Actuator module to operate a downhole tool

An actuator module that is usable with a subterranean well includes a housing, a stimulus detector and an actuator. The stimulus detector and the actuator are mounted to the housing, and the housing is adapted to form a releasable connection with a tubular string. The string has a downhole tool, and the housing is separate from the tool when the housing is connected to the string. The stimulus detector detects communication of a command-encoded stimulus downhole, and the actuator actuates the tool in response to the stimulus.

BACKGROUND

The invention generally relates to an actuator module to operate a downhole tool.

A testing or production system for a subterranean well may include various downhole tools that are remotely operated from the surface of the well. As examples, these tools may include a flapper valve, a ball valve, a sleeve, a packer, etc.

The downhole tool may operate in response to a fluid pressure. More specifically, a conventional pressure-operated downhole tool operates in response to a fluid pressure that exists either in a passageway of a tubing string (containing the downhole tool) or in the annulus of the well (that surrounds the tool). The fluid pressure may be a function of the weight of the column of fluid that extends to the surface of the well as well as any additional pressure that may be applied to the column from the surface of the well.

Several different pressure-operated downhole tools may be present in the well, and it may be desirable to selectively operate these tools at different times to perform different downhole functions. Different conventional techniques may be used to prevent a particular pressure-operated downhole device from operating until desired. For example, each pressure-operated downhole tool may respond only when the fluid pressure exceeds a particular pressure level. Thus, one particular downhole tool may only respond to the fluid pressure when the pressure exceeds some predetermined threshold, another downhole tool may respond when the fluid pressure exceeds a higher predetermined threshold, etc.

To achieve this type of pressure sensitive operation, a particular downhole tool may include a rupture disc to establish a barrier between the fluid pressure (present in a passageway of a tubing string or in an annulus of the well) and a piston head of an operator mandrel of the tool. When the fluid pressure exceeds a predetermined level, the rupture disc ruptures to permit the fluid pressure to act on the piston head to move the operator mandrel to actuate the downhole tool.

A potential challenge associated with the above-described control scheme is that the number of pressure-operated downhole tools in a particular well may be limited due to the limitations on the tubing pressure rating or surface pressure.

Another control scheme for selectively controlling downhole tools includes the communication of pressure pulses downhole. The identification of a particular downhole tool as well as a command (an “open valve” command, for example) for that tool may be encoded in these pressure pulses. A binary pattern of high and low pressure pulses may be used to distinguish a particular command or uniquely identify a particular downhole tool, as compared to controlling the tools using different pressure levels. Therefore, the pressure pulse-type control scheme remains within pressure ratings regardless of the number of downhole tools. However, a potential challenge with this arrangement is that downhole tools that decode and respond to the pressure pulses typically may be complex in design and are relatively expensive to make. Tools having other types of remote actuation (e.g., acoustic actuation) suffer from similar challenges.

Thus, there is a continuing need for an arrangement and/or technique that addresses one or more of the problems that are set forth above as well as possibly address one or more additional or different problems that are not set forth above.

SUMMARY

In an embodiment of the invention, an actuator module that is usable with a subterranean well includes a housing, a stimulus detector and an actuator. The stimulus detector and the actuator are mounted to the housing, and the housing is adapted to form a releasable connection with a tubular string. The string has a downhole tool, and the housing is separate from the tool when the housing is connected to the string. The stimulus detector detects communication of a command-encoded stimulus downhole, and the actuator actuates the tool in response to the stimulus.

In another embodiment of the invention, an apparatus that is usable with a subterranean well includes a detector and an actuator. The detector detects communication of a command-encoded stimulus downhole, and the actuator activates a pressure generating medium to actuate a downhole tool in response to the detection of the stimulus.

Advantages and other features of the invention will become apparent from the following description, drawing and claims.

