US2965174A

US2965174A - Off-shore well installation and method

Info

Publication number: US2965174A
Application number: US711290A
Authority: US
Inventors: John A Haeber
Original assignee: Shell Oil Co
Current assignee: Shell USA Inc
Priority date: 1958-01-27
Filing date: 1958-01-27
Publication date: 1960-12-20
Anticipated expiration: 1977-12-20

Description

Dec. 20, 1960 Filed Jan. 27, 1958 J. A. HAEBER OFF-SHORE WELL INSTALLATION AND METHOD 4 Sheets-Sheet 1 FIG. 5

INVENTOR:

JOHN A. HAEBER BY %\HYKCQ HIS AGENT Dec. 20, 1960 J. A. HAEBER OFF-SHORE WELL INSTALLATION AND METHOD Filed Jan. 27, 1958 4 Sheets-Sheet 2 FIG. 6

FIG. 7

INVENTORI JOHN A. HAEBER BYI% H '7 HIS AGENT Dec. 20, 1960 OFF-SHORE WELL INSTALLATION AND METHOD Filed Jan. 27, 1958 J. A. HAEBER 4 Sheets-Sheet 3 INVENTORI JOHN A. HAEBER aY: H14 C-JZ HIS AGENT Dec. 20, 1960 J. A. HAEBER 2,965,174

OFF-SHORE WELL INSTALLATION AND METHOD Filed Jan. 27, 1958 4 Sheets-Sheet 4 INVENTORI FIG. 9 JOHN A. HAEBER HIS AGENT United States Fatent John A. Haeb'er, Houston, Tex., assignor to Shell Oil Company, a corporation of Delaware Filed Jan. 27, 1958, Ser. No. 711,290

4 Claims. (Cl. 166-46) The invention relates to the drilling of off-shore oil and gas wells and pertains more particularly to an apparatus and a method of assembling an apparatus adapted to provide dry access and working space for the diverless drilling, completion and reworking of oil and gas wells drilled in the floor of bodies of water having depth up to about 200 feet. 7

With the increase in drilling activities at off-shore locations, many different types of equipment for carrying out well drilling operations in bodies of water have been suggested and designed. Various prior workers have proposed the use of a watertight housing to enclose and provide dry working space around a well-head installed 'on'the ocean floor in conjunction with caisson to provide -a dry access or passageway to the housing interior. However, the .prior proposals have involved the use of a very large diameter caisson and/ or the attachment of the watertight housing to the largest pipe (the conductorvpipe ,or the drivepipe) installed in a well either by ce- -inenting around such a pipe after the pipe is set in :the earth, or by welding the'housing to such a pipe and then driving the pipe into the'earth with the housing attached. A large diameter caisson possesses many disadvantages, mainly due to the size and the complexity of the equipment required to transport the caisson and handle it at a drilling location.

On the other hand, to seal and attach a housing to a pipe set in water-covered earth by means of cementing is a slow and relatively unreliable operation, particularly when it must be conducted under a body of salt 'water. These problems are not overcome by attaching the housing to a pipe prior to driving the pipe in the ocean floor. Driving a pipe with an attached housing not only requires unusually large driving equipment but introduces a risk as to whether the pipe and attached housing can be driven to a predetermined depth through the particular earth formation in which the well is located.

It is therefore a primary object of the present invention to provide an apparatus and method of installing an ap paratus which readily provides the necessary space for the diverless drilling, completion and reworking of 1mderwater wells.

A further object of this invention is to provide an underwater housing for the drilling operation which is made watertight when a conductor pipe or drive pipe is driven therethrough.

A watertight housing that encloses and provides working'space around an underwater well-head must satisfy a number of requirements. It must be water-tightly connected to a conductor pipe or drive pipe that has a diameter in the order of 30 inches. During the drilling of a well and at the installation of a well-head assembly, the housing must enclose the pipe-hanging spools and valve assemblies, theblow-out preventor assemblies, master'and swabbing valves, and the like, that are associated with a graded series of pipesihaving diameters of from several inches to two feet or more. The minimum pracine tical dimensions needed to enclose and provide working space around the well head assemblies that are designed for high pressure drilling and standard completion equipment may in the order of magnitude of 10 by 20 feet. In addition, the housing must contain ports and packing glands arranged to form watertight seals around production tubes, control lines, and the like, piercing the housing wall, and must contain a water-tight door which can be opened to provide a passageway for personnel and equipment while a caisson is attached, said door being adapted to be closed to complete a watertight sealing around the well head when the caisson is removed.

