US3482408A

US3482408A - Telescoped caisson

Info

Publication number: US3482408A
Application number: US737259*A
Authority: US
Inventors: William F Manning
Original assignee: Mobil Oil Corp
Current assignee: ExxonMobil Oil Corp
Priority date: 1966-09-02
Filing date: 1968-03-29
Publication date: 1969-12-09
Anticipated expiration: 1986-12-09

Description

2 Sheets-Sheet 1 Original Filed Sept. 2, 1966 INVENTOR WILLIAM F. MANNING BY ATTORNEY Dec. 9, 1969 w. F. MANNING TELESCOPED CAISSON 2 Sheets-Sheet 2 Original Filed Sept. 2, 1966 INVENTOR WILLIAM F. MANNING United States Patent 3,482,408 TELESCOPED CAISSON William F. Manning, Dallas, Tex., assignor to Mobil Oil Corporation, a corporation of New York Original application Sept. 2, 1966, Ser. No. 577,040, now Patent No. 3,426,859, dated Feb. 11, 1969. Divided and this application Mar. 29, 1968, Ser. No. 737,259

Int. Cl. E02d /52; E02b 17/00; E21b 7/12 US. CI. 6146 3 Claims ABSTRACT OF THE DISCLOSURE This specification discloses apparatus for drilling and completing an offshore well above the surface of a body of relatively shallow water. A two-piece well protector is utilized, the well protector comprising lower pile and upper caisson sections. The lower pile section is first driven into the formation underlying the marine bottom with one of the recently developed underwater pile drivers. The caisson section is then lowered into the water and stabbed into or over the pile section and grout is injected therebetween to form the composite well protector.

This is a division of application Ser. No. 577,040, filed Sept. 2, 1966, now United States Patent No. 3,426,859.

The present invention is directed to a method and apparatus for drilling and completing an offshore well above the surface of the body of water, in relatively shallow water. More particularly, the invention relates to a twopiece caisson type of well protector which is relatively easy to handle and requires a minimum of energy to be driven into the subaqueous formations beneath the marine bottom.

Present developments in the offshore oil and gas industry indicate that drilling and production efforts will be extended to underwater areas such as the outer fringes of the continental shelves and the continental slopes where a submarine production system is the most practical method of reaching the subaqueous deposits. However, the shallower waters are still providing an abundance of hydrocarbon deposits. As the more prolific fields are developed in these shallow waters from above-surface platforms, the industry is searching for less expensive ways of reaching the subaqueous formations so that the less prolific fields will be economically available. One relatively inexpensive device that has been used extensively, particularly in the Gulf of Mexico, is the caisson type of well protector, either self-supporting or utilized in conjunction with a template or guy lines. At the present time one-piece, or welded up, well protectors are used. Driving the entire length of a well protector is inefficient due to the large mass involved, particularly as the water depth increases. In two hundred feet of water, where it is required that the well protector be driven one hundred twenty feet or more into the subaqueous formations, the length of the well protector may even be too long to be brought conveniently into an upright position under the pile driver.

Therefore, it is an aspect of the present invention to provide a two-piece well protector, each of the sections thereof being short enough to be easily handled in the upright position by conventional offshore derrick barges.

A further aspect of the present invention is to provide a two-piece well protector utilizing the advantages of underwater pile driving.

Other aspects and advantages of the present invention will be readily apparent from the following description, when taken in conjunction with the accompanying draw ings that illustrate useful embodiments in accordance with this invention, in which:

FIGURE 1 is a pictorial illustration of a two-piece well "ice protector of the present invention erected at a marine site for extending a subaqueous well to a point above the surface of a body of water;

FIGURES 2 through 5 illustrate the erecting of the two-piece well protector at the marine site in conjunction with an underwaterpile driver;

FIGURE 6 is a sectional view of a portion of a first embodiment of the well protector of the present invention illustrating the telescoping of the upper section over the lower section which has been driven into the subaqueous formations underlying the marine bottom; and

FIGURE 7 is an elevational sectional view of a portion of a second embodiment of the well protector of the present invention illustrating the stabbing of the uppersection into the lower section which has been driven into the subaqueous formations underlying the marine bottom.

The present invention relates to a two-piece telescoping well protector in which the lower, or pile, section is separately driven into the subaqueous formations by' an underwater pile driving technique. The invention further relates to the method of installing the two-piece well protector, in which the pile driving o eration is terminated when the pile section extends only the minimum distance above the marine bottom necessary for later connecting thereto the upper, or caisson, section designed to project above the surface of the water after installation, and the later step of lowering the caisson section down from the surface into telescopic cooperation with the pile section to form the well protector.

