BACKGROUND

[0001] In completing a well, drilling fluids, such as drilling mud and other fluids in the well during drilling, are circulated out of the well and replaced with a completion fluid. For example, the completion fluid is pumped down the bore of a production string to displace the drilling fluids up the annulus between the production string and wellbore wall, or vice versa. The completion fluids can take different forms, but are typically a so lids- free liquid meant to maintain control over the well well should downhole hardware fail, without damaging the subterranean formation or completion components. The fluid is typically selected to be chemically compatible with the formation, for example, having a specified pH.

DESCRIPTION OF DRAWINGS

[0002] FIGS. 1 A and IB are side partial cross-sectional views of example well systems. FIG. 1 A shows an open hole completion with well screens and FIG. IB shows a cased completion.

[0003] FIG. 2 is a detail half cross-sectional view of a production device having a time delay valve.

[0004] FIG. 3 is a detail cross-sectional view of one example valve.

[0005] Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

[0006] FIG. 1 A shows an example well system 10A in an open hole completion configuration. The well system 10A is shown as a horizontal well, having a wellbore 14 that deviates to horizontal or substantially horizontal in a subterranean zone of interest 24. Atype of production tubing, referred to as casing 16, is cemented in the wellbore 14 and coupled to a wellhead 18 at the surface 20. The casing 16 extends only through the vertical portion of the wellbore 14. The remainder of the wellbore 14 is completed open hole (i.e., without casing). A production tubing string 22 extends from wellhead 18, through the wellbore 14 and into the subterranean zone of interest 24. The production string 22 can take many forms, for example, as a continuous tubing string between the subterranean zone 24 and the wellhead 18, as a length of production liner coupled to the casing 16 at a liner hanger with a tieback liner extending from the liner hanger to the wellhead 18, and/or another configuration. A production packer 26 seals the annulus between the production string 22 and the casing 16. Additional packers 26 can be provided between the screen assemblies 12 to seal the annulus between the wellbore wall and the production string 22. The production string 22 operates in producing fluids (e.g., oil, gas, and/or other fluids) from the subterranean zone 24 to the surface 20. The production string 22 includes one or more well screen assemblies 12 (five shown). In some instances, the annulus between the production string 22 and the open hole portion of the wellbore 14 may be packed with gravel and/or sand. The well screen assemblies 12 and gravel/sand packing allow communication of fluids between the subterranean zone 24 and the interior of the production string 22. The gravel/sand packing provides a first stage of filtration against passage of particulate and larger fragments of the formation to the production string 22. The well screen assemblies 12 provide a second stage of filtration, and are configured to filter against passage of particulate of a specified size and larger into the interior center bore production string 22. One or more of the well screen assemblies 12 is provided with a flow control device 28 that controls flow through the well screen assembly 12, between the bore of the production string 22 and the

subterranean zone 24.

[0007] FIG. IB shows an example well system 10B in a cased completion configuration. In the well system 10B, the casing and/or a production liner (collectively casing 16) extends through the subterranean zone 24, and in certain instances, throughout the length of the wellbore 14. Like the production string 22 in the open hole context, the casing 16 operates as a production tubing in producing fluids from the subterranean zone 24 to the surface 20. The cased completion can take many forms, for example, as a continuous string of casing tubing between the subterranean zone 24 and the wellhead 18, a length of liner coupled to a casing tubing at a liner hanger with a tieback liner extending from the liner hanger to the wellhead 18, and/or another configuration. The casing 16 is provided with openings 32 to allow communication of fluid between the subterranean zone 24 and the interior of the casing 16 and a flow control device 38 between the openings 32 and the interior of the casing 16 that controls that flow.

[0008] In both instances, prior to completing the well system lOA or 10B, it is subjected to a fluid exchange operation where drilling fluids, such as drilling mud and other fluids in the well during drilling, are circulated out of the well and replaced with a completion fluid. For example, the completion fluid is pumped down the bore of a production string to displace the drilling fluids up the annulus between the production string and wellbore wall, or vice versa. During the fluid exchange operation, the flow control devices 28, 38 are set to a closed state, sealing against passage of fluid between the interior and exterior of the production string 22 or casing 16. Sealing the flow control devices 28, 38 makes the production string 22 or casing 16 respond to the circulation operation effectively as a continuous (unapertured) tubing. If the flow control devices 28, 38 were not sealed (i.e., open), the ability of the flow control devices 28, 38 to pass fluids could cause a short circuit of the circulation flow through the flow control devices 28, 38 and make it more difficult to effectively circulate the fluids from drilling out of the wellbore.

