Sacrificial Tool for Plugging and Abandoning a Wellbore and Methods Thereof

The present disclosure relates generally to tools used in oil and gas wells. More particularly, the present disclosure relates to downhole tools that may be run into a wellbore and used to help assist in wellbore isolation, and systems and methods pertaining to the same. Still, more particularly, the present disclosure relates to a sacrificial tool and method for isolating subterranean reservoirs.

When a well reaches the end of its lifetime, it is often permanently plugged and abandoned (P&A) by placing one or more cement plugs in the wellbore to isolate undesired reservoirs or production zones. To help form the cement plug, a bridge plug is typically set within the wellbore downhole from the undesired reservoir or production zone, and a cement slurry is then pumped downhole and discharged on top of the bridge plug. The cement slurry is pumped until a column of cement or “cement plug” is formed within the wellbore and extends across and otherwise surpasses the undesired reservoirs or production zones.

In the event a downhole tool is stuck within the wellbore, however, forming a cement plug in the wellbore may be difficult, if not possible. In some cases, for instance, a bottom hole assembly (BHA) may be stuck within the wellbore and extend across multiple undesired reservoirs or production zones that need to be plugged. In such cases, attempts to free the stuck BHA may not be possible, and the alternative option might be to sidetrack the wellbore. Prior to drilling the sidetrack wellbore, the conveyance connected to the BHA (e.g., drill pipe) is first cut and cement is then pumped to plug the wellbore with the BHA in place. However, attempting to pump cement across multiple reservoirs with the BHA in place, and utilizing conventional balanced cement plug methods, may not be possible since the BHA will largely prevent accessibility. Moreover, squeezing cement across the undesired reservoirs or production zones to be plugged may not achieve the required isolation since the cement would likely be squeezed into the highest permeable zone.

Various details of the present disclosure are hereinafter summarized to provide a basic understanding. This summary is not an extensive overview of the disclosure and is neither intended to identify certain elements of the disclosure, nor to delineate the scope thereof. Rather, the primary purpose of this summary is to present some concepts of the disclosure in a simplified form prior to the more detailed description that is presented hereinafter.

According to an embodiment consistent with the present disclosure, a method may include conveying a sacrificial tool into a wellbore on a conveyance, the wellbore penetrating one or more subterranean formations and the sacrificial tool including an overshot fishing tool, a tubing operatively coupled to and extending from the overshot fishing tool, and a liner hanger arranged at an upper end of the tubing. The method may further include receiving an uphole end of a downhole tool within with the overshot fishing tool, wherein the downhole tool is stuck in the wellbore adjacent the one or more subterranean formations, sealingly engaging the uphole end of the downhole tool, and circulating a cement through the sacrificial tool and the downhole tool and discharging the cement into an annulus defined between the downhole tool and an inner wall of the wellbore.

According to another embodiment consistent with the present disclosure, a sacrificial tool for plugging and abandoning a wellbore may include an overshot fishing tool configured to locate and sealingly engage an uphole end of a downhole tool stuck within the wellbore, the wellbore penetrating one or more subterranean formations, a tubing operatively coupled to and extending from the overshot fishing tool, and a liner hanger arranged at an upper end of the tubing. Cement pumped to the sacrificial tool via a conveyance is conveyed to the downhole tool and discharged from the downhole tool into an annulus defined between the downhole tool and an inner wall of the wellbore to isolate the one or more subterranean formations.

Any combinations of the various embodiments and implementations disclosed herein can be used in a further embodiment, consistent with the disclosure. These and other aspects and features can be appreciated from the following description of certain embodiments presented herein in accordance with the disclosure and the accompanying drawings and claims.

Embodiments of the present disclosure will now be described in detail with reference to the accompanying Figures. Like elements in the various figures may be denoted by like reference numerals for consistency. Further, in the following detailed description of embodiments of the present disclosure, numerous specific details are set forth in order to provide a more thorough understanding of the claimed subject matter. However, it will be apparent to one of ordinary skill in the art that the embodiments disclosed herein 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. Additionally, it will be apparent to one of ordinary skill in the art that the scale of the elements presented in the accompanying Figures may vary without departing from the scope of the present disclosure.

