US3189100A

US3189100A - Underwater wellhead with cement return line

Info

Publication number: US3189100A
Application number: US205586A
Authority: US
Inventors: John A Haeber; Raymond F Perner; Jr Frank Poorman
Original assignee: Shell Oil Co
Current assignee: Shell USA Inc
Priority date: 1962-06-27
Filing date: 1962-06-27
Publication date: 1965-06-15
Anticipated expiration: 1982-06-15
Also published as: GB999838A

Description

June 15, 1965 J. A. HAEBER ETAL UNDERWATER WELLHEAD WITH CEMENT RETURN L INE Filed June 27, 1962 2 Sheets-Sheet 1 25b 38 26b Ill 2 Ill 250 g 260 FIG.|

BY: LI

THEIR AGENT June 15, 1965 J. A. HAEBER ETAL 3,139,100

UNDERWATER WELLHEAD WITH CEMENT RETURN LINE Filed June 27, 1962 2 Sheets-Sheet 2 INVENTQRS:

J. A. HAEBER I R. F. PERNER FIG. 2 F. POORMAN, JR. 7

BY: 5. l-'

THEIR AGENT United States Patent M 3,189,1tltl UNDERWATER WELLHEAD WITH CEMENT RETURN LLNE Eohn A. flasher, Houston, Tern, and Raymond F. Perrier,

ltfctairie, and Frank Poorman, .lru, Lafayette, La, assignors to Shell Gil ompauy, New York, N.Y., a corporation of Delaware Filed Tune 27, 1962, Ser. No. 205,586

7 Qlaims. (Cl. 166-665) This invention relates to apparatus for use in drilling underwater oil and gas wells at offshore locations, and pertains more particularly to apparatus adapted to provide fluid communication between a vessel on the surface of a body of water and a wellhead assembly positioned on the ocean floor or at a substantial depth below the surface of the water during early cementing operations in the well.

In an attempt to locate new oil fields, an increasing amount of well drilling has been conducted at offshore locations, such for example, as oil the coast of Louisiana, Texas and California. As a general rule, the string of casing in a well, together with the tubing string or strings, extend to a point above the surface of the water where they are closed in a conventional manner that is used on land wells, with a conventional wellhead assembly being attached to the top of the casing. Recently, methods and apparatus have been developed for drilling and completing wells wherein both the well casinghead, and subsequently the Wellhead assembly and easing closure device, are located underwater at a depth sufficient to allow ships to pass over them. Preferably, the casinghead and the wellhead closure assemblies are located close to the ocean floor. In order to install well drilling equipment underwater and carry out well drilling operations on underwater wells at depths greater thanthe shallow depths at which a diver can easily operate, it is necessary to design entirely new equipment for this purpose.

Wells drilled in deep water, that is, in water 100 feet or more in depth, are generally drilled from vessels of varying designs commonly known as drilling barges or drilling vessels or platforms. One method of drilling underwater wells is described in copending patent application, Serial No. 830,538, filed July 30, 1959. In the method described in the above-identified patent application a shallow hole is first drilled in the ocean floor and a large-diameter pipe known as a foundation pile or a well conductor pipe is inserted and cemented in the hole. A casinghead, forming a portion of the wellhead assembly, is generally secured to the top of the well conductor pipe together with suitable guide means extending from the Wellhead assembly to the vessel on the surface of the ocean. The casinghead is provided at the head of the well conductor pipe so that subsequent concentric strings of pipe or casing and tubing may be hung in the well. After continuing drilling operations to a substantial depth, a string of pipe, often known as surface casing, is inserted into the well conductor pipe and hung from the casinghead in a manner well known to the art. In order to cement the surface casing pipe string in the well, it is necessary to pump cement down through a cementing pipe string, extending from the vessel on the surface above, and into the bottom of the surface casing from whence it flows up the annular space between the outside of the surface casing and the borehole wall of the well. In order to displace the cement slurry up the annular space outside the surface casing string, it is necessary to provide fluid discharge means from this annular space up the wellhead. Since the inner casing string or surface casing is seated in the casinghead, it is necessary to provide discharge ports through the wall of the casinghead or through the conductor pipe of Patented June 15, 1965 therein.

