GB2317630A - Alternate path well screen - Google Patents

Abstract

An alternate path well screen includes means for protecting the alternate flowpaths (e.g. a plurality of conduits 25) on the screen during installation and operation. This means is comprised of a shroud 30 having a plurality of radial openings 31 in the wall thereof, which is concentrically mounted on the screen and is connected at each end thereto whereby the shroud covers and protects the alternate flowpaths 25.

Description

F-7866 2317630 ALTERNATE-PATH WELL SCREEN WrM PROTECTIVE SHROUD The

present invention relates to an alternate-path well screen having a protective shroud thereon and in one of its aspects relates to an alternate-path, well screen of the type used in gravel-pack completions of a wellbore which has an outer shroud thereon to protect the alternate paths while the screen is being installed andlor removed.

In producing hydrocarbons or the like from loosely or unconsolidated andlor fractured formations, it is not uncommon to produce large volumes of particulate material along with the formation fluids. As is well known in the art, these particulates routinely cause a variety of problems and must be controlled in order for production to be economical. Probably the most popular technique used for controlling the production of particulates (e.g.. sand) from a well is one which is commonly known as "gravel packing.

is In a typical gravel pack completion, a screen is lowered into the wellbore on a workstring and is positioned adjacent the subterranean formation to be completed; e.g. a production formation. Particulate material, collectively referred to as ugravel", and a carrier fluid is then pumped as a slurry down the workstring where it exits through a ucross-over" into the well annulus formed between the screen and the well casing or open hole, s the case may be. The carrier liquid in the slurry normally flows into the formation andlor through the screen, itself, which, in turn, is sized to prevent flow of gravel therethrough.

This results in the gravel being deposited or "screened ouf in the well annulus where it collects to form a gravel pack around the screen. The gravel, in turn, is sized so that it forms a permeable mass which allows flow of the produced fluids therethrough and into the screen while blocking the flow of the particulates produced with the production fluids.

One of the major problems associated with gravel packing, especially where long or inclined intervals are to be completed, arises from the difficulty in distributing the gravel over the entire completion interval; i.e. completely ' packing the entire length of the well annulus around the screen. This poor distribution of gravel (i.e. incomplete packing of the interval) is often caused by F-7W -2 the carrier liquid in the gravel slurry being lost into the more permeable portions of the formation which, in turn, causes the gravel to form "sand bridges in the annulus before all of the gravel has been placed. Such bridges block further flow of slurry through the annulus which prevents the placement of sufficient gravel (a) below the bridge in top-to-bottom packing operations or)b) above the bridge in bottom-to-top packing operations.

To alleviate this problem, ualternate-path well screens have been developed which provide for good distribution of gravel throughout the entire completion interval even if sand bridges form before all of the gravel has been placed. For examples of such screens, see US Patents 4,945,991: 5,082, 052:

5,113,935: 5,417,284; and 5,419,394. In these well screens, the alternatepaths (e.g.. perforated shunts or by-pass conduits) extend along the length of the screen and are in fluid communication with the gravel slurry as the slurry enters the well annulus around the screen. If a sand bridge forms in the is annulus, the slurry is still free to flow through the conduits and out into the annulus through the perforations in the conduits to complete the filling of the annulus above and/or below the sand bridge.

Due to the relative small size of the alternate-paths, it is vitally important that they are not crimped or otherwise damaged during the installation of the screen. One proposal for protecting these conduits is to place them inside the outer surface of the screen: see US Patents 5,476,143 and 5,515,915.

However, this type of construction may substantially increase the cost of the screen over the cost of those screens now commercially-available. Accordingly, it appears more desirable, at least from an economic standpoint, to position and secure the by-pass conduits onto the external surface of several of many typical, existing commercially-available well screens. However, of course, this will expose the conduits to damage during installation of the screen.

The present invention provides an alternate-path, well screen which includes a shroud which protects the alternate flowpath on the screen during installation and operation. More particularly, the present screen is comprised of an elongated, cylindrical body which has a permeable section (e.g.. a screen F-78" section) therein. At least one alternate flowpath (e.g.. a plurality of conduits) is mounted on said body and extends along the length thereof. Each of said conduits have a plurality of openings spaced along its length through which a gravel slurry can be delivered to different levels within the well annulus around the screen when the screen is in an operable position within a wellbore.

A cylindrical shroud having a plurality of openings in the wall thereof, is concentrically mounted on said body and is connected at each end thereto whereby the shroud covers and protects the alternate flowpath during installation and operation.

BRIEF DESCRIPTION OF THE DRAWINGS

The actual construction, operation, and the apparent advantages of the present invention will be better understood by referring to the drawings in which like numerals identify like parts and in which:

FIG. 1 is an elevational view, partly in section, of the alternate-path well screen having a protective shroud in accordance with the present invention:

and FIG. 2 is a cross-sectional view of the well screen of FIG. 1 taken along line 2-2 of FIG. 1.

