Enhanced Cooling During Washover Operation

The disclosure generally relates to downhole tools for use in a wellbore formed in one or more subsurface formations, and in particular, to downhole tools used during equipment retrieval operations.

A washover operation may be a type of milling operation used during well workovers and intervention. Washovers may be performed across a variety of wells including oil and gas wells, geothermal wells, carbon sequestration wells (for use in carbon capture, utilization, and storage (CCUS) operations), high-temperature high-pressure (HTHP) wells, etc. Traditional washover operations may be limited in their ability to cool the cutting structure and elements being cut. A wash pipe may be placed in the well to free stuck equipment. The wash pipe may slip over the stuck pipe, and drilling mud may traditionally be pumped through it to flush out any debris in the annulus between the pipe and the wellbore. The wash pipe internal diameter (ID) may need to be large enough to engulf the downhole equipment, and the wash pipe outer diameter (OD) may need to be large enough to centralize in the casing/tubing to prevent offset cutting. The annular clearance between the wash pipe and the casing ID may be small, especially in minimum casing ID or in API special clearance casing applications. This clearance may be a factor of the downhole tool function, including but not limited to, reduction in extrusion gap, higher pressure ratings of tool and parent casing section, etc.

A bottom burn shoe may be attached to the end (bottom) of the washover pipe or washover assembly. The bottom burn shoe may be comprised of a portion of pipe including one or more sharp cutting edges or milling teeth designed to remove debris, scale, or other obstructions within the wellbore. Rotational force is applied to the washover pipe, causing the bottom burn shoe to cut through the obstruction. The bottom burn shoe may be built by layering crushed carbide or like hard material to form a matrix and brazed onto the pipe. The burn shoe OD normally needs to be big enough to mill through any external elements including but not limited to packers or like elastomer elements and any metallic components. If the burn shoe OD is too small, it may allow offset cuts (laying lowside) which may leave eccentric uneven segments of components high side downhole, requiring a separate retrieval method.

The annular clearance between the wash pipe OD and casing ID is very small. A successful washover operation may create debris small enough to pass across cutters and through the annular space. Debris that is too large may clog cutters and pack off the annular space, restricting flow back to surface. Restricting the flow path may cause temperature to increase rapidly. Increased temperature may negatively affect the bond within the cutting matrix as well as the components being milled through. A weakened bond may also cause the cutting structure to separate, leaving a bare pipe downhole without means of cutting.

Traditional bottom burn shoes have failed to mill through packer elements and support shoes (Whipstock Isolation System, WIS) due to carbide cutter wear, erosion, and failure from increased temperatures during milling. Current washover operations may need to mill through these materials.

The description that follows includes example systems, methods, techniques, and program flows that embody implementations of the disclosure. However, it is understood that this disclosure may be practiced without these specific details. In other instances, well-known instruction instances, protocols, structures, and techniques have not been shown in detail in order not to obfuscate the description.

Enhancing the design of the wash pipe and burn shoe by providing a larger effective flow path for debris to go may allow for longer milling operations, further axial milling distance, and increased reusability. Traditional wash pipe and burn shoe designs may have trouble milling through a whipstock isolation system's element package and retrieving the whipstock assembly back in a single run. This problem may be resolved by the below enhancements that increase fluid flow during milling to lower the temperatures experienced by the burn shoe cutters downhole. Lower operating temperatures may extend the life of the carbide cutters on the burn shoe.

Example implementations may adjust the burn shoe slot geometry such that the slots are wider by use of at least one angled side. Example implementations may adjust the burn shoe slot geometry such that the cutting lead angle is not flat for better initiating of cutting, similar to a milling bit. Example implementations may adjust the burn shoe slot geometry such that the slots channel towards at least one bypass flow area of any width and depth. Example implementations may introduce at least one bypass flow area per cutter slot on the OD of the wash pipe that may or may not intersect another bypass flow area. Example implementations may include a bypass flow path geometry which may project at any angle away from the bottom of the burn shoe. The bypass flow path geometry may become helical and convert to a straight path or vice versa. Some implementations of the bypass flow path could be constant across the length of the wash pipe. Example implementations may also include cutter slots and bypass flow areas configured to deliver cuttings, debris and cooling fluids from the burn shoe during a washover operation into the annular space. This may reduce the risk of packing off. Packing off the wellbore may increase the local temperature where milling takes place. Excessive heat at the cutting structure may weaken the brazing bond of the burn shoe and lead to tool failure. By keeping the debris and fluids moving, the cutting structure should last longer. Longer-lasting tools such as those described herein may be applicable for operations in deep extended-reach wells, geothermal wells, CCUS wells, high temperature wells, etc. Example implementations may also reduce the overall time for washover operations and may increase the opportunity of successful operations using current and future systems. Example implementations may also reduce the milling system's total cost of ownership (TCO) and reduce operational costs due to performing faster washovers.

