US 3380519 A
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Description (OCR text may contain errors)
April 30, 1968 J. H. FOWLER LANDING BASE Filed Nov. 5, 1965 INVENTOR.
BY WW maflw United States Patent 3,380,519 LANDING BASE John H. Fowler, Houston, Tex., assignor to Rockwell Manufacturing Company, Houston, Tex., a corporation of Pennsylvania Filed Nov. 3, 1965, Ser. No. 506,244 13 Claims. (Cl. 166-.5)
ABSTRACT OF THE DISCLOSURE An underwater well landing base and method for installing same. A skeleton landing base form is nonrigidly attached to a casing head which is in turn fastened to a conductor casing. The skeleton form comprises a cylindrically formed sheet afiixed at its upper and lower ends to angle iron rings. A thin sheet of material closes the lower end and provides non-rigid attachment of the form to the casing head. Reinforcing bars are attached and laced between the casing head and the outer portion of the form.
To install the landing base, the conductor casing, casing head and skeleton form are lowered to the floor of a body of water. The subsurface is penetrated with the conductor casing until the skeleton form contacts and conforms to the subsurface. At this time the reinforcing bars are placed in stress. Then a surface casing is installed telescopically in the conductor casing with an annular space therebetween. A surface casing head connected to the upper end of the surface casing seals the annular space from the body of water. Cement is pumped down through the surface casing, back up the annular space, and outwardly through ports in the casing head into the skeleton form and allowed to set forming a prestressed landing base integral with the casing cement and conforming to the subsurface.
This invention relates to a landing base and method of forming same for use in underwater exploration and production. More specifically, it describes a self-prestressing landing base.
In the past when drilling for offshore petroleum or gaseous deposits, it has been the practice to lower an already formed landing base or platform to the subsurface, said platform providing means for positioning the well head control equipment at the well site. Normally said platform has integral with it, a length of conductor casing which by some manner is caused to penetrate the subsurface, thereby initially anchoring the platform. Later, the platform and conductor casing are cemented in, the intent being to provide a rigid structure. Difiiculties have arisen in that not only does the subsurface tend to cave in or give adjacent the platform during and after the casing insertion and cementing, but also the material forming the platform is subject to varying stresses when positioned underwater. The result has been, on occasion, a shifting and/ or deteriorating base with resulting damage to control equipment and interruption of operations.
The present invention presents apparatus and a method for installing the same so that the difiiculties encountered in the use of preformed landing bases are substantially reduced. A skeleton form is non-rigidly attached to a conductor casing head and lowered along with the conductor into position conforming to the subsurface. Reinforcing bars interlaced between the head and form are placed in stress as the skeleton conforms to the subsurface. A surface casing is then lowered into the conductor and cement pumped through the casing and upwardly through the annular space between casing and conductor. Holes passing through the conductor head allow the cement to enter the skeleton form where the cement is allowed to harden.
This invention, therefore, provides for forming the rigid cement portion of the landing base coincident with the cementing in of the conductor casing, with resultant stability in both conformation and position. Thus the invention has as an object the formation of a landing base readily conforming to the subsurface strata.
A further object is the provision of a self-prestressing landing platform.
Another object is the provision of a base capable of being substantially for-med simultaneously with the cementing-in of the associated conductor casing.
A still further object is permitting the formation of a landing base in an economical and efficient manner.
These and still further objects will become apparent on consideration of the following appended description and drawings in which:
FIGURE 1 is a broken vertical section of the landing base skeleton being lowered into position;
FIGURE 2 is another broken vertical section depicting the base skeleton resting atop the subsurface with the surface casing and surface casing head and hanger;
FIGURE 3 is a further broken section through the structure of FIGURE 2 with the cement shown to have flowed into position; and
FIGURE 4 is a horizontal section through the landing base section showing the reinforcing bar configuration.
Inasmuch as the structural items are substantially symmetrical, it should be noted that partial sectional views adequately describe the entire device.
