# Patent

## Title
Methods for expanding tubular strings and isolating subterranean zones

## Abstract

Methods and apparatus for expanding tubulars are disclosed. The tubulars may be part of a tubular string for isolating one or more zones within a wellbore. In one embodiment, the tubular string includes a first expandable zone isolation unit disposed on a first side of a zone to be isolated, a second expandable zone isolation unit disposed on a second side of the zone to be isolated, and a perforated tubular disposed in fluid communication with a producing zone. The tubular string may be expanded using an expansion assembly having a first expander for expanding the first and second expandable zone isolation units and a second expander for expanding the at least one perforated tubular. Tags or markers along the tubular string may indicate locations where expansion is desired such that connections or connectors between joints are not expanded.

## Background
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a continuation-in-part of U.S. patent application Ser. No. 10/750,208, filed Dec. 31, 2003, now U.S. Pat. No. 7,124,826, which is a continuation of Ser. No. 10/217,833 filed Aug. 13, 2002, now U.S. Pat. No. 6,702,030, which is a continuation of Ser. No. 09/469,690 filed Dec. 22, 1999, now U.S. Pat. No. 6,457,532, which claims benefit of Great Britain applications GB9828234, GB9900835, GB9923783 and GB9924189; is a continuation-in-part of co-pending U.S. patent application Ser. No. 10/618,419, filed Jul. 11, 2003, which claims benefit of Great Britain application GB0216074.5; is a continuation-in-part of co-pending U.S. patent application Ser. No. 10/809,042, filed Mar. 25, 2004, which claims benefit of Great Britain applications GB0306774.1, GB0312278.5 and GB0316050.4 and is a continuation-in-part of U.S. patent application Ser. No. 10/618,419, filed Jul. 11, 2003, which claims benefit of Great Britain patent application GB0216074.5; and is a continuation-in-part of co-pending U.S. patent application Ser. No. 10/886,513, filed Jul. 7, 2004, which claims benefit of Great Britain application GB0316048.8.


BACKGROUND OF THE INVENTION
1. Field of the Invention
Embodiments of the invention generally relate to expanding tubulars and well completion. More particularly, embodiments of the invention relate to methods and apparatus for isolating a subterranean zone.
2. Description of the Related Art
Hydrocarbon wells typically begin by drilling a borehole from the earth's surface through subterranean formations to a selected depth in order to intersect one or more hydrocarbon bearing formations. Steel casing lines the borehole, and an annular area between the casing and the borehole is filled with cement to further support and form the wellbore. Flow of hydrocarbons or any other fluid into the wellbore occurs at locations along portions of the casing having openings therein, along a perforated tubular or a screen or along any portions of the wellbore left open or unlined with casing.
The wellbore typically traverses several zones within the subterranean formation. However, some of the zones may not produce hydrocarbons or may produce hydrocarbons at different reservoir pressures. For example, some zones produce water that contaminates the production of hydrocarbons from other zones and requires costly removal from the produced hydrocarbons. Thus, it is often necessary to isolate subterranean zones from one another in order to facilitate the production of hydrocarbons.
Prior zonal isolation assemblies are complex, expensive, and undependable and often require multiple trips into the well at significant time and expense. Prior methods and systems for isolating subterranean zones include the use of packers and/or plugs set within the casing, around the casing or in an open hole section to prevent fluid communication via the casing or the borehole from one zone to another. One method for isolating zones involves expanding a series of solid and slotted casing in the wellbore such that seals on the outside of the solid casing prevent the passage of fluids within the annulus in order to isolate a zone traversed by the solid casing.
However, expansion of solid casing can alter an inner seating surface within the solid casing that is used to isolate the zone, thereby preventing the use of conventional packers that seat inside the solid casing during subsequent completion operations. Further, expanding tubular connections downhole sometimes proves to be problematic due to changes in geometry of the connection during expansion and rotation across the connection caused by use of a rotary expansion tool. Additionally, the type of expander tool suitable for expanding solid tubulars may not be desirable for expanding a sand screen into supporting contact with a surrounding formation. For example, expanding sand screen requires use of significantly less force than when expanding solid tubulars in order to prevent damage to the sand screen. Furthermore, expanding long sections of solid tubulars is time consuming and can be complicated by a short operational life of some expander tools. In addition, factors such as stretching of a running string that an expander tool is mounted on makes it difficult or impossible to accurately determine an exact location downhole for expansion of only a desired portion of selected tubular members.
There exists a need for apparatus and methods for reliably and inexpensively isolating subterranean zones by selectively expanding an assembly of tubulars. Further, a need exists for a zonal isolation assembly that provides a seat for conventional packers used in completion operations.
SUMMARY OF THE INVENTION
Embodiments of the invention generally relate to methods and apparatus for expanding tubulars, which may be part of a tubular string for isolating one or more zones within a wellbore. In one embodiment, the tubular string includes a first expandable zone isolation unit disposed on a first side of a zone to be isolated, a second expandable zone isolation unit disposed on a second side of the zone to be isolated, and a perforated tubular disposed in fluid communication with a producing zone. The tubular string may be expanded using an expansion assembly having a first expander for expanding the first and second expandable zone isolation units and a second expander for expanding the at least one perforated tubular. Tags or markers along the tubular string may indicate locations where expansion is desired such that connections or connectors between joints are not expanded.



