Sand barrier for a level 3 multilateral wellbore junction

#A multilateral wellbore system by definition includes at least a primary wellbore and a lateral wellbore extending therefrom. The junction between the primary wellbore and the lateral wellbore in some cases is an avenue for sand and other particulate matter infiltration into the wellbore system which generally results in the entrainment of such particulate matter with the production fluid. Clearly, it is undesirable to entrain particulate matter in production fluid since those particulates would then need to be removed from the production fluid adding expense and delay to a final release of a product. The reasons for particulate infiltration through a junction in a multilateral wellbore are many, including the not entirely controllable window size and shape which is generated by running a milling tool into the primary wellbore and into contact with a whipstock whereafter the mill tool mills a window in the casing of the primary wellbore. The milling process itself is not precise and thus it is relatively unlikely that a precise window shape and size can be produced. Lateral liners run in to extend through a milled window and into a lateral borehole are constructed with regular patterns and sizes at the surface. When a regular pattern at the top of such a liner is seated against a milled window in the downhole environment, it is relatively unlikely that the liner flange will seat correctly in all regions of a milled window. This leaves gaps between the flange of the liner and the milled casing in the primary wellbore resulting in the aforesaid avenue for infiltration of particulate matter to the wellbore system. A device and method capable of reducing the amount of particulate matter infiltrating the wellbore system at a junction in a multilateral wellbore will be beneficial to downhole arts.

#Sand and other particulate matter is significantly excluded from junctions in level 3 multilateral wellbore systems by employing a thin walled sleeve having a premachined window therein in conjunction with the conventional milling of a window in the primary wellbore casing. The premachined window exhibits a known and easily controlled shape and size which lends itself to assurance that a commercially available liner hanger will seal thereagainst since the liner hanger and the sleeve are machined in controlled conditions at the surface for the purpose of sealing with one another. The installation of the sleeve with the premachined window ensures that at the ID of the wellbore casing, the window surface “seen” by the liner hanger system is one against which the liner hanger system is sealable. The seal of the liner hanger may be by any number of methods, two preferred methods being by an elastomeric seal placed between the flange of the liner hanger and the sleeve, and a metal-to-metal interference fit resulting in deformation of the window sleeve outward during installation of the liner. In addition a hook liner hanger embodiment is disclosed. All of these alternate methods of providing a seal are effective and each have benefits which are attractive for certain applications. The sleeve is preferably swaged at an uphole end thereof, a downhole end thereof, both or in its entirety depending upon the application and desires of the operator. In one embodiment, the casing itself of the primary wellbore is provided with a cylindrical recess capable of receiving the sleeve such that the ID of the sleeve is substantially the same diameter as the ID of the casing.

#Referring now to the drawings wherein like elements are numbered alike in the several Figures:

#FIG. 1 is a cross-section view of a thin walled sleeve with premachined window;

#FIG. 2 is a cross-section view of the thin walled sleeve installed on a running tool which is illustrated schematically, the running tool including a locating dog;

#Referring to FIG. 1, a thin walled sleeve 10 is illustrated having a premachined window 12. Sleeve 10 is preferably constructed of steel with a thickness of from 0.125 inch to 0.250 inch. A preferred thickness of 0.197 inch is selected to facilitate relatively easy swaging yet provide sufficient resiliency in the sleeve to ensure a close proximity of a liner extending therethrough to said sleeve sufficient to facilitate bridging of a particular matter which would otherwise pass between said sleeve and said liner to contaminate produced fluids. In another preferred embodiment the liner is sealed against said sleeve. In a preferred embodiment, bands 13 are positioned around sleeve 10 to aid in sealing and anchoring sleeve 10 against casing 20. Bands 13 are preferably elastomeric. It should be understood that one or more bands 13 may be employed as desired. The bands are visible in FIGS. 1, 2 and 10 but are not visible in other figures because they are compressed between sleeve 10 and the casing of the borehole.

#FIG. 2 schematically illustrates a running tool 14 on which sleeve 10 is mounted for being run into the hole (not shown). Running tool 14 may be any one of several commercially available running tools capable of releasably retaining a sleeve to be run downhole. Running tool 14 does however include a schematically illustrated locating dog 16 unique to applications of the thin walled sleeve 10. Locating dog 16 preferably is mounted on pin 18 which includes a torsional spring (not shown). Locating dog 16 follows an ID of a casing 20 until it reaches a milled window 22 whereat locating dog 16 automatically protrudes through window 22 while running tool 14 proceeds farther downhole. As locating dog 16 reaches a lower vee 24 of window 22, it will orient itself both linearly and rotationally to window 22. Because sleeve 10 is carefully oriented on running tool 14 at the surface to place locating dog 16 in a selected position relative to premachined window 12, the action of locating dog 16 in vee 24 linearly and rotationally orients sleeve 10 to the milled window 22.

#Once sleeve 10 is oriented properly within the hole, running tool 14 is used to swage an uphole end 26, a downhole end 28 or both 26 and 28 into contact with an ID 30 of casing 20. One preferred method for swaging sleeve 10 is to employ an inflatable swaging device incorporated into the running tool. If both uphole end 26 and downhole end 28 are intended to be swaged then preferably two inflatable tools will be utilized simultaneously. FIG. 3 illustrates, schematically, sleeve 10 swaged at uphole end 26 and downhole end 28.