[0009] FIG. 2 shows a schematic configuration of an example flow control device 200 that can be used as flow control device 28, 38. In the context of flow control device 38, the casing adjacent the flow control device 38 includes an inner tubing 202 and an outer tubing 208 that defines an axial flow passage 212 in between. The axial flow passage 212 is in communication with the openings 32 in the casing. The outer tubing 208 is sealed at one end to the tubing 202 and sealed to the flow control device 200 at its other end. Therefore, flow between the outer tubing 208 and the center bore 214 of the tubing 202 (and thus casing) must flow through the flow control device 200. The flow control device 200 operates as a flow restriction of specified characteristics to control the flow between center bore 214 and the exterior of the casing and surrounding subterranean zone. In certain instances, one or more other flow control devices 200 can be positioned on the tubing 202, for example, spaced along the casing. [0010] In the context of flow control device 28, the well screen assembly includes a base tubing 202 with a filtration screen assembly 208 positioned circumferentially about the tubing 202. The filtration assembly 208 is sealed at one end to the base tubing 202 and sealed to the flow control device 200 at its other end. Therefore, flow between the filtration assembly 208 and the center bore 214 of the base tubing 202 (and thus production string) must flow through the flow control device 200. The flow control device 200 operates as a flow restriction of specified characteristics to control the flow between center bore 214 and the exterior of the well screen assembly and surrounding wellbore annulus and subterranean zone. In certain instances, one or more other flow control devices 200 can be positioned on the base tubing 202, for example, at the opposing end of the screen assembly 208 and/or intermediate the ends of the screen assembly 208.

[0011] The filter assembly 208 is a filter that filters against passage of particulate of a specified size or larger. Filter assembly 208 can take a number of different forms and can have one or multiple layers. Some example layers include a preformed woven and/or nonwoven mesh, wire wrapped screen (e.g., a continuous helically wrapped wire), apertured tubing, and/or other types of layers. Filter assembly 208 defines an axial fluid passage 212 interior to the filter assembly 208 and/or between the filter assembly 208 and the base tubing 202. The axial fluid passage 212 communicates fluid axially along the length of the well screen assembly.

[0012] The flow control device 200 includes an annular housing 204 mounted on the tubing 202. The housing 204 defines an interior flow passage 206 that communicates between the internal center bore 214 of the tubing 202, via sidewall aperture 210 in the tubing 202, and the subterranean zone surrounding the well screen assembly, via the axial flow passage 212 of the filtration screen assembly 208. The flow control device 200 includes a flow restriction 222 in the flow passage 206 that can produce a specified fixed or variable flow restriction to flow through the flow passage 206. The flow restriction can be a partial restriction or can selectively seal the flow passage 206. The flow restriction 222 can take a number of forms, including fixed or variable orifices, manually operated valves (e.g., operated with a tubing conveyed and/or wire conveyed operating tool downhole or set at the surface by an operator), valves responsive to a surface or downhole signal (e.g., electric, hydraulic, acoustic, optical and/or other signal types), fluid responsive valves (e.g., responsive to fluid pressure, flow rate, viscosity, temperature and/or other fluid characteristics) including fluid diodes, and/or other types of flow restrictions. In certain instances, flow control device 200 can be a type of device referred to in the art as an inflow control device, and the flow restriction 222 can be the primary working components of such a device. A number of different inflow control device configurations can be used.

[0013] The flow control device 200 further includes a valve 216 in the passage 206 that is operable to change between sealing and allowing flow through the flow passage 206, and thus, change between sealing and allowing flow between the center bore 214 and the exterior of the tubing 202 (e.g., the subterranean zone). The valve 216 is communicably coupled to an electronic controller 218 of the flow control device 200. The controller 218 can include a battery and is configured to actuate (i.e., change) the valve between sealing and allowing flow.