BRIEF DESCRIPTION OF THE DRAWINGS
So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.
FIG. 1 is a partial section view of an isolation system having an expansion assembly and a tubular string, which is unexpanded and hung from a lower end of casing in a wellbore.
FIG. 2 is an enlarged section view of an expandable zone isolation (EZI) unit within the tubular string and an EZI expander of the expansion assembly activated inside the EZI unit.
FIG. 3 is a view of a portion of an alternative EZI unit that includes a profile for engagement with a surrounding formation upon expansion thereof.
FIG. 4 is a section view of a portion of another alternative EZI unit after expansion thereof against a formation to provide a labyrinth seal.
FIG. 5 is an enlarged section view of an expandable sand screen (ESS) member within the tubular string and an ESS expander of the expansion assembly activated and moved within the ESS member.
FIG. 6 is a partial section view of the tubular string in FIG. 1 after expansion thereof and insertion of a production tubing.
FIG. 7 is a partial section view of a tubular string after expanding an ESS member with an inflatable element of an alternative expansion assembly and prior to expansion of an EZI unit with a rotary expander of the expansion assembly.
FIG. 8 is a partial section view of a tubular string after expanding a garage portion of an EZI unit with a rotary expander of another alternative expansion assembly.
FIG. 9 is a partial section view of the tubular string shown in FIG. 8 after actuating an expandable cone of the expansion assembly in the garage portion and moving the expandable cone within the EZI unit.