It is a further object of the present invention to provide a caisson with means whereby itmay be readily connected in a water-tight manner to a housing positioned below the surface of water while the housingis still closed against the entry of water.

Another object of this invention is to provide a caisson of minimum diameter which at the same time is large enough to allow the simultaneous passage of both personnel and equipment such as pipe of drive pipe size.

A further object of this invention is to provide a caisson and housing which may be readily connected together .in :a fluidtight manner underwater when it is necessary to .enter the housing for servicing the well head installation.

These and other objects of this invention will be understood from the following description taken with reference to the drawing, wherein:

Figure 1 is a longitudinal view, taken partly in cross section, of the housing of the present invention.

Figure 2 is a plan view of the housing shown in Fig- ;ure. .1.

Figure 3 is another view, taken partly in longitudinal cross section, showing the housing of Figure '1 having well-head production equipment installed therein.

Figure 4 is a plan view of the cover of the access tube mounted on the top of the housing.

Figure 5 is a longitudinal view, taken in partial cross section, of a pipe guide and a pipe packing shoe secured to the bottom of the present housing.

Figure 6 is a view of the caisson guide structure secured to the top of the present housing.

Figure 7 is a longitudinal view, in partial cross section, of a caisson section and its caisson landing head assembly illustrated as being mounted on the access tube at the top of a housing in accordance with the present invention.

Figure 8 is a diagrammatic view showing the apparatus of the present invention suspended from an off-shore drilling barge prior to being lowered into the ocean.

Figure 9 is a diagrammatic view iilustrating a housing and caisson of the present invention positioned on the ocean floor and having a drive pipe extending therethrough. I

The present invention is directed to well drilling and controlling equipment which includes a housing which is provided with a closable access tube for personnel and equipment and watertight ports for the passage of fluid and control lines, said housing being adapted for connection to the largest pipe installed around an underwater well so that the housing forms a water-tight enclosure large enough for the construction of a well head assembly, and a caisson which is adapted to be detachably and water-tightly connected to the housing in communication with the personnel and equipment access tube so that the caisson forms a passageway large enough for the simultaneous passage of both equipment and personnel from above the water surface into the interior of the housing. i

The well-head housing of the present invention, which is illustrated in Figure 1 of the drawing,-comp'rises asteel cylindrical tank-like structure 1 which-maybe in theorder of 10 feet in diameter and 20 feet in height. Conical,

. 3 convex or dished heads 1a and 1b are welded to the upper and lower ends of housing cylinder 1, respectively. Fixedly secured to, and extending through, the upper end 1a, is a cylindrical access tube 2 of a diameter of about half that of the cylindrical housing 1.

The upper end of the access tube 2 is provided with an internal flange 3 or other suitable means for connecting it to a caisson landing head assembly (Figure 7) as will be described hereinbelow. The lower end of the access tube 2 is provided with a hinge tube cover or a trap door 4, which preferably swings downwardly into the chamber formed by the housing 1, and, if desired, may be made in two half sections for ease in installing.

vExtending through the bottom dished head 1b of the wellhead housing 1 is a drive pipe packing shoe 5 having removably secured to its upper end an inwardly tapering drive pipe guide. On the side of the housing 1, preferably near the top of the cylindrical section, are three fittings 7, 8 and 9 adapted to allow service lines to enter the housing 1 in a fluidtight manner. The upper fitting 7 is for an electrical conduit or for hydraulic control lines while the other fittings 8 and 9 are for pipe lines which extend through the housing and are connected to the well head to handle the flow therefrom at 8 and a line at 9 to introduce a fluid into the well to kill the well in the event that it has to be serviced.

In order to facilitate the handling of the housing, it is equipped with three towing eyes 10 and three lifting eyes 11. Also, a relief valve 12 is provided on the housing 1 so that in case the pressure within the housing 1 ever reaches an abnormal level, the relief valve 12 will open prior to reaching the bursting pressure of the housing 1. The ladder rungs 13, illustrated as welded onto the wall of the housing 1, are provided for use by personnel during flanging-up and completion operations. Ladder rungs 13a are provided to enable personnel to climb out of the housing through the access tube.

