Patent Application
20110073307
This invention relates to accumulating material downhole in a specified manner, e.g., to form a specified structure and/or to perform a specified function.
Downhole operations, e.g., drilling, completion, production, or treatment, pose challenges due to the remoteness of a well from the terrestrial surface as well as the confined space within the well. These challenges, as well as others associated with drilling and production of subterranean resources, can involve expensive and time-consuming efforts when problems arise downhole, such as intrusion of water into a portion of the well. For example, to correct a problem downhole, production may have to be suspended, tools removed from the well, and additional treatments applied to the well (e.g., introduction of additional tools or substances into the well), each with an associated large expenditure of time and resources.
Further, the development of problems downhole within a well can further lead to reduced resource production. For example, water may accumulate in an articulated portion of the well (i.e., heel portion), thereby reducing or preventing production from other portions of the well downhole from the first portion.
In one embodiment, a method includes applying a powered signal within a well; and accreting material at a specified location in response to the powered signal. In some embodiments, the method may further include introducing the material or one or more components thereof into the well. In some aspects, accreting material at the specified location may include forming a structure at the specified location. Forming the structure at the specified location may also include occluding an opening. Forming the structure at the specified location may also include forming a restriction to flow. In certain aspects, forming a barrier to flow may include positioning a porous member within a tubular; and changing a porosity of the porous member. Further, in some aspects, forming a structure at the specified location may include disposing a starter form at the specified location; and accumulating material onto the starter form. In some embodiments, accreting material at a specified location in response to the powered signal may include accreting dissolved materials naturally occurring within the well.
In some embodiments, the method may further include disposing a first element at a first position downhole and disposing a second element at a second position downhole, where accreting material at a specified location in response to the powered signal may include dissolving at least a portion of the second element; and depositing the dissolved portion of the second element onto the first element. The method may further include removing the accreted material from the specified location by reversing polarity of the applied powered signal to cause the accreted material to dissolve. In some embodiments, the method may further include removing the accreted material from the specified location by introducing a material within the well to dissociate the accreted material. In some instances, accreting material at a specified location in response to the powered signal may include accreting material from a sacrificial material.
In some specific embodiments, the method may further include disposing a plurality of different sacrificial materials downhole; and selectively applying the powered signal to one or more of the different sacrificial materials to form a layer of accreted material corresponding thereto. Selectively applying the powered signal to one or more of the different sacrificial materials to form a layer of accreted material corresponding thereto may include applying a different powered signal to each of the selected one or more different sacrificial materials. In some aspects, applying a powered signal within a well may include generating one of an electric potential, a magnetic field, or a sonic signal at a location within the well. In certain aspects, accreting material at a specified location in response to the powered signal may include accreting the material to an amount to cause actuation of a mechanism downhole.
In another general embodiments, a method for forming a structure downhole in a well includes generating an electric potential at a specified location downhole within the well causing deposition of dissolved solids at the location. In some specific embodiments, generating an electric potential at a location downhole within the well causing deposition of dissolved solids at the location may include accumulating the dissolved solids dispersed within a downhole liquid. The method may further include introducing one or more materials into the well to form the dissolved solids in response to the generated electric potential. In some aspects, introducing one or more materials into the well to form the dissolved solids in response to the generated electrical potential may include positioning an object formed from a sacrificial material in the well, the sacrificial material forming the dissolved solids in response to the electric potential.
In some specific aspects, positioning an object formed from a sacrificial material in the well may include positioning a first member adjacent a second member, where the first member forms an negative electrode and the second member forming a positive electrode; and generating the electric potential between the positive electrode and negative electrode. In some aspects, generating an electric potential at a location downhole within the well causing deposition of dissolved solids at the location within the well may include occluding an opening downhole with the dissolved solids. The method may further include actuating a mechanism downhole with the deposited solids.
In another general embodiments, a method includes forming an electric potential across a gap at a specified location within a well, where the gap is immersed in a liquid containing dissolved solids; and accumulating the dissolved solids at the specified location in response to the electric potential to form a structure. In some aspects, accumulating the dissolved solids at a location in response to the electric potential to form a structure may include accumulating the dissolved solids to occlude an opening to at least one of reduce or preclude fluid passage therethrough. In some aspects, accumulating the dissolved solids at a location in response to the electric potential to form a structure may include forming a coating over a portion of an object disposed downhole. The method may further include actuating a downhole mechanism with the formed structure.
The details of one or more implementations are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description and drawings, and from the claims.