DETAILED DESCRIPTION
Embodiments of the invention generally relate to a system for expanding tubulars, which may be part of a tubular string for isolating one or more zones within a wellbore. The tubular string may be located within cased hole, open hole or both cased and open hole portions of the wellbore. Furthermore, embodiments of the system may be used in other applications including pipelines and other tubulars such as found in power plants, chemical manufacturing facilities and chemical catalyst beds.
FIG. 1 illustrates a partial section view of an isolation system 100 disposed within a borehole 102 and secured by a conventional liner hanger 104 to a lower end of casing 106. The isolation system 100 includes an expansion assembly 108 at the lower end of a work string or running string 110 and a tubular string 112 made up of joints of expandable zone isolation (EZI) units 114, solid liner 116 and expandable sand screen (ESS) members 118. Arrangement of the EZI units 114, the solid liner 116 and the ESS members 118 in the desired sequence and number during makeup of the tubular string 112 determines which preselected portions of the borehole 102 that each joint respectively traverses when the tubular string 112 is positioned in the borehole 102. As such, the tubular string 112 may not include any of the solid liner 116. The system 100 enables fluid isolation of zones such as a water zone 120 from an oil/gas zone 122 due to the arrangement of joints within the tubular string 112. Generally, the zones to be isolated with the system 100 may include multiple zones with different fluids and/or multiple zones at different pressures depending upon the specific application. The EZI units are expandable solid tubular members capable of forming a seal with the borehole 102 when expanded. Thus, the EZI units 114 to be expanded to seal the annulus between the borehole 102 and the tubular string 112 span the water zone 120 to be isolated, and the ESS members 118 traverse at least a portion of the oil/gas zone 122. While the EZI units 114 traversing the water zone 114 are shown as only two joints, additional EZI units and/or solid liner may be disposed between the EZI units 114 depending on the length of the water zone 120.
The joints, whether the EZI unit 114, the solid liner 116 or the ESS member 118, of the tubular string 112 may couple to one another in any conventional manner since the connections are not required to be expanded with the system 100 disclosed herein. For example, the joints may couple to one another by non-expandable solid connectors 124, standard pin-box connections at the ends of each joint or welding. Furthermore, each of the ESS members 118 can have solid connection areas at each end thereof for threading with the solid connectors 124, thereby improving mechanical characteristics of the connection, such as tensile strength and torque resistance of the connections between the ESS members 118. In alternative embodiments, some or all of the connections between joints in the tubular string 112 are expanded. Examples of suitable expandable connections are disclosed in U.S. Pat. Nos. 6,722,443; 6,767,035; and 6,685,236 and U.S. patent application Ser. Nos. 10/741,418; 10/613,341; 10/670,133; 09/381,508; 10/664,584; 10/663,351; 10/313,920; 10/443,664; 10/408,748; and 10/455,655, which are all incorporated herein by reference.
Referring still to FIG. 1, the tubular string 112 may additionally include a hybrid tubular 126 coupled to a first joint of the ESS members 118. The hybrid tubular 126 includes an upper solid portion 128 and a lower perforated or slotted portion 130. In situations where the hybrid tubular is connected to the ESS members below an oil/gas zone, the upper portion would be slotted and the lower portion would be solid. Both the upper solid portion 128 and the lower slotted portion 130 are expanded during operation of the system 100. Thus, the hybrid tubular 126 enables continuous expansion between the interface between the solid and slotted portions 128, 130 without requiring expansion of a connection between tubulars. Alternatively, either the upper solid portion 128 or the lower slotted portion 130 may be expanded without expanding both portions 128, 130. The upper solid portion 128 may include a sealing material 132 such as lead, rubber or epoxy on an external surface of the hybrid tubular 126. Preferably, rubber seals are bonded to, or injection molded, to the external surface of the hybrid tubular 126 to provide the sealing material 132. Alternatively, the upper solid portion may include an external profile to engage the borehole 102 and/or an outer surface that forms a micro annulus when expanded against the borehole 102 to provide a labyrinth seal. Therefore, the hybrid tubular 126 may replace or be used in combination with a lower one of the EZI units 114 disposed below the water zone 120.
