US3434296A - Method and apparatus for connecting an underwater pipeline to an offshore installation - Google Patents

Description

M h 25, 1969 L. G. OTTEMAN ETAL 3,434,295

METHOD AND APPARATUS FOR CONNECTING AN UNDERWATER PIPELINE TO AN OFFSHORE INSTALLATION Filed Oct. 24, 1966 Sheet of s INVENTORSI F|G 3 LLOYD s. OTTEMAN RONALD GEER vvuzz THEIR AGENT M r h 5 1969 L. e. OTTEMAN ETAL 3,434,296

METHOD AND APPAEATUS FOR CONNECTING AN UNDERWATER PIPELINE TO AN OFFSHORE INSTALLATION Sheet Filed Oct. 24, 1966 INVENTORS LLOYD e. OTTEMAM RONALD L. GEER BY: HTZ

THEIR AGENT March 25, 1969 QTTEMAN ETAL 3,434,296

METHOD AND APPARATUS FOR CONNECTING AN UNDERWATER PIPELINE Filed Oct. 24, 1966 TO AN OFFSHORE INSTALLATION Sheet 3 of3 INVENTORSI LLOYD G. OTTEMAN RONALD L. GEER BYI munu mwt THEIR AGENT United States Patent M 3,434,296 METHOD AND APPARATUS FOR CONNECTING AN UNDERWATER PIPELINE TO AN OFFSHORE INSTALLATION Lloyd G. Otteman, Houston, Tex., and Ronald L. Geer,

Hacienda Heights, Calif., assignors to Shell Oil Company, New York, N.Y., a corporation of Delaware Filed Oct. 24, 1966, Ser. No. 588,876 Int. Cl. 1363b 35/04; F161 1/00; E21b 43/01 US. Cl. 61-72.3 9 Claims ABSTRACT OF THE DISCLOSURE Background of the invention This invention relates to offshore installations and more particularly to a method and apparatus for remotely connecting an underwater pipeline to an offshore installation or platform.

The production of gas and oil wells offshore frequently necessitates the use of an offshore installation mounted on the floor of the ocean and extending above the surface of the water. The so-called production platform is used after the well has been completed and provides a ready means of access to the well from the platform by means of a riser pipe extending from the platform to the wellhead. When it is desired to produce oil or gas to an underwater collecting facility, to another above water platform, floating production facility or directly to shore, a flowline is connected to the riser pipe and back down the installation to the ocean floor where it continues on the ocean floor to a collecting facility or to shore, etc. More than one well may be operated from the production platform with the individual flowlines from the various wells manifolded together and the collective production piped to shore through a pipeline. Also, the production facilities, i.e., separators, flow controls etc., are generally installed on the production platform. In relatively shallow waters the connecting of a flowline to the riser and to the installation is typically performed by deep sea divers. However, in relatively deep water, i.e., beyond diver capability, a flowline cannot be installed in this manner thus necessitating the use of tanker vessels to transport the oil or gas from the offshore location.

Presently, oil and gas wells are being developed offshore in water depths in excess of 100 feet which precludes the effective use of divers to perform functions on the ocean floor. However, it is still desirable to transport the produced oil or gas by means of a pipeline since it results in continuous production with lower operating costs.

Summary of the invention In summary, the invention provides a method and apparatus for connecting a flowline to an offshore platform by providing the platform with track means for lowering a slidably attached flowline guide intov a position adjacent the water floor. The guide is suitably held in place and a flowline, laying on the water floor, is pulled past the guide and up to the upper portion of the platform which extends above the water surface.

It is therefore a primary object of the present invention to provide a method and apparatus for connecting an underwater flowline to an offshore installation extending above the surface of a body of water.

3,434,296 Patented Mar. 25, 1969 ice Another object of the invention is to provide a method and apparatus for making the connection which can be performed entirely from the surface of the water without the necessity of divers.

A further object of the invention is to control the position and bending of the flowline as it passes from the floor of the body of water up to the surface.