Example tools and systems to be milled during a washover operation are now described.is a longitudinal sectiondiagram depicting example washover materials at a whipstock tip section, according to some implementations. A burn shoeof a wash pipe may be required to mill through various materials within one or more wellbores (including multilateral wellbores) within a subsurface formation. For example, the burn shoemay be configured to mill through a centralizer, whipstock tip bottom materials, a transition joint, and cement surrounding the transition jointas part of a washover operation. The burn shoeand wash pipe may engulf the whipstockafter milling the above materials for retrieval of the whipstock. The transition jointmay be used during drilling and the creation of a lateral borebranching from a main bore. The burn shoeand wash pipe coupled therewith may include a larger ID in order to engulf the whipstockbut a smaller OD than an ID of the casing.

is an illustrationdepicting washover materials on an example whipstock, according to some implementations. Similar to, a milling tool including a wash pipe and burn shoe may be used to mill outer elements (sealing elements, packer elements, centralizer, etc.) during a washover operation of a tool string in a wellbore. For example, the burn shoe may be used to mill through a plurality of centralizerspositioned along an OD of a whipstock assembly. The milling tool may also be used to mill through a cement sealand various support shoes and packer elementsin order to retrieve the whipstock assemblyfrom a wellbore. In some implementations, the support shoes and packer elementsmay include elastomeric components, rubber components, etc. Rotation may be applied to the wash pipe and burn shoe to mill out the support shoes and packer elements, centralizers, cement seal, etc.

is a diagramdepicting an example bottom burn shoe with a first cutter profile, according to some implementations. A bottom burn shoemay be positioned at an end of a wash pipe of a milling tool. The bottom burn shoe (also referred to as the “burn shoe”) may include a plurality of cutters. The bottom burn shoemay include at least four cutter slotshaving a cutter slot profile. The cutter slotsmay separate the cutters and/or cutting structures used for milling. As shown, each cutter slot may include an axial sideand an angled side. The axial sidemay be straight or substantially oriented (parallel) with the longitudinal axis of the bottom burn shoe. For example, the axial sidemay include some lead angle to initiate cutting better (i.e., less than or equal to 15°). Therefore, “substantially oriented” may be defined as having a lead angle of less than or equal to 15° from the longitudinal axis of the bottom burn shoe. The angled sidemay include a taper angle between 0° and 90° which channels into a bypass area. The bypass areamay be a shallower OD area of the bottom burn shoe. The axial sideand angled sidemay form a V-shaped cutter slot profile, as shown in.

is a diagramdepicting an example bottom burn shoe with a second cutter profile, according to some implementations. A bottom burn shoemay include a plurality of cutters. Each pair of cuttersmay include a cutter slotdisposed between them having a cutter slot profile. In, the cutter slotmay include a cutter slot profile having a first sideand a second side. In some implementations, the first sideand second sidemay include a lead angle on both sides or may both include straight sides which are substantially oriented with the longitudinal axis of the bottom burn shoe. In other implementations, each side may include a taper angle between 1° and 90° (straight). Regardless of lead angle for cutting or the taper angle used, each cutter slotmay channel into a bypass area. The bypass areamay utilize various geometries. For example, straight, grooved, and helical bypass areas may be used. In some implementations, the straight cut or grooved bypass areas may be a lower cost option when compared to helical bypass areas. Other geometries of the bypass area(s)may also be possible. The first sideand second sidemay form a U-shaped cutter slot profile, as shown in.

is a diagramdepicting an example bottom burn shoe with a third cutter profile, according to some implementations. A bottom burn shoemay include a plurality of cutters. Each pair of cuttersmay include a cutter slotdisposed between them having a cutter slot profile. In, the cutter slotmay include a cutter slot profile having a first sideand a second side. In some implementations, the first sideand second sidemay include cutter slot profiles with side similar to the sides-and-of, respectively. Similar to, each cutter slotmay channel into a bypass area.