Embodiments in accordance with the present disclosure generally relate to a sacrificial downhole tools that may be run into a wellbore to help assist in wellbore plug and abandonment operations. As disclosed herein, proper and required cement isolation of undesired subterranean formations can be achieved through the use of a sacrificial tool that includes an overshot fishing tool used to engage and establish circulation through a stuck downhole tool that may be arranged adjacent the undesired subterranean formations. Once circulation through the stuck downhole toolis established, a liner hanger included in the sacrificial tool can be set and cement can then be pumped down through the downhole tool and displaced into the surrounding annulus. The overshot fishing tool and the stuck downhole toolare left within the wellbore as the cement cures to achieve proper reservoir isolation

depicts a schematic view of an example well systemthat may incorporate the principles of the present disclosure. As illustrated, the well systemincludes a wellboredrilled into the Earth's surface and penetrating one or more subterranean formations, shown as a first formation, a second formation, and a third formation. The formations-may be hydrocarbon-bearing formations, but could alternatively be water-bearing formations. While three formations-are shown in, more or less than three formations-may be present in the well system.

As the wellboreis drilled, portions of the wellboremay be progressively lined with strings of casing or wellbore liner. More specifically, a first string of casing, alternately referred to as “surface casing,” may extend from the well surface. One or more strings of intermediate casing(one shown) may be concentrically arranged within the first string of casingand extend from the well surface and past the distal end of the first string of casing. A last string of casingmay extend from the well surface and past the string(s) of intermediate casing. Each string of casing-may be cemented in place and help prevent collapse of the wellboreand the influx of subterranean fluids except from predetermined wellbore locations.

The well systemmay further include a linersecured to and extending from the last string of casing. The linermay be secured to the casingusing a liner hanger, which include slips and one or more wellbore isolation devices or “packers”. Similar to the strings of casing-, the linermay be cemented in place. An open holesection of the wellboreextends past the linerand penetrates the formations-

For a variety of reasons, it may be desired to plug and abandon (P&A) the wellboreto ensure that strata, particularly freshwater aquifers, are adequately isolated from formation fluids that may emanate from the subterranean formations-. The P&A process essentially entails depositing a column of cement in the wellborethat spans the formations-and thereby prevents formation fluids from migrating into the wellboreand potentially flowing uphole. Ideally, the wellboreis free and unobstructed from any downhole obstructions or tools that may span or otherwise be located adjacent the formations-. In such cases, a cement slurry can be pumped downhole and progressively deposited in the wellboreuntil a column of cement forms and spans the formations-. The solidified cement is sometimes referred to as a “cement plug”.

In some cases, however, a downhole toolmay be stuckin the wellboreadjacent one or more of the formations-, thus making it difficult to properly place (form) the cement plug. The downhole toolmay become stuckin the wellboreas a result of numerous actions or mishaps that occur downhole and have no bearing on the principles of the present disclosure. The downhole toolmay comprise, for example, a bottom hole assembly (BHA) for a drilling operation, or a completion string that spans all or a portion of the formations-, but could alternatively comprise other types of downhole tools, such as heavy weight drill pipe, drill pipe, or any type of downhole tubular potentially caught with an overshot.

The downhole toolmay be connected to or form part of a downhole tubularconfigured to convey the downhole toolinto the wellboreand capable of conveying fluids from the well surface to the downhole tool. The downhole tubularmay form part of a bottom hole assembly (BHA) and may include, but is not limited to, drill pipe and production tubing. Upon determining that the downhole toolis stuckwithin the wellbore, the downhole tubularmay be severed or cut, leaving the downhole tooland a severed portion of the downhole tubularwithin the wellbore. The stuck downhole tooland severed downhole tubularcan be referred to as a “fish”.

According to embodiments of the present disclosure, proper and required cement isolation of the formations-may be achieved through the use of a sacrificial tool that includes an overshot fishing tool used to engage and establish circulation through the stuck downhole tool. Once the overshot fishing tool is properly engaged with the stuck downhole tool, circulation through the stuck downhole toolis established, following which a liner hanger included in the sacrificial tool can be set and cement can then be pumped down through the downhole tooland displaced enough to have the cement extend to at or level with the liner hanger. The overshot fishing tool and the stuck downhole toolare left within the wellbore as the cement cures to achieve proper reservoir isolation.

is another schematic view of the well system, including an example sacrificial toolaccording to one or more embodiments of the present disclosure. As described herein, the sacrificial toolmay be used to undertake a P&A process that isolates the subterranean formations-. As illustrated, the sacrificial toolincludes an overshot fishing tool, a tubingof a predefined length coupled to the overshot fishing tool, and a liner hangerarranged at an upper end of the tubing. In some applications, the combination of the overshot fishing tooland the tubingmay be referred to or otherwise characterized as a sacrificial overshot on tubing.

