METHOD AND APPARATUS FOR SETTING AND REINFORCING DROPPED FABRIC NESTED CASING

Abstract

A system for deploying a fabric liner in a wellbore includes a free-to-fall sub and a shoe track. The free-to-fall sub includes a weighted compartment that is filled with a first fluid that increases the weight of the free-to-fall sub and at least one stabilizing wheel that centralizes the free-to-fall sub within the wellbore. The shoe track incudes a plurality of orifices that release a second fluid into the fabric liner. The fabric liner retains the second fluid between the shoe track and the fabric liner. The free-to-fall sub is rigidly fixed to a downhole end of the fabric liner such that the fabric liner supports the free-to-fall sub within the wellbore.

Description

BACKGROUND

Drilling an oil or gas well consists of drilling from the surface of the earth until an objective depth, referred to as the “casing point,” is reached. A string of pipes, called a casing string, is then run into the wellbore. After a casing string is run through a drilled section, this casing is anchored, with cement, in order to isolate the drilled section from the remainder of the well. Once the casing string is cemented, the next section is drilled with a smaller diameter than the first section. This process is then repeated until the total depth is reached. However, there are cases where this practice fails due to loss of circulation regions, which prohibit a casing string from being properly cemented.

Lost circulation regions are regions in which excessive fluid loss to a surrounding formation occurs. These regions typically include formations that are inherently fractured, cavernous, or have high permeability and may be the result of improper drilling conditions or excessive downhole pressure. Due to cement being lost to the lost circulation region during a casing operation, isolating the casing may be impossible in situations where the lost circulation is not mitigated. In addition, lost circulation regions may cause structural integrity problems when attempting to cement a casing string, such as in cases where the lost circulation region occurs due to a weakened formation.

SUMMARY

A system for deploying a fabric liner in a wellbore includes a free-to-fall sub and a shoe track. The free-to-fall sub may include a weighted compartment that is filled with a first fluid that increases the weight of the free-to-fall sub and at least one stabilizing wheel that centralizes the free-to-fall sub within the wellbore. The shoe track incudes a plurality of orifices that release a second fluid into the fabric liner. The fabric liner retains the second fluid between the shoe track and the fabric liner. The free-to-fall sub is rigidly fixed to a downhole end of the fabric liner such that the fabric liner supports the free-to-fall sub within the wellbore.

A method of deploying a fabric liner in a wellbore includes fixing a free-to-fall sub to a downhole end of a fabric liner. The free-to-fall sub may include a weighted compartment that is filled with a first fluid that increases the weight of the free-to-fall sub and at least one stabilizing wheel that centralizes the free-to-fall sub within the wellbore. The method further includes fixing the fabric liner to a surface end of the wellbore, deploying the free-to-fall sub within the wellbore until the free-to-fall sub reaches the bottom of the wellbore, and running, in-hole, a casing string and a modified shoe track into the fabric liner. The modified shoe track includes a plurality of orifices configured to release a second fluid into the fabric liner into the fabric liner, and the shoe track includes a plurality of orifices configured to release a second fluid into the fabric liner. Finally, the method includes retaining, by the fabric liner, the second fluid between the casing string and the wellbore.

BRIEF DESCRIPTION OF DRAWINGS

Specific embodiments of the disclosed technology will now be described in detail with reference to the accompanying figures. Like elements in the various figures are denoted by like reference numerals for consistency. The sizes and relative positions of elements in the drawings are not necessarily drawn to scale. For example, the shapes of various elements and angles are not necessarily drawn to scale, and some of these elements may be arbitrarily enlarged and positioned to improve drawing legibility.

FIG. 1 shows an apparatus in accordance with one or more embodiments of the present disclosure.

FIG. 2 shows an apparatus in accordance with one or more embodiments of the present disclosure.

FIG. 3 shows an apparatus in accordance with one or more embodiments of the present disclosure.

FIG. 4 shows an apparatus in accordance with one or more embodiments of the present disclosure.

