the riser to which it is attached, into the innermost string of casing; suspending and latching said tubing hanger and tubing string in said tubing head; and removing said pressure control equipment and the remainder of said other risers.

19. A method of completing an underwater well as set forth in claim 18, characterized in that prior to running said tubing hanger the method further comprises the steps of: lowering a orientation means through said pressure control equipment and said riser to which it is attached; and latching said orientation means to said tubing head, said tubing hanger being provided with means engageable with said orientation means on said running of said tubing hanger to align said tubing hanger and tubing string in a predetermined orientation.

20. A method of completing an underwater well as set forth in claim 19, characterized in that prior to removing said pressure control equipment, the method further comprises the steps of: removing the alignment means of said orientation means; and after removing said pressure control equipment, attaching an adapter to said well around said tubing head and said tubing hanger.

21. A method of completing an underwater well as set forth in claim 20, characterized by the further steps of: packing off an annular space between said tubing head and said adapter; and attaching a Christmas tree to said adapter.

22. A method of completing an underwater well as set forth in claim 18, characterized by the further steps of: attaching an adapter to one of said hanger head means with an annular space between said adapter and said tubing head; packing off said annular space; and attaching a Christmas tree to said adapter.

23. Underwater well completion apparatus comprising: a first casing string penetrating the floor of a body of water; hanger head means connected to the upper end of said first casing string near the floor of said body of water; riser means connected to said hanger head means extending upwardly through said body of water to the surface of said body of water; pressure control means connected to the upper end of said riser means; a second casing string lowerable through said pressure control means and said riser means; casing hanger means supporting said second casing string on said hanger head means; tubing head means lowerable through said pressure control means and saId riser means; connecting said tubing head means to said casing hanger means; tubing hanger means lowerable through said pressure control means and said riser means to a position within said tubing head means to be supported thereby; and at least one tubing string supported by said tubing hanger means and lowerable through said pressure control means and said riser means.

24. Underwater well completion apparatus as set forth in claim 23 further comprising: orientation means lowerable through said pressure control means and said riser means for connection to said tubing head means; and said tubing hanger means including means for engaging said orientation means for positioning said tubing hanger means within said tubing head means at a predetermined angular orientation relative thereto.

25. Underwater well completion apparatus as set forth in claim 24 wherein said orientation means includes a helically generated upperwardly facing surface.

26. Underwater well completion apparatus as set forth in claim 24 wherein said riser means and at least a portion of said orientation means are removable and re-engageable with said tubing head means to permit subsequent removal and replacement of said tubing hanger means in the same said predetermined angular orientation.

27. Underwater well completion apparatus as set forth in claim 23 wherein said tubing hanger means is provided with remotely actuable latch means to lock said tubing hanger means to said tubing head means.

28. Underwater well completion apparatus comprising: conductor casing means penetrating the floor of a body of water; casing head means affixed to said conductor casing means near said floor; other casing means concentrically disposed within said conductor casing means; hanger head means connected to said other casing means, said hanger head means being provided with support means engageable with other support means surrounding said hanger head means, to limit longitudinal movement of said other casing means and said other hanger head means; riser means connected to at least one of said hanger head means extending upwardly therefrom to drilling means above the surface of said body of water; pressure control means connected to the upper end of at least one of said riser means; casing hanger means suspending a string of casing lowerable through said pressure control means and the riser means to which it is attached and supported by the innermost of said hanger head means; tubing head means lowerable through said pressure control means and the riser means to which it is attached for connection to said casing hanger means; tubing hanger means lowerable through said pressure control means and said riser means to a supported position within said tubing head means; at least one tubing string connected to said tubing hanger means and lowerable therewith through said said pressure control means and said riser means to said supported position; and characterized in that said tubing hanger means is provided with latch means engageable with said tubing head means on longitudinal movement of said tubing string relative to said tubing hanger means.

29. Underwater well completion apparatus as set forth in claim 28 further comprising: orientation means lowerable through said pressure control means and said riser means for connection to said tubing head means; and said tubing hanger means including means for engaging said orientation means for positioning said tubing hanger means within said tubing head means at a predetermined angular orientation relative thereto.

30. Underwater well completion apparatus as set forth in claim 29, wherein said orientation means includes an upwardly facing helical surface terminating at a longitudinal slot and said engaging means including key means engageable with said helical surface and slidable thereon to rotate said tubing hanger means to allow said key meAns to engage said slot means.

31. Underwater well completion apparatus as set forth in claim 29 wherein at least a portion of said orientation means is removable from said tubing head means and subsequently re-engageable therewith in the same previous orientation.