In a preferred embodiment, each of the ESS members 118 include a base pipe with axially overlapping slots surrounded by one or more layers of mesh or weave and an outer perforated shroud disposed around an exterior thereof. However, the ESS member 118 may be any perforated tubular, slotted tubular or commercially available screen and may not even provide sand exclusion. A last one of the ESS members 118 preferably couples to a solid pipe end member 134, which couples to a guide nose 136 at the end of the tubular string 112. The solid pipe end member 134 provides integrity to the end of the tubular string 112 during lowering of the tubular string 112, and a coned end of the guide nose 136 directs the tubular string 112 through the borehole 102 as the tubular string 112 is lowered. In alternative embodiments, the isolation system 100 ends with the last EZI unit 114 and/or hybrid tubular 126 leaving the well as an open hole well.
The expansion assembly 108 of the system 100 includes an EZI expander 138, an ESS expander 140 and an expander selection mechanism such as a diverter valve 142 disposed between the EZI expander 138 and the ESS expander 140. As shown in FIG. 1, the running string 110 releases from the tubular string 112 upon running the tubular string 112 into the borehole 102 and setting the liner hanger 104 such that further lowering of the running string 110 through the tubular string 112 positions the expansion assembly 108 proximate a first desired location for expansion. A tag 144 along the inside diameter of the EZI unit 114 identifies the first desired location for expansion by interfering with a mating tag locator 146 disposed on a top portion of the EZI expander 138. While a lower portion of the expansion assembly 108 passes through the tag 144 when the expanders 138, 140 are not actuated, the interference between the tag 144 and tag locator 146 prevents further passage and lowering of the running string 110.
The tag 144 may be any restriction along the inside diameter of a tubular such as the EZI unit 114 in order to accurately identify a depth/location for expansion. Preferably, a machined section of tubular coupled (e.g., welded) to another tubular section of the EZI unit 114 that is to expanded forms the tag 144. Alternatively, the tag 144 may include an annular crimp in the wall of the EZI unit 114, a weld bead on an inside surface of the EZI unit 114, a ring affixed to the inside surface or a salt bag disposed on the inside surface.
FIG. 1 also shows an alternative embodiment for identifying the location where expansion of a wellbore tubular is desired to begin and/or end. In this embodiment, a battery (not shown) operates a radio frequency transmitter and receiver 147 coupled to the expansion assembly 108, and a radio frequency identification device (RFID) such as a passive RFID 145 is disposed on the tubular to be expanded such as the EZI unit 114. The location of the passive RFID 145 on the EZI unit 114 identifies where expansion is desired to begin. In operation, the transmitter and receiver 147 transmits a signal at the appropriate frequency to excite the passive RFID 145. The transmitter and receiver 147 receives a response signal from the passive RFID 145 only when in close enough proximity that the transmitted signal can be detected and responded to and the response signal can be received. Upon receipt of the response signal, the transmitter and receiver 147 sends an actuation signal to an operator that actuates the expander assembly 108 accordingly. Alternatively, the transmitter and receiver 147 may send an actuation signal directly to an expansion tool in order to actuate the expansion tool.
FIG. 2 shows the EZI expander 138 actuated inside one of the EZI units 114 in order to expand a length of the EZI unit 114. U.S. Pat. No. 6,457,532, which is hereby incorporated by reference, describes in detail an example of a rotary expander such as the ESS expander 140 and the EZI expander 138 of the system 100. In general, the expanders 138, 140 include a plurality of radially slidable pistons 200 radially offset at circumferential separations. Exposure of the backside of each piston 200 to pressurized fluid within a hollow bore 202 of the expanders 138, 140 actuates the pistons 200 and causes them to extend outward. Disposed above each piston 200 are rollers 203, 204, 205.
Prior to actuation of the EZI expander 138, raising the running string 110 by a predetermined distance such as a couple of feet positions the rollers 203 of the EZI expander 138 at or above the tag 144. Thus, the EZI expander 138 expands the tag 144 as the EZI expander 138 moves through the EZI unit 114. Once the tag 144 is expanded, the tag locator 146 can pass beyond the tag 144 enabling expansion of the rest of the EZI unit 114 and/or other tubulars located lower in the tubular string 112.