FIG. 5 shows an apparatus in accordance with one or more embodiments of the present disclosure.

FIG. 6 shows an apparatus in accordance with one or more embodiments of the present disclosure.

FIG. 7 shows an apparatus in accordance with one or more embodiments of the present disclosure.

FIG. 8 shows an apparatus in accordance with one or more embodiments of the present disclosure.

FIG. 9 shows a flowchart of a method in accordance with one or more embodiments of the present disclosure.

DETAILED DESCRIPTION

Specific embodiments of the disclosure will now be described in detail with reference to the accompanying figures. In the following detailed description of embodiments of the disclosure, numerous specific details are set forth in order to provide a more thorough understanding of the disclosure. However, it will be apparent to one of ordinary skill in the art that the disclosure may be practiced without these specific details. In other instances, well known features have not been described in detail to avoid unnecessarily complicating the description.

Throughout the application, ordinal numbers (e.g., first, second, third, etc.) may be used as an adjective for an element (i.e., any noun in the application). The use of ordinal numbers is not intended to imply or create any particular ordering of the elements nor to limit any element to being only a single element unless expressly disclosed, such as using the terms “before”, “after”, “single”, and other such terminology. Rather, the use of ordinal numbers is to distinguish between the elements. By way of an example, a first element is distinct from a second element, and the first element may encompass more than one element and succeed (or precede) the second element in an ordering of elements.

In addition, throughout the application, the terms “upper” and “lower” may be used to describe the position of an element in a well. In this respect, the term “upper” denotes an element disposed closer to the surface of the Earth than a corresponding “lower” element when in a downhole position, while the term “lower” conversely describes an element disposed further away from the surface of the well than a corresponding “upper” element. Likewise, the term “axial” refers to an orientation substantially parallel to the well, while the term “radial” refers to an orientation orthogonal to the well.

In general, one or more embodiments of the disclosure include a method and apparatus for setting and reinforcing a fabric nested casing into a wellbore with a lost circulation region. When drilling in a total-loss region, no drilling mud is returned to the surface of the well. This leads to the height of the fluid column to be reduced, thereby reducing the pressure in the well and potentially leading to a catastrophic loss of well control. When drilling in a partial-loss region, an amount of drilling mud (e.g., greater than about 20 barrels/minute) that significantly affects the drilling operation may be lost in the surrounding foundation, but some drilling mud will still return to the surface. Lost circulation may occur, for example, when drilling through a foundation having fractures or caverns, which may be naturally occurring or may also occur from the drilling operation.

In order to complete successful cementing operations in a lost circulation region, a fabric liner may be sent downhole to the bottom of the well, followed by the casing string run inside this fabric liner. Fluid is then pumped through the casing, into the annular space between the casing and the fabric liner such that the fabric liner covers a lost circulation region of the well. Accordingly, the systems, devices, and methods disclosed herein may be used for remediating partial and total loss occurrences when a casing string is cemented.

FIG. 1 shows a schematic diagram illustrating a well site 11. In general, well sites may be configured in a myriad of ways. Therefore, well site 11 is not intended to be limiting with respect to the particular configuration of the drilling equipment. The well site 11 is depicted as being on land. In other examples, the well site 11 may be offshore, and drilling may be carried out with or without use of a marine riser.

As shown in FIG. 1, a wellbore 13 has been drilled into a subterranean formations 15. The subterranean formations 15 includes a lost circulation region 19, which may be detected through the loss of drilling mud return. Once a wellbore 13 section is drilled to a casing point, the bottom-hole assembly is retrieved and the casing is run and cemented in-hole. However, due to the presence of the loss zone, there is a high probability that any cementing operations will fail because cement is lost in the lost circulation region 19 rather than anchoring the casing.

