Abstract:
A downhole actuator apparatus that selectively maintains a pressure differential between two pressure regions in a well. The apparatus includes a body defining first and second chambers. A piston is slidably disposed in the body and is selectively moveable between first and second positions. A barrier is disposed in the body to selectively separate the first and second chambers. A fluid is disposed in the first chamber between the barrier and the piston. A control system that is at least partially disposed within the body is operable to generate an output signal responsive to receipt of a predetermined input signal. The output signal is operable to create a failure of the barrier such that at least a portion of the fluid flows from the first chamber to the second chamber and the piston moves from the first position to the second position.

Description:
FIELD OF THE INVENTION 
     This invention relates, in general, to equipment utilized in conjunction with operations performed in subterranean wells and, in particular, to a downhole actuator apparatus having a chemically activated trigger. 
     BACKGROUND OF THE INVENTION 
     Without limiting the scope of the present invention, its background will be described in relation to setting packer assemblies, as an example. 
     In the course of completing a subterranean well, one or more packer assemblies are commonly installed at various locations within the well to isolate the wellbore annulus from the production tubing. Typically, a packer assembly incorporates a slip arrangement for securing the packer against the casing or liner wall and an expandable elastomeric element for creating a reliable hydraulic seal to isolate the annulus. In this manner, the packer assemblies are capable of supporting the production tubing and other completion equipment in the well and providing a seal between the outside of the production tubing and the inside of the well casing to block movement of fluids in the annulus to, for example, isolate a production interval. 
     Such production packers as well as other types of downhole tools may be run downhole on production tubing to a desired depth in the wellbore. Certain production packers may be set hydraulically by creating a pressure differential across a setting piston. For example, this pressure differential may be generated by creating a pressure differential between the fluid within the production tubing and the fluid within the wellbore annulus. This pressure differential shifts the setting piston to actuate the production packer into sealing and gripping engagement with the wellbore casing or liner. To prevent premature actuation of the setting piston, an actuator assembly including a rupture disc may be positioned in the flow path between the pressure differential. When it is desired to set the production packer, sufficient pressure may be applied to burst the rupture disc, thereby allowing the actuator assembly to operate and providing a fluid path for the differential pressure to operate on the setting piston. 
     As operators increasingly pursue more complicated completions in deep water offshore wells, highly deviated wells and extended reach wells, the use of rupture discs to create a downhole pressure barrier has become more difficult due to the lack of pressure headroom between the downhole hydrostatic pressure and the burst or collapse pressure of the downhole tubulars. Accordingly, a need has arisen for a downhole actuator assembly operable to selectively prevent and allow the application of a pressure differential to a hydraulically set downhole tool. A need has also arisen for such a downhole actuator assembly that is operable for use in complicated completions in deep water offshore wells, highly deviated wells and extended reach wells. 
     SUMMARY OF THE INVENTION 
     The present invention disclosed herein is directed to an improved downhole actuator assembly operable to selectively prevent and allow the application of a pressure differential to a hydraulically set downhole tool. In addition, the downhole actuator assembly of the present invention is operable for use in complicated completions in deep water offshore wells, highly deviated wells and extended reach wells. 
     In one aspect, the present invention is directed to a downhole actuator apparatus that has a body defining first and second chambers and a piston slidably disposed in the body that is selectively moveable between first and second positions. A barrier is disposed in the body to selectively separate the first and second chambers. A fluid is disposed in the first chamber between the barrier and the piston. A control system that is at least partially disposed within the body is operable to generate an output signal responsive to receipt of a predetermined input signal. The output signal is operable to create a failure of the barrier such that at least a portion of the fluid flows from the first chamber to the second chamber and the piston moves from the first position to the second position. 
     In one embodiment, the body defines a fluid path between two pressure regions and the piston is sealably disposed in the fluid path to maintain a pressure differential between the two pressure regions when the piston is in the first position. In this embodiment, the piston may include a piston area that is exposed to pressure from at least one of the pressure regions to bias the piston from the first to the second position. Alternatively or additionally, the piston may be biased toward the second position from the first position by a spring. In another embodiment, the fluid in the first chamber prevents the piston from moving to the second position until failure of the barrier. In this embodiment, fluid may be one or more substantially incompressible fluids, one or more compressible fluids or may be a combination of one or more substantially incompressible fluids and one or more compressible fluids. 