In the event of a poor cement job in cementing the surface casing in the well, formation pressures encountered by the well may attempt to escape up the annular space between the surface casing and the conductor pipe and escape out the side discharge ports therein or in the easinghead. Thus, it is an object of the present invention to provide valve means in a cement return line from an underwater well casinghead so that the line may be closed to prevent the escape of well pressures therefrom.

The cement return line which extends from the casinghead and is in communication with the annular space therein outside the surface casing, generally extends to the vessel at the surface of the ocean. If desired, drilling fluid may be circulated up this line during one stage of drilling the well. During well cementing operations, it may be found that there has been a breakdown in a porous section of the formation traversed by the well which may be caused by the great weight of a column of cement acting against the formation. If a breakdown of the formation occurred during the drilling of the well, lost circulation additives would be added to the drilling mud to plug the zone so that drilling mud would not be lost to the formation but would return to the vessel. However, due to the greater weight of cement compared to drilling mud, a formation breakdown might occur during cementing operations.

It is therefore another object of the present invention to provide a cement return line assembly on an underwater wellhead whereby fluid or cement returning out the return line can be selectively dumped out of the line at substantially the level of the wellhead thereby reducing the chance of a formation breakdown due to the weight of the cement column and the pressure being applied to it in order to force a returning column of fluid all the way back to the vessel at the surface of the ocean.

A further object of the present invention is to provide a cement return line from an underwater well with a quick disconnect unit whereby the major fluid control components-of the cement return line assembly can be disconnected and retrieved and brought back to the drilling vessel after the surface casing has been cemented within a well.

It is another object of the present invention to provide a return line from an underwater wellhead which can be employed as a choke line during drilling operations and as a cement return line during cementing operations, while at the am .e time being provided with a flow control valve selectively operable to open or close the line during emergency blowouts.

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 diagrammatic view taken in longitudinal projection illustrating a floating drilling platform positioned on the surface of the ocean with an underwater Wellhead assembly positioned on the ocean floor; and,

FIGURE 2 is a diagrammatic view taken in longitudinal projection and partially in cross section illustrating the cement return line assembly of the present invention.

Referring to FIGURE 1 of the drawing, a drilling platform or vessel 11, of any suitable floatable type is illustrated as floating on a surface of a body of water 12 and substantially fixedly positioned over a preselected drilling location by suitable barge positioning means or by being anchored to the ocean floor 13 by suitable anchors (not shown) connected to anchor lines 14 and 15. Equipment of this type may be used when carrying on well drilling operations in water depths varying from about to 1500 feet or more. The drilling barge is equipped with a suitable derrick 16 as well as other auxiliary equipmerit needed during the drilling of a well. The derrick 16 is positioned over a drilling slot or well 13 which extends vertically through the barge in a conventional manner. When using the equipment of the present invention, the slot of the barge 11 may be either centrally located or extended from one edge. However, drilling operations may be carried out over the side of the barge, platform or vessel without the use of a slot. Additionally, it is to be understood that the equipment of the present invention may also be used when drilling a well from any suitable operational base positioned above the surface of the water, such for example, as from a drilling barge having feet extending to the ocean floor or from a platform permanently positioned on the ocean floor.

A typical underwater wellhead structure is illustrated in FIGURE 1 as comprising a base member 21 which is positioned on the ocean floor 13 and is fixedly secured to a conductor pipe or larger-diameter well casing 22 which extends down into the well, which has been previ ously drilled, and is preferably cemented therein. Thus, the base structure 21 is rigidly secured to the ocean floor in order to support two or more vertically-extending

guide columns

23 and 24 adapted to receive and guide therein guide arms 25 and .26, 25a and 26a, and 25b and 26b, which are arranged to slide on vertically-extending

guide cables

27 and 28. The lower ends of the

guide cables

27 and 28 are anchored to the base structure 21 within the

guide columns

23 and 24, while extending upwardly through the water to the drilling vessel 11 where they are preferably secured to constant tension hoists 31 and 32. It is to be understood that in an emergency a single guide arm or guide cable extending between the base structure 21 and drilling vessel may be employed to position a piece of equipment on the wellhead, although a guide system having at least three guide cables is preferred.