DETAILED DESCRIPTION

Referring toFIG. 1, an embodiment of a subterranean well system10includes a tubular string18that extends into a subterranean well. As an example, the string18may be used for purposes of producing well fluids from one or more formations of the well. Alternatively, the string18may be used for another purpose, such as performing tests in the well. The string18may include, for example, an upper22and a lower25downhole tool that may be used to perform various possible downhole functions. As examples, the tool22,25may be a flapper valve, a ball valve, a sleeve valve, a circulation valve, a packer, etc. As depicted inFIG. 1, in addition to the string18, the system10includes a well casing string14that lines a wellbore into which the string18extends.

Fluid inside an annulus11or inside a central passageway28of the well may serve as a medium for propagating pressure-encoded stimuli from the surface of the well down to a region near the tools22and25for purposes of controlling operations of the tools. These pressure pulses may be created by a fluid pump12that is located at the surface of the well. Alternatively, fluid that exists inside the central passageway28or annulus11may serve as a medium for propagating the command-encoded stimuli downhole.

The tools22and25, however, may be incapable by themselves to respond to the command-encoded pressure pulses. Instead, in some embodiments of the invention, each tool22,25is a pressure-operated tool that is actuated when an operator mandrel of the tool22,25moves (i.e., is “actuated”) in direct response to an applied pressure that appears on a pressure inlet port (not shown inFIG. 1) of the tool22,25. As examples, the source of this fluid pressure may be fluid that exists either in the central passageway28of the string18or in the annulus11of the well.

Although neither tool22,25has the ability to directly respond to a command-encoded stimuli (a series of pressure pulses, for example) that are communicated from the surface of the well, the string18includes actuator modules300(actuator modules300aand300b, depicted as examples) that decode these stimuli and selectively control operations of the tools22and25in response to these stimuli. More specifically, in some embodiments of the invention, the actuator module300acontrols communication of fluid pressure to the pressure inlet port of the upper tool22, and the actuator module300bcontrols communication of fluid pressure to the pressure inlet port of the lower tool25and25. In the description of the actuator modules300aand300bherein, the reference numeral “300” refers to the design of each actuator module300a,300bshared in common.

In some embodiments of the invention, the actuator modules300are separate from either tool22,25, and each module300is constructed to be releasably connected to the string18. The actuator modules300are generally not specifically designed for any particular tool (although they could be, in some embodiments of the invention) so that a particular module300may be used with any pressure-operated tool for purposes of converting that tool into a tool that may be remotely controlled from the surface via command-encoded stimuli.

In some embodiments of the invention, the actuator modules300aand300bmay be installed in a carrier housing assembly24, a portion of the string18that includes fluid communication paths between the actuator modules300aand300band the tools22and25.

By default, the actuator module300isolates the pressure inlet ports of the associated tool (i.e., the upper tool22for the actuator module300aand the lower tool25for the actuator module300b) from fluid pressure to maintain the tool in its non-actuated state. However, in response to detecting a command for the associated tool (encoded in the stimuli), the actuator module300opens communication to the pressure inlet port of the associated tool so that fluid pressure (in the central passageway28or annulus11) causes actuation of the tool.

As a more specific example, the actuator module300a,may by default, isolate the pressure inlet port of the upper tool22from a column of fluid that is present inside a central passageway of the string18. The actuator module300amonitors this fluid for pressure pulses. A series of pressure pulses may then be communicated downhole for purposes of uniquely identifying, or addressing, the upper tool22. The actuator module300adecodes this sequence of pressure pulses to determine that a command for the upper tool22is forthcoming. One or more additional pressure pulses may follow the first series of pressure pulses to indicate a command (an “open valve” command or a “close valve” command, as examples) for the upper tool22. In response to decoding the command, the actuator module300amay then permit communication between the pressure inlet port of the upper tool22and the column of fluid to cause actuation of the upper tool22. More specifically, in response to fluid from the central passageway entering the pressure inlet port of the upper tool22, pressure may be exerted on a piston head of an operator mandrel of the upper tool22to cause the tool22to perform some downhole function.