During expansion of the EZI unit 114, the ESS expander 140 remains deactivated since fluid flow through the bore 202 diverts to an annulus between the EZI unit 114 and the diverter valve 142 prior to the fluid reaching the ESS expander 140. While any diverter valve may be used to divert the fluid from reaching the ESS expander 140 based on differences in flow rate through the bore 202, the diverter valve shown in FIG. 2 includes a body 223 and an internal sliding sleeve 208 connected by keys 211 to an external sliding sleeve 209 that is biased by a spring 210. When the EZI expander is actuated, increased fluid flow increases the pressure of the fluid that acts on a first annular piston surface 215 formed on the inside of the external sliding sleeve 209 due to ports 213 through the body 223 to the bore 202. As the first annular piston surface 215 of the external sliding sleeve 209 moves relative to the body 223, a seal such as an o-ring 221 de-energizes and permits fluid to pass to a second annular piston surface 217 formed on the inside diameter of the external sliding sleeve 209, thereby increasing the overall piston area acted on to move the diverter valve 142 to a diverted position and providing the necessary additional force to close the fluid path through the bore 202. Moving the diverter valve 142 to the diverted position moves the external sliding sleeve 209 against the bias of the spring 210 and aligns apertures 212 in the external sliding sleeve 209 with flow through ports 214 extending through the body 223 to the bore 202. Additionally, a closing member 219 engages the internal sliding sleeve 208 to block further fluid flow through the bore 202 when the diverter valve 142 is in the diverted position. Thus, the diverter valve 142 in the diverted position directs flow through the flow through ports 214 that are open to the annulus between the EZI unit 114 and the diverter valve 142.
An external surface of the EZI unit 114 may include a sealing material 216 such as lead, rubber or epoxy. The sealing material 216 prevents the passage of fluids and other materials within the annular region between the EZI unit 114 and the borehole 102 after the EZI unit 114 is expanded to place the sealing material 216 into contact with the borehole 102. Preferably, one or more elastomer seals are bonded to, or injection molded, to the external surface of the EZI unit 114 to provide the sealing material 132. The sealing material 216 may include a center portion with a different hardness elastomer than end portions of the sealing material 216 and may further have profiles formed along an outside surface in order to improve sealing with the borehole 102.
The actual tubular body of the EZI unit 114 may additionally include an upper section 218 where the tag 144 and the sealing material 216 are located and a lower section 220. If the upper and lower sections 218, 220 are present, the upper section 218 is made from a material that is more ductile than a material from which the lower section 220 is made. A weld may couple the upper and lower sections 218, 220 together. Lowering and rotating of the running string 110 with the EZI expander 138 actuated expands a length of the EZI unit 114 along the upper section 218. The distance that the EZI expander 138 travels can be measured to ensure that only the EZI unit 114 is expanded and connections or connectors 124 (shown in FIG. 1) between joints are not expanded. As an alternative to measuring the distance traversed or to confirm the measurement, changes noticed relating to the expansion process can identify that the EZI expander 138 has completed expansion of the upper section 218 having the sealing material 216 thereon since expansion becomes more difficult and the rate of travel of the EZI expander 138 decreases once the EZI expander 138 reaches the lower section 220. Thus, the tag 144 effectively identifies a start point where expansion is desired while the lower section 220 effectively identifies an end point for expansion. The tag 144, the sections 218, 220 having different material properties and the RFID devices provide examples of positive downhole markers. Thus, the positive downhole markers ensure that correct portions of downhole tubulars or combinations of downhole tubulars are expanded. Further, expanding operations that utilize the positive downhole markers can occur without expanding connections or connectors 124 between the downhole tubulars.
Fluid flow through the bore 202 to the EZI expander 138 is stopped once the EZI expander reaches the lower section 220 of the EZI unit 114, thereby deactivating the expansion assembly 108. The expansion assembly 108 is then lowered to the next location where expansion is desired as may be marked by another downhole marker such as the passive RFID 145 (visible in FIG. 1) and expansion is commenced as described above. Once the EZI units 114 on each side of the water zone 120 are expanded, fluid and other material from the water zone 120 can not pass into an interior of the tubular string 112 since all the walls of the joints traversing the water zone 120 are solid. Additionally, fluid and other material from the water zone 120 can not pass to other regions of the annulus between the tubular string 112 and the borehole 102 since the seals 216 block fluid flow. In this manner, the system 100 isolates the water zone 120.
FIG. 3 illustrates a portion of an alternative EZI unit 314 that includes a bump profile 316 and an edge profile 317. The bump profile 316 engages with a surrounding formation within a borehole 302 when the EZI unit 314 expands, and the edge profile 317 penetrates into the formation when the EZI unit 314 expands. Thus, the edge and bump profiles 316, 317 seal an annulus 318 between the EZI unit 314 and the borehole 302 upon expansion of the EZI unit 314. The edge and bump profiles 316, 317 may be an integral part of the EZI unit 314 or a separate ring of metal or other hard material affixed to the exterior of the EZI unit 314. The EZI unit 314 may include any number and combination of the bump and edge profiles 316, 317.