Looking first at FIGURE 1, the necessary equipment for lowering the base of this invention is shown. Such equipment includes a tubular handling joint, said joint being joined in an appropriate manner to handling tool 21. This latter mentioned tool is capable of, by virtue of coarse threads 22, meshing with similar threads formed on the interior surface of casing head 31, said casing head forming a portion of the landing base generally indicated at 30.
The casing head is generally cylindrically formed, having a central aperture 32 therethrough. An angular shoulder 33 is formed in head 31 adjacent the juncture of its upper surface and bore or aperture 32, permitting resting thereon of cooperating shoulder 22 of handling tool 21 as well as other parts later described.
Aflixed to the lower end of casing head 31, and specifically being connected, as by welding, at an adjacent shoulder 34, may be conductor casing 50, of a desired length.
One or more radially directed conduits or passageways are formed extending through the walls of easing head 31. Underneath such passageways, head 31 is seen to be reduced in thickness and accommodating a rolled ring formed by angle iron 40, said ring being perforated by spaced bar-accommodating perforations 41, said ring being rigidly afiixed to shoulder 37.
Circumscribing casing head 31 is a cage-like structure comprised of perforated cylinder forming sheet affixed along its upper inner and lower inner surfaces to respective ring rolled angle irons 81, 82. Such a cage assembly is non-rigid ly attached to the lower reaches of casing head 31 by virtue of a thin sheet 84 of suitable material, Interlocking the cage structure with angle iron 40 are lengths of reinforcing bar 90, said bar continuously being wrapped or laced through apertures 41 in angle iron 40, out apertures 85 in cage sheet 80, inwardly through adjacent apertures 85, through other apertures 41 and so forth, to substantially encompass and link casing head 31 with the cage structure.
Thus in operation, the casing head-cage structure forming the skeleton of the landing base will be lowered, conventionally by the landing tool handling joint and associated drill pipe, until the conductor casing reaches and penetrates the subsurface. At this time the subsurface may be penetrated by the conductor casing by air jetting, if necessary. During this operation the landing base will be positioned and rest atop the subsurface. Further, during the lowering operation and penetration of the subsurface by casing 50, thin sheet 84 will become disengaged from casing head 31, being non-rigidly affixed thereto, causing said sheet and cage assembly to settle in order to conform to or fit the ocean floor. This also causes the reinforcing bar pattern 90 to elongate, or to be stressed. This situation is depicted more accurately in FIGURE 2.
On the landing base skeleton being positioned in substantial conformity with the ocean floor, and the reinforcing bars being elongated thereby, the surface casing 100 and surface casing head 101 shown in FIGURE 2 would be lowered, through the interior of conductor casing head 40 and conductor casing 50. Of course this action would be preceded by removal, by unscrewing, of handling tool and joint 21, 20. Surface casing 100 may be afiixed to surface casing head 101 in a normal manner, as by welding, with said surface casing extending below the lowermost reaches of conductor casing 50. It may be seen in both FIGURES 2 and 3, that angular shoulder 103 of surface casing head 101 rests upon and is positioned by shoulder 33 of conductor casing head 31. On members 100, 101 being in position, surface casing cement may be ejected through the lower exit (not shown) of surface casing 100 in a conventional manner, wherein it, the cement, will be forced upward into and through the annulus intermediate the surface and conductor casings, outwardly through passageways 35 in conductor casing head 31 and into the area 88 intermediate sheet 80 and the exterior of conductor casing head 31, as shown in FIGURE 3. This action not only cements the casings in place, but also forms a rigid platform or landing base, the latter not only conforming to the subsurface configuration, but also being prestressed by virtue of the reinforcing bars 90 initially elongating on reaching the subsurface, but also being in tension under the weight of the string of equipment, casing, blow-out preventors pressing down on the conductor casing head.
Thus it is seen how with this inventive apparatus and method of operation a self pre-stressing landing base may be formed in substantial conformity with the subsurface configuration adjacent a well site, thus overcoming difficult-ies commensurate with caving in occurring during insertion of the conductor casing and later operation.