In such scenarios, a free-to-fall sub 31 according to embodiments of the present invention may be used to remediate a lost circulation region 19. Specifically, the free-to-fall sub 31 and fabric liner 21 are released into the wellbore 13. After that, a casing string (e.g., shown in FIG. 2) is run inside the fabric liner and cement is pumped such that the cement is contained inside the fabric and is prevented from drifting into the loss zone 19.

To deploy the free-to-fall sub 31 and fabric liner 21 into the wellbore 13, the surface end of the fabric liner 21 is fixed to a roller 25, while the downhole end of the fabric liner 21 is fixed to the free-to-fall sub 31 at the rig floor 14. Due to this arrangement, when the free-to-fall sub 31 is deployed by dropping or releasing the free-to-fall sub 31 in the wellbore 13 the fabric liner 21 extends to the bottom well, covering the lost circulation region 19. Fluid is then pumped into the fabric liner 21. The fluid pumped into the fabric liner 21 may be cement, a cement slurry, or a resin configured to harden and retain its shape. The presence of the fabric liner prevents fluid from being lost into the lost circulation region 19.

The fabric liner 21 is formed of one or more flexible materials including Kevlar, polymers, polyesters, nanocellulose, or natural materials such as cotton, wool, silk, or linen. Initially, the fabric liner 21 is formed as a single sheet that may include one or more layers of the aforementioned materials. The fabric liner 21 is then rolled onto a roller 25 fixed to the rig floor 14, and a downhole end of the fabric liner 21 is attached to a surface end of the free-to-fall sub 31. The lengthwise sides (i.e., the sides which extend in a downhole direction) of the fabric liner 21 are woven or welded such that the fabric liner 21 forms a cylinder.

The free-to-fall sub 31 includes a body formed of a drillable material such as steel, aluminum, phenolic materials, elastomers, or other material that can be drilled by a polycrystalline diamond compact (PDC) or equivalent drill bit after casing and cementing operations are completed. As shown in FIG. 1, the free-to-fall sub 31 is cylindrically shaped with a conical nose that advantageously retains the free-to-fall sub 31 upright during deployment within the wellbore 13. The free-to-fall sub 31 can also include a weighted compartment 33 disposed in the cylindrical portion of the body of the free-to-fall sub 31. Prior to deploying the free-to-fall sub 31, the weighted compartment 33 is filled with a first fluid such as water, drilling mud, or cement that weights the free-to-fall sub 31 in order to retain the fabric liner 21 in an axial orientation when the free-to-fall sub 31 is deployed in the wellbore 13. The weighted compartment 33 is sealed by a sealing device (not shown) such as a plug, door, or valve, which ensures that the first fluid cannot escape the weighted compartment 33 once the weighted compartment 33 is filled.

The roller 25 includes a rolling element 27 that the fabric liner 21 is fixed to and wound around, which includes a tubular metal body that is attached to a stand 29 using bearings (not shown). By way of example, the fabric liner 21 may be welded to the rolling element 27 or may be bolted or simply wound around the rolling element 27. The roller 25 is rigidly fixed to the rig floor 14 via the stand 29, which is positioned near a fabric hanger 23 in order to facilitate the deployment of the free-to-fall sub 31 and fabric liner 21. For example, the stand 29 of the roller 25 may be bolted to the rig floor 14, or temporarily fixed in place by other means to prevent movement. Both the stand 29 and rolling element 27 may be formed of one or more of the following materials: steel, aluminum, iron, metal alloys, or equivalent.

Deploying the fabric liner 21 into the wellbore 13 includes lowering the free-to-fall sub 31 to the lower axial end, or bottom, of the wellbore 13. Lowering the free-to-fall sub 31 may include dropping the free-to-fall sub 31 into the wellbore 13, by wire-line or slick-line (not shown), with a release mechanism, or by unrolling the fabric liner 21 from the roller 25 such that the free-to-fall sub 31 is slowly lowered into the wellbore 13 with the fabric liner 21.

