Downhole chemical storage method for well mitigation and reservoir treatment

Abstract

A method includes providing a well (200) extending from a surface (203) to a subsurface, drilling a main tunnel (210) extending from the well in an outward direction at a first axial location along the well (200) using a radial drilling, installing a chemical storage assembly (220, 320, 450) in the main tunnel, and injecting chemicals from the chemical storage assembly (220, 320, 450) into the well (200).

Description

Background Art

[0001] Wells are drilled into underground formations to produce valuable resources, such as oil and natural gas. Wells are usually drilled by moving a rotating drill bit attached to the end of a drill string through the ground to form a wellbore. The drill string and the attached drill bit can be rotated and extended underground using a drilling rig at the surface of the well. Drilling fluid (also referred to as "drilling mud" or simply "mud") is used to facilitate drilling the wellbore into the ground. As the drill string and drill bit rotate to drill out the wellbore, one or more mud pumps at the surface of the well circulate the drilling fluid through the well, wherein the drilling fluid may flow out of the ground of the well, through the drill string, out of the end of the drill string, and return to the well through an annulus formed around the outside of the drill string to return to the ground of the well. When the wellbore is formed, a string of casing and / or liner can be installed to line the wellbore wall. Casing can be installed in the well by pumping cement into the annular space formed between the casing string and the wellbore wall. Wells may be drilled to extend vertically, horizontally, or in other directions through the ground.

[0002] Radial drilling refers to a method of drilling small tunnels (usually a few inches in diameter) that extend generally radially from the main well into the formation (usually to a maximum of about 300 to 400 feet). Radial drilling is often used to access trapped oil or gas in the formation near the wellbore and to increase production. Radial drilling tools are usually deployed in the main well using coiled tubing, although slickline has also been used. Unlike a drill string, which is made of multiple rigid pipe sections that are threaded together in an end-to-end manner, coiled tubing is a long, continuous length of pipe that is wound on a reel for storage or transportation and then straightened to be pushed into the well.

[0003] Radial drilling may include radial jet drilling, where high pressure fluid is jetted through a radial drilling tool to penetrate and form a tunnel, or mechanical radial drilling, where a radial drill bit (rotated by a downhole mud motor) may be used to drill the tunnel. When radial drilling from a cased hole, radial drilling may include a combination of milling through the casing with a radial drill bit and jetting the tunnel from the milled hole in the casing.

[0004] The radial drilling tools may vary depending on the radial drilling technology used, and may include, for example, downhole mud motors, nozzles and hoses, milling bits, etc. For example, a typical radial drilling system 100 is shown in FIG. 1 , which may be used to drill a tunnel 101 extending radially from a cased main well 102 through a formation 103. A whipstock 104 (also known as a deflector shoe) may be lowered into the main well 102 through a pipe 105. One or more stabilizers 109 may be placed around the pipe 105 to keep the whipstock 104 centered within the pipe 105. A coiled pipe 106 with radial drilling equipment attached at the end may extend through the pipe 105. The radial drilling equipment may include a downhole mud motor 107 and a radial drill bit 108, which may be rotated by the mud motor 107 through a flexible pipe 110. As the mud motor 107 rotates the radial drill bit 108, the radial drill bit 108 may be directed through the whipstock 104 at a turn 111 (“heel”) to contact and penetrate the main well casing into the formation 103 surrounding the main well 102. In a radial jet drilling operation, after the tunnel 101 is launched from the main well 102, the radial drill bit 108 may be removed, and a high pressure nozzle and hose may be extended through the whipstock 104 to spray high pressure fluid to hydraulically impact and extend the tunnel 101 into the formation 103.

[0005] Radial drilling is different from coiled tubing sidetracking procedures and conventional horizontal drilling, which can be used to drill branch wellbores, for example, to drill multilateral wells. A multilateral well is a well with two or more branch wells drilled from a main well, which can allow a well to produce from several reservoirs via the branch wells (rather than drilling multiple separate wells from the ground to different reservoir areas). The main difference between radial drilling and conventional sidetracking or horizontal drilling is that radial drilling is typically operated on a much smaller scale, for example, 2 to 4 orders of magnitude smaller than conventional sidetracking and horizontal drilling. For example, a branch wellbore (sometimes referred to as a lateral wellbore) can be drilled around a heel that is typically hundreds or thousands of feet in length at an angle to the main well. In contrast, radial drilling typically involves a change in direction with a smaller radius of curvature that occurs completely around a whipstock, for example, with a heel ranging from a few inches to a few meters. For example, radial drilling techniques can produce tunnels extending from the main well at an angle of 90 degrees or less. Due to the small radius of curvature of the radially drilled tunnel, longer conventional drilling tools used to drill branch wells will not fit in the radially drilled tunnel. Summary of the invention

[0006] This summary is provided to introduce a selection of some 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.