In Figure 2, the position of the access tube 2 is shown relative to the center of the housing 1 and the drive pipe packing shoe 5 which is concentrically positioned in the bottom of the housing 1. As illustrated, the access tube 2 is eccentrically positioned in the top of the housing 1 in a manner such that the access tube is positioned as far as possible to one side of the center of the housing but is displaced no further than a vertical line extending upwardly from the periphery of the pipe packing shoe 5. That is, the displacement away from the center of the housing is such that it is still possible to pass through the housing 1 the access tube 2'and the packing shoe 5 a pipe having a diameter substantially equal to the inside diameter of the packing shoe 5. Alternatively, the pipe packing shoe 5 may be eccentrically positioned in the bottom of the housing 1 while the access tube 2 is positioned concentrically in the top of the housing. Thus, it will be seen that pipe may be inserted through the packing shoe 5 while personnel or other equipment may be lowered through the other portion of the access tube. At the same time it is desired to employ an access tube of a relatively small diameter so as to facilitate its handling and construction.

The housing 1 of Figure 1 is shown in Figure 3 with a high-pressure Christmas tree installed therein. A packing-shoe cover-plate 14 is shown as being welded over the annulus between the packing shoe 5 and a 30 inch drive pipe 80 after the drive pipe guide 6 has been removed. This packing shoe cover plate 14 permanently seals the inside of the housing 1 against entry of sea water past the drive pipe packing elements contained in the shoe 5. A cement return line 15 is shown attached to the drive pipe 80. This line is used during cementing operations when setting well casing 83. A drive-pipe cover-plate 16 may be welded over the top of annulus between the drive pipe 80 and the well casing 83.

. A casing head 17 is installed after the casing 83 has been run into the well, cemented and cut off above the drive-pipe cover-plate 16. Any desired arrangement of spools, valves and other Christmas tree components may be mounted above the casing head 17. As illustrated in Figure 3, the Christmas tree is provided with casing spools 18 and 19, a tubing head 20, a tubing head valve 121, master valves 21a and 21b, a cross 22 and a swabhing valve 23.

The access tube cover 4 of the housing 1 is shown in Figure 4 as comprising a hinged plate member having a hole 24- formed therein for a tubing extension (not shown) which extends from the swabbing valve 23 of Figure 3 upwardly through the cover 4. Hence the hole 24 and the cover 4 must be positioned in a manner such that it is in register directly over the center line of the swabbing valve 23 and hence of the well, thus permitting swabbing of the well after the cover door is closed. In addition, a manway 25 is provided in the access tube cover 4 so that personnel may move in and out of the well-head housing 1 after the access tube cover 4 has been closed. The cover 4 in normal position is hinged to the flange at the bottom of the access tube 2 and is bolted in position when closed. A small circular cover (not shown) is provided which may be bolted 'over the manway 25 to close it in a fluidtight manner.

The drive pipe packing shoe 5 of Figure 1 is illustrated in Figure 5 as being provided with suitable packing means, for example, a rubber packing-ring assembly 31 and multi-V fibre packing rings 32 which are designed to prevent water from entering the empty well head housing 1 by packing off around the drive pipe after a drive pipe 80 has been driven to total depth. If desired, plastic packing ports 29 may be provided so that any minor leaks past the multi-V fibre packing 32 and the packingring assembly 31 can be squeezed off and stopped with a plastic packing compound if necessary. A series of jetting ports 30 are provided in the packing shoe 5 and in a cover plate 33 that closes the bottom of the shoe 5. The plate 33 is made of a plastic or other material, preferably friable, which may be readily knocked out by forcing a drive pipe therethrough. The ports 30 are designed to direct jet streams of water into the soil at the time the housing 1 is set on the ocean floor.

A caisson guide structure 34 is shown in Figure 6 which is adapted to be removably secured to the top of the access tube 2 of the housing 1. The purpose of the caisson guide structure 34 is to provide a guide frame for landing a caisson or the caisson landing head assembly 39 thereof which will be described hereinbelow with regard to Figure 7. The guide structure 34 consists of three guide frame legs 36 and a guide frame head 37 to which a marker buoy mooring eye 38 may be attached. The guide structure 34 is designed to be secured, as by bolts, to three base plates 35 located inside the access tube 2.