Now looking to FIGURE 1 a two-piece well protector, generally designated 10, consists of a lower tubular section, hereinafter referred to as a pile section 12, anchoring the structure in a marine bottom 13 and an upper tubular section, hereinafter referred to as a caisson section 14, for extending the well protector from the upper terminus of the pile section 12 to a point above the surface 15 where a small production deck 16 is supported a distance above the water necessary to insure that waves will not impinge on it, and has extending up therefrom a production wellhead 18, completing a subaqueous well, the casings and tubing thereof being hung through the unimpeded throughbore of the well protector 10. While the production deck 16 may in some cases be large enough to accommodate a helicopter, in the more usual instance only enough additional space (for example, a common size is 11 x 18) is provided for a fog signal 20 and personnel working on the wellhead 18. A flowline 21, supported along the well protector 10 from the upper end thereof to the marine bottom 13, connects the wellhead 18 with a nearby production facility through a portion of the flowline laid on the marine bottom. A circular landing deck 22 is concentrically fixed to the caisson section 14 at the mean low water line and a ladder 24 extends between the landing deck 22 and the production deck 16 above. While in this illustration the caisson section 14 is shown as being tapered, and supported in part, against lateral loads by a plurality of guy lines 26, the remainder of this discussion applies equally as well to a constant diameter caisson, and to a caisson supported by a template structure, or completely self-supporting.

Referring now to FIGURES 2 through 5, the procedure to be followed in erecting a well protector 10 is illustrated. Looking to FIGURE 2, pile section 12 is held suspended beneath the surface 15 of the body of water with its lower end either just above or resting on the marine bottom 13. The pile section 12 is connected at its upper end to a submerged pile driving device, generally designated 28, which is in turn supported from a derrick mounted on a floating barge or mobile platform nearby (not shown), by a releasable connection 30. The connection 30 can be a hydraulically actuated clamp or a simple J-slot connector,

or any other type of connection which can be later remotely released. The pile driving device 28 comprises a casing 32, containing an anvil and a hammer (not shown), and a framework 34 extending from the upper end of the casing 32 to the derrick. Communication lines extending from the casing 32 to the derrick for actuating the pile driving hammer are supported within the framework 34.

The pile driving device 28 may be one of those recently developed and offered to the industry for underwater pile driving and which consists of a watertight chamber enclosing a pile driving hammer and anvil. By driving the hammer up in the chamber with compressed air, and then releasing the compressed air so that the hammer will drop down on the anvil, a useful amount of energy can be imparted through the anvil to drive the pile section of the well protector vertically into the formations underlying a marine bottom. A pile driving device of this type is offered by the MKT Corporation and is described in their brochure entitled MKTPile Driving Equipment, published June 1964.

FIGURE 3 shows the pile section 12 after it has been driven the required distance into the formations underlying the marine bottom 13. The pile driving device 28 is being withdrawn subsequent to the release of the connector 30. Enough of the pile section 12 is left extending above the marine bottom 13 for stabbing the caisson section 14 thereover.

In FIGURE 4 the caisson section 14 is suspended from the derrick barge and is being lowered through the water to be stabbed over the pile section 12. A landing base and guidelines as described in the RF. Bauer et al. Patent No. 2,808,229, issued Oct. 1, 1957, may be utilized to guide the caisson section 14 over the pile section 12. Alternatively jet guiding means hung in the caisson section 14 may be used in conjunction with an underwater. televiewer or a driver radioing instructions to the surface.

FIGURE 5 shows the caisson section 14 stabbed over and grouted to the pile section 12. A conductor pipe 36 is suspended from above the upper end of the well protector and extends therethrough into the marine bottom. 13. The conductor pipe 36 may be jetted, drilled, or hammer-driven into the underlying formations. The drilling rig for handling the conductor pipe 36, drilling a well therethrough, setting casings, and the other various operations necessary for completing the well, as well as the mud tank and other equipment, will be located on floating barges or jack-up rigs adjacent the well protector 10.

FIGURE 6 shows a first configuration of the well protector 10A comprising a pile section 12A adapted to have a caisson section 14A stabbed .thereover, A small diameter upper portion 38, and a tapered intermediate portion 40 of the pile section 12A act in conjunction with a stabbing bell 42 on the lower end of the caisson section 14A to permit the caisson section 14A to be stabbed easily over the pile section 12A. Centering guides 44 are welded within the caisson section 14A to guide the conductor pipe 36 into the small diameter upper portion 38 of the pile section 12A and to act as stops to prevent the caisson section 14A from telescoping too far over the pile section 12A and sinking into unconsolidated surface formations of the marine bottom 13. A releasable grout line 46 extends the length of the caisson section 14A. At the lower end of the caisson section 14A the grout line 46 is connected to a port through the wall thereof, so that grout can be injected into the annulus or chamber 48 between the caisson section 14A and the pile section 12A. A grout seal 50 is mounted in the lower end of the caisson section 14A to prevent the leakage of grout. To hold the caisson section 14A rigidly to the pile section 12A while the grout is setting, a remote ballistic connecting device such as that described in my copending application entitled Ballistic Jacket-Pile Connection, Ser. No. 489,527, filed Sept. 23, 1965, may be used.