     In one embodiment, the barrier may be a disc member. In another embodiment, the control system may include a signal detector, a control circuit and a trigger, such that upon receipt of the predetermined input signal by the signal detector, the control circuit activates the trigger to create the failure of the barrier. In this embodiment, the predetermined input signal may be a surface generated signal such as a wireless signal, an electromagnetic signal, an acoustic signal, a pressure signal, an electrical signal, an optical signal or the like. Alternatively, the predetermined input signal may be a downhole generated signal such as a signal from a timer, a downhole sensor or the like. Also, in this embodiment, the output signal may be heat generated by the trigger that melts at least a portion of the barrier, pressure generated by the trigger that shifts a piercing assembly that forms an opening through the barrier, a chemical jet generated by the trigger that makes an opening in the barrier or the like. In this and other embodiments, the trigger may include an energetic material such as pyrotechnic compositions, flammable solids, explosives, thermites and the like. 
     In another aspect, the present invention is directed to a downhole actuator apparatus that has a body defining first and second chambers and a fluid path between two pressure regions. A piston is slidably disposed in the body and selectively moveable between first and second positions. The piston is sealably disposed in the fluid path to maintain a pressure differential between the two pressure regions when the piston is in the first position. A barrier is disposed in the body to selectively separate the first and second chambers. A fluid is disposed in the first chamber between the barrier and the piston. The fluid is operable to selectively prevent the piston from moving to the second position. A control system is disposed at least partially within the body. The control system includes a signal detector, a control circuit and a thermite trigger, such that upon receipt of a predetermined input signal by the signal detector, the control circuit activates the thermite trigger to create a failure of the barrier enabling at least a portion of the fluid to flow from the first chamber to the second chamber and the piston to move from the first position to the second position, thereby allowing fluid communication between the two pressure regions. 
     In a further aspect, the present invention is directed to a downhole actuator apparatus that includes a body defining a fluid path between two pressure regions. A barrier is disposed in the fluid path to maintain a pressure differential between the two pressure regions. A control system is at least partially disposed within the body. The control system includes a signal detector, a control circuit and a thermite trigger, wherein upon receipt of a predetermined input signal by the signal detector, the control circuit activates the thermite trigger to create a failure of the barrier, thereby allowing fluid communication between the two pressure regions. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of the features and advantages of the present invention, reference is now made to the detailed description of the invention along with the accompanying figures in which corresponding numerals in the different figures refer to corresponding parts and in which: 
         FIG. 1  is a schematic illustration of a well system including a plurality of actuators used to operate well tools by controlling fluid communication between pressure regions in the well according to an embodiment of the present invention; 
         FIGS. 2A-2B  are cross sectional views of a downhole actuator apparatus for controlling fluid communication between pressure regions in the well in first and second operating positions according to an embodiment of the present invention; 
         FIGS. 3A-3B  are cross sectional views of a downhole actuator apparatus for controlling fluid communication between pressure regions in the well in first and second operating positions according to an embodiment of the present invention; 
         FIGS. 4A-4B  are cross sectional views of a downhole actuator apparatus for controlling fluid communication between pressure regions in the well in first and second operating positions according to an embodiment of the present invention; and 
         FIGS. 5A-5B  are cross sectional views of a downhole actuator apparatus for controlling fluid communication between pressure regions in the well in first and second operating configurations according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     While the making and using of various embodiments of the present invention are discussed in detail below, it should be appreciated that the present invention provides many applicable inventive concepts, which can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative of specific ways to make and use the invention, and do not delimit the scope of the invention. 
     Referring initially to  FIG. 1 , a well system that is schematically illustrated and generally designated  10 , includes a plurality of well tools that are interconnected to form a tubular string  12  that has been installed in casing string  14  that is cemented in a wellbore  16 . Each of the illustrated well tools includes an actuator for operating that well tools between its operating positions or configurations. Specifically, the illustrated well tools are depicted as a circulating valve  18 , a tester valve  20 , a multi-sampler tool  22 , a packer  24  and a choke  26 . As depicted, actuator  28  is used to operate circulating valve  18 , actuator  30  is used to operate tester valve  20 , actuators  32 ,  34  are used to control flow into sample chambers  36 ,  38  of a multi-sampler tool  22 , actuator  40  is used to set packer  24  and actuator  42  is used to operate choke  26 . 