Due to situations where a wellbore 13 may not be consistently vertical during deployment, the free-to-fall sub 31 also includes one or more stabilizing wheels 35 that are disposed on an outer surface of the free-to-fall sub 31. The stabilizing wheel 35 aids in deploying the fabric liner 21 in the wellbore 13 by preventing situations where the free-to-fall sub 31 gets stuck to the side of the wellbore 13, prevents the fabric liner 21 from twisting during deployment, and allows the free-to-fall sub 31 to be deployed into non-vertical sections of the wellbore 13. The stabilizing wheel 35 may be embodied as a pneumatic or solid wheel with a rubber, silicone, polyurethane, or other polymer exterior, and may be oriented axially or radially on the free-to-fall sub 31. Additionally, the stabilizing wheel 35 may be attached to the free-to-fall sub 31 by an armature (not shown) that extends from the free-to-fall sub 31, or, as shown in FIG. 1, the stabilizing wheel 35 may be attached directly to the free-to-fall sub 31 by connecting the stabilizing wheel 35 to an outer surface of the free-to-fall sub 31.

Once the free-to-fall sub 31 is lowered to the axial end of the wellbore 13, the fabric liner 21 is detached or cut from the roller 25 and fixed to the rig floor 14. As shown in FIG. 1, the fabric liner 21 is attached to a fabric hanger 23 that extends around a rotary table (not shown). However, the fabric liner 21 may be fixed to the surface 14 through a variety of methods including: attaching the fabric liner 21 to a dedicated sleeve attached to a rotary table (not shown) or bell nipple (not shown), or on a fabric hanger 23 or packer element that retains the fabric liner 21 against the walls of the previous casing string 17. The fabric liner 21 therefore forms a cylindrical tube with an opening at its surface end, and a closed downhole end that is fixed to the free-to-fall sub 31 such that the downhole end of the fabric liner rests at the bottom of the well.

As shown in FIG. 2, once the free-to-fall sub 31 is deployed within a wellbore 13, a casing string 39 with a specially-designed shoe track 37 is run into the fabric liner 21 through the opening of the fabric liner 21. The modified shoe track 37, which is further described below, is fixed to the axial end of the casing string 39 by screwing the shoe track 37 to the casing string 39. The casing string 39 is run through the fabric liner 21 until the shoe track 37 abuts against to the free-to-fall sub 31. The shoe track 37 is then connected to the free-to-fall sub 31 by press-fitting the shoe track 37 into the free-to-fall sub 31.

In order to allow fluid to flow between the shoe track 37 and the free-to-fall sub 31, the free-to-fall sub 31 further includes a fluid port 34 that is configured to fluidly connect the shoe track 37 to the free-to-fall sub 31 and the wellbore 13. The fluid port 34 may be used by an operator to establish well control by creating circulation behind the fabric liner 21 through the free-to-fall sub 31, if needed.

Once the shoe track 37 is connected to the free-to-fall sub 31, a second fluid 41 is pumped through the casing string 39 and shoe track 37, which fills and expands the fabric liner 21 until the liner 21 covers the lost circulation region 19 as shown in FIG. 3. The second fluid 41 may include cement, a cement slurry, or resin that is configured to harden and retain its shape under heavy loads. Because fabric liner 21 extends above and below the lost circulation region 19, once the second fluid 41 hardens the lost circulation region 19 is remediated and the casing string 39 is fully cemented within the wellbore 13. A drilling operation is continued by drilling through the shoe track 37 and free-to-fall sub 31, and further drilling into the subterranean formations 15.

FIGS. 4-8 depict various embodiments of a shoe track 37 according to one or more embodiments of the present invention that are used to fill a fabric liner 21 with a second fluid 41 that retains a casing string 39 to the fabric liner 21 within a wellbore 13.