[0007] In one aspect, embodiments disclosed herein relate to a method comprising providing a well extending from the surface to the subsurface, drilling a main tunnel extending in an outward direction from the well at a first axial position along the well using radial drilling, installing a chemical storage assembly in the main tunnel, and injecting a chemical from the chemical storage assembly into the well.

[0008] In another aspect, embodiments disclosed herein relate to a method that includes providing a well extending from the surface to the ground, drilling a main tunnel extending from the well in an outward direction for a length, and installing a chemical storage assembly in the main tunnel. After installation, a downhole tool can be moved through the well and through the main tunnel to perform well operations. During or after performing the well operations, chemicals can be injected from the chemical storage assembly.

[0009] In still another aspect, embodiments disclosed herein relate to a system comprising a well extending through an underground formation, a main tunnel extending a length outward from the well at a first axial position along the well, a chemical storage assembly installed in the main tunnel, a secondary tunnel extending outward from the well, and a power source installed in the secondary tunnel, wherein the power source is connected to the chemical storage assembly.

[0010] Other aspects and advantages will be apparent from the following description and appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Wherever possible, similar or identical reference numbers are used in the drawings to identify common or identical elements. The drawings are not necessarily drawn to scale and certain features and certain views of the drawings may be shown exaggerated in scale for the sake of clarity.

[0012] FIG. 1 shows an example of a conventional radial drilling technique in a downhole well.

[0013] Figure 2 An example of a chemical storage system in a well according to an embodiment of the present disclosure is shown.

[0014] Figure 3 An example of a chemical storage assembly according to an embodiment of the present disclosure is shown.

[0015] Figure 4 An example of a chemical storage assembly according to an embodiment of the present disclosure is shown.

[0016] Figure 5An example of a chemical storage assembly according to an embodiment of the present disclosure is shown.

[0017] Figure 6 An example of a chemical storage system in a well according to an embodiment of the present disclosure is shown.

[0018] Figure 7 An example of a chemical storage assembly stored in a tunnel extending outward from a well is shown according to an embodiment of the present disclosure.

[0019] Figure 8 An example of a method according to an embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0020] Embodiments of the present disclosure are described in detail below with reference to the accompanying drawings. In the following detailed description, many specific details are set forth in order to provide a more thorough understanding of the claimed subject matter. However, it is apparent to one of ordinary skill in the art that the described embodiments can be implemented without these specific details. In other cases, in order to avoid unnecessarily complicating the description, well-known features are not described in detail.

[0021] Embodiments disclosed herein generally relate to systems and methods for storing chemicals in one or more small tunnels (or ratholes) formed outside a well in a well. Chemicals can be stored in a chemical storage assembly capable of releasing the stored chemicals into the well, such as for well mitigation, well maintenance, damage prevention, reservoir treatment, or other downhole operations utilizing chemical additives. Tunnels for accommodating chemical storage assemblies can be drilled using reservoir tunneling techniques such as radial drilling. By using systems and methods according to embodiments of the present disclosure to store chemicals in tunnels outside a well, well operations can be performed without interference from stored chemicals. For example, conventional downhole completion operations have limited access and small spaces for equipment installation in a well that is producing. According to embodiments of the present disclosure, by providing a chemical storage assembly in a tunnel outside a well, one or more downhole completion operations (which may or may not include the use of chemicals stored in a chemical storage assembly) can be performed in a well without interference from the chemical storage assembly, and without removing production equipment for separate chemical injection operations.

[0022] Figure 2An example of a system according to an embodiment of the present disclosure is shown. As shown, a chemical storage system according to an embodiment of the present disclosure can be provided along a well 200 extending through an underground formation 201. The well 200 can be drilled using conventional drilling techniques and can be cased or uncased. For example, as the drilling fluid circulates through the well, a drill bit attached to the end of the drill string can rotate and move through the formation 201 to drill out the wellbore wall. After drilling the wellbore, a length of the wellbore can be cased or remain uncased, wherein casing includes lowering a casing string into the wellbore and pumping cement between the annular space formed between the wellbore wall and the casing string. However, other drilling and casing / liner techniques known in the art can be used to form the well 200.