The sacrificial toolmay be conveyed downhole on a conveyance, such as drill pipe or production tubing. Once the sacrificial toolis conveyed to the proper location to locate and engage the downhole tool, the liner hangermay be actuated to secure the sacrificial toolwithin the wellboreand, more particularly, within the liner. The sacrificial toolmay then be used to perform cement isolation with the downhole toolin place.

The overshot fishing toolmay include a cylindrical housingsized to locate and receive an upper (uphole) end of the downhole tooland, more particularly, the downhole tubular. The housingmay include and otherwise be equipped with one or more sealsfor sealingly engaging the uphole end of the downhole tubularwhen received within the housing. More specifically, upon receiving the uphole end of the downhole tubularwithin the overshot fishing tool, the sealsmay sealingly engage the outer surface of the downhole tubular, thus placing the sacrificial toolin fluid communication with the downhole tool. Consequently, fluids conveyed to and through the tubingto the overshot fishing toolwill be conveyed into the downhole toolvia the downhole tubular.

The sacrificial toolis shown inengaged with the downhole tool. Prior to establishing communication between the sacrificial tooland the downhole tool, however, a fluidmay be conveyed downhole through the conveyanceand circulated through the sacrificial tool. The fluidmay include, but is not limited to, a drilling fluid (e.g., water-based muds, oil-based muds, etc.), a completion fluid, or any combination thereof. The fluidmay be circulated with a predefined (known) pressure to flow through the sacrificial tooland overshot fishing tooldischarged into the wellborevia the end of the overshot fishing toolto be returned to the well surface. As the fluidcirculates, various measurements may be recorded including, but not limited to, a surface pressure (i.e., fluid pressure of the fluidreturning to the well surface), pick up weight, slack off weight, and circulation flow rate. Recording such measurements will provide baseline measurements prior to the sacrificial toolestablishing communication with the downhole tool, which may help confirm successful subsequent engagement. Moreover, circulating through the sacrificial toolmay also ensure that there is no blockage in the sacrificial toolprior to engagement with the downhole tool, and to potentially clean any debris from the uphole end of the downhole tool.

Once fluid communication between the sacrificial tooland the downhole toolis established, the fluidmay continue to be circulated to further establish fluid circulation through the downhole tool. The fluidmay be transmitted to the downhole toolvia the sealed interface between the sacrificial tooland the downhole tool. The fluidmay be discharged from the downhole tooland into the portion of the wellboredownhole from the downhole tool. The fluidmay then be able to circulate back uphole within the annulus defined between the downhole tooland the inner walls of the wellbore.

To confirm proper engagement (coupling) of the sacrificial toolwith the downhole tool, and to further confirm circulation through the downhole tool, the surface pressure, the pick-up weight, the slack off weight, and the circulation flow rate may again be measured. If an increase in the surface pressure and the pick-up weight is observed, and a decrease in the slack off weight is observed, that may provide a positive indication (confirmation) that the sacrificial toolis properly engaged with the downhole tooland, more particularly, that the overshot fishing toolis fluidly coupled to the uphole end of the downhole tubular.

After confirming that the sacrificial toolis properly coupled to the downhole tool, the liner hangermay be activated with the conveyancein tension to secure the sacrificial toolwithin the liner. More particularly, the liner hangermay be conveyed downhole on a running toolcoupled to the distal end of the conveyance. The tubingmay provide and otherwise define a polished bore receptacle, and the distal end of the running toolmay be configured to be releasably coupled to the sacrificial toolat the polished bore receptacle. The running toolmay be configured to connect the conveyance(e.g., tubing, drill pipe, etc.) to the liner hangerand the sacrificial tool. The running toolmay be sized to be received within the polished bore receptacle.

The liner hangermay include one or more sets of slips, and activating the liner hangermay include manipulating the running toolvia the conveyanceto force the slips into gripping engagement with the inner wall of the liner. In some embodiments, the liner hangermay be configured to be set using a hydraulically-actuated system. Thereafter, the pick-up weight and the slack off weight of the conveyancemay again be recorded to establish a new baseline prior to releasing the running tool. If there is a decrease in the pick-up weight and the slack off weight, that may be an indication (confirmation) that the liner hangeris properly set. Accordingly, after hanger slips are set, the pick-up weight should be less than the prior measurement recorded after engagement.

is another schematic view of the well systemshowing progressive operational steps in plugging and abandoning the wellbore, according to one or more embodiments of the present disclosure. After confirming that the liner hangeris properly set, as described above, the running toolmay be released (disengaged) from the sacrificial toolwithout pulling the running toolout of the polished bore receptacleof the tubing.