In accordance with the present invention, a caisson is provided to extend from the housing 1, located at the ocean floor to a level above the surface of the water. Preferably, the caisson comprises a plurality of caisson sections which are preferably flanged at each end so as to be bolted together. One section of caisson 49 is shown in Figure 7 with its lower flange 48 fixedly secured to a flange 47 at the top of a caisson landing assembly 39. The landing head assembly 39 comprises a cylindrical steel shell or housing 40, and a rubber packer 41 or other suitable seal means which can be used to seal off the inside of the well head housing 1 and the caisson 49 from water surrounding said caisson, by applying a hydraulic pressure between the shell 40 and the rubber packing 41 of the landing head assembly 39. Pressure in the hydraulic fluid reservoir 42 is controlled from the surface through a hydraulic line 43. The caisson landing head assembly 39 is equipped with a guide skirt 44 which centers the caisson 49 over the access tube 2 when the caisson 49 is being lowered to the well-head housing 1 from a servicing unit, such as a barge. The

landing head assembly 39 is provided with an internal flange 46 adapted to contact and be secured to a mating flange 3 at the top of the access tube 2 by a man working .within the caisson 49. A guide notch 45 may be provided in the landing head assembly which forces the caisson 49 to rotate slightly just before landing, thus lining up the holes in the landing head flange 46 with the holes in the access tube internal flange 3.

The caisson 49 is preferably provided with a longitudinal baflle 50 which separates the caisson 49 into two compartments, the right hand compartment being used for running drilling string and other tools in and out of the well while the left hand compartment is used for the passage of personnel.

The apparatus of the present invention is preferably assembled at a drilling location in-a manner illustrated in Figure 8. The apparatus may be assembled from any suitable elf-shore platform or other structure but is prefe'rably assembled within a submersible drilling barge having an upper hull 65 with a drilling deck or platform 67, and a lower hull 68 with a drilling slot 64 therein, said lower hull 68 being shown as positioned on the mud line 69 below the water surface 66. The well-head housing 1, which has been floated into position below the upper hull 65, is hoisted into position and secured by suspension lines 72 so that it is located beneath the point where the rotary table (not shown) will later be installed in the drilling deck 67. With the well head housing 1 suspended in this manner, the caisson landing head assembly 39 and a section of caisson 49 are secured thereto.

The well head housing 1 and section 49 may be lowered stepwise so that additional sections of caisson 49 may be bolted to the uppermost section of caisson until said caisson is of a length suflicient to allow the well head housing 1 to rest on the mud line with the upper end of the caisson well above the water line as shown in Figure 9. Prior to submerging the well-head housing ii in the water the

service conduits

73, 74 and 75 are secured to the housing 1. By connecting one of the

fluid conduits

73 or 74 to the discharge of a pump, fluid may be pumped from the surface down through the housing to jet the housing into the mud as illustrated.

With the caisson and housing suspended from the upper hull 65 by caisson tie-down turnbuckles 78, in a manner shown in Figure 9, a drive pipe 80 and a caisson driver 79 are suspended from the upper hull 65. A guide shoe 81 is secured to the lower end of the drive pipe. After the drive pipe has been driven to the desired depth, the drive pipe guide (Figure l) is removed and a packing shoe cover plate is welded between the top of i the packing shoe 5 and the drive pipe, as illustrated in Figure 3. The drive pipe is then cut off within the housing and the upper portion is removed.

With the drive pipe 80 secured to the bottom of the housing 1, normal drilling operations may be carried on through the caisson 49, housing 1 and drive pipe 80 in a manner well known to the art. Upon completion of well drilling operations, the caisson landing head assembly 39 (Figure 7) is disconnected from the access tube 2 after the caisson guide structure 34 of Figure 6 has been attached to the access tube 2. The caisson 49 is then withdrawn upwardly to the deck of the barge together with the caisson landing head assembly 39. A marker buoy (not shown) is floated over the drilling location with its anchor lying secured to the mooring eye 38 (Figure 6) of the caisson guide structure 34.

From the above description it may be seen that many advantages are realized in using apparatus of the present invention. By incorporating a drive pipe packingshoe in the bottom of the housing and an access tube at the top thereof, the housing 1 can be placed at the mud line at any given drilling location prior to its attachment to the drive pipe 80. This makes it possible to wash the housing 1 to a desired depth down into the earth by attaching the caisson 49 to the housing, lower- .ing the entire assembly so that the housing .1 rests on the earth, and pumping fluid down through the caisson 49 into the housing and out of the ports 30 in the bottom of the housing to contact and wash away the earth around the bottom of the housing. This would not be possible if the drive pipe had previously been attached to the bottom of the housing 1.