Each bypass areamay be comprised of any width and/or depth. Each bypass areamay project axially down the length of the wash pipe. Each bypass areamay take on an angled path that may or may not intersect with another bypass area. For example, each bypass areamay be helical and never intersect a second bypass area. In some implementations, each bypass areamay be straight and never intersect a second bypass area along the length of the wash pipe. Each bypass areamay follow a different path down the wash pipe and include at least one path geometry.

The cutter slots,, andmay include various side geometries, widths, and lead angles. The cutter slots,, andmay also include various cutting angles for each individual cutter. The cutting angle may refer to the angle at which each cutter contacts a cutting material, whereas the lead angle may refer to the angle(s) of each side of the cutter slot, forming the cutter slot profile. Some implementations of the cutter slots,, andmay be angled in a direction of rotation of the burn shoe to increase fluid flow around the burn shoe during milling. The cutter slots,, andmay be of any suitable size, width, taper, depth, etc. to optimize fluid flow around the annular space between the burn shoe and casing during milling. Additional or fewer cutter slots may be used on each burn shoe, and other geometries and/or configurations may also be possible. Each of the bypass areas,, andmay also be of any suitable size, width, taper, depth, etc. to optimize fluid flow around the annular space between the burn shoe and casing during milling. Other bypass area geometries and configurations may also be possible.

Each of the bypass areas may lead into one or more bypass flutes along a length of the burn shoe, as shown in. In some implementations, the bypass flutes may allow more flow area in the annular space between the wash pipe OD and the casing ID for better debris management and effective cooling during the washover operation. Annular clearance between the burn shoe/wash pipe OD and casing ID may be minimal, as the burn shoe/wash pipe may need to be large enough to engulf a tool downhole and mill through its supporting structures without damaging the tool and without damaging the casing. Therefore, the increased bypass area offered by the bypass flutes, both individually and in a merged configuration (i.e., two or more bypass flutes merge to create a larger bypass area) may assist in both temperature control and material removal during washover operations.

The bypass flutes may increase the total bypass area along the length of the burn shoe. In some implementations, the bypass flutes may extend along at least a portion of the wash pipe coupled with the burn shoe. The bypass flutes may use crushed cutting material to build up a cutting OD along an exterior of the burn shoe. Larger chunks of milled material may or may not be crushed into smaller pieces (e.g., crushed between the burn shoe and casing via rotation of the milling tool) as they travel along the bypass flutes in the annular space between the burn shoe/wash pipe and the casing. In some implementations, one or more of the bypass flutes may intersect and combine into a larger annular flow area. Some materials may be hard to break down during washover operations (such as rubber). The larger annular flow area may allow the extra annular space for these larger materials to move without plugging the annulus between the burn shoe and casing.

is a diagramdepicting an example burn shoe including helical bypass flutes, according to some implementations. The diagramincludes a burn shoehaving a plurality of cutters, each pair of cutters having a cutter slot disposed in between. The burn shoealso includes helical bypass flutes. As shown, the helical bypass flutesare configured with a right-hand helix orientation for clockwise milling (from the perspective of the wash pipe). However, helical bypass flutes may also be configured with a left-hand configuration for counterclockwise milling. Other configurations may be possible. For example, a right-handed helix and left-handed helix may be used on the same burn shoe. Right-hand or left-hand helical bypass flutes may be selected regardless of a direction of milling. The helical bypass flutesmay induce fluid and/or particulate flow through and along the annular space of the burn shoeduring a washover or milling operation.

is a diagramdepicting an example burn shoe including straight bypass flutes, according to some implementations. The diagramincludes a burn shoewhich may be coupled to a wash pipe for washover operations. The burn shoemay include a plurality of cutters, each pair of cutters having a cutter slot disposed in between. The burn shoeincludes straight bypass flutes. The straight bypass flutesmay allow for an increased bypass area between the burn shoeand an interior surface of one or more casing joints in a wellbore.

is a diagramdepicting an example burn shoe crushing cutting material along a helical band, according to some implementations. Similar to, the diagramincludes a bottom burn shoehaving a plurality of cuttersand helical bypass flutes. A helix bandmay include an area having an OD consistent with a top burn shoecoupled with the wash pipe. Cuttings material during milling may be crushed between the OD of the helix bandand a casing joint cemented downhole. At least a portion of the cutting material may also travel along the bypass fluteswith a wellbore fluid during milling.

is a flowchart depicting an example method of operations, according to some implementations. Operations of a methodmay be performed in part by software, firmware, hardware, or a combination thereof. Such operations are described with reference to. However, such operations may be performed by other systems or components. The operations of the methodbegin at block.