It is noted that the example given above is just one out of many possible scenarios for addressing and communicating a command to a downhole tool. For example, in some embodiments of the invention, a particular stimulus may encode a command and the identification of a tool together. As another example, in some embodiments of the invention, non-fluid command-encoding stimuli may be communicated downhole. For example, in some embodiments of the invention, command-encoded stimuli may be communicated downhole by way of acoustic waves that propagate downhole via the tubing wall of the string18or other well component. The acoustic-conveyed and fluid-conveyed stimuli are examples of wireless stimuli (i.e., stimuli that are not communicated downhole on a wireline, cable or other electrical wire) that may be communicated downhole for purposes of operating a downhole tool. Other types of stimuli and other types of encoding commands in these stimuli are possible and are within the scope of the appended claims.

Regardless of the type of stimuli that are communicated downhole or the manner in which commands are encoded in these stimuli, the actuator module300provides an intermediary function of decoding these stimuli and controlling one or more downhole tools that are otherwise incapable of responding to these stimuli. In some embodiments of the invention, the actuator module300is a self-contained unit that may be used with a wide variety of pressure-operated downhole tools. More specifically, the actuator module300may be assembled to a particular string to convert a tool of the string into a remotely actuated tool. Thus, a particular downhole tool does not need to be designed to decode and operate in response to command-encoded stimuli. Instead, the tool may have a much simpler design in that the tool may be designed to operate in response to a fluid pressure level; and if remote operation of the tool via command-encoded stimuli is desired, the actuator module300may be assembled on a particular string along with that tool.

The actuator module300, in some embodiments of the invention, permits the addition of control functions that are specific to a particular well. Thus, the actuator module300permits control adaptation that is specific to a particular environment without requiring direct modification of the tool for this environment. For example, in some embodiments of the invention, the actuator module300may be used in an open hole completion, i.e., a completion in which no plugs or other seals exist for purposes of building up a fluid pressure (hydrostatic or otherwise) in the tubing or annulus to operate a downhole tool. For this scenario, in some embodiments of the invention, the actuator module300may include a sufficient propellant or similar pressure generating medium that ignites or expands when heated to supply the force needed to actuate an associated downhole tool, as described further below. Alternatively, in some embodiments of the invention, the actuator module300may include a gas spring or other source of stored energy.

Turning now to a more detailed example of an embodiment of the string18,FIGS. 2,3,4and5depict consecutive sections18A,18B,18C,18D and18E, respectively, of the string18. Section18A is the uppermost tubing section that is depicted in these figures, and section18E is the lowermost tubing section that is depicted in these figures.

FIG. 2is the tubing section18A that contains an uppermost section24A of the carrier housing assembly24according to an embodiment of the invention. This section24A establishes a communication passageway for linking the actuator module300ato the upper tool22. As shown, the section24A includes an upper housing section30that is generally coaxial with a longitudinal axis29of the string18and circumscribes a central passageway28of the string18. The lower end of the upper housing section30is concentric with and is connected to (threadably connected to, for example) an intermediate housing section50. Seals are formed between the two housing sections30and50.

The upper housing section30includes a longitudinal communication path34that is capable of communicating fluid for purposes of exerting pressure on a pressure inlet port (not shown) of the upper tool22to actuate an operator mandrel of the upper tool22. The pressure inlet port of the upper tool22is connected to an outlet port32of the communication path34; and the actuator module300a(not shown inFIG. 2) controls fluid flow through the communication path34, as described in more detail below. Due to this arrangement, when the actuator module300apermits fluid to flow through the path34, the fluid is communicated to the pressure inlet port of the upper tool22for purposes of acting on a piston head of an operator mandrel of the upper tool22to perform some tool function. Not shown inFIG. 2are the components of the upper tool22that are connected to operate from this port32.