The present disclosure relates to forming structures downhole by accumulating already existing materials and/or materials introduced into a well to perform a specified function. For example, the fowled structures may be used to obstruct fluid flow of production or injection fluids, carry mechanical loads, control electrical, thermal, or magnetic properties of components, mechanically actuate a component, as well as others. The materials may be induced to form the specified structure, such as by application of a potential downhole. For example, electrical, magnetic, sonic, or even biological potentials may be established downhole to form specified structures in specified locations to perform specified functions.
In many wells, water is usually present therein due to the presence of water in one or more subterranean formations intersected by the well. Dissolved in the water may be any number of different types of dissolved substances, e.g., minerals and compounds. The dissolved substances, such as salts, metals, bacteria, as well as other materials, may be induced to form structures to perform specified functions. A particularly desirable function involves conformance control, also referred to as control of water downhole. In typical applications, formation of specified structures may be accomplished where the water has a similar mineral content as that of sea water. For example, a location downhole that interfaces with water having a sufficient mineral content may be used as a nucleation site for a specified structure.
In one implementation, some substances contained in the water downhole may be made to react and precipitate out or form other materials. These precipitates may also be made to deposit at specified locations in the well. For example, in some implementations, accretion using electrolysis may be used to form the specified structures. Referring to
As shown, the well 10 includes a well bore 20 extending from a terranean surface 30 into subterranean zones 40 and 50. In some implementations, the well bore 20 may extend into additional or fewer subterranean zones. A portion of the well bore 20 may be lined with a casing 60. A tubing string 70 extends through the well bore 20 forming an annulus 80 between the casing 60 and/or an interior surface 90 of the well bore 20 and the tubing string 70. Packers 100, 110 are disposed in the annulus 80 to isolate portions of the annulus 80. Additional or fewer packers may also be used. As shown, the packers 100, 110 are used to isolate portions 120 and 130 of the well bore 20 adjacent subterranean zones 40 and 50, respectively.
The tubing string 70 may also include screens 140 and 150 in the isolated well portions 120, 130. Water may be captured within the well bore 20 such that at least a portion of the screens 140 and/or 150 are in contact with or partially or fully submerged in the water. The screens may function to prevent passage of debris contained in the production fluids (produced from the subterranean zones 40 and 50) into the tubing string 70. In the illustrated example, the subterranean zone 40 may produce petroleum with little or no water entrained therein while subterranean zone 50 may produce a petroleum and water mixture. Although the well shown in
The well 10 also includes a structure formation system 160. In the illustrated example, the structure formation system 160 includes a power source 170 for generating a voltage, a switch 180 for activating or deactivating the power source 170, a controller 185 for controlling application of the generated voltage, and a sensor 190 for monitoring formation of the specified structure. The structure formation system 160 is coupled to the screen 150. In some implementations, the structure formation system 160 may include additional or fewer elements. For example, in some implementations, the structure formation system 160 may include only a power source 170 while others may also include a switch, such as switch 180. Further, in other implementations, the structure formation system 160 may be coupled to both the screens 140 and 150 or only to screen 150. In still other implementations, separate structure formation systems may be coupled to the screens 140 and 150.
In some implementations, a voltage as low as five volts may be used to accrete material from the water to form the specified structure. However, voltages higher or lower may also be used. For example, voltages as low as one, two, three, or four volts may be used, while voltages of six, seven, eight, nine, ten, or higher voltages may be used. In some instances, the voltage applied may depend upon the equipment located at a well site. Thus, the equipment requirement to form specified structures may be kept low. For example, an automotive or similar type of battery provided at a job site may be sufficient to form the specified structure. Further, the rate at which a structure is formed may be adjusted, i.e., increased or decreased, by adjusting the voltage applied. It is also noted that where a fluid flow exists, such as through a screen or other opening, and it is specified to limit or prevent flow through the screen or opening, as the structure begins to form a barrier to the flow, the flow of fluid containing the dissolved materials may continue until the opening is completely obstructed. Accordingly, the fluid flow may continue to supply the growing structure with additional material.
In
The accretion process can be initiated in-situ if the appropriate chemicals are naturally occurring downhole within the accumulated water within the well. Alternately, the needed chemicals may be injected from the surface into the well, such as during a well treatment operation, to seed the fluids downhole so that the accretion may be promoted and the specified structure formed.
Electrical power may be supplied downhole in any number of ways. For example, electrical power may be provided by one or more power sources included as part of a tubing string or wireline. In some implementations, the power sources provided in downhole may be one or more batteries. Alternately, the needed power may be generated downhole, such as with a turbine generator operated by fluid flow; one or more heat engines, solid-state energy converter, and/or nuclear-powered energy source; one or more flow induced vibrating devices; one or more acoustic energy conversion devices; one or more vibration energy conversion devices; or a combination of one or more of these devices. In still other implementations, electrical power may be transmitted downhole via one or more electrical leads extending from the surface.