A still further object of the invention is to position a flowline guide member on the installation near the floor of the body of water to control the position and bending of the flowline.

These and other objects will become apparent from a reading of the following detailed description of the invention taken in conjunction with the accompanying drawings in which:

Brief description of the drawings FIGURE 1 is an elevation of an offshore installation showing the flowline guide member being lowered down one leg of the installation;

FIGURE 2 is the same elevation showing the guide member in place;

FIGURE 3 is the same elevation showing a flowline pulled through the guide and connected to the installation;

FIGURE 4 is a vertical cross section taken through the flowline guide member at the lower end of a support of the installation;

FIGURE 5 is a horizontal cross section showing the flowline guide member and track guide on which it travels;

FIGURE 6 is an elevation of an offshore installation incorporating an alternative arrangement in accordance with the invention;

FIGURE 7 is a detailed vertical cross section of a portion of the flowline guide member showing a mechanical lock device to prevent upward movement of the guide member on the track guide;

FIGURE 8 is a detailed vertical cross section of the flowline guide member similar to FIGURE 7 showing an alternative mechanical lock; and

FIGURE 9 is an elevation view showing a modified arrangement in accordance with the invention wherein a plurality of guide members are employed.

Description of the preferred embodiments Referring now to FIGURE 1, an offshore installation is shown in the form of a production platform indicated generally at 10. The platform includes supporting structure 11 which is anchored to the floor 12 of a body of water 13 in a suitable manner. An upper portion 14 of the platform 10 is arranged to remain above the surface 15 of the body of water 13 and serves as a work area and support for a variety of equipment such as a crane 16.

The particular design and construction of the offshore installation does not form a part of the invention so long as the installation is positioned over or near a gas or oil well. As shown in FIGURES 1, 2 and 3, the platform 10 is located directly over a production wellhead 18. EX- tending between the wellhead 18 and the upper portion 14 of the platform is a riser 19 which carries the produced gas or oil.

FIGURES 1, 2 and 3 are elevation drawings showing the sequence of connecting a flowline 2-3 to the riser 19 utilizing a preferred form of the present invention. FIG- URE 1 shows a flowline guide member 20 being lowered down a leg 21 of the platform on a track guide 22. In FIGURE 2 the flowline guide member is shown in its operative position near the floor 12 of the body of water 13. The flowline is shown connected to the riser 19 in FIGURE 3, after having been pulled through the flowline guide member 20 and up to the surface.

The track guide 22 is secured to the platform leg 21 and extends substantially the length of the leg. As shown in FIGURE 4, the track guide 22 has aT cross section and slidably mates with carriages 24 formed on the flowline guide member 20. The carriages 24 are formed with inwardly turned flanges 25 to prevent the flowline guide member from coming off the track guide 22. Although the flowline guide member 20 may descend along the track guide 22 under its own weight, it is preferably to employ a pipe string 26 as best shown in FIGURE 1 to assist and control the lowering of the flowline guide member. As the member 20 is lowered additional lengths of pipe are added to the string until the flowline guide member reaches its operative position as shown in FIGURE 2. A retractible pipe gripper or slip 27 secured to the platform serves to hold the assembled pipe string 26 as additional lengths are added. After the flowline guide member is installed, the pipe string 26 may be detached and brought to the surface as will be subsequently described.

The flowline guide member is preferably a ]-shaped horn as shown in detail in FIGURE 4. The flared mouth portion 28 permits some alignment deviation of the flowline as it enters the flowline guide member 20. The converging walls direct and position the flowline so that it will align with and pass through a vertically positioned throat portion 29 of the flowline guide member. It will be observed that as the flowline 23 passes the flowline guide member 20, the flowline, which is preferably made of steel, is plastically deformed and re-straightened in a continuous manner. Thus, the size and curvature of the flowline guide member must be such as to prevent buckling or over-straining of the flowline. Tests have shown that flowlines up to the largest diameters in use today can be accommodated without permanent damage to the flowline provided the J-tube has adequate dimensions.