As described below, in some embodiments of the invention, the fluid (and thus, the fluid pressure) to control the upper22and lower25tools is the fluid inside the central passageway28of the string18. Thus, the actuator module300acontrols the communication of fluid between the passageway28and the communication path34so that the actuator module300acontrols when tubing pressure appears at the outlet port32. As described herein, the actions of the actuator module300amay be controlled via command-encoded stimuli that are communicated downhole. However, in some embodiments of the invention, the actuator module40includes a mechanical mechanism that may be used to bypass this remote control for purposes of mechanically actuating the tool.

More specifically, in some embodiments of the invention, the carrier housing assembly24may include a sleeve40that is circumscribed by the housing section30and is coaxial with the longitudinal axis29of the string18. The interior surface of the sleeve40has a profile that may be engaged by a shifting tool. By default, the sleeve40covers a radial port36(in the housing section50) that establishes communication between the central passageway28and the communication path34. O-rings43and47are located above and below the port36. More specifically, these o-rings43and47are located in exterior annular grooves of the sleeve40and circumscribe the sleeve40to form seals between the exterior surface of the sleeve40and the interior surface of the intermediate housing section50. These seals, in turn, isolate the central passageway28of the string from the communication path34when the sleeve40is in its default position.

However, a shifting tool may be inserted into the central passageway28to engage the inner profile of the sleeve40for purposes of moving the sleeve40in an upward direction. When this occurs, the O-rings41and43no longer seal off fluid communication between the passageway28and the communication path34(and thus, the pressure inlet port of the upper tool22). Thus, the shifting tool may be used to engage and move the sleeve40for purposes of actuating the upper tool22.

As depicted inFIG. 2, in some embodiments of the invention, the communication path34may be routed on different sides of the tool22. In this manner, as depicted inFIG. 2, the communication path34depicted on the right-hand side ofFIG. 2is linked to a lower communication path34located on the left-hand side ofFIG. 2by an annular chamber35. This annular chamber35may be formed between the exterior surface of the intermediate housing section50and the interior surface of the upper housing section30.

FIG. 3depicts a section24B of the carrier housing assembly24, just below the section24B section24A.FIG. 4depicts the next lower section24C of the carrier housing assembly24. More specifically,FIGS. 3 and 4depict portions of the two actuator modules300aand300b. The actuator modules300aand300bare generally located in the same longitudinal position along the string18. However, the actuator module300ais rotated 180 degrees with respect to the actuator module300b, so that each actuator modules300is oriented in the appropriate position for controlling the associated tool22,25. Each actuator module300partially circumscribes the longitudinal axis29of the string18, and the actuators300general reside in an annular cavity92formed in the intermediate housing section50. More particularly, the annular cavity92circumscribes a radially thinner portion50B of the intermediate housing section50; and the annular cavity92is located between two radially thicker portions50A and50B of the intermediate housing section50.

In the following description, common reference numerals are used to discuss components that the actuator modules300aand300bshare in common. A specific reference to a component of the actuator module300ais made using the suffix “a,” and a specific reference to a component of the actuator module300bis made using the suffix “b.” Thus, as an example, the reference numeral “70” refers to a propellant cartridge of either actuator module300. The reference numeral “70a”refers to the propellant cartridge of the actuator module300a,and the reference numeral “70b”refers to the propellant cartridge of the actuator module300b.

Referring toFIGS. 3 and 4, the actuator module300a, in some embodiments of the invention, is effectively a particular annular cartridge that conforms to the curved contour of the annular cavity92. Thus, the housing of the actuator module300conforms to the current contour of the annular cavity92so that the housing fits inside the cavity92and partially circumscribes the longitudinal axis29. Thus, the housing of the actuator module300is constructed to form a releasable connection with the string18in that the module300may be inserted into the cavity92, and then secured in place, the module300may be removed in a similar manner. Furthermore, the module300is separate from either downhole tool22or26tool22or25.