Example implementations for providing electrical power downhole are shown in
In still other implementations, a sacrificial material may be provided downhole and used to form the specified structure. For example, such a material may be used when the water does not include the needed dissolved substances or a particular type of material to form the structure is specified. Formation of a flow barrier using this method is illustrated in
In other instances, the positive electrode may be in the form of a sacrificial sheet. When the voltage is applied, material from the sacrificial sheet is accreted onto the negative electrode. Thus, in instances where the negative electrode is a screen, the accreted material fills the openings in the screen. This process may continue until the openings are completely filled, preventing fluid passage through the screen.
Structures formed with these methods provide numerous advantages and benefits. For example, formations formed as described herein provide structures downhole that need not be inserted from the surface. In some instances, the accreted materials have a relatively high strength (e.g., 4,000 psi) and may be structurally stronger than cement. Further, as discussed in more detail below, the structures may also be easily removed. The structures may be chemically removed by introduction of one or more chemicals into the well to dissolve the structure. For example, an acid treatment to the well may be used to dissolve the material without leaving potentially troublesome solid particles. The pH or other ion concentration of the fluid may be used to start, control, stop, or reverse the rate of growth of the accretion.
Additionally, forming structures as described herein can be utilized at any time during the life of a well and at essentially any location within the well. Moreover, forming structures as described has low associated costs due to, for example, the low power requirement needed to form the structures and the abundance downhole of the materials used to form the structures.
A functionally graded material, e.g., a stratified, layered, or alloyed structure, may also be formed.
Closing one of the switches while maintaining the other switches open causes the corresponding material to migrate and accrete onto the negative electrode 1020. Therefore, in some instances, each of the materials 1002, 1004, 1006 may be made to form separate layers on the negative electrode 1020 by separately applying the associated voltages thereto (i.e., closing the associated switch while maintaining the other switches open). Alternately, one or more of the switches 1014, 1016, and 1018 may be closed together to form a composite material on the negative electrode 1020. For example, as shown in
A layered structure, such as the structure described above with respect to
As mentioned above, a structure formed according to the above discussion may be easily removed. For example, polarity of the circuit can be reversed so that the negative electrode and positive electrode have reversed roles.
In some aspects, as illustrated in
Additionally, as illustrated in
Example applications of forming specified structures includes forming seals around multi-lateral junctions within a wellbore. For example,
Downhole tool 2200, typically, performs one or more functions within the well bore 2105 upon activation or actuation. For example, the downhole tool 2200 may be a valve which restricts, modulates, or otherwise controls a flowrate of one or more fluids communicated between the terranean surface and the subterranean zones. Downhole tool 2200 may, alternatively, be a moveable sleeve that operates to permit or prevent fluid flow between the subterranean zones and an interior of the well bore 2105 (e.g., through one or more perforations in the casing 2100). As yet another example, the downhole tool 2200 may be a plug or packer operable to substantially seal the interior of the wellbore 2105 enclosed by the casing 2100 between the terranean surface and a subterranean zone or between two or more subterranean zones.
In some embodiments, the tool 2200 may be mechanically actuated by, for example, inserting and/or removing a separate tool through at least a portion of the tool 2200. Alternatively, the downhole tool 2200 may be hydraulically operated, such that application or removal of a fluid pressure at or on the tool 2200 actuates the tool 2200. For instance, as illustrated in
Structure formation system 2300, as illustrated, is coupled to and/or within the fluid conduit 2130 and, typically, functions to control the flowrate of fluid 2110 communicated to the downhole tool 2200. The structure formation system 2300 includes a controller 2310, a first screen 2340, and a second screen 2350. Alternatively, the structure formation system 2300 may include different, additional, or fewer components in accordance with the present disclosure. The first screen 2340 has a fine mesh and is disposed across the conduit 2130 and within the flowpath of the fluid 2110. The second screen 2350, typically, has a coarser mesh as compared to the first screen 2340 and is disposed adjacent the first screen 2340 and insulated therefrom. The first and second screens 2340, 2350 may form a negative electrode and positive electrode, respectively.