[0023] The chemical storage system may include one or more tunnels 215 extending outwardly from the well 200 at various axial and / or circumferential locations around the well 200. Figure 2 In the example shown, the system includes a plurality of tunnels 215 located at various locations around the well 200, including a primary tunnel 210 located at a first axial location along the well 200, an additional primary tunnel 211 located at the first axial location and located at a different circumferential location around the well 200 than the primary tunnel 210, a secondary tunnel 212 located at a second axial location along the well 200, a tertiary tunnel 213 located at a third axial location along the well 200, and a quaternary tunnel 214 located at a fourth axial location along the well 200. The amount and location of the tunnels 215 extending from the well 200 may vary based on, for example, the chemical storage assemblies used and the amount of chemicals stored.

[0024] Tunnel 215 can be formed using tunneling techniques known in the art, such as radial jet drilling or mechanical radial drilling. In some embodiments, radial drilling tools can be deployed using coiled tubing, wherein the radial drilling tool may include a radial drill bit attached to the end of a flexible line. The coiled tubing can be used to guide the radial drilling tool through a whipstock to radially drill a small tunnel extending outward from the well. The coiled tubing can be a large diameter (e.g., 2 inches or more) coiled tubing that typically has high axial and torsional stiffness, or a small diameter (e.g., 5 / 8 inch) coiled tubing with limited axial stiffness and low torque resistance. The coiled tubing can serve as both a recovery line for the radial drilling tool and a power supply line for the radial drilling tool. In some embodiments, sidetracking drilling can be used to form a tunnel, which is a technique conventionally used to drill a new branch wellbore from an existing well with poor or no productivity. When using sidetrack drilling techniques, rather than drilling a new wellbore to increase production through the new wellbore, sidetrack drilling can be used to drill a relatively short distance to a "dead end" where the tunnel formed may be long enough to store the components described herein, but not long enough to reach additional production locations.

[0025] The tunnel 215 drilled from the well 200 may be distinguished from a typical well (e.g., a main well extending from the ground to an underground formation or a branch well extending from the main well to another formation) because the tunnel 215 may be limited in size and location so as not to reach a producing reservoir. In other words, the tunnel 215 may be drilled in a non-producing area outside the well so that fluids do not flow out of the surrounding formation through the tunnel 215 and into the well 200. Additionally or alternatively, the tunnel 215 may be distinguished from a typical well in size, wherein the tunnel 215 may be much smaller than the well 200. For example, the tunnel 215 may have a size that is too small to fit conventional drilling tools.

[0026] According to an embodiment of the present disclosure, tunnel 215 may extend outwardly from well 200 by a length 216 and may have a diameter 217. The length 216 and diameter 217 of tunnel 215 may vary, for example, according to the tunneling technique used to form the tunnel and the components stored in the tunnel. According to an embodiment of the present disclosure, the length 216 of tunnel 215 may be, for example, in the range between 3 feet and 300 feet. In some embodiments, the length 216 of tunnel 215 may be less than 200 feet (e.g., less than 100 feet). The diameter 217 of tunnel 215 may be, for example, in the range between 1 inch and 6 inches. In some embodiments, tunnel 215 may be formed to have a diameter less than 4 inches. In some embodiments, tunnel 215 may be designed to have a smaller diameter than the diameter of well 200 from which it extends. For example, the diameter of well 200 may be in the range of about 9 inches to 3 inches, while tunnel 215 may have a diameter in the range of about 7 inches to less than 1 inch. In some embodiments, the diameter of tunnel 215 extending from a well having a 3-inch diameter casing may be as small as 0.5 inches.

[0027] In addition, tunnel 215 can extend outward from well 200 at an axial angle 218 measured between the wall of well 200 and the wall of tunnel 215 adjacent to the opening of tunnel 215, wherein axial angle 218 may be, for example, in the range of about 45 degrees to about 90 degrees. Axial angle 218 may depend on the tunneling technology. For example, a sidetracked wellbore may have a "dogleg" severity of less than 45 degrees per 100 feet of route length.