Additionally, the arrangement of the present apparatus also has the advantage of using -a length of drive pipe which may be readily driven into the earth whereas if the length of drive pipe had been preselected and secured to the bottom of the housing it might happen that due to the character of the formations encountered, the drive pipe could not be entirely driven into the earth so that the housing was flush with the bottom or ocean floor. The fluidtight connection formed by the drive pipe packing shoe 5 around the drive pipe makes the housing 1 substantially watertight as soon as the drive pipe is run through thehousing 1 so that the housing and caisson can be pumped out immediately to make it possible for operating personnel to enter.

The relatively small caisson diameter materially reduces the equipment requirements necessary for handling it while at the same time adequate space is provided in the housing 1 which is of substantially larger diameter. The unique arrangement of the relatively small caisson, caisson landing head assembly and access tube makes it possible for a crew member to enter the housing while pipe of drive pipe size extends through the caisson. Since the housing 1 and the drive pipe form a watertight enclosure that can be entered by a crew member while the drive pipe extends through the caisson 49, it is also possible to cut off the drive pipe at any desired length, as well as to carry on welding operations within the housing so as to m ke a permanent seal between the drive pine and the housing.

I claim as my invention:

1. An underwater well head and caisson apparatus for use in drilling oil and gas wells in land covered by a body of water, said apparatus comprising a tank-like housing adapted to form on the floor of a body of w"ter a chamber the size sufficient to contain an oil well Christmas tree, port means concentrically positioned in the bottom of said housing of the size sufiicient to enable the largest pipe in said well head apparatus to pass therethrough, a pipe driven through said port me ns into the earth below said body of water, a well-head Christmas tree mounted on said pipe, a drive pipe packing shoe carried by said housing adjacent to the port means to form a fiuidtight seal with said pipe positioned in said port means, an access tube eccentrically positioned in the top of said housing forming entrance means into said housing, said access tube being of a diameter substantially smaller than the diameter of said housing while being positioned in a manner such that the center through said housing is positioned within the tube and at a minimum distance from the periphery thereof equal to at least the radius of the largest pipe to be used in the well installation, caisson means adapted to be removably secured to the top of said access tube and to extend to a point above the water-level of said body of water and cover means for closing said access tube in a fluidtight manner when said caisson is removed.

2. A method of installing a well head housing and caisson assembly at an off-shore drilling location which comprises locating a drilling barge at said location, positioning and suspending a well head housing beneath the operating platform of the barge and above the water, releasably attaching a caisson to the top of said well head housing when said housing is above the water, lowering said housing and caisson until said housing is on the ocean floor with the upper end of the caisson above the water level, driving a pipe through said housing into the ocean floor, cutting olf the top of said pipe within said housing, and we ding together said housing and pipe in a fluidtight man ner.

3. A method of installing a well head housing and caisson assembly at an off-shore drilling location which comprises locating a drilling barge at said location, transporting a well head housing to said barge and hoisting it beneath the operating platform of the barge and suspending it above the water, releasably attaching a caisson to the top of said well head housing when said housing is above the water, lowering said housing and caisson until said housing is on the ocean floor with the upper end of the caisson above the water level, jetting the housing into the ocean floor, driving a pipe through said housing into the ocean floor, cutting oii the top of said pipe within said housing, and welding together said housing and pipe in a fiuidtight manner.

4. A method of installing a well head housing and caisson assembly at an off-shore drilling location which comprises locating a drilling barge at said location, floating a well head housing to said barge and hoisting it bemeans the caisson above the water level, jetting the housing into the ocean floor, driving a pipe through said housing into the ocean floor, cutting otf the top of said pipe within said housing, welding together said housing and pipe in a References Cited in the file of this patent UNITED STATES PATENTS 809,633 Scheibe Jan. 9, 1906 843,606 Hornbeck et al Feb. 12, 1907 2,534,480 Shannon Dec. 19, 1950 2,622,404 Rice Dec. 23, 1952 2,684,575 Pryor et al. July 27, 1954 2,691,272 Townsend et al Oct. 12, 1954 2,699,321 Nelson Jan. 11, 1955 2,854,215 Cox et al. Sept. 30, 1958 FOREIGN PATENTS 160,865 Great Britain Apr. 7, 1921