Since the flowline guide member serves only as a guide and a reaction member for the flowline 23 so that the flowline will accurately and readily translate from a horizontal position to a substantially vertical position, it will be apparent that the flowline guide member 20 may take other forms. For example, it may take the form of an inverted curved channel, arcuately spaced rollers or other forms without departing from the invention. The essential feature is that the flowline guide member employed has a curved reaction surface against which the flowline 23 acts.

Suitable locking means are provided to prevent upward movement of the flowline guide member 20 when it is lowered in place on the track guide 22. Typical locking means are shown in FIGURE 5 in which a first latch means in the form of a hydraulic cylinder 30 is mounted on the flowline guide member 20 adjacent the throat portion 29 and operatively receives a locking piston 31 which extends under hydraulic pressure to stab a second latch means in the form of an apertured block 32 secured to the platform leg 21. Secured to the block 32 are pins 33 carried by slots 34 in the bracket 35 so that the block 32 may move vertically to compensate for slight misalignment. The bracket 35 is formed integrally with the leg 21 or it may be suitably secured to the leg, e.g., by welding.

The hydraulic cylinder 30 is actuated by means of hydraulic pressure introduced through the pipe string 26. The lower end of the pipe string 26 has secured thereto a cable adaptor 36 threadably secured and extending into the throat 29 of the flowline guide member 20. The adaptor carries a packer 37 near its lower end to form a sealed annulus 38 between the adaptor 36 and the throat portion 29 of the flowline guide member 20. Hydraulic fluid in the pipe string 26 enters the annulus 38 by means of a port 39 in the adaptor. The annulus 38 is in turn in communication with the cylinder 30 through port 40 in the throat 29 of the flowline guide member. Thus, pressurized hydraulic fluid is supplied to the cylinder 30 through pipe string 26, port 39, annulus 38 and port 40. The cylinder 30 is equipped with a one-way valve (not shown) so that once the piston 31 is actuated, the hydraulic fluid cannot leave the cylinder 30. In the event of pressure loss past the seals in the cylinder, the piston 31 will remain in the locked position by virtue of ring 41 carried by the block 32. The ring 41 is received in an annular groove on the piston 31 as shown in FIGURE 5.

In some installations it may be desirable to recover the flowline guide member 20 to the surface. In this case a releasable locking means may be employed. For example, cylinder 30 may be double-acting so that locking piston 21 may be retracted and the guide member 20 recovered to the surface. Other suitable releasing locking means will be readily apparent to one skilled in the art.

The arrangement for removing the pipe string after the flowline guide member is installed will now be described. Referring to FIGURE 5, the pipe string 26 is threadably attached to the throat 29 of the flowline guide member with a reverse-helix or left-hand thread. The remaining threaded connections coupling the pipe string 26 are of conventional right-hand design. Thus, clockwise rotation of the pipe string 26 at the surface disconnects the pipe string 26 from the flowline guide member 20 while the remainder of the string 26 stays intact. The pipe string 26 can then be brought to the upper portion 14 of the platform 10 and disassembled length-by-length.

One end of a flexible pulling cable 43 is attached to the adaptor 36 and is therefore recovered to the upper portion 14 of the platform 10 with the pipe string 26. The cable 43 threads through the flowline guide member 20 and the other end is held at the surface 15 by suitable means, e.g., a pipe laying barge 44 as shown in FIGURE 1. The cable 43 is connected to the flowline 23 preferably after the flowline guide member 20 has been lowered and locks in place. By applying tension to the cable 43 by means of the crane 16 or other suitable hoisting means, the flowline is pulled through the flowline guide member 20 and up to the upper portion 14 of the platform 10. Preferably, the barge 44 lays a length of the flowline along the ocean floor 12 at least equal to the water depth prior to pulling the flowline through the flowline guide member or the barge may lay pipeline continuously with the pulling operation.