At block, the methodincludes cutting, via rotation of a first tubular, one or more support structures of a device positioned in at least one wellbore formed in one or more subsurface formations. For example, a first tubular such as the burn shoemay be used during an equipment retrieval operation of a whipstockin a well. The burn shoemay be used to mill through one or more support structures of the whipstock, such as the centralizer, whipstock tip bottom materials, cement seal, support shoes and packer elements, etc. The burn shoemay also be used to mill through cement surrounding the whipstockand transition joint. The whipstockmay be fished from the well after the cutting is complete.

The first tubular may include a number of radial cutters disposed circumferentially along one end, and wherein a cutter slot is formed between each pair of radial cutters. For example, the burn shoemay include a number of cutters. Each pair of cutters may form a cutter slothaving a cutter slot profile formed by the first sideand second side. Flow progresses to block.

At block, the methodincludes cooling, via fluid flow through one or more bypass channels disposed along an outer diameter of the first tubular, the first tubular during the cutting. For example, each cutter slot may lead into a bypass flute. As the burn shoeis rotated during milling, fluid flow may be induced through each of the cutter slots and along each bypass flute. The fluid and cuttings material from the milling operation may flow between an annular space created by the bypass flutesand a casing ID. As shown in, the helical bypass flutes may induce fluid flow when the burn shoeis milling in a clockwise direction. This fluid flow may cool the cuttersand burn shoe.

Various properties may be adjusted or altered to optimize milling operations using the above-described burn shoe(s). For example, one or more bypass flutes may merge to form a larger annular flow area for increased fluid and cuttings flow. A cutter slot profile of each cutter slot may be adjusted to improve fluid channeling into bypass areas and into the bypass flutes. For example, the lead angle of each side of the cutter slots, the cutting angle of each angle of the cutter slots, the depth of each cutter slot, a quantity of cutter slots on the burn shoe, the width of each cutter clot, taper of each cutter slot, etc. may be adjusted. Flow of the methodceases.

Various modifications to the implementations described in this disclosure may be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other implementations without departing from the spirit or scope of this disclosure. Thus, the claims are not intended to be limited to the implementations shown herein but are to be accorded the widest scope consistent with this disclosure, the principles and the novel features disclosed herein.

Certain features that are described in this specification in the context of separate implementations also may be implemented in combination in a single implementation. Conversely, various features that are described in the context of a single implementation also may be implemented in multiple implementations separately or in any suitable sub-combination. Moreover, although features may be described as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination may in some cases be excised from the combination, and the claimed combination may be directed to a sub-combination or variation of a sub-combination.

While operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. Further, the drawings may schematically depict one more example process in the form of a flow diagram. However, some operations may be omitted and/or other operations that are not depicted may be incorporated in the example processes that are schematically illustrated. For example, one or more additional operations may be performed before, after, simultaneously, or between any of the illustrated operations. Additionally, other implementations are within the scope of the following claims. In some cases, the actions recited in the claims may be performed in a different order and still achieve desirable results.

Unless otherwise specified, use of the terms “up,” “upper,” “upward,” “uphole,” “upstream,” or other like terms shall be construed as generally away from the bottom, terminal end of a well; likewise, use of the terms “down,” “lower,” “downward,” “downhole,” or other like terms shall be construed as generally toward the bottom, terminal end of the well, regardless of the wellbore orientation. Use of any one or more of the foregoing terms shall not be construed as denoting positions along a perfectly vertical axis. In some instances, a part near the end of the well can be horizontal or even slightly directed upwards. Unless otherwise specified, use of the terms “subsurface formation” or “subterranean formation” shall be construed as encompassing both areas below exposed earth and areas below earth covered by water such as ocean or fresh water.

Use of the phrase “at least one of” preceding a list with the conjunction “and” should not be treated as an exclusive list and should not be construed as a list of categories with one item from each category, unless specifically stated otherwise. A clause that recites “at least one of A, B, and C” may be infringed with only one of the listed items, multiple of the listed items, and one or more of the items in the list and another item not listed. As used herein, a phrase referring to “at least one of” a list of items refers to any combination of those items, including single members. As an example, “at least one of: a, b, or c” is intended to cover: a, b, c, a-b, a-c, b-c, and a-b-c.

As used herein, the term “or” is inclusive unless otherwise explicitly noted. Thus, the phrase “at least one of A, B, or C” is satisfied by any element from the set {A, B, C} or any combination thereof, including multiples of any element.