The first and second screens 2340 and 2350 may be electrically connected to the controller 2310. Typically, the controller 2310 includes a power source 2320 and a switch 2330. In some embodiments, however, one or both of the power source 2320 and switch 2330 may be separate from or external to the controller 2310. The power source 2320 is coupled to the first and second screens 2340, 2350. When the switch 2330 is closed, a voltage is applied to the screens 2340, 2350. The second screen 2350 may be used as a sacrificial material, and the applied voltage causes the material forming the second screen 2350 to be attracted to and form a barrier structure on the first screen 2340. As the barrier structure continues to build, openings in the first screen 2340 fill with the deposited material from the second screen 2350 to eventually cause a complete barrier to flow through the conduit 2130. By stopping or substantially stopping fluid 2110 from flowing to the downhole tool 2200, the tool 2200 may be actuated or deactuated. Further, reversing the polarity of the power source 2320 may allow the deposited material to be removed from the first screen 2340, thereby allowing fluid 2110 to flow again to the downhole tool 2200. Of course, by varying the voltage from the power source 2320, modulation and partial restriction of the fluid 2110 through the first screen 2340 may be achieved by varying the porosity of the barrier formed by the deposited material.
In some implementations, the first screen 2340 may be a 200 mesh stainless steel screen while the second screen 2350 may be a copper or copper alloy screen having a mesh coarser than the first screen, although other materials may be used. In other implementations, the second screen 2350 may be formed from a material including magnesium or calcium. In still other implementations, the second screen 2350 may be formed from materials that accrete onto the first screen 2340.
Although the description discusses formation of structures using an electrical potential, the disclosure is not so limited. For example, a specified structure may be formed using a magnetic field at a location downhole. Magnetic particles existing downhole, either naturally occurring or intentionally added, may be accumulated at a specified location using a magnetic field. In some instances, the magnetic particles may be iron particles. In some instances, the added particles may be of a specified size. For example, the particle size may be set to ensure close packing of the material with a minimum of interstitial space. For example, a bimodal distribution of particle sizes may be established downhole to ensure close packing. Application of the magnetic field drives the magnetic particles into a specified location to form a specified structure, such as a plug or other conformance control structure. The magnetically formed structure may be maintained even after removal of the magnetic field by, for example, friction forces between the magnetic particles as a result of packing, an adhesive, and/or a latching mechanism.
Still other structures may be formed using acoustic energy. For example, acoustic energy of a specified frequency and wavelength may be used to drive particles into a specified location. Over time as the acoustic energy is maintained, the particles accumulate to form a structure. For example, a standing acoustical wave may be established, such as by adjusting the frequency of the acoustical energy, to drive the particles to a particular location. In some instances, the structure may be used for conformance control or for any other purpose. The acoustic energy may be maintained for the life of the built structure, or the acoustic energy may be removed after formation of the structure, in which case the structure may be maintained by the packing frictional forces discussed above.
Further, structures may be formed downhole using biological elements. For example, a bacteria colony may be established and accumulated at a specified position within well. For example, the location of the colony may be defined by where nutrients are or introduced into or concentrated within the well. Further, the biological elements may be controlled to occupy one or more locations within a well by the use of one or more structures placed downhole.
Structures formed as discussed above may be used to perform any number of functions. For example, as explained above, structures may be used for conformance control, i.e., the water control. As such, the formed structures may be used to restrict or block flow to or from one or more portions of the well. Also, the structures may be used to create a pressure downhole. The created pressure may be utilized to actuate a mechanism, such as to move a valve or sleeve. For example, limiting a fluid flow downhole may cause an associated increase in the fluid pressure. This pressure may be used for useful work downhole, for example. The structure may be used as a barrier to prevent tool passage into a portion of the well. For example, some well tools involve passing a spherical member down a tubular. A structure may be formed that prevents passage of such a spherical member. As explained above, the formed barrier may later be removed and, at such time, the spherical member would be allowed to pass through the tubular.
Other applications include forming a structure to patch holes in or repair damage to a tubular, such as a well casing, a tubing string, etc. As also explained above, the formed structures may be used to form a protective coating to prevent or reduce corrosion. For example, the protective structure could be formed when a corrosive or otherwise destructive fluid is experienced downhole. Further, the disclosure is not limited to any particular type of well. For example, structures may be formed in production or injection wells. For instance, in an injection well, a structure may be formed to prevent or reduce flow of injected materials into “thief zones” of the well, i.e., zones within the well into which the injected material is lost thereby reducing or preventing proper treatment of the surrounding subterranean zone. Additionally, the wells need not be petroleum wells. Thus, a water well or any other type of well may be within the scope of this disclosure. Other applications include zonal isolation with barriers, fluidic control systems, and actuators.
A number of implementations have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of this disclosure. Accordingly, other implementations are within the scope of the following claims.