[0014] The valve 216 can take a number of different forms. FIG. 3 shows one example of a valve 300 that can be used as valve 216. The valve 300 includes a pressure barrier 302 in the flow passage 206 that seals against passage of fluid through the flow control device. A linear actuator 304, communicably coupled to the controller 218, is positioned adjacent the pressure barrier 302 and includes a piercing tip 306. When actuated by the controller 218, the linear actuator 304 extends its piercing tip 306 into and rupturing the pressure barrier 302 to allow passage of fluid through the flow passage 206. The linear actuator 304 can be an electromagnetic actuator that moves the piercing tip 306 by the interaction of magnetic fields, a pyrotechnic actuator that moves the piercing tip 306 via pressure from an ignited pyrotechnic, and/or another type of linear actuator. The barrier can be a ceramic, plastic, composite, or metallic thin plate and/or another configuration. Since the barrier is ruptured, once the valve 300 has been actuated, it cannot be resealed. In another example, the linear actuator 304 can be provided with a stopper, rather than a piercing tip, that can be inserted or withdrawn from the flow passage 206 multiple times to allow or seal against flow through the flow passage 206. In another example, the linear actuator 304 is replaced with a chemical actuator. The chemical actuator is communicably coupled to the controller 218 and is positioned proximate the pressure barrier 302. When activated by the controller 218, the chemical actuator sends a jet of fluid into and weakening the pressure barrier 302 to allow passage of fluid through the flow passage 206. The chemical actuator can send a heated jet of fluid such as from an exothermic oxidation-reduction reaction (thermite reaction). The chemical actuator can send a corrosive jet of fluid such as from an acid producing reaction. Yet other examples of valve 216 exist and can be used.

[0015] In certain instances, the controller 218 is provided with an electronic timing circuit that enables the controller 218 to actuate the valve 216 after a specified time delay. For example, the specified time day can be hard coded into the controller 218 and/or can be set by an operator remotely or while the flow control device 200 is at the terranean surface (out of the wellbore). In certain instances, the controller 218 is configured so that an operator can access the controller 218 to initiate counting the specified time delay remotely or while the controller 218 is at the terranean surface (out of the wellbore). Alternately or additionally, the controller 218 can be configured to initiate counting the specified time delay based on the controller 218 detecting specified stimuli. In certain instances, the stimuli can be an in- well event associated with a well fluid exchange circulating out fluids from drilling and prior operations and replacing those fluids with completion fluid. In certain instances, the controller 218 can be configured to actuate the valve 216 without the time delay based on the stimuli and, in such instances, can be provided without the timer.

[0016] In certain instances, the time delay can be selected based on the expected duration of time to complete a well fluid exchange, for example, to actuate the valve 216 after the fluids in the well from drilling and prior operations have been circulated out and replaced with completion fluids. In addition to the time to exchange the fluids, this time can account for additional time, such as time to assemble and run the production string into the wellbore (e.g., if counting the delay is initiated at the surface), time to arrange and hook up the equipment needed for the well fluid exchange operation, the scheduling and availability of the equipment and other resources needed for the well fluid exchange operation, and other operations that might be performed prior to or in connection with the well fluid exchange. In instances using multiple flow control devices 200 in the same string (e.g., a string having multiple well screen assemblies), the time delay can be different for different of the flow control devices 200. In certain instances, the time delay can be many minutes (e.g., when counting is initiated after the fluid exchange operation) or many hours (e.g., when counting is initiated during or prior to the fluid exchange operation) or many days (e.g., when counting is initiated while the controller 218 is at the surface). In certain instances, the time delay can be selected based on other basis.

[0017] In certain instances the flow control device 200 includes one or more sensors communicably coupled to the controller 218 for sensing the stimuli. FIG. 2 shows a sensor 220a configured to sense a characteristic in the center bore 214 and a sensor 220b configured to sense a characteristic in the annulus between the production string and the wellbore wall. In other instances, fewer (e.g. one or none) or more sensors could be used, and the sensors could be provided to sense stimuli in different locations. The controller 218 can be configured to begin counting the specified time delay based on input from one or both sensors 220a, 220b and/or can be configured to actuate the valve 216 (without the time delay) based on input from one or both sensors 220a, 220.

Depending on the configuration of the valve 216, the valve can be opened or closed in response to the stimuli. In certain instances, multiple stimuli can open and close and operate the valve 216 multiple times. Notably, the controller 218 can be configured to operate independently and automatically to begin counting the specified time and/or operate the valve 216 without a connection by a control line outside of the well.