32. Underwater well completion apparatus comprising: conductor casing means penetrating the floor of a body of water; casing head means attached to said conductor casing means near said floor; other casing means concentrically disposed within said conductor casing means; hanger head means connected to said other casing means, said hanger head means being provided with support means engageable with other support means surrounding said hanger head means, to limit longitudinal movement of said other casing means and said other hanger head means; casing hanger means suspending a string of casing from said innermost hanger head means; tubing head means connected above said casing hanger means in communication with said casing suspended by said casing hanger means and having a maximum diameter no greater than the inside diameter of the innermost casing means; tubing hanger means supported on said tubing head means; at least one tubing string supported by said tubing hanger means; adapter means connected to one of said hanger head means above and in communication with said innermost casing means, an annular sace being left between said adapter and said tubing head means; a Christmas tree assembly connected above said adapter means, said Christmas tree assembly being provided with at least one flow bore; and nipple means between said tubing hanger means and said Christmas tree assembly providing fluid type flow communication between said tubing string and said Christmas tree assembly flow bore.

33. Underwater well completion apparatus as set forth in claim 32, further comprising packoff means installed in said annular space to prevent fluid passage therethrough.

34. Underwater well completion apparatus as set forth in claim 32, wherein said tubing head means and said tubing hanger means are provided with orientation means for positioning said tubing hanger means within said tubing head means in a predetermined angular orientation relative thereto.

35. An apparatus for orienting a tubing hanger within a well, comprising: a support aligned and affixed within such well; orientation means for aligning such tubing hanger in a predetermined orientation; said support having guide means to properly align said orientation means within such well; and said orientation means including alignment means for aligning such tubing hanger within such well, connection means for connecting said orientation means and said support, and release means for disconnecting said alignment means from said connection means.

36. An apparatus as defined in claim 35 wherein said orientation means further includes re-engagement means for re-engaging said alignment means and said connection means in said predetermined orientation within the well.

37. An apparatus as defined in claim 35 wherein said alignment means includes a bushing having a dual 180* ramp at its upper end and a vertical slot communicating with the ramp at its lowermost intersection for engagement with a key mounted to such tubing hanger whereby the key contacts said ramp and rotates such tubing hanger until such key fully engages said vertical slot.

38. An apparatus as defined by claim 37 wherein: said connection means includes a sleeve having a plurality of recesses on its lower end; and said support including a cylinder mounted within such well with said guide means including a plurality of lugs affixed to the upper end of said cylinder for engagement with said recesses whereby said orientation means is predeterminely aligned with said support.

39. An apparatus as defined by claim 38 wherein: said connection means includes a snap ring retractably installed in an annular recess in the internal surface of the upper end of said cylinder for retracting into a mating annular recess in the external surface of said sleeve upon alignment of the recesses.

40. An apparatus as defined by claim 39 wherein said release means includes shear links connecting said bushing and said sleeve whereby an upward force on said bushing causes said links to break disconnecting said alignment means from said connection means.

41. An apparatus as defined by claim 40 wherein said bushing has a plurality of notches engageable with a plurality of pins on the upper end of said sleeve whereby said alignment means may be re-engaged with said connection means after release with said alignment means in said predetermined orientation.

42. A tubing hanger for suspending a string of tubing from a tubing head within a well comprising: a cylindrical body having a vertical bore and a counterbore; a nipple reciprocably mounted within said bore and adapted for connection with such string of tubing; a plug reciprocably mounted within said counterbore having an upper plate and a lower plate; said plug being held against the bottom of said counterbore by a shear pin; said upper plate having an annular latch groove in its periphery in which an expandable latch is mounted; said lower plate having an annular recess in its periphery in which a snap ring is mounted; and said nipple being affixed to said upper plate whereby upon landing said tubing hanger said nipple continues moving downwardly shearing said shear pin thereby causing said plug to move downward in said counterbore until said latch expands into an annular recess in the internal surface of such tubing head and said snap ring engages an annular groove in the internal surface of such tubing head thereby connecting said tubing hanger to said tubing head.

43. A tubing hanger as defined by claim 42 wherein said upper plate and said lower plate are connected by shear bolts whereby upon moving said nipple upward said bolts break causing said upper plate to engage the bottom of the counterbore leaving the lower plate in position due to said snap ring thereby permitting said latch to retract into said recess in said upper plate and said tubing hanger to be removed from the well.

44. An apparatus for completing a well where the well includes an outer casing supported in the ground and a casing hanger mounted within the outer casing, comprising: a tubing head mounted on such casing hanger; a tubing hanger suspending a string of tubing from said tubing head; an adapter for connection with a Christmas tree; said adapter being connected to such outer casing; and a packoff member mounted within said adapter and around a portion of said tubing head for sealingly engaging the external surface of said tubing head and the internal surface of said adapter.

45. An apparatus as defined in claim 44 wherein said packoff member includes: an upper ring; a lower ring; and a seal sandwiched between said upper and said lower ring; said seal being compressed into sealing engagement with said external surface of said tubing head and said internal surface of said adapter as said lower ring engages an annular restrictive shoulder in said adaPter.