Although a single embodiment has been discussed, it must be obvious that numerous modifications are possible by one skilled in the art without departing from the spirit of the invention, the scope of which is intended to be limited only by the following claims:
1. A method of forming a landing base for underwater operation including the following steps:
non-rigidly afiixing a base skeleton to a casing head and conductor casing assembly;
lowering said skeleton, head and easing from the water surface to the floor of the body of water;
imbedding a substantial portion of the casing in the subsurface; and
causing a cement-type substance to pass through the casing and into the skeleton after said skeleton has been positioned on the floor.
2. A method of forming a landing base for underwater operation including the following steps:
non-rigidly affixing a base skeleton to a casing headconductor casing assembly;
lowering said skeleton and assembly from the water surface to the floor of the body of water;
causing said conductor casing to penetrate the subsurface;
telescopically passing surface casing through said 'conductor casing; and
causing a cement-type substance to pass down through said surface casing, up the annulus intermediate said conductor and surface casing and into the skeleton, thereby after hardening forming a rigid landing base.
3. A method of forming a landing base for underwater operation including the following steps:
non-rigidly afiixing a base skeleton to a casing headconductor casing assembly;
lowering said skeleton and assembly from the water surface to the floor of a body of water;
causing a connection between said skeleton and said assembly to become disconnected;
penetrating the subsurface with said conductor casing;
passing surface casing through said conductor casing;
forcing a cement-type substance down through said surface casing, up the space intermediate said conductor and surface casings, out the conductor casing head and into the space defined by said skeleton, thereby after hardening forming a rigid landing base.
4. A method of forming a landing base for underwater operation including the following steps:
non-rigidly aflixing a base skeleton to a casing head conductor casing assembly;
attaching reinforcing material in a linking relationship with said skeleton and said assembly;
lowering said skeleton and assembly from the surface to the floor of a body of water; penetrating the subsurface with said conductor casing; causing a connection between said skeleton and said assembly to become disconnected thereby placing said reinforcing material in a stressed condition;
forcing a cement-type substance through said casing and into said skeleton, thereby forming, after hardening, a rigid landing base.
5. The method of claim 4 wherein said cement-type substance on entering said skeleton is caused to encompass said stressed reinforcing material.
6. A landing base including a casing head rigidly affixed to a length of easing; skeleton means non-rigidly affixed to said casing head, said skeleton means comprising substantially vertical sidewalls surrounding said casing head; and reinforcing means interlacing a unitary extension of said head and said skeleton means sidewalls.
7. The base of claim 6 wherein means are provided initially joining said skeleton sidewalls and said head that may become disassociated from said head on said base striking the floor of a body of water.
8. The device of claim 6 wherein said head possesses passageway means directed toward the interior of said skeleton.
9. A landing base including a casing head and casing assembly; skeleton means comprising sidewalls substantially concentric with said casing head; interlaced reinforcing means linking said head and said sidewalls for limited movement therebetween; and means for directing flow of a structurally reinforcing material through said head into the space defined by said skeleton.
10. The base of claim 9 wherein means are provided releasably linking said sidewalls to said head, said releasable means capable of being disassociated from said head on the base striking a surface.
11. A remotely positionable self-adjusting landing base skeleton having concentric exterior enclosure and interior means and reinforcing bar means linkingly interlaced therebetween to allow limited axial movement of said exterior enclosure relative to said interior means; a semiflexible sheet of material rigidly attached to one end of said exterior means, said reinforcing means assuming a web pattern when interlaced; and said interior means having such a configuration as to permit afiixing to a casing head.
12. The base of claim 11 whereby said interior means 5 may shift in position relative to said exterior enclosure 3,186,486 thereby causing said reinforcing means to be stressed. 3,252,528 13. The base of claim 12 wherein said interior means 3,315,742 is afiixed to a casing head.
References Cited 0 302,089
UNITED STATES PATENTS 1443M) 2,988,144 6/1961 Conrad 166-.5 3,159,218 12/1964 Wilde "166.6
6 6/ 1965 Rhodes et a1 166--.6 5/ 1966 Nicolson 166.5 4/ 1967 Nicolson 166.6
FOREIGN PATENTS 11/1917 Germany. 2/1963 Germany.
JAMES A. LEPPINK, Primary Examiner.