Specifically, FIG. 4 depicts a shoe track 37 according to one or more embodiments of the invention that includes: upper orifices 63 which are symmetrically disposed around an outer periphery of the shoe track 37, a plurality of rupture discs 49 disposed in the upper orifices 63, a base 55, and a vertical portion 43. The vertical portion 43 extends from a base 55 of the shoe track 37 to the casing string 39, and the base 55 extends radially with respect to the wellbore 13. The plurality of rupture discs 49 are used to allow the second fluid 41 to fill the annular space between the fabric liner 21 and casing string 39.

The shoe track 37 further includes a float valve 47 that is fluidly connected to the fluid port 34. The float valve 47 is disposed within the base 55 that is configured to prevent the second fluid 41 from re-entering the shoe track 37, and a plurality of check valves 48 disposed within the upper orifices 63 about the periphery of the shoe track 37. The plurality of check valves 48 are configured to prevent the second fluid 41 from re-entering the shoe track 37 and the casing string 39, and may include ball valves, globe valves, butterfly valves, or equivalent.

In order to begin filling the fabric liner 21 with the second fluid 41, a first plug 51 is pumped with the second fluid 41 through the casing string 39 and vertical portion 43 of the shoe track 37 such that the first plug 51 seals a downhole end of the shoe track 37, which includes a lower orifice 64 and the float valve 47, from the second fluid 41. By way of example, the first plug 51 can be formed from plastics such as high-density polyethylene, nylon, or equivalent, or the first plug 51 may be formed from steel or aluminum. The first plug 51 includes an outer portion 65 and an inner portion 67, where the inner portion 67 has a smaller cross section than the outer portion 65. As shown in FIG. 4, the inner portion 67 is sized to fit within the lower orifice 64 of the base 55, and the outer portion 65 is sized to abut against the base 55 such that the outer portion 65 prevents the second fluid 41 from entering the float valve 47.

Once the first plug 51 is seated within the lower orifice 64, the second fluid 41 is pumped through the casing string 39 and vertical portion 43 in order to form a fluid column of the second fluid 41. Additional pressure is then applied through the second fluid 41 to break the plurality of rupture discs 49 and the second fluid 41 exits the upper orifices 63 into the space between the fabric liner 21 and the casing string 39. The rupture discs 49 may be formed from a nickel and aluminum based alloy, steel, chromium, or equivalent, and are configured to burst upon a requisite differential pressure being reached. Specifically, the cross section of the rupture discs 49 and upper orifices 63 are determined by the selected additional differential pressure to be applied after the first plug 51 is seated and blocks the fluid path through the lower orifice 64.

As shown in FIG. 5, after a predetermined period of time a second plug 53 is released into the second fluid 41 and travels with the second fluid 41 until the second plug 53 rests in the shoe track 37. The predetermined period of time depends on the amount of cement to be pumped behind the casing and inside the fabric liner, and an operator's discretion. In order to seal the upper orifices 63, and thus the surface end of the shoe track 37, the second plug 53 travels through the casing string 39 and the vertical portion 43 of the shoe track 37 until the second plug 53 rests on a ledge 45 of the shoe track 37, thereby preventing the second fluid 41 from exiting the upper orifices 63 and sealing the second fluid 41 in the space between the fabric liner 21 and the shoe track 37. The ledge 45 is sized such that the first plug 51 can move through the opening created by the ledge 45, while the second plug 53 is sized such that the second plug 53 seals the shoe track 37 when an outer portion of the second plug 53 abuts against the ledge 45.

By way of example, and similar to the first plug 51, the second plug 53 may be formed from plastics such as high-density polyethylene, nylon, or equivalent, or the first plug 51 may be formed from steel or aluminum. Additionally, the second plug 53 includes an outer portion 68 and an inner portion 66, where the inner portion 66 has a smaller cross section than the outer portion 68.

Once the second fluid 41 has filled the fabric liner 21, the fabric liner 21 fully covers the lost circulation region 19, and no fluid may enter the lost circulation region 19. Upon sealing the lost circulation region 19 and fully filling the fabric liner 21, the second fluid 41 hardens, and the drilling operation may resume by drilling through the shoe track 37 and free-to-fall sub 31.