The housing of the actuator module is formed from an upper housing section63a(FIG. 3), a middle housing section90aand a lower housing section140athat are sealably connected together. The upper housing section63ahas an upper outlet port62athat communicates fluid from the central passageway28for purposes of actuating the upper tool22. The upper housing section63ais constructed to be inserted into a chamber54that is formed in the portion50A of the housing section50. This chamber54, in turn, is in communication with the communication path34. O-rings reside in annular grooves that are formed in the exterior surface of the upper housing section50afor purposes of forming a seal between the outlet port62aand the chamber54.

The housing section63b(effectively being the lower housing section given the orientation of the module300bdepicted in the figures) of the actuator module300bis likewise constructed to be inserted into a chamber160(FIG. 4) that is communication with a communication path200that extends to the lower tool25.

Each actuator module300includes a propellant cartridge70, a mechanism that includes a piston assembly78that the cartridge70drives for purposes of controlling communication between a radial port64that opens into the central passageway28and the outlet port62. Referring toFIG. 7that depicts a more detailed schematic diagram of the cartridge70a,the housing section63includes a radial opening that aligns with a corresponding radial opening in the portion50B of the housing section50to form the radial port64. The piston assembly78moves inside a chamber65that is circumscribed by the housing section63. The chamber65, in turn, opens into the outlet62.

The piston assembly78includes a piston head80that controls communication between the radial port64and the outlet port62. In this manner, an O-ring74is located in an exterior groove of the piston head80between the port64and the outlet62. The O-ring74forms a seal between the piston head80and the interior surface of the housing section63. Thus, in its default position (depicted inFIG. 7), the piston head80seals off communication between the radial64and outlet62ports.

The piston head80is connected to a stem81(of the piston assembly78) that extends inside a propellant assembly84of the cartridge70. The actuator module300activates the propellant assembly84when actuation of the associated tool is desired. When activated, the propellant assembly84moves the piston assembly78to retract the seal formed by the piston head80to a position in which the piston head80no longer seals off communication between the radial64and outlet62ports.

As a more specific example, when the propellant assembly80a(depicted inFIG. 7) is activated, the assembly80amoves the piston assembly78ato a position in which the o-ring74is below the radial port64.

FIG. 8depicts a more detailed schematic diagram of the propellant assembly84. As shown, the stem81of the piston assembly78extends into an opening in a housing301of the assembly84and is connected at its lower end to a piston head300. The piston head300defines a first chamber302(above the piston head300) and a second chamber (below the piston head300) inside the housing301. The assembly84includes a propellant304that is located in the first chamber302, along with an ignition device303. The second chamber310may be at atmospheric pressure. Due to this arrangement, when the propellant304ignites (via a current that is applied to the ignition device303), the propellant304burns to produce gases inside the first chamber302. These gases, in turn, force the piston head300in a downward direction and therefore, force the stem81(and piston assembly78) in a downward direction to permit communication between the radial64(FIG. 7) and outlet62ports.

In some embodiments of the invention, the chamber302is in communication with the communication path34so that the gases from the ignition of the propellant may act on the operator mandrel of the upper tool22. In this manner, in some embodiments of the invention, the propellant produces a sufficient force to actuate the tool without completely relying on fluid pressure from the annulus or central passageway. Such an arrangement may be advantageous for purposes of operating a tool in an open bore completion.

Referring back toFIG. 3, the ignition of the propellant inside the cartridge70, and thus, the action of the cartridge70is controlled by electronics110of the actuator module300. More specifically, wires100extend between the cartridge70and the electronics110. The electronics110is also connected to a pressure transducer104that is in communication (via communication path106) to the central passageway28of the string18. The electronics110monitors the pressure (via the transducer104) inside the passageway28to detect a command stimulus that is transmitted from the surface of the well. Thus, in some embodiments of the invention, the electronics110monitors the pressure to detect and decode any command-encoded stimuli that appear in the fluid inside the central passageway28.

As a more specific example, when the electronics110adetects a command for the upper tool22, the electronics110asends an electrical current to the cartridge70aso that the cartridge70aopens communication between the central passageway28and the communication path34for purposes of actuating the upper tool22. Likewise, when the electronics110bdetects a command for the lower tool25, the electronics110bactivates the cartridge70bto establish communication between the central passageway28and the communication path200.