[0028] The chemical storage assembly 220 according to an embodiment of the present disclosure may be designed to be assembled in a tunnel 215 drilled from a well 200. According to an embodiment of the present disclosure, the chemical storage assembly 220 may include a chamber (compartment) in which chemicals may be stored and distributed. For example, the chemical storage assembly 220 may include a chemical storage chamber (e.g., a container) for containing chemicals and a dispensing mechanism (e.g., a pump) in fluid communication with the chemical storage chamber, wherein the dispensing mechanism may be used to distribute chemicals from the chamber. In some embodiments, one or more additional chemical storage chambers may be in fluid communication with the dispensing mechanism so that a single dispensing mechanism may dispense chemicals from multiple chemical storage chambers. In some embodiments, the chemical storage chamber may be a pill capsule containing chemicals, wherein the pill capsule may be dissolved under certain downhole environmental conditions to distribute chemicals. Various configurations of chemical storage chambers and dispensing mechanisms that work together to store and distribute chemicals may be used to form a chemical storage assembly 220 assembled in a tunnel 215.

[0029] For example, Figure 2As shown, the chemical storage assembly 220 can be designed as a single tool 222 having a chemical storage chamber and an integrated dispensing mechanism, or as a multi-component assembly including a chemical storage chamber 224 separate from but in fluid communication with a dispensing mechanism 226. Additionally, in some embodiments, the chemical storage assembly 220 can have one or more components (e.g., a pump or controller) powered by a power source 228 (e.g., a battery). Different components of the chemical storage assembly can be installed in different tunnels 215.

[0030] Figures 3 to 5 A small number of examples of chemical storage assemblies 220 that can be used in systems according to embodiments of the present disclosure are shown. However, many other configurations of chemical storage assemblies according to embodiments of the present disclosure can be used. The configuration and amount of chemical storage chambers used in chemical storage assemblies 220 according to embodiments of the present disclosure can be designed or selected, for example, based on the amount of chemicals that need to be stored.

[0031] refer to Figure 3 , the chemical storage assembly 220 may include multiple components stored in separate tunnels 215. For example, the chemical storage assembly 220 may include tools 222 stored in a primary tunnel 211 located at a first axial position along the well 200, additional chemical storage chambers 224 stored in a secondary tunnel 212 located at a second axial position along the well 200, and a power source 228 stored in a tertiary tunnel 213 located at a third axial position along the well 200.

[0032] The tool 222 may have a dispensing mechanism 226 integrated with the chemical storage chamber 225. The dispensing mechanism 226 may be a plunger pump or other type of pump that can apply pressure to the chemical (e.g., a fluid chemical or a chemical provided in a solution) in the chemical storage chamber 225. The pump may be activated to pump the chemical out of the chemical storage chamber 225 through an opening 227 (e.g., a nozzle or a valved opening). The dispensing mechanism 226 may be operated via a controller 229, which may be powered by a power source 228. For example, the dispensing mechanism 226 (such as a pump) may be programmed via the controller 229 to dispense (e.g., pump) a controlled dose of the chemical from the chemical storage chamber 225. In some embodiments, the chemical may be compressed within the chemical storage chamber 225 (e.g., compressed into a compressed fluid), and the dispensing mechanism 226 may be a valved opening that can selectively release a certain amount of the compressed chemical. In such an embodiment, a power source 228 may be used to power the operation of the valved opening. Although a specific example of a tool 222 having an integrated dispensing mechanism 226 and chemical storage chamber 225 is discussed herein, other configurations of the tool 222 are contemplated to provide a device capable of spraying stored chemicals.

[0033] According to an embodiment of the present disclosure, the dispensing mechanism 226 may be powered by a power source 228, which may be disposed in a separate tunnel (e.g., Figure 3 ), or may be integrally provided with tool 222. For example, Figure 3 As shown, a power source 228 (e.g., a rechargeable battery) can be electrically connected to a controller 229 for the dispensing mechanism 226 so that the power source 228 can power the operation of the dispensing mechanism 226. One or more cables 221 can be used to electrically connect the power source 228 and the tool 222. The cable 221 can extend from the power source 228 in one tunnel 213 and extend along the wall 202 of the well to a different tunnel 211 that accommodates the tool 222. Since the size of the tunnel 215 (e.g., formed by mechanical radial drilling) may be limited, providing the power source 228 in a tunnel separate from the tool 222 can allow the use of a larger chemical storage chamber and / or a larger power source. In some embodiments, the power source can be located above the chemical storage assembly, where a power cable can be run through the well to connect the chemical storage assembly to a power source located at the surface of the well.