FIGS. 6-8 depict an alternate embodiment of the present invention in which upper shear pins 61 and lower shear pins 62 are used to seal the upper orifices 63 with sleeves.

Specifically, as seen in FIG. 6, the shoe track 37 includes an opening sleeve 57 disposed at a downhole end of the shoe track 37 and a closing sleeve 59 disposed at a surface end of the shoe track 37. The opening sleeve 57 is disposed within the vertical portion 43 of the shoe track 37 such that the opening sleeve 57 covers the upper orifices 63 of the shoe track 37, while the closing sleeve 59 is disposed within the shoe track 37 above the opening sleeve 57. The opening sleeve 57 and closing sleeve 59 are annular in shape and may be formed of the same material as the shoe track 37 such that the opening sleeve 57 and closing sleeve 59 are drillable during a drilling operation. In addition, the opening sleeve 57 and the closing sleeve 59 are fixed to the shoe track 37 using the upper shear pins 61 and lower shear pins 62, respectively, which are configured to retain the opening sleeve 57 and the closing sleeve 59 to the shoe track 37 above the upper orifices 63 until sheared.

As shown in FIG. 7, in order to shear the lower shear pins 62 and shift the opening sleeve 57 downhole, a first plug 51 is pumped with the second fluid 41 down the casing string 39 with a shoe track 37 until the first plug 51 abuts against the opening sleeve 57. An inner opening sleeve diameter 69 is sized in conjunction with the first plug 51 such that the first plug 51 seals the entirety of the inner opening sleeve diameter 69, and thus the opening sleeve 57, which causes pressure to develop in the shoe track 37 when the second fluid 41 is pumped into the shoe track 37. Once the pressure of the second fluid 41 overcomes the shearing force of the lower shear pins 62, the opening sleeve 57 is released from the shoe track 37 and is shifted open. At this point, the second fluid 41 is free to flow through the upper orifices 63 into the fabric liner 21, which then inflates.

Upon inflating the fabric liner 21 by pumping the cement, a second plug 53 is pumped down the casing string 39 until the second plug 53 abuts against the closing sleeve 59 as shown in FIG. 8. In particular, the size of the second plug 53 is chosen according to the size of the inner closing sleeve diameter 70 such that the inner closing sleeve diameter 70 is sealed by the second plug 53. This second plug 53 is followed by a portion of the second fluid 41 and a displacement fluid disposed above the second plug 53. Once the pressure from the portion of the second fluid 41 overcomes the threshold of the upper shear pins 61, the closing sleeve 59 is released and closed, thereby sealing the upper orifices 63 and preventing the second fluid 41 from flowing through the shoe track 37.

Following the sealing of the upper orifice 63, the second fluid 41 hardens in the annular space between the fabric liner 21 and the casing string 39, and within the shoe track 37. As discussed above, once the second fluid 41 hardens, the casing string 39 is fully isolated. At this point, drilling operations may be continued by drilling through the shoe track 37 and free-to-fall sub 31, and further drilling into the subterranean formations 15.

FIG. 9 depicts a flowchart showing a method of deploying a fabric liner 21 within a wellbore 13 according to one or more embodiments of the invention. While the various flowchart blocks in FIG. 9 are presented and described sequentially, one of ordinary skill in the art will appreciate that some or all of the blocks may be executed in different orders, may be combined or omitted, and some or all of the blocks may be executed in parallel. Furthermore, the blocks may be performed actively or passively.

In block 910, a free-to-fall sub 31 is fixed to the downhole end of fabric liner 21. The free-to-fall sub 31 may be fixed to the fabric liner 21 by welding, bolting, or applying an adhesive between the fabric liner 21 and the free-to-fall sub 31. The free-to-fall sub 31 may include a weighted compartment 33 that is filled with a first fluid to increase the weight of the free-to-fall sub 31. The free-to-fall sub 31 also includes at least one stabilizing wheel 35 configured to centralize the free-to-fall sub 31 within the wellbore 13.