Centrally positioned above the base plate 21 and fixedly secured thereto, or to the conductor pipe 22, is a well casinghead unit 33 which is provided with a lateral discharge port to which a cement circulation or fluid return line 34 is connected to provide fluid commmunication with the annular space between the inner wall of the easinghead 33 and the outer wall of another string of pipe, such, for example, as a string of surface casing 35 which is hung from the interior of the casinghead 33. During drilling operations the casinghead is closed by a wellhead connector unit 35 having one or more blowout preventers 37 connected to the top thereof with a landing head 38 of a marine conductor pipe 39 secured to the top of the blowout preventer. The marine conductor pipe 39 extends upwardly through the water to a position above the surface thereof adjacent the barge 11. During drilling operations a drill pipe extends down through the marine conductor pipe 39, while during cementing operations the cementing pipe string may be employed which extends down through the marine conductor pipe. Alternatively, cement may be pumped down the marine conductor pipe 39 without the use of a cementing string.

As shown in FIGURE 2 the cement circulation or fluid return line 34 is provided with flow control means which may include a check valve 40 and/or a remotely-operable flow control valve 41, as well as a discharge or dump valve 42. The flow control and

dump valves

41 and 42 are provided with suitable remotely-

actuatable operators

43 and 44 having

suitable control lines

45 and 46 which may be in the form of electrical transmission lines or pressure hoses which may be bundled together at a cluster fitting 47 and then extend to the vessel 11 at the surface. The flow control ring valve 41 and the dump valve 42 may be valves of any suitable type, one suitable type being six-inch, one thousand p.s.i. type F valves with hydraulic operators manufactured by Cameron Iron Works, Houston, Texas. The valves, for example, valve 42 may be provided with downwardly extending stem protectors 48 with a vent hole 49 for the valve.

Suitable conduit disconnect apparatus is provided in the cement circulation or fluid retrurn line 34 whereby the

controllable valves

41 and 42 may be recovered together with the preferably flexible upper part of the circulation line 34 after cementing operations have been completed. Any suitable conduit disconnect device may be employed such for example as telescoping sleeves that are shear pinned together and detachable by an upward pull on line 34-. However, it is preferred that a remotely-actuatable disconnect unit 51 be employed. The unit shown comprises a tubular body member 52 having a reduceddiameter portion 53 which is insertable in a preferably vertically-extending extension 54 which is welded to the upper end of the dump valve housing 55. The body member 52 of the disconnect unit 51 is provided with a plurality of outwardly-extendible latching dogs 56 which are cammed outwardly by the lower end of a downwardlymoving tubular piston 57 slidably mounted for limited vertical movement in chamber 58 which may be supplied with fluid pressure above and below the piston through conduits 59 and 69. The dogs 56 are adapted to engage circumferential grooves 61 in the inner wall protecting the stem 50 of e of the tubular extension 54.

Fixedly secured to the lower end of the tubular body member 52 of the disconnect unit 51 is a spider in the form of a plurality of radially-extending vanes 62 which extend outwardly from a central pin 63 which is in surface contact with the top of the closure element or valve member 64 of the check valve 46. Thus, when the apparatus of the present invention is assembled on the vessel to the form shown in FIGURE 2, with the tubular body member 52 of the disconnect unit 51 latched in the tubular extension 54 of the check valve, the pin 63 holds the closure element of valve member 64 of the check valve open so that fluid may circulate past it and through the spaces between the vanes 62 and thence upwardly through the disconnect unit 51, valve 41 and the upward extension of a return line 34 which extends to the barge at the surface. The closure element 64 of the check valve is preferably provided with suitable spring means 65 whereby the closure elements urged upwardly to close the check valve 40 when the disconnected unit 51 is unlatched from the tubing extension 54 and pulled upwardly out of the tubing extension.

During the cementing of a well when fluid is discharged from the casinghead 33 into the fluid return line 34, the fluid normally flows past the closure element 64 of the check valve up through the disconnect unit 51 and through the flow control valve 41 and thence to the vessel at the surface. In the event that abnormal pressures are encountered flow through the line can be shut off by means of the flow control valve 41 which is remotely actuatable from the surface. If on the other hand it appears that there has been a breakdown of the formation during cementing of the well so that cement is being lost to the formation and return fluid is not being received at the drilling vessel at the surface of the ocean, both the flow control valve 41 and the dump valve would be opened so that the return fluid from the well could be discharged into the ocean at a point adjacent the well, thus eliminating pressure losses incurred in the return line 34 between the wellhead and the barge as well as reducing the hydrostatic head of the column of liquid in the return line to the barge. After cementing operations have been completed the conduit disconnect unit 51 is unlatched so that it and the control valve assembly above can be withdrawn to the vessel leaving only the check valve closing the horizontal run of the fluid return line 34 while all of the vertical run of the line is recovered at the vessel.