A modification of the invention is shown in FIGURE 6. In this arrangement a flowline conductor pipe 45 is attached to the flowline guide member 20 and extends to the upper portion 14 of the platform 10. The conductor pipe 45 is used to lower the flowline guide member 20 into place in a manner similar to that described in the preferred embodiment when the pipe string 26 is used. However, after the flowline guide member 20 is in place, the conductor pipe 45 is not removed and it serves as a conductor or conduit for the flowline 23. In order to assure a more rigid system, the conductor pipe is preferably fitted with pipe carriages 46 slidably carried on the track guide 22. The pipe carriages 46 may take any form to permit the conductor pipe 45 to slide down the guide 22, e.g., they may be similar in conduction to the carriages 24 carried by flowline guide member 20.

Since the conductor pipe 45 remains in place, a flowline pulling cable (not shown) is threaded through the conductor pipe 45 and flowline guide member 20 prior to installation. In addition, suitable hydraulic or mechanical locking means are provided to prevent upward movement of the guide member 20 and conductor pipe 45 after they are installed. Two forms of mechanical locking means are shown in FIGURES 7 and 8, respectively. Referring now to FIGURE 7, the flowline guide member 20 is fitted with a pivotally mounted latch 47 arranged to swing upwardly to clear the stop 48 on the track guide 22. Spring 49 and pusher 50 bias the carriage 24 upwardly thus bringing latch 47 into locked engagement with stop 48 to prevent upward movement of the flowline guide member 20. In the arrangement shown in FIG- URE 8 a plurality of spring bias pawls 51 carried by flowline guide member 20 mate with latch plate 52 on the track guide 22.

It will be readily apparent that other locking means may be employed, e.g., a hydraulic arrangement similar to that disclosed in the preferred embodiment shown in FIGURES 1-5. Since the conductor pipe 45 remains in place and serves as a conduit for flowline 23 it cannot act as a hydraulic line and thus an additional conduit must be employed to carry the hydraulic fluid if the hydraulic locking means shown in FIGURE 5 is utilized. Also, it will be apparent that the preferred embodiment may employ mechanical locking means such as disclosed in FIG- URES 7 and 8.

The operation of the preferred form of the invention will now be described with reference to FIGURES 1-5. The flowline guide member 20 is installed on the upper end of the track guide 22 by sliding the carriages 24 onto the track guide. A length of pipe is attached to the upper end of the flowline guide member 20 and successive pipe lengths are added to form the pipe string 26 as the flowline guide member 20 is lowered into place near the ocean floor 12. A flexible cable 43 is threaded through the pipe string and flowline guide member 20 before the assembly is lowered into place. As seen in FIGURE 1, the cable 43 extends from the upper portion 14 of the platform 10 through the pipe string 26 and flowline guide member 20 to a lay barge 44. As the assembly is lowered, additional cable is payed out from the lay barge 44. When the flowline guide member 20 is placed as shown in FIG- URE12, it is locked by the hydraulic arrangement shown in FIGURES 4 and 5. The pipe string 26 is then removed from the flowline guide and retrieved to the surface. A flowline 23 is attached to the flexible cable on the lay barge 44 and the barge begins laying pipe along the ocean floor by moving in a direction away from the platform 10 as the end of the flowline 23 is brought near the mouth portion 28 of the flowline guide member 20 by applying tension on the cable 43 from the upper portion 14 of the platform 10. The flowline 23 may then be pulled through the flowline guide member 20 and up to the surface by means of the cable 23 as the lay barge continues to lay the flowline on the floor 12 of the body of Water 13. After the flowline is brought to the upper portion .14 of the platform it is connected to the riser 19 by any suitable means. For example, the flowline 23 may be fitted with a flange 54 and joined to the riser by means of a flanged pipe elbow 53.

In the embodiment shown in FIGURE 6 a flowline conductor pipe 45' is used in place of the pipe string 26 and remains in place as an additional guide and protector for the flowline 23. The sequence of lowering the flowline guide member 20 into place and pulling the flowline 23 through the guide member and up to the surface is the same as that described in the preferred embodiment.