[0034] Additionally, in some embodiments, one or more additional chemical storage chambers 224 may be fluidly connected to a chemical storage chamber 225 in the tool 222. The additional chemical storage chamber 224 may be useful when a large amount of chemicals needs to be stored and these chemicals cannot fit within a single tunnel (e.g., due to size limitations of tunneling technology). The additional chemical storage chamber(s) 224 may be fluidly connected to the tool 222 via one or more conduits 223. The conduits 223 may extend from the additional chemical storage chamber 224 in one tunnel 212 and extend along the wall 202 of the well to a different tunnel 211 housing the tool 222. In some embodiments, activation of a dispensing mechanism 226 (e.g., a pump) in the tool 222 may draw fluid chemical from the additional chemical storage chamber 224 into the tool 222. However, other mechanisms may be used to direct fluid chemical from the additional chemical storage chamber 224 to the tool 222 for injection into the well.

[0035] Reference now Figure 4 , Figure 4Another example of a chemical storage assembly according to an embodiment of the present disclosure is shown. The chemical storage assembly may include a tool 222 disposed in a main tunnel 211 extending outward from the well 200, and a power source 228 disposed in a separate secondary tunnel 212 extending outward from the well 200. The tool 222 may be a self-contained device that stores chemicals in a chemical storage chamber 225 portion of the tool, wherein an integrated dispensing mechanism 226 may eject chemicals from the chemical storage chamber 225 out of an outlet 227 and into the well 200. The tool 222 may be disposed underground without any additional chemical storage chambers. In such an embodiment, once all or most of the chemicals are ejected from the chemical storage chamber 225 in the tool 222, the tool 222 may be removed from the main tunnel 211 and refilled at the surface of the well 200.

[0036] The tool 222 may be connected to a power source 228 via one or more cables 221 , which may extend from the power source 228 in the secondary tunnel 212 to the tool 222 in the primary tunnel 211 .

[0037] In some embodiments, a non-metallic seal 219 may be installed at the opening of the main tunnel 211 to isolate the main tunnel 211 and its contents from the downhole environment in the well 200. The non-metallic seal 219 may be made of a rubber or polymer material and may have a diameter substantially equal to the diameter of the main tunnel opening. The non-metallic seal 219 may have an opening through which an opening 227 of the tool 222 may extend to inject chemicals stored in the tool 222 into the well 200. In other embodiments, a non-metallic seal may be provided with a dissolvable portion or bursting disc that may dissolve or burst when certain downhole conditions (e.g., downhole pressure, downhole temperature, and / or chemical composition of the fluid flowing through the well) are reached. Different chemicals may be affected by prolonged storage in a downhole pressurized and heated environment in different ways. By isolating the tunnel and its contents from the downhole environment using non-metallic seals 219, the stored chemicals can be protected from degradation or other effects of the downhole environment and / or can be stored for extended periods of time. According to embodiments of the present disclosure, in order to maintain or replace components in the tunnel 211, the non-metallic seals 219 can be removed (or dissolved or blasted).

[0038] refer to Figure 5 , Figure 5Another example of a chemical storage assembly according to an embodiment of the present disclosure is shown. The chemical storage assembly may include a pill capsule 222 containing a chemical 230. The pill capsule 222 may be kept in a main tunnel 211 extending outward from the well 200, and under a trigger condition, the pill capsule 222 may dissolve to release the chemical 230 stored therein. For example, the pill capsule 222 may dissolve under certain downhole environmental conditions (such as pH fluid conditions or downhole temperature conditions in the well 200) to distribute the chemical. In some embodiments, the encapsulated chemical in the pill capsule 222 may be kept in the tunnel 211 using friction. For example, the outer diameter of the pill capsule 222 may be equal to or slightly smaller than the inner diameter of the tunnel 211, so that the friction between the inner diameter of the tunnel 211 and the outer diameter of the pill capsule 222 keeps the pill capsule 222 in the tunnel 211). In some embodiments, the pill capsule 222 may be combined with the design of the same mechanism that keeps the packer inside the wellbore (e.g., having an expandable outer diameter) so as to keep the pill capsule 222 in the tunnel 211. In some embodiments, a separate small packer may be used to retain the pill capsule 222 within the tunnel 211 .

[0039] Examples of chemical storage systems have been shown for use with vertical wells 200, such as Figure 2 As shown, the chemical storage system extends from the ground 203 to a certain depth into the formation 201. However, the chemical storage system disclosed herein can also be used with horizontal wells and other directional wells. In addition, the chemical storage system can be assembled in a main well extending from the ground 203 and opening at the ground 203, or assembled in a branch well extending from the main well and opening to the main well.

