Expandable well screen

Details Expandable well screen Expandable well screen

1998-05-01

2001-11-13

Suchfield, George (Department: 3672)

Wells

Expansible anchor or casing

Expansible casing

C166S230000, C166S233000

Reexamination Certificate

active

06315040

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to an expandable well screen for preventing migration of solid particles into a hydrocarbon fluid production well.
More particularly, the invention relates to an expandable well screen which comprises a number of filter sheets which are secured in an iris-shaped configuration and co-axial to an expandable slotted carrier tube such that as a result of expansion of the tube the amount of overlap between adjacent filter sheets is reduced.
BACKGROUND OF THE INVENTION
An expandable well screen is disclosed in applicant's co-pending U.S. patent application Ser. No. 08/745,391, filed on Nov. 8, 1996, now U.S. Pat. No. 5,901,789, which is incorporated herein by reference PCT/EP96/04887, which has issued as U.S. Pat. No. 5,901,789 and which is incorporated herein by reference.
FIG. 3 of this prior art reference discloses that the filter sheets consist of plates in which a series of circular perforations are present. The size of these perforations is chosen such that solid particles larger than the size of the hole are prevented from flowing into the well.
A suitable expandable slotted carrier tube for use with the screen is disclosed in U.S. patent application Ser. No. 72,290, filed on Jun. 7, 1993, now U.S. Pat. No. 5,366,012, which is incorporated herein by reference. PCT/EP93/01460, which has issued as U.S. Pat. No. 5,366,012, which is incorporated herein by reference.
It has been found that filter sheets which are secured to an expandable slotted carrier tube are deformed considerably during the process of expanding the carrier tube by moving an expansion mandrel therethrough. The carrier tube normally shortens during the expansion process as a result of opening of the axial slots towards a diamond shape.
This may cause the filter sheets to buckle to accommodate the carrier tube shortening and friction between the overlapping filter sheets and the carrier tube or tubes may cause the filter sheets to tear.
An object of the present invention is to provide a well screen comprising an iris-shaped configuration of filter sheets which do not buckle and which slide easily relative to each other and relative to the carrier tube during the process of expanding the carrier tube.
SUMMARY OF THE INVENTION
The well screen according to the invention thereto comprises filter sheets having slots which are oriented in a substantially circumferential orientation with respect to the carrier tube.
When used in this specification the reference to a circumferential arrangement of slots means that the slots each are directed in a substantially tangential orientation with respect to the carrier tube and such that the slots are oriented substantially transversal to the central axis and any axial slots of the carrier tube.
Preferably the filter sheets consist of elongate strips with staggered rows of slots in a transversal direction with respect to a longitudinal axis of each strip.
The pattern of slots is preferably such that alternate rows are displaced up to half a slot pitch in the transverse direction, the length of the slots is greater than half the transverse slot pitch, and the pattern of slots is continued through the longitudinal edges of the strips.
It is also preferred that each strip is secured at regularly spaced points along its length to the expandable slotted carrier tube and that each strip is secured to the expandable slotted carrier tube at said points by either spot welding, brazing, soldering, gluing, riveting or screwing the strip to the tube at each of said points.
These and further aspects, features and advantages of the well screen according to the present invention will become apparent from the accompanying claims, abstract and the following detailed description with reference to the drawings.


REFERENCES:
patent: 2812025 (1957-11-01), Teague et al.
patent: 3353599 (1967-11-01), Swift
patent: 5366012 (1994-11-01), Lohbeck
patent: 5901789 (1999-05-01), Donnelly et al.
patent: WO 93/01460 (1992-07-01), None
patent: WO 9604887A1 (1996-02-01), None
patent: WO 97/17524 (1997-05-01), None
International Search Report completed Aug. 10,1998.

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