Implementation #1: An apparatus comprising: a first tubular having a number of radial cutters disposed circumferentially along one end, wherein a cutter slot is formed between each pair of radial cutters; and a plurality of bypass channels disposed along an outer diameter of the first tubular, wherein each cutter slot leads into a bypass channel.

Implementation #2: The apparatus of Implementation 1, wherein each bypass channel of the plurality of bypass channels includes a smaller outer diameter than the outer diameter of the first tubular, and wherein the plurality of bypass channels allow at least one of a first wellbore fluid and cuttings material to flow around the first tubular.

Implementation #3: The apparatus of any one or more of Implementations 1-2, wherein at least a portion of the bypass channels merge into a larger flow area around the first tubular.

Implementation #4: The apparatus of any one or more of Implementations 1-3, wherein each bypass channel is a helical bypass channel.

Implementation #5: The apparatus of any one or more of Implementations 1-4, wherein each bypass channel is a straight bypass channel.

Implementation #6: The apparatus of any one or more of Implementations 1-5, wherein each cutter slot includes a first side and a second side, and wherein at least one of the first side and the second side are substantially oriented with a longitudinal axis of the first tubular.

Implementation #7: The apparatus of any one or more of Implementations 1-6, wherein at least one of the first side and the second side of each cutter slot are oriented at a lead angle.

Implementation #8: A system comprising: a casing string cemented within at least one wellbore formed in one or more subsurface formations; a wash pipe coupled to a first tubular, wherein the first tubular includes, a number of radial cutters disposed circumferentially along one end, wherein a cutter slot is formed between each pair of radial cutters; and a plurality of bypass channels disposed along an outer diameter of the first tubular, wherein each cutter slot leads into a bypass channel.

Implementation #9: The system of Implementation 8, wherein each bypass channel of the plurality of bypass channels includes a smaller outer diameter than the outer diameter of the first tubular, and wherein the plurality of bypass channels allow at least one of a first wellbore fluid and cuttings material to flow within an annulus between the casing string and the first tubular.

Implementation #10: The system of any one or more of Implementations 8-9, wherein at least a portion of the bypass channels merge into a larger flow area around the first tubular.

Implementation #11: The system of any one or more of Implementations 8-10, wherein each bypass channel is a helical bypass channel.

Implementation #12: The system of any one or more of Implementations 8-11, wherein each bypass channel is a straight bypass channel.

Implementation #13: The system of any one or more of Implementations 8-12, wherein each cutter slot includes a first side and a second side, and wherein at least one of the first side and the second side are substantially oriented with a longitudinal axis of the first tubular.

Implementation #14: The system of any one or more of Implementations 8-13, wherein at least one of the first side and the second side of each cutter slot are oriented at a lead angle.

Implementation #15: A method comprising: performing an equipment retrieval operation of a device in at least one wellbore formed in one or more subsurface formations, the equipment retrieval operation including, cutting, via rotation of a first tubular, one or more support structures of the device, wherein the first tubular includes a number of radial cutters disposed circumferentially along one end, and wherein a cutter slot is formed between each pair of radial cutters; and cooling, via fluid flow through one or more bypass channels disposed along an outer diameter of the first tubular, the first tubular during the cutting.

Implementation #16: The method of Implementation 15, further comprising: altering a quantity of cutter slots disposed on the first tubular; altering a depth of each cutter slot; and altering a width of each cutter slot, wherein each cutter slot feeds into a bypass channel of the one or more bypass channels.

Implementation #17: The method of any one or more of Implementations 15-16, further comprising: determining a geometry of the one or more bypass channels, wherein at least a portion of the bypass channels include helical bypass channels and wherein at least a portion of the bypass channels include straight bypass channels; and moving, via the rotation of the first tubular, at least a wellbore fluid and cuttings material through the one or more bypass channels, wherein each bypass channel of the one or more bypass channels includes a smaller outer diameter than the outer diameter of the first tubular.

Implementation #18: The method of any one or more of Implementations 15-17, wherein moving, via the rotation of the first tubular, at least the wellbore fluid and cuttings material through the one or more bypass channels includes moving at least the wellbore fluid and cuttings material through a larger annular flow area formed by merging two or more of the bypass channels around the first tubular.

Implementation #19: The method of any one or more of Implementations 15-18, further comprising: determining a cutter slot profile of at least one of a first side and a second side of each cutter slot, wherein at least a portion of the cutter slots include a side substantially oriented with a longitudinal axis of the first tubular, and wherein at least a portion of the cutter slots include a side oriented at a lead angle.