Selective zonal isolation within a slotted liner

Selective isolation of a zone within a slotted liner completion of a wellbore is accomplished by expanding the original slotted liner to the full inner diameter of the wellbore into the annular area normally found around slotted liners. At least one solid tubular is run into the expanded area of the slotted liner and expanded at least in that section of the wellbore to be isolated. A custom expandable slotted liner can be run and expanded within the existing expanded slotted liner if excessive splits or rips should occur in the existing slotted liner due to expansion. Epoxies, rubber, or other sealing materials can also be utilized to better effect a seal between the liners.

BACKGROUND OF THE INVENTION
 1. The Field of the Invention
 The present invention relates to a method to provide isolation within a
 zone of a wellbore lined with a slotted liner by placing an expandable
 liner within the zone to be isolated.
 2. The Prior Art
 There is a great deal of prior art relating to isolating portions of a
 wellbore for various reason. For example, a zone may be producing water or
 gas and needs to be shut off for more effective production of the
 petroleum being recovered. Also, a zone may be producing sand or
 collapsing and creating debris and needs to be isolated to maintain and
 efficient operation. However, different problems arise when the wellbore
 has been completed with the insertion of a known slotted liner.
 One example of the prior art is U.S. Pat. No. 5,366,012 which describes a
 method of completing uncased sections of a wellbore by placing, at a
 predetermined position in the wellbore, a liner which is provided with a
 plurality of overlapping slots. The upper end of the liner is fixed in
 place and an upwardly tapering expansion mandrel is drawn upwardly through
 the slotted liner expanding it outwardly to engage the walls of the
 wellbore. This circumferentially outward movement is facilitated by the
 opening of the slots, together with a slight shortening of the overall
 length of the liner. Slotted liner completions of this type leave an
 annular area around the slotted liner which makes zonal selectivity nearly
 impossible.
 Another suitable method for sealing between a lining and wellbore, casing
 or pipeline is shown in U.S. Pat. No. 5,494,106. This patent describes a
 deformable annular seal which is lowered into the wellbore in a deformed
 or contracted state, which does not impede insertion. Once in place the
 seal is expanded. During expansion of the seal it is hardened to form a
 substantially permanent repair.
 Another method for lining a casing is shown in U.S. Pat. No. 5,454,419 in
 which a tubular polymeric material is lowered into the wellbore in a
 stretched condition, due to a series of weights attached to the leading or
 bottom end. When properly positioned, the weights are released and the
 tubular material returns to its normal condition in which it presses
 against the walls to the wellbore.
 SUMMARY OF THE INVENTION
 The selective zonal isolation system of the present invention can be
 utilized within a slotted liner completion to selectively isolate, either
 permanently or temporarily, sections of the wellbore for such applications
 as fluid shutoff or stimulation purposes. The subject selective zonal
 isolation system works by first expanding an existing slotted liner in the
 wellbore to the full inner diameter of the hole. Then one or more solid
 tubular members are run into the expanded area and are expanded at least
 in that section of the wellbore to be isolated. It is also possible to use
 expandable packers to selectively isolate the section. Additionally, if
 excessive splits or rips should occur in the existing slotted liner, after
 expansion, a custom second expandable slotted liner can be run into the
 wellbore and expanded within the original expanded slotted liner. Epoxies,
 rubber, or other sealing materials can also be utilized to better effect a
 seal. The same methodology could also be utilized in solid uncemented pipe
 sections to increase the effective wellbore radius. Benefits are sealing
 or zonal isolation of existing slotted liner, perforated pipe, sand
 control device or open hole or other completion system.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
 The wellbore 10 (FIGS. 1 and 2) has a first expandable liner 12 in place
 and running through a zone of the wellbore to be isolated. Generally this
 first liner, when expanded, does not fully contact all surfaces of the
 wellbore and it can contain a number of tares and/or rents in the slots. A
 second liner 14 (FIGS. 3 and 4) is inserted into the wellbore and
 positioned to cover at least the zone of the wellbore 10 to be isolated.
 Then the second liner 14 is expanded to sealing engage the first expanded
 slotted liner 12 sealing the openings therein to isolate that portion of
 the wellbore. This sealing can be improved by the addition of sealing
 materials (not shown), such as epoxies, rubber and the like.
 While only a single second liner 14 has been shown, it is within the scope
 of the present invention to include insertion of more than one second
 liner. It is also within the scope of the invention that these second
 liners have physical characteristics different from one another so that,
 for example, a first liner would have characteristics suitable for
 withstanding high pressures while the next liner would have
 characteristics suitable for withstanding erosive effects of the flow
 through the wellbore.
 It should be noted when any slotted liner is expanded, many things can
 happen to it since wellbores are never smooth cylinders. For example,
 while it is hoped that the majority of the slots will open as expected
 allowing the slotted liner to expand, the wellbore walls are never uniform
 and expansion will be at various rates in different directions and for
 different distances. This variation in expansion can stress the slotted
 liner producing tares, rents and other openings which, while not adversely
 affecting the task of the slotted liner, can result in problems for
 subsequently sealing portions of the wellbore protected by such a slotted
 liner.
 The selective zonal isolation system of the present invention can be
 utilized within a slotted liner completion to selectively isolate, either
 permanently or temporarily, sections of the wellbore for such applications
 as fluid shutoff or stimulation purposes. Current slotted liner
 completions leave an annular area around the slotted liner which makes
 zonal selectivity nearly impossible. The selective zonal isolation system
 according to the present invention works by first expanding the current
 slotted liner to the full inner diameter of the wellbore, running at least
 one solid tubular liner into the expanded area and expanding at least that
 section of the tubular liner in the area to be isolated. Additionally, if
 excessive splits or rips should occur in the existing slotted liner after
 expansion, a custom expandable slotted liner (not shown) can be run into
 the wellbore and expanded within the existing expanded slotted liner.
 Epoxies, rubber, or other sealing materials (also not shown) can also be
 utilized to better effect a seal between the expanded slotted liner and
 the tubular liner.
 The same methodology of the present invention could also be utilized in
 solid uncemented pipe sections to increase the effective wellbore radius.
 While a metal tubular liner has been shown in the drawings, the liner is
 not so limited. The tubular liner could be made from a wide variety of
 metals and plastics materials. For example, a memory metal could be used.
 The tubular liner would be formed on the surface, deformed for insertion
 into the wellbore, and reformed when in position. Likewise, the tubular
 liner could be formed and folded or compressed and later expanded or
 reformed when it position by use of a mechanical device such as a mandrel
 or an inflatable member, or by a hydropneumatic force, including an
 explosive force.
 Benefits of the present invention include sealing or zonal isolation of
 existing slotted liner, perforated pipe, sand control device or open hole
 or other completion system.
 The present invention may be subject to many modifications and changes
 which would occur to one skilled in the art. Thus the described embodiment
 should be considered in all respects as illustrative and not restrictive
 of the scope of the subject invention as defined by the accompanying
 claims.