FIG. 4 shows a portion of another alternative EZI unit 414 after expansion thereof against a formation to provide a labyrinth seal 416 defined by a micro annulus between the EZI unit 414 and a borehole 402. Like the sealing material 216 and the profiles 316, 317 described above, the labyrinth seal 416 prevents flow through the annulus between the EZI unit 414 and the borehole 402. Using an expansion tool such as a rotary expander described herein that is capable of compliantly expanding the EZI unit 414 enables formation of the labyrinth seal 416. The various sealing arrangements disclosed may be used in any combination. For example, the profiles 316, 317 shown in FIG. 3 may be used in combination with the labyrinth seal 416 shown in FIG. 4 and/or the sealing material 216 shown in FIG. 2.
Referring back to the system 100 shown in FIG. 1, fluid flow once again is stopped to the expansion assembly 108 once all the EZI units 114 (and the hybrid tubular 126 if present) above the ESS members 118 have been expanded. Then, the expansion assembly is lowered a given distance proximate the first joint of the ESS members 118. The distance may be determined by a tally or another downhole marker (not shown) such as described with the EZI units 114.
FIG. 5 illustrates the ESS expander 140 actuated inside one of the ESS members 118 and moved within the ESS member 118 in order to expand a length of the ESS member 118. The ESS member 118 may contact the formation to further support the borehole 102 once expanded. To actuate the ESS expander 140, fluid flow through the bore 202 is at a different flow rate compared to operations where it is desired to only actuate the EZI expander 138 and not the ESS expander 140. The spring 210 biases the sliding sleeves 208, 209 of the diverter valve 142 upward at a reduced flow rate, thereby closing the fluid passage to the flow through ports 214 and opening a fluid passage through the bore 202. The EZI expander 138 does not expand the ESS member 118 even though the EZI expander 138 may be actuated at the different flow rate since the ESS member 118 is already expanded by the ESS expander 140 located ahead of the EZI expander 138 by the time that the EZI expander 138 passes through the ESS member 118.
One feature making the ESS expander 140 especially adapted for expansion of the ESS members 118 may involve the use of a staged expansion to reduce weave stresses of the ESS members 118. Thus, a leading set of rollers 205 expands the ESS member 118 to a first diameter and a lagging set of rollers 204 completes expansion of the ESS member 118 to a final diameter. Additionally, the ESS expander 140 may not apply as much force as the EZI expander 138 even though at least the lagging set of rollers 204 extend to a greater diameter than the rollers 203 of the EZI expander 138.
In one embodiment, fluid flow to the expansion assembly 108 is stopped at the end of each of the ESS members 118 such that the connections or connectors 124 (shown in FIG. 1) are not expanded as the expansion assembly is lowered to subsequent ESS members for expansion. Alternatively, the expansion assembly 108 may not provide sufficient force to expand the connectors 124 when operated at the different flow rate used to actuate the ESS expander 140 such that the connectors 124 are not expanded even without stopping flow to the expansion assembly 108. In still other embodiments, the connections between the ESS members 118 are expanded.
FIG. 6 shows the tubular string 112 in FIG. 1 after expansion thereof and insertion of a production tubing 600. The production tubing 600 includes a packer 602 seated within a portion of the tubular string 112 that is not expanded. Thus; the production tubing 600 provides a fluid path to the surface for flow from the ESS members 118 when the production tubing 600 is present. The production tubing 600 may include sliding sleeves (not shown) to further select and control production from the oil/gas zone 122. Additional EZI members disposed within the tubular string 112 may isolate any additional non-productive zones such as the water zone 120, and additional ESS members may be disposed within the tubular string 112 at any additional oil/gas zones. When multiple oil/gas zones are present, a packer such as the packer 602 may be positioned between the ESS members 118 and the additional ESS members in order to enable separation and control of production from the various oil/gas zones.
While the expansion process of the tubular string 112 described above occurs in a top-down manner using the ESS expander 140 and the EZI expander 138, a similar bottom-up expansion process may incorporate the various aspects disclosed herein. Furthermore, alternative embodiments of the invention utilize an expansion assembly having other combinations of expander tools known in the industry for expanding solid tubulars and perforated or slotted tubulars. For example, U.S. patent application Ser. Nos. 10/808,249 and 10/470,393, which are incorporated herein by reference, describe expandable expanders that may be used as the expansion assembly.