[0040] For example, Figure 6An example of a chemical storage system installed in a horizontal portion 305 of a well 300 is shown. The well 300 may be a branch well extending from a main well 302 to a reservoir formation, wherein the main well 302 may extend from the surface 301 through an underground formation 303. A first main tunnel 310 may be drilled outwardly from the horizontal portion 305 of the well 300 at a first axial position along the well 300. A first chemical storage assembly 320 according to an embodiment of the present disclosure may be located in the first main tunnel 310. At least one additional main tunnel 312 may be drilled at a first axial position and extend outwardly from the well 300 in a direction different from the first main tunnel 312. At least one additional chemical storage assembly 322 according to an embodiment of the present disclosure may be located in each of the additional main tunnels 312. When the chemical storage system includes a plurality of chemical storage assemblies 320, 322 assembled in a downhole tunnel, the chemical storage assemblies 320, 322 may be of the same type and configuration, or may be of different types (e.g., different distribution mechanisms) with different configurations (e.g., different numbers of connected additional chemical storage chambers).

[0041] Furthermore, one or more tunnels may be drilled at the same or different axial locations along the well. Figure 2 A plurality of tunnels 211, 213, 214 formed at different axial positions along the well 200 are shown, as well as a plurality of tunnels 211, 210 formed at the same axial position of the well 200. In some embodiments, more than two tunnels may be formed at the same axial position along the well. For example, Figure 7 A cross-sectional view of the well 400 is shown at an axial position along the well 400, wherein four tunnels 410, 420, 430, 440 extend outwardly from the well 400 in different directions at the same axial position along the well 400. Each tunnel 410, 420, 430, 440 may house one or more components of a chemical storage assembly 450 according to embodiments of the present disclosure.

[0042] According to an embodiment of the present disclosure, a plurality of tunnels can be drilled at a single axial position along a well using a simplified tunnel excavation procedure, and the simplified tunnel excavation procedure includes rotating a tunnel excavation tool at a single axial position to drill a plurality of tunnels. For example, in a method of forming a tunnel using mechanical radial drilling, a whipstock (e.g., 104 in FIG. 1) can be sent to an axial position in the well via a pipeline (e.g., 105 in FIG. 1) and oriented in a first rotational position. A radial drill bit (e.g., 108 in FIG. 1) can be guided through the whipstock to drill into the surrounding strata from the well outward in a first direction. After drilling into the strata for a length to form a first tunnel, the radial drill bit can be retracted and the whipstock can be rotated (e.g., a quarter turn) while remaining in the axial position to a second rotational position. The radial drill bit can then be redirected by the whipstock to drill into the strata from the well outward in a second direction. After drilling into the strata for a length to form a second tunnel, the radial drill bit can be retracted and the whipstock can be rotated (e.g., a quarter turn) while remaining in the axial position to a third rotational position. The radial drill bit can then be redirected by the whipstock to drill outward from the well into the formation in a third direction. This rotation and drilling process can be repeated to form additional tunnels at the same axial location. Using this rotation and drilling process can allow multiple tunnels to be formed in a single location without having to move and reposition the whipstock to different axial locations along the well.

[0043] After one or more tunnels are drilled out of the well, a chemical storage assembly may be installed within the tunnel(s). According to embodiments of the present disclosure, the same tools used to drill the tunnels may also be used to place chemical storage equipment within the drilled tunnels (e.g., coiled tubing or drill strings). For example, in some embodiments, one or more or all components of the chemical storage assembly may be installed within the tunnel using the same whipstock used to guide a radial drilling tool to drill the tunnel. In such embodiments, a flexible running tool may be used to guide the component(s) of the chemical storage assembly through the whipstock and into the tunnel. The running tool may hold the chemical storage assembly in a certain orientation so that when the running tool releases the chemical storage assembly, the opening for ejecting chemicals from the chemical storage assembly may face the well.

[0044] In some embodiments, the system can be designed to retain the chemical storage assembly within a tunnel extending from the horizontal portion of the well so that the chemical storage assembly can remain within the tunnel even when fluid is circulating through the well. For example, in some embodiments, as the tunnel is drilled from the horizontal portion of the well, the chemical storage assembly can remain within a tunnel extending laterally or in a downward direction from the horizontal portion. In some embodiments, as the tunnel is drilled from the horizontal portion of the well, the chemical storage assembly can be retained within the tunnel extending from the horizontal portion of the well using a clamping element, such as a separate small packer mounted around the chemical storage assembly to retain the chemical storage assembly within the tunnel.

