Preform or matrix tubular structure for casing a well

Details Preform or matrix tubular structure for casing a well Preform or matrix tubular structure for casing a well

1995-11-03

1997-12-09

Tsay, Frank

Wells

Packers or plugs

Expanded by confined fluid from central chamber, pump or...

166195, E21B 2304

Patent

active

056950080

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to a preform or matrix tubular structure for casing a well, in particular a drilled oil well.
In the present description, and in the claims, the term "casing" is used to designate a tube for consolidating a well, the term "preform" is used to designate a tubular structure which is initially flexible and which is subsequently hardened to bond intimately and permanently against the wall of a well (thus constituting a casing), and the term "matrix" is used to designate a structure that is flexible and recoverable, serving as a tool for expanding a preform and pressing it against the wall of the well prior to setting.
The term "production tubing" is used to designate a smaller diameter coaxial tube inside a casing and serving to convey the fluid produced by the well (in particular water or oil).
The tubing is centered and sealed relative to the casing by means of a hydraulically inflatable plug, commonly known as a "packer".
2. Art Background
For casing an oil well, and for similar applications, flexible and settable tubular preforms have already been proposed that are designed to be instaled while in the folded state--a state in which they occupy little radial size--and then to be radially unfolded by applying internal pressure thereto. In that technique, which is described in particular in documents FR-A-2 662 207 and FR-A-2 668 241, the preform, after being radially deployed, possesses a shape that is accurately cylindrical, and of well-determined diameter.
After being installed in a well or in pipework, the wall of the preform is caused to set, e.g. by polymerizing a wall which is composite in structure being made up of a resin impregnating filamentary sleeves. The sleeves ensure the the preform is radially inextensible.
In those techniques, it is necessary to provide for the diameter of the deployed casing to be slightly smaller than the diameter of the hole to be cased so that the wall of the hole does not alter the cylindrical shape of the casing. In general, even if it is very small or even vanishes in places, the annular space that is formed in this way must be filled with cement to complete sealing between the hole and the installed casing.
In addition, while in its folded state, the tubular preform has a radial section that is less than about half its developed radial section, and in most cases that suffices, but in some applications it can be insufficient. That is why, the object of the present invention is to solve the above problem by proposing a preform whose structure is of deformable shape suitable for bearing against the walls of the hole to be cased (or of the casing to be lined) while nevertheless not exceeding certain limits, with deformation being controlled and variable as a function of various applications.
Another object of the invention is to provide a preform whose degree of expansion is considerably greater than that obtained with known devices of the above-specified kind, expansion of the preform taking place in two steps, initially by radial deployment, and subsequently by radial expansion.


SUMMARY OF THE INVENTION

To achieve this result, the invention provides a braided tubular structure which is described below, the structure being equally applicable to a radially-expandable matrix, i.e. to a removable (and reusable) tool serving to expand a preform for the purpose of casing a well, and regardless of whether the preform possesses the structure of the invention.
According to the invention, these results are achieved by the fact that the proposed preform or matrix tubular structure comprises at least one braid of flexible strands made up of fibers that cross over with a certain amount of play so as to enable the structure to expand radially while shrinking axially under the effect of excess pressure being applied inside the preform or the matrix.
In a preferred embodiment, the braiding comprises two series of strands crossing over symmetrically on either side of the generator lines of the tubul

REFERENCES:
patent: 4963301 (1990-10-01), Davis et al.
patent: 5001961 (1991-03-01), Spain
patent: 5337823 (1994-08-01), Nobileau
patent: 5549947 (1996-08-01), Quigley et al.
patent: 5573039 (1996-11-01), Mang

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