US3426859A

US3426859A - Telescoped caisson

Info

Publication number: US3426859A
Application number: US577040A
Authority: US
Inventors: William F Manning
Original assignee: Mobil Oil Corp
Current assignee: ExxonMobil Oil Corp
Priority date: 1966-09-02
Filing date: 1966-09-02
Publication date: 1969-02-11
Anticipated expiration: 1986-02-11

Description

Feb. H, 1969 w. F. MANNING TELESCOPED CAISSON Sheet Filed Sept. 2, 1966 l INVENTOR WILLIAM FI MANN/NG BY Mew j?, k/

ATTORNEY Feb, l, i969 W.F.MANN1NG TELESCOPED CAISSON .filed sept.

INVENTOR WILLIAM E MANNING United States Patent O 3,426,859 TELESCOPED CAISSON William F. Manning, Dallas, Tex., assignor to Mobil Oil Corporation, a corporation of New York Filed Sept. 2, 1966, Ser. No. 577,040 US. Cl. 175-9 7 Claims Int. Cl. E21b l5/02, 17/04 ABSTRACT F THE DISCLOSURE This specification discloses a method and 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 interconnecting lower pile and upper caisson sections. The lower pile section is rst driven into the formations 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 to form the composite well protector. A well is drilled through the well protector and is completed by a wellhead supported on the upper end of the well protector.

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 elds 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 ineicient 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 su-baqueous 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 drawings that illustrate useful embodiments in accordance with this invention, in which:

FIGURE 1 is a pictorial illustration of a two-piece well protector of the present invention erected at a marine ICC 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 twopiece well protector at the marine site in conjunction with an underwater pile 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 upper section 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 operation 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 alower 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 from 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 l1 x 18') is provided for a fog signal 20 and personnel working on the wellhead 18. A tlowline 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 fixedto 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 protecter 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 iloating barge or mobile platform nearby (not shown), by a releasable connection 30. The connection 3G can be a hydraulically actuated clamp or a simple I-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 Awithin 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 MKT-Pile Driving Equipment, published lune 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 1R. F. Bauer et al. Patent No. 2,808,229, issued Oct. l, 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 diver 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 proteetor 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 sinkin-g 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 ]acket-Pile Connection, Ser. No. 489,527, led Sept. 23, 1965, may be used.

FIGURE 7 shows a second configuration of the two-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 V56 therea'bove 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 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 12B. 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 thereof, 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 method for installing a well protector at a marine site, said well protector extending from a distance above the surface of a body of water to a distance into the -formations underlying the marine bottom, comprising the `following steps in the order recited:

(a) lowering a pile section of said well protector through said body of water with an underwater pile driving assembly attached to the upper end thereof;

(b) driving said pile section into said formations underlying said marine bottom by means of said underwater pile driving assembly until only enough of said pile section extends above the marine bottom to be connected to a caisson section of said well protector to be stabbed down from above said surface;

(c) releasing said pile driving assembly from said pile section and withdrawing said pile driving assembly;

(d) stabbing down said caisson section through said body of water until the lower end of said caisson section is in a telescopic relationship with the upper end of said pile section while the upper end of said caisson section remains above said surface; and

(e) Xedly connecting said telescoped portions of said pile and caisson sections.

2. A method for installing a well protector at a lmarine site as recited in claim 1, wherein said pile section is driven into said formations underlying said marine bottom far enough to provide the sole support for a caisson section extending therefrom to above the surface of the body of water and having production equipment on a deck on the upper end thereof.

3. A method for installing a well protector at a marine site as recited in claim 1 where all of said steps are performed remotely by personnel located above said surface of said body of water.

4. A method for drilling a well in formations underlying a marine bottom through a well protector installed at a marine site, said well protector to extend from a distance above the surface of a body of water to a distance into the formations underlying the marine bottom, comprising the following steps in the order recited:

(d) stabbing down said caisson section through said body of water until the lower end of said caisson section is in a telescopic relationship with the upper end of said pile section while the upper end of said caisson section remains above said surface;

(e) xedly connecting said telescoped portions of said pile and caisson sections; and

(f) drilling a well through producing formations underlying said marine bottom through said well protector from above said surface of said body of water.

5. A method for installing a well protector at a marine site, said well protector extending from a distance above the surface of a body of water to a distance into the formations underlying the lmarine bottom, comprising the following steps in the order recited:

(a) lowering a pile section of said well protector through said body of water with an underwater pile driving assembly in contact with the upper end thereof;

(b) driving said pile section into said `formations underlying said marine bottom by 'means of said underwater pile driving assembly until only enough of said pile section extends above the marine bottom to be connected to a caisson section of said well protector to be stabled down from above said surface;

(c) withdrawing said pile driving assembly from contact with the upper submerged end of said pile section;

6. A method for completing an offshore well through a wellhead located above the surface of a body of water on the upper end of a well protector installed at a marine site, said well protector extending from a distance above the surface of a body of water to a distance into formations underlying the marine bottom, comprising the following steps in the order recited:

(b) driving said pile section into said formations underlying said marine bottom by means of said underwater pile driving assembly until only enough of said pile section extends above the marine bottom to be connected to a caisson section of said well protector to be stabbed down lfrom above said surface;

(d) stabbing down said caisson section through said -body of water until the lower end of said caisson section is in a telescopic relationship with the upper end of said pile section while the upper end of said caisson section remains above said surface;

(f) drilling a well into producing formations underlying said marine bottom through said well protector from above said surface of said body of water.

7. A method for completing an offshore well, as recited in claim 6, including the following additional steps:

(g) installing a deck on the upper end of said well protector to be used at least during production operations; and (h) mounting a wellhead on the upper end of said well protector and completing said well therethrough.

References Cited UNITED STATES PATENTS 2,503,516 4/ 1950 Shrewsbury 175--8 X 2,854,215 9/1958 Cox et al 166.5 2,906,500 9/1959 Knapp et al. 166-.5 2,959,016A 11/1960 Parks a 166-.5 X 3,101,798 8/1963 Wilson et al 175-8 3,202,218 9/196'5 Watts et al 166-.5 3,330,338 7/1967 Dozier 166-.5 3,352,357 11/1967 Van Eek 166-.5

JAMES A. LEPPINK, Primary Examiner. RICHARD E. FAVREAU, Assistant Examiner.

U.S. Cl. X.R. 61-46