In block 920, the surface end of the fabric liner 21 is fixed to the rig floor 14. This can be done through a variety of methods including attaching the fabric liner 21 to a dedicated sleeve attached to a rotary table (not shown) or bell nipple (not shown), or on a fabric hanger 23 that retains the fabric liner 21 against the walls of the previous casing string 17. Alternatively, the fabric liner 21 may be anchored to the surface 14 by hanging grommets (not shown) of the fabric liner 21 on hooks or other protrusions (not shown) disposed on the rig floor 14.

In block 930, the free-to-fall sub 31 is deployed within the wellbore 13 such that the free-to-fall sub 31 sits at the lower axial end of the wellbore 13 with the fabric liner 21 extending either throughout the entire wellbore 13 or the open-hole area below the previous casing string 17, if set. Deploying the free-to-fall sub 31 may include one or more of the following: lowering the free-to-fall sub 31 by a wire-line, slick-line, dropping the free-to-fall sub 31 down the wellbore 13, or using a second roller (not shown) to slowly lower the free-to-fall sub 31 into the wellbore 13.

In block 940, the casing string 39 is run in-hole into the fabric liner 21 until the shoe track 37 connects to the free-to-fall sub 31. The shoe track 37 includes a plurality of upper orifices 63 that are configured to release a second fluid 41 into the fabric liner 21. As described above, the second fluid 41 is pumped through the casing string 39 and shoe track 37 until the second fluid 41 exits the plurality of upper orifices 63 into the space between the casing string 39 and the fabric liner 21. The second fluid 41 may include cement, a cement slurry, or resin that is configured to harden and retain its shape under heavy loads.

In block 950, the second fluid 41 is retained, by the fabric liner 21, in the annular space between the casing string 39 and wellbore 13 by the fabric liner 21, where the second fluid 41 hardens in order to isolate the area behind the casing string. Following the hardening of the second fluid 41, the drilling operation is recommenced by drilling through the shoe track 37 and the free-to-fall sub 31.

Accordingly, the aforementioned embodiments as disclosed relate to devices and methods useful for setting a casing when drilling in a total, severe, or partial loss region.

As noted above, the lost circulation of drilling mud is a common challenge encountered when drilling a wellbore. Lost circulation of drilling mud may be the result of naturally fractured foundations, improper drilling conditions, or excessive downhole pressure. Excessive downhole pressures may induce fractures in the wellbore, which causes drilling mud to be lost to the downhole formations. While some fluid loss may be expected, total loss can cause loss of wellbore control, wellbore instability, stuck equipment, and formation damage due to plugging of pores and pore throats by mud particles. In extreme cases, lost circulation problems may force the abandonment of the well or prohibit a casing string from being set.

The drilling industry has made several advances to prevent a failed cementing job due to a lost circulation region. On the prevention side, a drilling crew may try to cure the loss-of-circulation zone by pumping LCM (loss-of-circulation material) or cement plugs into the lost circulation region. However, cement is typically heavier than the drilling fluid, and, thus, even if losses are cured during the drilling phase of drilling operation, the cement may induce losses during the cementing phase due to the higher hydrostatic pressure exerted on the well. Using a differential-valve (DV) has also been proven to be an efficient solution for many scenarios. However, the presence of an un-cemented area under a packer of the DV tool can also cause wellbore instability or force the removal of the failed cementing job. Accordingly, methods and embodiments of the invention as disclosed herein address the challenges of remediating a lost circulation region by sealing the lost circulation region without the potential of losing cement to the lost circulation region, and without necessitating the need for LCMs to be pumped into the well.

Although only a few embodiments of the invention have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the example embodiments without materially departing from this invention. Accordingly, all such modifications are intended to be included within the scope of this disclosure as defined in the following claims.

