Patent Application
20250027371
Section milling over a given length of a well casing is essential in plug and abandonment operations, which may require the removal of casing in order to isolate the wellbore with cement. Casings, which are generally composed of steel, generally damage or dull conventional milling tools due to excessive friction. As a result, milling equipment requires frequent replacement in order to complete casing removal. Further, conventional milling tools typically have a low rate of penetration, which results in a costly milling process.
This summary is provided to introduce a selection of concepts that are further described below in the detailed description. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter.
In one aspect, embodiments disclosed herein relate to hybrid-milling tools that include a milling rotary body, which may be connected to a toolstring at a first end of the milling rotary body (e.g., via a threaded connection). One or more milling knives may extend outwardly from the milling rotary body at a second end of the milling rotary body, opposite the first end. A laser head may extend axially from the second end of the milling rotary body, wherein the laser head is configured to rotate about a central axis of the milling rotary body. A fiber optic cable may extend through the milling rotary body, wherein the fiber optic cable is connected to the laser head.
In another aspect, embodiments disclosed herein relate to methods for cutting through a casing wall in a well using hybrid-milling tools according to embodiments disclosed herein. Such methods may include lowering the hybrid-milling tool on a toolstring to a target section of a casing wall in a wellbore of a well, generating a laser beam from a laser power generator, directing the laser beam from the laser power generator, through a fiber optic cable, to the laser head of the hybrid-milling tool, and emitting the laser beam from the laser head at a first laser power. The laser head may be rotated about a central axis of the hybrid-milling tool while the laser beam is emitted from the laser head to create a helical groove in the casing wall with the laser beam in the target section. After at least a portion of the helical groove is created in the target section, milling knives on the hybrid-milling tool are used to cut through the target section of the casing wall.
In yet another aspect, embodiments disclosed herein relate to systems that include a toolstring lowered into a wellbore of a well and a hybrid-milling tool secured to a first end of the toolstring. The hybrid-milling tool includes a milling rotary body extending from the toolstring at the first end, one or more milling knives extending outwardly from the milling rotary body at a second end of the milling rotary body, and a laser head extending from the second end of the milling rotary body. A fiber optic cable may extend along the toolstring and through the milling rotary body to the laser head.
Other aspects and advantages of the claimed subject matter will be apparent from the following description and the appended claims.
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 size 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. Further, the particular shapes of the elements as drawn are not necessarily intended to convey any information regarding the actual shape of the particular elements and have been solely selected for ease of recognition in the drawing.
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 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.
It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a fracture” includes reference to one or more of such fractures.
In the following description of
In one aspect, embodiments disclosed herein relate to a hybrid-milling tool comprising one or more milling knives and a laser head. More specifically, the hybrid-milling tool may be configured to create a helical groove in a casing wall using a laser beam emitted from the laser head, weakening the integrity of the casing wall. The one or more milling knives may then be used to cut through the weakened casing wall. In another aspect, embodiments disclosed herein relate to a downhole tool, which may include a hybrid-milling tool secured to a toolstring, where the downhole tool may be lowered into a wellbore until it reaches a target section of a casing within the wellbore. In yet another aspect, embodiments disclosed herein relate to operating a downhole tool, which may include a hybrid-milling tool secured to a toolstring, in a target section of a casing within a wellbore.
The well 100 has three strings of casing: conductor casing 114, surface casing 116, and production casing 118. The casing strings are made of a plurality of long high-diameter tubulars threaded together. The tubulars may be made out of any durable material known in the art, such as steel. The casing strings 114, 116, 118 are cemented in place within the well 100. Casing strings may be fully or partially cemented in place without departing from the scope of the disclosure herein.
Each string of casing, starting with the conductor casing 114 and ending with the production casing 118, decreases in both outer diameter and inner diameter such that the surface casing 116 is nested within the conductor casing 114 and the production casing 118 is nested within the surface casing 116. Upon completion of the well 100, the inner circumferential surface 120 of the production casing 118 and the space located within the production casing 118, make up the interior of the well 100.