[0018] In one example, one or both of the sensors 220a, 220b can be flow rate sensors and the controller 218 can look for a specified flow rate or pattern of flow rates resulting from the circulation of fluids from a fluid exchange. In another example, one or both of the sensors 220a, 220b are fluid pressure sensors. In certain instances, the controller 218 can look for a specified pressure or pattern of pressures resulting from the circulation of fluids. In certain instances, the controller 218 can look for a pressure pattern corresponding to running the controller into a subterranean formation. In another example, one or both of the sensors 220a, 220b are temperature sensors. In certain instances, the controller 218 can look for a specified temperature or pattern of temperatures resulting from the circulation of fluids (e.g., resulting from introduction of the initially cooler completion fluids that lower the temperature. The temperature will increase after the completion fluids are no longer circulated.). In certain instances, the controller 218 can look for a temperature pattern corresponding to running the controller into the subterranean formation. In yet another example, one or both of the sensors 220a, 220b are pH sensors and the controller 218 can look for a specified pH or pattern of pH resulting the circulation of fluids (e.g., from the drilling fluids being replaced by completion fluids of a different pH). In yet another example, one or both of the sensors 220a, 220b can be acoustic sensors that listen for changes in flow, passage of tools used in the fluid exchange or other events associated with the fluid exchange operation.

Examples of acoustic sensors include but are not limited to accelerometers, strain gauges, piezoelectric materials, magneto strictive materials, and other ferroelectric materials. In yet another example, the controller 218 can be coupled to a strain sensor in or near the seal element of the production packer to determine when the production packer has been activated (e.g., typically done after the fluid exchange is complete). In yet another example, one or both of the sensors 220a, 220b can be magnetic sensors to sense passage of a magnetic (permanent and/or electromagnetic) ball, spheroid, dart, magnetic tag on a well tool and/or another magnetic device through the bore 214. Thus, an operator can send the magnetic device from the surface through the bore 214 at a chosen time to initiate the timers and/or actuate the controller 218 to actuate the valve 216. Other examples of sensors and stimuli exist. Notably, both sensors 220a, 220b need not be of the same type of sensor, and the controller 218 can be configured to look for specified characteristics in multiple domains (flow rate, pressure, temperature, pH, acoustic noise, and/or other domains) concurrently.

[0019] The controller 218 can be configured to determine the occurrence of an event associated with a well fluid exchange based on input from the sensors (e.g., sensors 220a or 220b) and, in turn, begin counting the specified time delay or actuate the valve 216 based on the determination that the fluid exchange has occurred. The event can be associated with the beginning, end or another event in the fluid exchange. In certain instances, the controller 218 can be configured to respond differently to different stimuli. For example, the controller 218 can start the timer in response to certain stimuli or certain patterns of stimuli, open the valve 216 in response to certain stimuli or certain patterns of stimuli, and close the valve in response to certain stimuli or certain patterns of stimuli. In one example of a controller 218 responsive to magnetic stimuli, each time the controller senses passage of a magnetic device, the valve 216 changes state (i.e., opens or closes).

[0020] Thus, in operation, the flow control device 200 is provided into the wellbore in an initial closed state, sealing against flow between the bore 214 and the exterior of the production tubing. In configurations where the timer is initiated at the terranean surface, the operator accesses the controller 218 to begin counting the specified time delay. The flow control device 200 (and production tubing caring it) is run into position in the wellbore, and the fluid exchange operation is begun. Completion fluid is pumped down the bore 214 to displace the drilling fluids up the annulus between the production tubing and wellbore wall, or vice versa. In the sealed state, the valve 216 makes the production tubing respond to the circulation operation effectively as a continuous (unapertured) tubing, preventing short circuits through the flow control device 200. In configurations where the timer is initiated by in- well stimuli, the controller 218 looks for the specified stimuli and in response to the stimuli, initiates the timer. At the expiration of the specified time delay, the controller 218 operates the valve 216 to open, allowing flow between the bore 214 and the exterior of the production tubing. In configurations where the controller 218 operates without a timer, the controller 218 operates the valve 216 to open in response to the stimuli. In certain instances, additional stimuli can close and later re -open the valve 216.

[0021] A number of embodiments have been described. Nevertheless, it will be understood that various modifications may be made. Accordingly, other embodiments are within the scope of the following claims.