Title: Flush Mounted Tubular Patch

FIELD OF THE INVENTION

[0001] The field of this invention is tubular patches applied by expansion and more particularly those that result in a flush mounting of the patch so that the internal diameter of the well is not reduced from patching.

BACKGROUND OF THE INVENTION

[0002] Downhole well tubulars sometimes develop leaks and need to be repaired. On technique to make such a repair is called cement squeezing. In this technique, cement is pumped into an isolated zone and hopefully into the damaged portions and the cement is allowed to set up. After setup the excess cement is drilled out of the wellbore and the repair is pressure tested to see if it has been successful. If it still fails to hold pressure the process can be repeated as many times as necessary until pressure integrity is regained. This process can work but it is extremely time consuming and could get very expensive if ultimately it doesn't work in a particular application. The cement is brittle and can break over time. These types of patches are difficult to make in a short interval and progressively get more problematic with a longer interval.

[0003] Another technique is to place a patch in the area of the damaged tubular and expand the patch into a sealing relationship. This technique is well known and it will also reduce the inside diameter of the wellbore.

[0004] What is needed and provided by the present invention is a technique for patching a tubular downhole without reducing the inside resulting diameter and without aggravating the existing failure in the tubular that has brought the need to apply a patch. The details of the method will be more readily understood by those skilled in the art from

a review of the description of the preferred embodiment and the claims that appear below.

SUMMARY OF THE INVENTION

[0005] Casing or other well tubulars that have failed are repaired in a manner that doesn't reduce the final inside diameter and doesn't further propagate the failure. The tubular needing repair is first expanded on at least one zone above and below the damaged area. This expansion in an undamaged area arrests failure propagation when the damaged area is then expanded. After the damaged area is expanded, the patch coupled preferably with exterior seals is positioned in the expanded zone of the damaged tubular and expanded. The procedure can also be accomplished in a single trip into the well.

DETAILED DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 shows a section of a damaged tubular downhole;

[0007] Figure 2 is the view of Figure 1 showing expansion above the damaged section;

[0008] Figure 3 is a view of Figure 2 showing the expansion of the damaged zone;

[0009] Figure 4 is the view of Figure 3 showing the placement of the patch in position; and

[0010] Figure 5 is the view of Figure 4 showing the patch with exterior seals expanded into sealing position in the damaged zone.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0011] Figure 1 shows a casing 10 that is either damaged itself or has damage in the adjacent perforations 12. There is cement 14 around the casing 10 in the wellbore 16. As a first step in the method an undamaged zone 18 is expanded. Zone 18 can be above the damaged area 20 or it can be below or it can be both above and below. Preferably, when expanding bottom up the zone 18 is uphole from the damaged area 20. Expanding

zone 18 will require expansion of the cement 14 and the formation 22 beyond it. The formation beyond can be rock that will expand but the higher the pore pressure, Young's modulus and Poisson's ratio, the harder will it be to accomplish the expansion. This makes formations with lower reservoir pressure, Young's modulus and Poisson's ratio more likely candidates for the method.

[0012] The reason an undamaged zone on either or both sides of a damaged zone is expanded first is that a failure or crack that defines the damaged zone will want to propagate if the damaged portion itself is initially expanded. Using the initial expansion in the undamaged zone acts as a stop to crack propagation. This step is illustrated in Figure 2.

[0013] Figure 3 illustrates expansion of the damaged zone 20 after one or more undamaged zones 18 have been expanded. Ideally, the damaged zone 20 is expanded to the same diameter of the previously expanded undamaged zone 18 so that in Figure 3 they appear to be a single expanded zone. While the separate expansions do not need to be exactly to the same degree, this is likely to occur especially if the technique employed has expansion starting in zone 18 and continuing in the same direction into zone 20. Those skilled in the art can appreciate that zone 18 can be expanded in one direction while zone 20 can be expanded in the same or the opposite direction. Alternatively, with certain expansion techniques such as using an inflatable there may be no direction of expansion if the inflatable is long enough to cover an entire zone in a single inflation. One way the expansion can take place is with a variable diameter swage that con do an undamaged zone 18 above or/and below the damaged zone 20 and then be collapsed and repositioned to go into the damaged zone to complete that expansion.

[0014] Figure 3 shows the two zones of expansion on the tubular 10 having been concluded and now ready to accept a patch 22 that is shown with external seals 24 and 26. In the final step, the patch 22 is expanded to an inside diameter 28 that is preferably at least as large as the original well diameter 30. The patch 22 is shown sealed against the tubular 10. The seals 24 and 26 are understood to be optional. The patch 22 is shown as a single piece but can be in sections. The above procedure is shown in a single well

location but can be used in multiple locations within the well. While a cemented tubular is shown, the presence of cement is for background purposes and the method is equally available in the case of uncemented tubulars.

[0015] The illustrated method can also be accomplished in a single trip using a single or multiple swage devices. The patch is simply run in and temporarily supported from the run in string. An adjustable swage and related anchor and stroker are suspended below on the running string. The initial expansion of zones 18 and 20, as described above, are accomplished. The swage is then repositioned adjacent the joined expansion zones that are shown in Figure 3. The temporary support for the patch on the run in string is released allowing the patch to drop down against the swage and relatch to the run in string until the initial expansion of the patch anchors it at which time the latch can be overcome or otherwise released to allow the swage to pass through the patch and the entire assembly can be retrieved to the surface. Alternatively, multiple swages can be used with multiple anchor/ strokers to actuate each swage separately. Initially, the damaged tubular is expanded as described above using hydraulic pressure that leaves the other anchor and stroker inoperative. After the damaged tubular is expanded as described above, the patch is placed into position in the previously expanded area and a ball is dropped to now make the second anchor and stroker assembly active while isolated the initial anchor and stroker. The patch is then expanded and the entire assembly removed from the well. In either case the method is accomplished in a single trip because the damaged casing is expanded and the patch is delivered and expanded all in a single trip.

[0016] The above description is illustrative of the preferred embodiment and many modifications may be made by those skilled in the art without departing from the invention whose scope is to be determined from the literal and equivalent scope of the claims below.