The majority of the length of the conductor casing 114, surface casing 116, and production casing 118 are located underground. However, the surface-extending portion of each casing string is housed in the casing head 108, also known as a wellhead, located at the surface location 110. The surface-extending portion of each casing string may include a casing hanger (not pictured) that is specially machined to be set and hung within the casing head 108. There may be multiple casing heads 108 depending on the number of casing strings without departing from the scope of the disclosure herein.
During production of the well, production tubing may be deployed within the production casing 118. The production tubing may include a plurality of tubulars connected together and may be interspersed with various pieces of equipment such as artificial lift equipment, packers, etc. When deployed, the majority of the length of the production tubing is located in the interior of the well 100 underground. However, the surface-extending portion of the production tubing is housed in the tubing head 106 which is installed on top of the casing head 108. The surface-extending portion of the production tubing may include a tubing hanger (not pictured) that is specially machined to be set and hung within the tubing head 106. The production tree 102 is connected to the top of the tubing head 106 using the tubing bonnet 104. The tubing bonnet 104 is an adapter comprising one or more seals (not pictured).
In accordance with one or more embodiments, the production casing 118 may comprise a portion made of slotted casing or screen such that production fluids may flow into the production casing 118 from the formation. In other embodiments, the production casing 118 may include perforations made through the production casing 118, cement, and wellbore in order to provide a pathway for production fluids to flow from the production zone of the surrounding formation into the interior of the well 100.
Production fluids may travel from the interior of the well 100 to the surface location 110 through the production tubing. A pipeline (not pictured) may be connected to the production tree 102 to transport the production fluids away from the well 100. The well 100 depicted in
Plug and abandonment operations are typically executed to prepare a well, such as well 100, to be closed permanently. A well 100 may be closed permanently if logs have determined that production operations have drained the reservoir, for example. Plug and abandonment operations may include removing casing from the well 100 in order to isolate the wellbore with cement. Embodiments disclosed herein relate to a downhole milling tool for use in casing removal in preparation for plug and abandonment operations.
In one or more methods according to embodiments of the present disclosure, a section of casing may be removed from a well 100, for example, for plug and abandonment operations or other purpose. In one or more embodiments, the well 100 may be prepared for casing removal by removing any production tubing deployed in the well. A hybrid-milling tool 124 in accordance with one or more embodiments of the present disclosure may then be sent down the well 100 to a downhole location. For example, the hybrid-milling tool 124 may be deployed into the well 100 via a toolstring 126. The hybrid-milling tool 124 may then be rotated and operated using surface equipment to cut the casing (e.g., production casing 118), as described in more detail below.
Turning now to
A fiber optic cable 202 may be coupled to the toolstring and may extend through a milling rotary body 204 from a first end 203 of the milling rotary body 204. For example, a fiber optic cable may be run through (within) a coiled tubing to a connected hybrid-milling tool to deliver a high power laser. The milling rotary body 204 may be coupled to the toolstring, e.g., via a threaded connection.
One or more milling knives 206 may extend circumferentially around the milling rotary body 204 at a second end 205 of the milling rotary body 204. The milling knives 206 may extend radially outward from the milling rotary body 204 a distance capable of contacting the casing 201, such that as the milling knives rotate with the milling rotary body 204 about a central axis 212, the milling knives may contact and cut around the inner surface of the casing 201 wall. In some embodiments, the milling knives may extend radially outward from the milling rotary body in a linear or helical pattern along a length of the milling rotary body. In some embodiments, the milling knives may have an abrasive outer cutting surface.
A laser head 208 may extend from the second end of the milling rotary body 204, opposite the connection end to the toolstring. The laser head 208 may be configured to rotate about the central axis 212 of the milling rotary body 204.
In one or more embodiments, the laser head 208 may be configured to emit a laser beam 210 in a direction outwardly from the tool's central axis 212, directed towards the casing 201 wall. For example, as shown in
In one or more embodiments, the hybrid-milling tool 200 may be lowered into the wellbore 207 until a target section 214 of the casing 201 is reached. The target section 214 may refer to a section of casing 201 which is to be removed, e.g., for appropriate plug and abandonment operations.