[0045] In embodiments where the chemical storage assembly has multiple components installed in multiple tunnels, the components can be connected together before or after each component is installed in its respective tunnel. For example, according to an embodiment of the present disclosure, a chemical storage assembly having a chemical storage chamber and an integrated dispensing mechanism can be installed in a main tunnel extending from the well at a first axial position along the well. A power source (such as a rechargeable battery) can be installed in a secondary tunnel extending from the well at a different second axial position along the well. The power source in the secondary tunnel can then be connected to the chemical storage assembly in the main tunnel. In some embodiments, the power source can be installed in a secondary tunnel extending from the well at the same first axial position along the well as the main tunnel, wherein the power source and the chemical storage assembly can be connected together at the first axial position along the well.

[0046] Reference now Figure 8 , Figure 8 An example of a method 800 for assembling and using a chemical storage system according to an embodiment of the present disclosure is shown. In various embodiments according to the present disclosure, one or more steps shown in the example may be repeated or omitted. In addition, a method according to an embodiment of the present disclosure may include steps not described herein. Figure 8 Additional steps shown in .

[0047] As shown, method 800 may include providing a well extending through a subterranean formation (step 810) and drilling at least one tunnel extending outward from the well (step 820). A chemical storage assembly may be installed in the tunnel(s) (step 830), wherein the chemical storage assembly may include a chemical stored in at least one chemical storage chamber and a dispensing mechanism.

[0048] After the chemical storage system is set up in the well, chemicals can be injected from the chemical storage assembly into the well (step 840). In some embodiments, chemicals can be injected from the installed chemical storage assembly during or after performing well operations. For example, well operations can include well repair operations, such as repair work or production stimulation of an existing production well, maintenance procedures performed on a well, remedial treatments on a well, or operations including removing and / or replacing a production string from a well (e.g., after the well has been killed and a workover rig has been placed at the well). Chemicals from one or more installed chemical storage assemblies can be injected during or after performing well operations, for example, where the injected chemicals can be used in well operations.

[0049] In some embodiments, well operations may include moving a downhole tool (e.g., a production tubing string) through the well and past the chemical storage assembly and the tunnel to perform the well operations. By providing the chemical storage assembly in a tunnel formed outside the well, the downhole tool may be moved through the well and past the assembly without being disturbed by the chemical storage assembly.

[0050] According to embodiments of the present disclosure, after the chemical is ejected from the chemical storage assembly, the chemical storage assembly may be pulled out of the tunnel to remove the chemical storage assembly from the well (step 850). In some embodiments, brine may be circulated through the well while the chemical storage assembly is being removed. The chemical storage assembly may be removed from the well, for example, using a running tool.

[0051] The methods and systems described herein can be used in vertical well sections, horizontal well sections, and other directional well sections for various applications. Examples of applications in which the methods and systems described herein can be used include, but are not limited to, the following:

[0052] 1) Provide downhole chemicals to protect expensive completion equipment and tools downhole;

[0053] 2) H2S mitigation using various H2S scavenging chemicals including but not limited to methylenebisoxazolidine (MBO), ethylenedioxy dimethanol (EDDM), 2-ethyl zinc salts, glyoxal, hemiacetal, and monoethanolamine (MEA) triazine;

[0054] 3) H2S adsorption, using H2S adsorption chemicals stored in tunnels to adsorb H2S after reservoir acid treatment to protect downhole equipment; using scale inhibitors as chemicals, including inorganic phosphates, organic phosphorus and organic polymer backbones, such as PBTC (phosphonobutane-1,2,4-tricarboxylic acid), ATMP (aminotrimethylenephosphonic acid) and HEDP (1-hydroxyethylidene-1,1-diphosphonic acid), polyacrylic acid (PAA), phosphino polyacrylates (such as phosphino polycarboxylic acid (PPCA)), polymaleic acid (e.g. para-methoxyamphetamine (PMA)), maleic acid terpolymers (MAT), sulfonic acid copolymers, such as SPOCA (sulfonated phosphonocarboxylic acid), polyethylene sulfonate, polyphosphonocarboxylic acid (PPCA) and diethylenetriamine-penta (methylenephosphonic acid) DTPMP;

[0055] 4) Reduce corrosion, where corrosion inhibitors can be used as stored chemicals, including quaternary amines, amides, imidazolines, and phosphate compounds;

[0056] 5) Chemical treatment using encapsulated inhibitors and other chemicals;

[0057] 6) storing the surfactant in a chemical storage assembly;

[0058] 7) Removal of condensate;

[0059] 8) Fluid lifting;

[0060] 9) Scale inhibitors for sandstone reservoirs; and

[0061] 10) Other reservoir treatments.