In some embodiments of the invention, the pressure transducer104senses pressure in the well annulus, instead of pressure in the central passageway28. Therefore, in these embodiments of the invention, the pressure commands are transmitted down the annulus of the well instead of through the tubing. In other embodiments of the invention, the pressure transducer104may be replaced with another type of transducer, such as a transducer to detect an acoustic wave that propagates along the tubing string18for purposes of communicating the downhole command. Other variations are possible.

In some embodiments of the invention, the pressure in the tubing or annulus does not actuate the particular tool. In this manner, a string18may be located in an open hole arrangement in which sufficient hydrostatic pressure does not exist to operate the tool. For these embodiments of the invention, the cartridge70may be replaced with a cartridge that has a sufficient amount of propellant to produce gas that delivers a sufficient force at the outlet port62to move a particular operator mandrel without requiring assistance by pressure that is exerted by fluid in the central passageway28or annulus. Many other variations are possible, depending on the particular embodiment of the invention.

Referring toFIG. 4, among the other features of the actuator module300, in some embodiments of the invention, the module300includes a battery120for purposes of providing power to the circuit110, as well as providing the power to activate the cartridge70. In some embodiments of the invention, the electronics110may activate a switch (not shown) (a relay switch, for example) for purposes of draining the battery120after the activation of a particular tool for purposes of preventing later inadvertent operation of the tool. The housing section140of the actuator module300, may, in some embodiments of the invention, form a projection145on one end of the module300for purposes of securing the module in place. In this manner, the projection145extends into the annular cavity92so that an outside curved plate148that circumscribes the projection145may be secured to the housing section50B for purposes of locking one end of the actuator module300in place. The other end of the actuator module300extends either into the cavity54(for the actuator module300a) or the cavity160(for the actuator module300b).

FIG. 5depicts the lowest section24D of the carrier housing. This section24D forms an interface between the actuator module300band the lower tool25. As shown, the communication path200opens into an annular chamber202that is formed where the housing section50is connected to a lower concentric housing section240. A radial port206is located in the interior wall of the housing section50for purposes of forming communication between the chamber202and the passageway28. However, an inner sleeve210blocks this communication. The sleeve210has an inner profile that may be engaged by a shifting tool for purposes of sliding the tool210to permit communication between the passageway222and28, in a similar fashion to the use of the sleeve40, discussed above.

The passageway200communicates with a longitudinal passageway222that is formed in the housing section240. This passageway222extends to an operator mandrel of the lower tool25. In some embodiments of the invention, the carrier housing assembly24may include a flow restrictor220that is located in line with the communication path222for purposes of metering the flow to restrict operation of the operator mandrel of the lower tool25.

FIG. 6depicts the interface between the communication path222and an operator mandrel250of the lower tool25. As an example, the operator mandrel250may be a flow tube of a flapper valve, a sleeve of a particular circulation valve, etc. As shown, the operator mandrel250includes a piston head246that has an upper surface242in communication with the communication path222. Therefore, when the actuator module300bopens communication through the port64b(or alternatively, when the sleeve210is moved), pressure is applied to the upper surface242to move the operator mandrel250. Other variations are possible.

Thus, to summarize operation of the actuator module300according to some embodiments of the invention, the actuator module300includes a pressure transducer104that indicates the pressure of fluid in the central passageway28. The electronics110is coupled to the pressure transducer104to monitor this pressure and decode commands and tool identifications from any detected pressure pulses. In response to detecting a command that directs actuation of the tool that is associated with the actuator module300, the module300communicates a current through the propellant cartridge70to ignite the propellant inside the cartridge70to cause the piston assembly78to move. This movement of the piston assembly78, in turn, permits communication between the ports62and64to allow fluid pressure for the passageway28to act on an operator mandrel of the tool. Other variations are possible.