With the running tooldisengaged from the sacrificial tool, cementmay be pumped downhole via the conveyanceand to the sacrificial tool. The cementmay be conveyed into the downhole toolfrom the sacrificial toolvia the sealed engagement between the overshot fishing tooland the uphole end of the downhole tubular. The cementmay then be discharged from the downhole toolinto the wellboreand, more particularly, into an annulusdefined between the downhole tooland an inner wall of the wellbore. As the cementis continuously pumped into the annulus, a column of the cementmay begin to form and grow within the annulus.

In some embodiments, a wiper plugmay be dropped within the conveyanceand hydraulically displaced along the conveyancewith a fluid(e.g., drilling fluid) pumped from the well surface. As the wiper plugis forced down the conveyance, the cementis progressively discharged out of the downhole tooland into the annulus. In some embodiments, the wiper plugmay be displaced sufficiently down the conveyanceand toward the downhole toolto discharge enough cementto reach the location of the liner hanger. In at least one embodiment, the column of the cementwithin the annulusmay stop level at the liner hanger.

is another schematic view of the well systemshowing progressive operational steps in plugging and abandoning the wellbore, according to one or more embodiments of the present disclosure. After pumping the cementinto the annulus, and optionally pumping until the cementreaches the liner hanger, the running tool() may be pulled out of the polished bore receptacleto reverse out any excessive cementand in preparation for final pull out of hole (POOH). This reversing process of the cementenables proper isolation of the subterranean formations-while having the ability to release the conveyance().

As illustrated in, the cementhas been pumped into the annulusand is allowed to cure with the downhole tooland the sacrificial toolremaining within the wellbore. The resulting column of cementspans the subterranean formations-, which ensures isolation of the formations-, but may also enable sidetracking the wellboreinstead of expending valuable resources and time attempting to recover the downhole toolor accepting to leave the downhole toolin the open holewith improper cement isolation between the formations-. Once isolation is achieved, sidetracking from a shallow depth can commence. Consequently, less time and money may be expended attempting to retrieve the downhole toolin order to properly plug and abandon the wellborebefore sidetrack operation.

is a schematic flowchart of an example methodof isolating one or more undesired subterranean formations, according to the embodiments described herein. As illustrated, the methodmay include conveying a sacrificial tool into a wellbore on a conveyance, at step. The wellbore may penetrate one or more subterranean formations and the sacrificial tool may include an overshot fishing tool, a tubing operatively coupled to and extending from the overshot fishing tool, and a liner hanger arranged at an upper end of the tubing. The methodmay further include locating with the sacrificial tool a downhole tool stuck in the wellbore, as at. In some embodiments, the downhole tool may be stuck in the wellbore adjacent the one or more subterranean formations. Moreover, the sacrificial tool may be operatively coupled to or form part of a severed portion of a downhole tubular.

The methodmay further include receiving and sealingly engaging an uphole end of the severed portion of the downhole tubular with the overshot fishing tool, as at. A cement may then be circulated through the sacrificial tool and the downhole tool, as at, and the cement may be discharged into an annulus defined between the downhole tool and an inner wall of the wellbore, as at. In some embodiments, discharging the cement into the annulus will progressively form a column of cement within the annulus that spans the one or more subterranean formations, and thereby isolates the subterranean formations, as at.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, for example, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “contains”, “containing”, “includes”, “including,” “comprises”, and/or “comprising,” and variations thereof, when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

Terms of orientation are used herein merely for purposes of convention and referencing and are not to be construed as limiting. However, it is recognized these terms could be used with reference to an operator or user. Accordingly, no limitations are implied or to be inferred. In addition, the use of ordinal numbers (e.g., first, second, third, etc.) is for distinction and not counting. For example, the use of “third” does not imply there must be a corresponding “first” or “second.” Also, if used herein, the terms “coupled” or “coupled to” or “connected” or “connected to” or “attached” or “attached to” may indicate establishing either a direct or indirect connection, and is not limited to either unless expressly referenced as such.

While the disclosure has described several exemplary embodiments, it will be understood by those skilled in the art that various changes can be made, and equivalents can be substituted for elements thereof, without departing from the spirit and scope of the invention. In addition, many modifications will be appreciated by those skilled in the art to adapt a particular instrument, situation, or material to embodiments of the disclosure without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed, or to the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims. Moreover, reference in the appended claims to an apparatus or system or a component of an apparatus or system being adapted to, arranged to, capable of, configured to, enabled to, operable to, or operative to perform a particular function encompasses that apparatus, system, or component, whether or not it or that particular function is activated, turned on, or unlocked, as long as that apparatus, system, or component is so adapted, arranged, capable, configured, enabled, operable, or operative.