FIGURE 7 shows a second configuration of the two- .4 piece well protector 10B in which the caisson section 14B is designed to be stabbed into the pile section 12B. In this arrangement a simple tubular pile may be utilized, the caisson section 14B having a lower tapered portion 52 to facilitate the stabbing operation. Spaced a distance up the caisson section 14B, a plurality of radially positioned guide plates 54 are welded to the outer surface of the caisson section 14B, the lower triangular portions of the guide plates 54 acting to center the caisson section 14B in the pile section 12B while the integral horizontal surfaces 56 thereabove act to limit the distance which the caisson section 14B can be stabbed into the pile section 12B. As in the prior embodiment a grout seal is necessary. The grout seal 58 is mounted on the outside of the caisson section 14B just above the lower tapered section 52. A grout line 60 would be previously fixed within the caisson section 14B and connected to a port extending through the caisson wall at the lower end thereof just above the grout seal 58 so that grout could be injected into the annulus or chamber 62 between the walls of the caisson section 14B and the pile section 128. If ballistic connectors are utilized for this embodiment, they should be fastened to the outer face of the wall of the pile section 12B prior to its being driven into the marine bottom 13.

Although the present invention has been described in connection with details of the specific embodiments there of, it is to be understood that such details are not intended to limit the scope of the invention. The terms and expressions employed are used in a descriptive and not a limiting sense and there is no intention of excluding such equivalents, in the invention described, as fall within the scope of the claims. Now having described the apparatus and method herein disclosed, reference should be had to the claims which follow.

What is claimed is:

1. A marine well protector for supporting a production wellhead or the like above the surface of a body of water comprising:

a tubular pile section adapted to be positioned partially into the bottom of said body of water, said pile section being of a length sufiicient to extend above the bottom after it is in position;

a tubular caisson section adapted to be telescopically fitted to the portion of said pile section which extends above the bottom of said body of water when said pile section is in position, said caisson section being of a length sufificient to extend from adjacent said bottom to a point above the surface of said body of water; and

means operably associated with said caisson section for connecting permanently said caisson section to said pile section when said sections are in telescoping relationship, said connecting means comprising a line connected to said caission section for injection of grout between said caisson and pile sections when said sections are in position.

2. A well protector as recited in claim 1 wherein the internal dimensions of said caisson section are larger than the external dimensions of said pile section whereby said caisson section will telescope over said pile section and wherein said connecting means further includes:

a stabbing bell fixed to the lower end of said caisson section;

guide means within the lower portion of said caisson section adapted to center a conductor pipe lowered through said caisson section and to coact with the upper portion of said pile section to limit the telescoping of said caisson section over said pile section;

a grouting chamber formed between the telescoped portions of said caisson and pile sections, said line connected to said caisson section for injecting grout in fluid communication with said chamber; and

means fixed to said caisson section for sealing the lower end of said chamber.

3. A marine Well protector for supporting a production Wellhead or the like above the surface of a body of Water comprising:

a tubular pile section to be driven into the formations underlying the marine bottom, said pile section being of a length sufficient to support at least a partial section of said well protector;

a tubular caisson section telescopically fitted to the upper end of said pile section at the marine bottom, the caisson section being of a length sufiicient to extend from the marine bottom to a point above the surface of the body of Water; and

means for connecting said pile and said caisson sections together whereby an unimpeded throughbore is formed, said connecting means comprising:

a tubular portion of said caisson section for coacting with the open upper portion of said pile section to permit said caisson section to be stabbed into said pile section;

guide means fixed to the outer surface of said caisson section and coacting with said pile section to center said caisson section within said pile section and to limit the telescoping of said caisson section within said pile section;

a grouting chamber formed between the portions of said caisson and said pile sections which are in telescoped relationship;

means fixed to outer section of said caisson section for sealing the lower end of said chamber; and

means for injecting grout into said chamber from above the surface of a body of water, said grout injecting means comprising a grout line extending through said caisson section and operably connected to said chamber through the Wall of said caisson section at the lower end thereof.

References Cited UNITED STATES PATENTS 2,906,500 9/1959 Knapp et al 61--46.5 X 3,020,956 2/1962 Suderow 61--46.5 3,209,544 10/1965 Borrmann 61--46.5

JACOB SHAPIRO, Primary Exagrniner US. Cl. X.R.