[0062] By using the methods and systems described herein, multiple types of chemicals can be stored downhole and used for various well applications as needed. By storing the chemicals in a tunnel outside the well, well operations can be performed without interference from the chemical storage components and without requiring intermittent downtime for individual chemical injection operations.

[0063] While the present disclosure has been described with respect to a limited number of embodiments, those skilled in the art having benefit of this disclosure will appreciate that other embodiments can be designed which do not depart from the scope of the present disclosure as described herein. Accordingly, the scope of the present disclosure should be limited only by the claims appended hereto.

Claims

1. A method comprising: providing a well extending from the surface to the ground; drilling a main tunnel extending in an outward direction from the well at a first axial position along the well using radial drilling; installing a chemical storage assembly in the main tunnel, wherein the chemical storage assembly includes a chemical stored in the chemical storage assembly; as well as The chemical is injected from the chemical storage assembly into the well.

2. The method of claim 1, wherein the chemical storage assembly further comprises a pill capsule containing the chemical.

3. The method according to claim 1 or 2, wherein the injection of the chemical is triggered by a change in downhole environmental conditions.

4. The method according to claim 1, further comprising: drilling a secondary tunnel extending from the main shaft at a second axial position along the shaft; installing a power source in the secondary tunnel; as well as Connecting the power source to the chemical storage assembly.

5. The method according to claim 1 or 4, further comprising: After spraying the chemical, pulling the chemical storage assembly out of the main tunnel to remove the chemical storage assembly; as well as Upon removal of the chemical storage assembly, brine is circulated through the well.

6. The method of any one of claims 1 to 5, wherein the radial drilling comprises orienting the radial drill bit in the outward direction from the well using a whipstock as the radial drill bit drills out of the main tunnel, wherein the method further comprises: rotating the whipstock in the well to orient the radial drill bit in a second outward direction from the well; as well as An additional main tunnel is drilled from the wellbore at the first axial position in the second outward direction.

7. The method according to any one of claims 1 to 6, further comprising installing a non-metallic seal at the opening of the main tunnel to isolate the main tunnel from a downhole environment in the well.

8. A method comprising: providing a well extending from the surface to the ground; drilling a main tunnel in an outward direction from the well extending a length from the well; installing a chemical storage assembly in the main tunnel; moving a downhole tool through the well and through the main tunnel to perform well operations; as well as During or after performing the well operation, chemicals are injected from the chemical storage assembly.

9. The method of claim 8, wherein the well operation is a well intervention operation comprising extending a production tubing string through a main well.

10. The method of claim 8 or 9, wherein the main tunnel is less than 300 feet in length.

11. The method according to any one of claims 8 to 10, further comprising: drilling a secondary tunnel extending outwardly from the well at a different axial position than the primary tunnel; installing a chemical storage room in said secondary tunnel; as well as Connecting the chemical storage chamber to a dispensing mechanism in the chemical storage assembly in the main tunnel.

12. The method according to any one of claims 8 to 10, further comprising: drilling a secondary tunnel extending outwardly from the well at a different axial position than the primary tunnel; installing a power source in the secondary tunnel; connecting the power source to a controller in the chemical storage assembly; as well as A controlled dose of the chemical is ejected from the chemical storage assembly using the controller.

13. A system comprising: Wells, which extend through underground formations; a main tunnel extending a length outwardly from the well at a first axial position along the well; a chemical storage assembly installed in the main tunnel; a secondary tunnel extending outwardly from the shaft; and A power source is installed in the secondary tunnel, wherein the power source is connected to the chemical storage assembly.

14. The system of claim 13, wherein the well is a branch well extending from a main well, and the main well extends from the surface to underground.

15. The system of claim 13 or 14, wherein the chemical storage assembly comprises: a chemical storage room, which contains chemicals; and A pump is in fluid communication with the container.

16. The system of claim 15, wherein the pump is programmed to pump controlled doses of the chemical.

17. The system of any one of claims 13 to 16, further comprising an additional main tunnel at the first axial position, the additional main tunnel extending outwardly from the well in a different direction than the main tunnel.

18. The system according to any one of claims 13 to 17, further comprising: an additional tunnel extending outwardly from the well; and A chemical storage chamber is disposed in the additional tunnel, wherein the chemical storage chamber is fluidly connected to the chemical storage assembly in the tunnel.

19. The system of any one of claims 13 to 18, wherein the primary tunnel and the secondary tunnel have a diameter of less than 7 inches.

20. The system of any one of claims 13 to 19, wherein the primary tunnel and the secondary tunnel extend outwardly from a horizontal section of the well.

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