Other embodiments are within the scope of the following claims. For example,FIG. 9depicts an alternative arrangement for the cartridge70in which the piston head80is replaced with a piston head352. The piston head352may, in some embodiments of the invention, be connected to a solenoid valve (instead of to the cartridge70) so that the piston head352slides in or out upon excitation of the solenoid valve.

The piston head352slides in the chamber65. However, unlike the piston head of the cartridge70, the piston head352has a spear-shaped upper surface353that, when the piston is moved in the appropriate direction, punctures a rupture disc356that isolates the radial64and outlet62ports. Thus, as an example, the piston head352may be moved in a direction to puncture the rupture disc356for purposes of allowing communication between the radial64and outlet62ports. It is noted that for this embodiment, the piston head352may move in an opposite direction than the piston head of the previously described cartridge70when the actuator module300actuates the associated tool. Thus, for this arrangement, the propellant-containing and atmospheric chambers may be juxtaposed inside the propellant assembly84.

As an example of another embodiment of the invention, two or more actuator modules may be redundant for a particular tool. Thus, these actuator modules provide a redundant control in that if one of the modules should fail, a circuit activates one of the remaining actuator(s) to control the tool.

The embodiments described above describe operations for a single shot tool (i.e., a tool that is operated for purposes of placing the tool in a particular state (an open state, for example) in a particular direction). However, it is noted that the principals described herein may be applied to multiple shot devices. In this manner, a particular actuator module300may be activated for purposes of directing an operator mandrel in one direction, and another actuator module300may be actuated for purposes of directing the operator mandrel in another direction. Thus, by way of example, one actuator module300may be used for purposes of opening a valve (for example), and another actuator module may be used for purposes of closing the valve.

FIG. 10depicts an arrangement400that may be used in some implementations of the above-described multiple shot tools. In this manner, the arrangement400includes an operator mandrel310that may be moved in one direction for purposes of opening a valve (as an example) and in another direction for purposes of closing the valve (as examples). For example, the arrangement400may include a communication path406in communication with a particular actuator module. As shown, the path406may be in communication with a radial path440that may be sealed by an internal sleeve, consistent with the arrangements described above. Thus, the communication path406communicates pressure in response to the actuation of a particular actuator module. Upon communication of this pressure, the pressure acts against a piston surface423of the operator mandrel410for purposes of moving the operator mandrel in a particular direction.

The arrangement400also includes another passageway404in communication with another actuator module. As shown, the passageway404is also in communication with a radial passageway430that may be blocked by an inner sleeve. Thus, when a pressure is communicated through the passageway404, this pressure operates on a surface421on another piston head420of the operator mandrel410. This action forces the operator mandrel in another direction. It is noted that the surfaces423and421may be of different areas allowing the dual operation of the mandrel410. An atmospheric chamber414may be present between the two piston heads420and440. Other variations are possible.

As examples of other embodiments of the invention, in the arrangement described above, a particular actuator module is facing in one direction and another actuator module is facing in an opposite direction. However, it is noted that in other embodiments of the invention, a particular tool string may include redundant actuators that face in the same direction. Therefore, if one of these redundant actuators fails, another actuator may be used in its place.

As an example of another embodiment of the invention, the actuator module may control more than one downhole tool. In this manner, the actuator module may, for example, contain a propellant cartridge and associated piston assembly for each downhole tool that is actuated by the actuator module. Separate communication paths in the carrier housing extend from the actuator module to the various tools.

In some embodiments of the invention, the propellant of the propellant cartridge may be replaced by another pressure generating medium. For example, in some embodiments of the invention, the propellant may be replaced by an explosive, and this explosive may be detonated by, for example, a detonation device. Depending on the particular embodiment of the invention, the explosive moves the piston assembly to permit the communication of fluid pressure to the operator mandrel of the tool. In some embodiments of the invention, the explosive products a sufficient force that is used to drive the operator mandrel of the tool in an open bore completion.