FIG. 7 illustrates a tubular string 712 after expanding an ESS member 718 with an inflatable element 740 of an alternative expansion assembly 708 and prior to expansion of an EZI unit 714 with a rotary expander 738 of the expansion assembly 708. The inflatable element 740 may be a packer used to expand a tubular as disclosed in U.S. Pat. No. 6,742,598, which is herein incorporated by reference in its entirety. In another example, an expandable cone may be used to expand perforated or slotted tubulars disposed within a tubular string and a rotary expander may be used to expand solid tubulars disposed within the tubular string.
FIG. 8 shows a tubular string 812 after expanding a garage portion 850 of an EZI unit 814 with a rotary expander 852 of another alternative expansion assembly 808. The garage portion 850 provides an expanded section of the EZI unit 814 where an expandable cone 854 can be actuated to an expanded position without having to expand the EZI unit 814. Alternatively, the garage portion 850 may be formed by an inflatable element. FIG. 9 illustrates the tubular string 812 shown in FIG. 8 after actuating the expandable cone 854 of the expansion assembly 808 in the garage portion and moving the expandable cone 854 within the EZI unit 814 in order to complete expansion of the EZI unit 814. An ESS member 818 disposed within the tubular string 812 may be expanded by the rotary expander 852 alone, the expandable cone 854 alone or by the rotary expander 852 and the expandable cone 854 in combination, as with the EZI unit 814. U.S. patent application Ser. No. 10/808,249, which is incorporated herein by reference, describes a similar expansion process.
In yet a further alternative embodiment, the ESS expander 140 of the system 100 illustrated in FIG. 1 is disposed behind the EZI expander 138 and remains on when the EZI expander 138 is supplied with pressurized fluid during the expansion of the EZI units 114. However, the ESS expander 140 does not expand the EZI units 114 since the ESS expander 140 can be designed to not apply sufficient force to expand a solid tubular member such as the EZI units 140. For example, limiting the piston area that radially moves the rollers 204, 205 (shown in FIGS. 2 and 5) of the ESS expander 140 outwards limits the force that the ESS expander 140 can apply. The EZI expander 138 can be selectively turned off by the expander selection mechanism such as the diverter valve 142 when the ESS expander 140 is used to expand the ESS members 118 or the slotted portion 130 of the hybrid tubular 126 such that the EZI expander 138 does not harm the ESS members 118 or the slotted portion 130. Any downhole marker along the tubular string 112 may be used to identify the desired locations for turning the EZI expander 130 off and/or on.
As described herein, an expansion assembly such as the expansion assemblies 108, 708, 808 shown in FIGS. 1, 7 and 8 may be selected to include any combination of a first expander having a first expansion mode and a second expander having a second expansion mode. The first and second expanders may be operatively connected to provide the expansion assembly that is run into the wellbore as a unit in a single trip. The term “expansion mode” as used herein refers broadly to a characteristic of the expander such as a force capable of being supplied by the expander during expansion, a type of expander (e.g., rotary expander, expandable cone, packer or inflatable element), and a diameter of the expander for staging expansion and/or selecting a final diameter upon expansion.
A method for isolating a subterranean zone includes making up a tubular string at the surface, coupling the tubular string to a liner hanger with the expansion assembly stabbed therein to provide a system, running the system into the borehole to depth, setting the liner hanger, releasing the running string from the liner hanger, running into the tubular string until a mating tag on the expansion assembly contacts a tag in a tubular, raising the expansion assembly a predetermined distance prior to expanding, expanding a length of the tubular including the tag to permit the mating tag to pass through the tag upon expansion thereof and stopping expanding upon reaching a section of the tubular made from a less ductile material than the length of the tubular. In one embodiment, a method includes locating a tubular string in a borehole, wherein the tubular string includes a first expandable zone isolation unit disposed on a first side of a zone to be isolated, a second expandable zone isolation unit disposed on a second side of the zone to be isolated, and a perforated tubular disposed in fluid communication with a producing zone, expanding middle portions of the first and second expandable zone isolation units while leaving the ends of the first and second expandable zone isolation units unexpanded, expanding a middle portion of the perforated tubular while leaving the ends of the perforated tubular unexpanded.
While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