BEST KNOWN MODE FOR CARRYING OUT THE INVENTION

Referring more particularly to the drawings, FIG. 1 illustrates the lower end of a producing andlor injection well 10. Well 10 has a wellbore 11 which extends from the surface (not shown) through an unconsolidated andlor fractured production andior injection formation 10. As shown, wellbore 11 is cased with casing 13 and cement 14 which have perforations 15 therethrough to establish fluid communication between formation 12 and the interior of casing 13. While well 10 is illustrated as a substantially vertical cased well, it should be recognized that the present invention is equally usable in open-hole andior underreamed completions as well as in horizontal andior inclined wellbores.

Alternate-path, well screen 20 of the present invention is shown positioned within wellbore 11 adjacent the completion interval of formation 12 and forms an annulus 19 between the screen and the casing 13. As shown, F-78" well screen 20 is comprised of an elongated, cylindrical body 21 which includes a permeable "screen' section 22. The term "screen" is used generically herein and is meant to include and cover all types of those structures commonly used by the industry in gravel pack operations which permit flow of fluids therethrough while blocking the flow of particulates (e.g commercially- available screens, slotted pipes, prepacked screens andlor liners, or combinations thereof). Screen 20 may be of one continuous length or it may consist of sections (e.g.. 30-foot sections) connected by subs or blanks as will be understood in the art.

Alternate flowpaths (e.g shunts means) are mounted on the external surface of screen 20. As shown in FIGS 1 and 2, shunt means are comprised of at least one (four shown) perforated conduits 25 which extend longitudinally along the external surface of screen 20. Each conduit 25 has a plurality of openings 26 positioned along its length and is open at either or both ends to is receive gravel slurry or all conduits can be manifolded together (not shown) and fluidly connected to outlets 28 in cross-over 22 to receive gravel slurry during a gravel pack operation. The construction of screen 20 to this point is basically the same as that of known prior art alternate-path screens. Unfortunately, however, by positioning by-pass conduits 25 on the exterior of screen 20, the conduits are vulnerable to damage as the screen is installed into wellbore 11.

In accordance with the present invention, a protective shroud 30 is positioned onto screen 20 over conduits 25. Shroud 30 is comprised of a cylinder made of a strong, durable material, e.g.. steel, which is secured at its upper and lower ends to the body of the screen by welding or the like. The shroud 30 has a plurality of openings 31 (only some of which are numbered in the figures) through the wall thereof. By positioning the rigid shroud over the conduits 26, the conduits are protected from any accidental blows or the like during the assembly and installation of the screen which might otherwise severely damage or destroy the conduits for their intended purpose.

In operation, alterriate-path screen 20 with protective shroud 30 in place is lowered into well bore 11 and is positioned adjacent formation 12. Packer 29 F-7866 is set as will be understood in the art. Gravel slurry is then pumped down the workstring and through outlet ports 28 in cross-over 22 into annulus 19. As the slurry loses fluid to the formation andlor through screen 20, gravel from the slurry is deposited in the annulus to form a gravel pack around the screen as will be understood in the art.

If excessive liquid is lost from the slurry before the annulus is filled with gravel, a sand bridge (dotted lines 32 in FIG. 1) is likely to form which will block further flow of gravel through the annulus and prevent further filling of the annulus below the bridge. If and when this happens, the gravel slurry is still free to flow through conduits 25 and out openings 26 therein and then exit through openings 31 in shroud 30 into annulus 19 to by pass bridge 19 and finish filling the annulus. Again, shroud 30 protects conduits 25 both during the installation of screen 20 and the placement of the gravel pack around the screen.

F-7866

Claims (8)

What is claimed is:

1. An alternate-path well screen comprising:

an elongated body having a permeable section therein; at least one alternate flowpath extending along the length of said body;and a shroud surrounding body and covering said alternate flowpath to protect said alternate flowpath during installation and operation.

2. The alternate-path, well screen of claim 1 wherein said shroud is comprised of a cylinder positioned concentrically over said body and said at least one alternate flowpath and connected to said body.

is

3. The alternate-path, well screen of claim 2 wherein said cylinder has a plurality of openings in the wall thereof.

4. The alternate-path, well screen of claim 1 wherein said at least one alternate flowpath comprises:

a conduit mounted on said body and extending along the length thereof, said conduit having a plurality of openings spaced along its length.

5. The alternate-path, well screen of claim 1 wherein said at least one alternate flowpath comprises:

a plurality of conduits mounted on said body and extending along the length thereof, each of said conduit having a plurality of openings spaced along its length.

F-7866 -7

6. An altemate-path, well screen comprising:

a elongated body having a permeable section therein; at least one alternate flowpath extending along the length of said body;and a cylindrical shroud having a plurality of radial openings in the wall thereof, said shroud being concentrically mounted on said body and connected at each end to said body thereby covering said alternate flowpath to thereby protect said alternate flowpath during installation and operation.

7. The alternate-path, well screen of claim 6 wherein said at least one alternate flowpath comprises:

a conduit mounted on said body and extending along the length thereof, said conduit having a plurality of openings spaced along its length.

is

8. The alternate-path, well screen of claim 6 wherein said at least one alternate flowpath comprises:

a plurality of conduits mounted on said body and extending along the length thereof, each of said conduit having a plurality of openings spaced along its length.