Claims

1. A system for deploying a fabric liner in a wellbore, the system comprising:

a free-to-fall sub, the free-to-fall sub comprising: a weighted compartment that is filled with a first fluid that increases a weight of the free-to-fall sub; and at least one stabilizing wheel configured to centralize the free-to-fall sub within the wellbore; and

a modified shoe track comprising a plurality of orifices configured to release a second fluid into the fabric liner;

wherein the fabric liner is configured to retain the second fluid in an annular space between a casing string and the wellbore such that the second fluid is prevented from being lost in subterranean formations; and

wherein the free-to-fall sub is rigidly fixed to a downhole end of the fabric liner.

2. The system as claimed in claim 1, wherein the at least one stabilizing wheel is disposed on an outer surface of the free-to-fall sub.

3. The system as claimed in claim 1, wherein the fabric liner is configured to receive the casing string and the modified shoe track when the fabric liner is deployed in the wellbore.

4. The system as claimed in claim 1, further comprising: a first plug configured to seal the downhole end of the modified shoe track.

5. The system as claimed in claim 1, wherein the free-to-fall sub comprises a fluid port that fluidly connects the modified shoe track and the fabric liner to the free-to-fall sub.

6. The system as claimed in claim 5, further comprising: a second plug configured to seal a surface end of the modified shoe track.

7. The system as claimed in claim 1, further comprising a plurality of rupture discs that are configured to break due to applied differential pressure through the second fluid.

8. The system as claimed in claim 7, wherein the plurality of rupture discs are disposed around an outer periphery of the modified shoe track.

9. The system as claimed in claim 7, wherein the modified shoe track comprises a plurality of check valves that are configured to prevent the second fluid from re-entering the casing string.

10. The system as claimed in claim 1, wherein the modified shoe track comprises an opening sleeve configured to prevent the second fluid from exiting the free-to-fall sub.

11. The system as claimed in claim 1, wherein the modified shoe track comprises a closing sleeve configured to prevent the second fluid from re-entering the modified shoe track.

12. The system as claimed in claim 1, further comprising: a roller disposed at a surface end of the wellbore configured to unroll the fabric liner when the free-to-fall sub is being deployed in the wellbore.

13. The system as claimed in claim 1, further comprising: a fabric hanger configured to retain the fabric liner at a surface end of the wellbore.

14. A method of deploying a fabric liner in a wellbore, the method comprising:

fixing a free-to-fall sub to a downhole end of the fabric liner, the free-to-fall sub comprising: a weighted compartment that is filled with a first fluid that increases a weight of the free-to-fall sub; and at least one stabilizing wheel configured to centralize the free-to-fall sub within the wellbore;

fixing the fabric liner to a surface end of the wellbore;

deploying the free-to-fall sub within the wellbore until the free-to-fall sub reaches a bottom surface of the wellbore;

running, in-hole, a casing string and a modified shoe track into the fabric liner, the modified shoe track comprising a plurality of orifices configured to release a second fluid into the fabric liner; and

retaining, by the fabric liner, the second fluid between the casing string and the wellbore.

15. The method of claim 14, further comprising: sealing, by a first plug, a downhole end of the modified shoe track such that pressure develops within the modified shoe track.

16. The method of claim 14, further comprising: sealing, by a second plug, a surface end of the modified shoe track once the fabric liner has been filled with fluid.

17. The method of claim 14, wherein deploying the free-to-fall sub within the wellbore further comprises unrolling the fabric liner from a roller disposed at the surface end of the wellbore.

18. The method of claim 17, further comprising: detaching the fabric liner from the roller once the free-to-fall sub is deployed within the wellbore.

19. The method of claim 14, wherein running the casing string and the modified shoe track in hole comprises inserting the casing string and the modified shoe track into the fabric liner such that the fabric liner is configured to receive the casing string and the modified shoe track when the fabric liner is deployed in the wellbore.

20. The method of claim 14, further comprising drilling through the free-to-fall sub and the modified shoe track once the second fluid has hardened.