In addition, several flowline guide members 20 may be installed on the same platform leg to accommodate a plurality of flowlines. To accomplish this, a plurality of track guides 22 may be installed about the leg of a platform with each track guide 22 arranged to accommodate a flowing guide member 20 as described above. Alternatively or in addition, more than one guide member 20 may be lowered together on the same track guide 22. For example, as shown in FIGURE 9 a cluster of three flowline guide members 20 may be joined and lowered down track 22 on platform leg 21 to accommodate three separate flowlines.

Having thus described the invention, what is claimed is:

We claim as our invention:

1. A method for connecting a flowline to an olfshore installation positioned on the floor of a body of water and having a portion extending above the surface of said body of water comprising:

positioning at least one track guide means on said installation from substantially the floor of said body of water to the surface thereof;

slidably mounting at least one flowline guide means on said track means;

directionally orienting said guide means at the water surface in the direction said guide means is to be positioned near the floor of said body of water;

lowering and guiding said flowline guide means down said track guide means from the portion of said installation above the surface of said body of water to a position near the floor of said body of water;

fixedly positioning said flowline guide means near the lower end of said installation to prevent at least upward movement thereof;

pulling one end of said flowline past and in operative contact with said flowline guide means to the portion of said installation above said body of water; and,

connecting said end of said flowline to said installation.

2. The method as defined in claim 11 including the further steps of:

connecting one end of an elongated lowering element to said flowline guide means prior to lowering said flowline guide means down said track guide means;

disconnecting said elongated lowering element from said flowline guide means after said flowline guide means is fixedly positioned; and,

retrieving said elongated lowering element to the portion of said installation extending above said body of water.

3. The method as defined in claim 1 including the further step of:

connecting a flowline conductor pipe to said flowline guide means of sutficient length to extend past the surface of said body of water when said flowline guide means is lowered and fixedly positioned.

4. The method as defined in claim 1 including the further step of:

positioning in said flowline guide means a flexible pulling element of a length equal to at least the depth of said body of water of both said guide means.

5. An apparatus for connecting a flowline to an offshore installation positioned on the floor of a body of water and having a platform extending above the surface of said body of water comprising:

track guide means secured to and forming part of said installation and extending substantially the height of said structure between the surface and floor of said body of water;

a generally curved flowline guide means for guiding said flowline from a substantially horizontal to a substantially vertical position;

said flowline guide means including carriage means adapted to be slidably secured on said track guide means; and,

means engageable with said flowline guide means for positioning said flowline guide means on said installation adjacent the floor of said body of water including first and second cooperating latching means, the first of said latching means carried by said flowline guide means and the second of said latching means carried by said installation.

6. The apparatus as defined in claim 5 wherein said apparatus includes:

a flexible pulling element positioned in said flexible guide means,

said element being connectible to one end of said flowline and having a length equal to at least the depth of said water above said flowline guide means.

7. The apparatus as defined in claim 6 wherein said apparatus includes:

pulling means positioned near the surface of said body of water and connectible to the free end of said flexible pulling element, said pulling means being operable to pull said flowline past said flowline guide means.

8. The apparatus as defined in claim .5 wherein said flowline guide means comprise a plurality of generally I- shaped fiowline guides.

9. An apparatus for connecting a fiowline to an offshore installation positioned on the floor of a body of water and having a platform extending above the surface of said body of water comprising:

track guide means secured to and forming part of said installation and extending substantially the height of said structure between the surface and floor of said body of water;

a generally curved flowline guide means for guiding said flowline from a substantially horizontal to a substantially vertical position;

said flowline guide means including carriage means adapted to be slidably secured on said track guide means; and,

means engageable with said flowline guide means for positioning said fiowline guide means on said installation adjacent the floor of said body of water including a flowline conductor pipe connected to said flowline guide means of a length sufiicient to extend past the surface of said body of water, said conductor pipe including carriage means adapted to be slidably secured on said track guide means.

References Cited UNITED STATES PATENTS 3,226,728 12/1965 Walvoord 6172.3 X 3,298,092 1/1967 Dozier et al 61-723 X JACOB SHAPIRO, Primary Examiner.

US. Cl. X.R.

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