We claim as our invention:

ll. An underwater drilling wellhead assembly fixedly positioned to the ocean floor and adapted to have an operational platform positioned substantially thereabove, said wellhead assembly comprising (a) a tubular well member extending into the ocean floor and fixedly positioned therein with the upper end thereof extending above the ocean floor,

(b) side conduit means extending substantially laterally from said tubular well member and being in communication with the interior thereof, said side conduit means extending upwardly from said drilling wellhead assembly to said operational platform at the surface of a body of water,

(0) conduit disconnect means in said side conduit means at a level adjacent said wellhead assembly, and

(d) first valve means in said side conduit means between the tubular well member and the conduit disconnect means,

(e) wherein said side conduit means has fluid discharge port means through the wall thereof downstream of said disconnect means when flow is outwardly from the well and in communication with the ocean on the side of the disconnect means away from the wellhead assembly substantially at the level of said wellhead assembly, and there being remotely actuatable second valve means normally closing said discharge port means.

2. The apparatus of claim 1 wherein said side conduit means has a substantially horizontal run for a short distance from the tubular well member and then turning to a substantially vertical run which extends upwardly to the platform at the surface, and wherein at least the conduit disconnect means is positioned in the vertical run.

3. The apparatus of claim 1 wherein said conduit disconnect means comprises pipe connector means having disengageable mating portions, one portion thereof operatively engaging said first valve means to hold it open when said mating portions of said connector means are engaged.

4. The apparatus of claim 1 wherein said first valve means comprises a check valve having a closure member engageable with a portion of said conduit disconnect means and held open thereby when said conduit disconnect means is engaged.

5. The apparatus of claim 1 including valve operator means mounted on and operatively connected to said second valve means and power transmission line means extending from said valve operator means to said operational platform at the surface.

6. The apparatus of claim 5 including third valve means in said side conduit means adjacent said discharge port means thereof for controlling fluid flow through said side conduit means.

7. The apparatus of claim 6 including valve operator means on said second and third valve means and operator means on said conduit disconnect means.

References Cited by the Examiner UNITED STATES PATENTS 2,127,728 8/38 Grant 166-76 X 2,923,531 2/60 Bauer et a1. -7 2,970,646 2/61 Knapp et al. 166-665 X 3,064,735 11/62 Bauer et al. 16666.5 3,090,437 5/ 63 Geer l6666.5 3,099,316 7/63 Johnson 166-665 X 3,100,525 8/ 63 Smith et a1. 166-2l FOREIGN PATENTS 874,178 8/57 Great Britain.

CHARLES E. OCONNELL, Primary Examiner.

Claims

1. AN UNDERWATER DRILLING WELLHEAD ASSEMBLY FIXEDLY POSITIONED TO THE OCEAN FLOOR AND ADAPTED TO HAVE AN OPERATIONAL PLATFORM POSITIONED SUBSTANTIALLY THEREABOVE SAID WELLHEAD ASSEMBLY COMPRISING (A) A TUBULAR WELL MEMBER EXTENDING INTO THE OCEAN FLOOR AND FIXEDLY POSITIONED THEREIN WITH THE UPPER END THEREOF EXTENDING ABOVE THE OCEAN FLOOR, (B) SIDE CONDUIT MEANS EXTENDING SUBSTANTIALLY LATERALLY FROM SAID TUBULAR WELL MEMBER AND BEING IN COMMUNICATION WITH THE INTERIOR THEREOF, SAID SIDE CONDUIT MEANS EXTENDING UPWARDLY FROM SAID DRILLING WELLHEAD ASSEMBLY TO SAID OPERATIONAL PLATFORM AT THE SURFACE OF A BODY OF WATER, (C) CONDUIT DISCONNECT MEANS IN SAID SIDE CONDUIT MEANS AT A LEVEL ADJACENT SAID WELLHEAD ASSEMBLY AND (D) FIRST VALVE MEANS IN SAID SIDE CONDUIT MEANS BETWEEN THE TUBULAR WELL MEMBER AND THE CONDUIT DISCONNECT MEANS,