Turning now to
The laser power generator 304 can be controlled at the surface to direct a laser through a fiber optic cable 202 to the laser head 208 of the hybrid-milling tool 200. The power of the laser power generator 304 may be altered to change the intensity of the emitted laser beam according to the needs of the job, e.g., casing material and thickness.
Once the laser head 208 has reached the target section 214, the laser beam 210 may be emitted, such that it is directed towards the casing 201 wall. As the laser beam 210 contacts the casing wall, the laser beam 210 may then begin to create a groove 302 in the casing 201 wall. In one or more embodiments, a groove 302 may refer to a partial cut, weakening, or damage of the casing 201. The laser head 208 may be rotated about the central axis 212 of the milling rotary body 204 as the laser beam 210 is emitted from the laser head to create a helical groove 302 in the casing 201 wall in the target section 214 as the hybrid-milling tool 200 continues to lower further into the wellbore 207. In one or more embodiments, the helical groove 302 may weaken the integrity of the casing 201 wall. The one or more milling knives 206, following the laser head 208 as the tool is continued to be lowered through the well, may then be used to cut through the casing 201 wall. The introduction of a helical groove 302 into the casing 201 wall prior to cutting with the one or more milling knives 206 may ease the milling process and increase the rate of penetration.
Initially, a hybrid-milling tool 200 may be provided on a toolstring in a wellbore 207 of a well 100, S402. The hybrid-milling tool 200 may include a fiber optic cable 202, a milling rotary body 204, one or more milling knives 206 and a laser head 208. The hybrid-milling tool 200 may be lowered to a target section 214 of the casing 201 wall disposed within the wellbore 207, S404.
A laser beam 210 may be generated from a laser power generator 304, S406. Further, the laser beam 210 may be directed from the laser power generator 304 to the laser head 208 through the fiber optic cable 202, S408. The laser beam 210 may then be emitted from the laser head 208 at the first power, S410. the laser beam 210 may be directed towards the casing 201 wall. In one or more embodiments, a thickness of the casing 201 wall may be determined, and the first laser power may be selected based, at least in part, on the thickness of the casing 201 wall. In some embodiments, the thickness of the casing 201 wall and supporting cement, if any, may change. In such embodiments, the change in thickness may be detected and a second laser power may be selected based, at least in part, on the change in thickness. The laser beam 210 may then be generated by the laser power generator 304 at a second power.
The laser head 208 may be rotated about a central axis 212 of the milling rotary body 204, S412. For example, the laser head may be rotated with the entire hybrid-milling tool from surface tools (e.g., using a rotary table at the surface to rotate the toolstring on which the hybrid-milling tool is connected). In other embodiments, a laser head may be rotated electrically downhole. As the laser head 208 rotates, the laser beam 210 may create a helical groove 302 in the casing 201 wall in the target section 214, S414. The helical groove 302, in accordance with one or more embodiments, may extend in length as the hybrid-milling tool 200 is lowered further down the wellbore 207. In one or more embodiments, the helical groove 302 may weaken the integrity of the target section 214 of the casing 201 wall. The one or more milling knives 206 may then cut through the casing 201 wall, S416.
Embodiments of the present disclosure may provide at least one of the following advantages. Milling of steel casings or tubulars generally creates an excess of friction, which may lead to dulling of milling tools. As such, conventional milling procedures typically result in lower rates of penetrations and a shorter lifetime of milling tools. Embodiments of the present disclosure relate to a hybrid-milling tool which combines a laser beam and one or more milling knives to first weaken the integrity of a casing prior to cutting the casing. By weakening the casing prior to attempting to cut the casing, embodiments of the present disclosure ease the milling process, increase the rate of penetration, and extend the lifetime of milling tools.
Although only a few example embodiments 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. Although multiple dependent claims are not introduced, it would be apparent to one of ordinary skill that the subject matter of the dependent claims of one or more embodiments may be combined with other dependent claims.