## Claims

1. A method of expanding a tubular string in a borehole, comprising:
locating the tubular string in the borehole, wherein the tubular string includes a first expandable zone isolation unit disposed on a first side of a zone to be isolated, a second expandable zone isolation unit disposed on a second side of the zone to be isolated, and a perforated tubular disposed in fluid communication with a producing zone;
expanding middle portions of the first and second expandable zone isolation units while leaving the ends of the first and second expandable zone isolation units unexpanded; and
expanding a middle portion of the perforated tubular while leaving the ends of the perforated tubular unexpanded.

2. The method of claim 1, wherein expanding the middle portions of the first and second expandable zone isolation units forms labyrinth seals between an outside of the first and second expandable zone isolation units and the borehole.

3. The method of claim 1, wherein expanding the middle portions of the first and second expandable zone isolation units causes edge profiles on an outside of each of the first and second expandable zone isolation units to penetrate into a surrounding formation.

4. The method of claim 1, wherein expanding the middle portions of the first and second expandable zone isolation units includes actuating a first expander and expanding a middle portion of the perforated tubular includes actuating a second expander.

5. The method of claim 4, further comprising selectively deactivating the second expander during expanding the middle portions of the first and second expandable zone isolation units.

6. The method of claim 1, further comprising running an expander tool into the tubular string until a mating tag on an outside of the expander tool contacts a tag disposed along an inside diameter of the first expandable zone isolation unit proximate a start of the middle portion of the first expandable zone isolation unit.

7. The method of claim 6, further comprising stopping expanding upon reaching a section of the first expandable zone isolation unit made from a less ductile material than the middle portion of the first expandable zone isolation unit.

8. The method of claim 6, further comprising raising the expander tool a predetermined distance prior to expanding the middle portion of the first expandable zone isolation unit.

9. The method of claim 1, further comprising setting a packer in an unexpanded tubular of the tubular string.

10. The method of claim 1, further comprising:
providing the tubular string having a downhole marker proximate a pre-selected location for expansion;
running an expander tool into the tubular string until a corresponding feature coupled to the expander tool identifies the downhole marker; and
expanding at least a portion of the tubular string in response to identifying the downhole marker.

11. The method of claim 10, wherein the downhole marker includes a radio frequency identification device.

12. The method of claim 10, wherein the downhole marker includes a passive radio frequency identification device and the corresponding feature includes a radio frequency identification device detector.

13. The method of claim 10, further comprising determining a location to stop expanding based on an additional downhole marker.

14. A method of expanding a tubular string in a borehole, comprising:
locating the tubular string in the borehole, wherein the tubular string includes an expandable zone isolation unit disposed adjacent a zone to be isolated and a perforated tubular disposed in fluid communication with a producing zone;
expanding a middle portion of the expandable zone isolation unit while leaving the ends of the expandable zone isolation unit unexpanded; and
expanding a middle portion of the perforated tubular while leaving the ends of the perforated tubular unexpanded.

15. The method of claim 14, further comprising:
providing the tubular string having a tag along an inside diameter thereof proximate a pre-selected location for expansion;
running an expander tool into the tubular string until a mating tag contacts the tag; and
expanding a first section of the tubular string including the tag to permit the mating tag to pass through the tag of the tubular string upon expansion thereof.

16. The method of claim 15, further comprising determining a location to stop expanding based on a downhole marker.

17. The method of claim 16, wherein the downhole marker includes a second section of the tubular string having a different material property than the first section of the tubular string.

18. The method of claim 15, further comprising raising the expander tool a predetermined distance prior to expanding the length of the tubular string.

19. The method of claim 15, wherein the tag includes a restriction along the inside diameter of the tubular string.

20. The method of claim 15, wherein the tag includes a crimp in the tubular string to form a restriction along the inside diameter of the tubular string.

21. The method of claim 14, wherein expanding the middle portions of at least one of the expandable zone isolation unit and the perforated tubular includes actuating a packer to cause the expanding.

22. The method of claim 21, wherein expanding the middle portion of the perforated tubular includes actuating the packer to cause the expanding.