     In each of these cases, the actuators are used to operate the corresponding well tool by controlling fluid communication between pressure regions in the well. For example, when the pressure regions are blocked from one another, the well tool is in one position and when there is fluid communication between the pressure regions, the well tool is actuated to another position. The pressure regions could be, for example, an interior flow passage  44  of tubular string  12  and an annulus  46  formed radially between tubular string  12  and casing  14 . In another example, the pressure regions could be interior flow passage  44  of tubular string  12  and an interior chamber within a sample chamber  36 ,  38  or the pressure regions could be two chambers with a sample chamber  36 ,  38  such as a nitrogen charged chamber and an atmospheric chamber. As a further example, the pressure regions could be sections of a control line leading from the surface to a well tool, sections of a control line between well tools or other similar control line configuration. Accordingly, it is to be understood by those skilled in the art that the actuators of the present invention may be used to operate the corresponding well tools by controlling fluid communication between any two pressure regions in the well without departing from the principles of the present invention. 
     Even though  FIG. 1  depicts the actuators of the present invention in a specific well system, it should be understood by those skilled in the art that the actuators of the present invention are equally well suited for use with a wide variety of well tools in other types of well systems. Also, even though  FIG. 1  depicts the actuators of the present invention in a vertical section of a wellbore, it should be understood by those skilled in the art that the actuators of the present invention are equally well suited for use in wells having other configurations including slanted wells, deviated wells, horizontal well or wells having lateral branches. Accordingly, it should be understood by those skilled in the art that the use of directional terms such as above, below, upper, lower, upward, downward, left, right and the like are used in relation to the illustrative embodiments as they are depicted in the figures, the upward direction being toward the top of the corresponding figure and the downward direction being toward the bottom of the corresponding figure. 
     Referring now to  FIGS. 2A-2B , a downhole actuator apparatus for controlling fluid communication between pressure regions in the well is depicted in first and second operating positions and is generally designated  50 . It should be noted that actuator  50 , as well as the other actuator embodiments described below, may operate as any of the actuators described above with reference to  FIG. 1  or may operate as a component part or subassembly of such an actuator assembly, for example, to pilot another component of the actuator assembly or associated well tool. In the illustrated embodiment, actuator  50  has an axially extending generally tubular body or housing assembly  52 . In the illustrated embodiment, housing assembly  52  includes two housing members  54 ,  56  that are securably coupled together at a threaded coupling  58 . Housing member  56  includes a port  60  and a port  62  that are respectively in communication with different pressure regions in the well. For example, port  60  may be associated with a relatively high pressure region  64 , such as the wellbore annulus, a pressurized gas chamber, the central flow path of a tubular string or the like. Likewise, port  62  may be associated with a relatively low pressure region  66 , such as an atmospheric chamber, a sample chamber or the like. 
     Slidably and sealingly disposed within housing member  56  is a piston  66  that initially blocks communication between ports  60 ,  62 , as best seen in  FIG. 2A . Piston  66  is biased to the left by pressure acting on a differential piston area  68 . Initially, displacement of piston  66  to the left is substantially prevented a fluid  70  disposed within a fluid chamber  72 . Fluid  70  is preferably a substantially incompressible fluid such as a hydraulic fluid but could alternatively be a compressible fluid such as nitrogen, a combination of substantially incompressible fluids, a combination of compressible fluids or a combination of one or more compressible fluids with one or more substantially incompressible fluids. Preferably, while fluid  70  prevents piston  66  from moving sufficiently to the left to open communication between ports  60 ,  62 , piston  66  is able to float as pressure differences between pressure region  64  and fluid chamber  72  are balanced. 
     Securably and sealingly positioned between housing member  54  and housing member  56  is a barrier assembly  74  that includes a barrier  76  and a support assembly  78  having a fluid passageway  80  defined therethrough. Barrier  76  initially prevents fluid  70  from escaping from chamber  72  into a chamber  82  of housing member  54 . Barrier  76  is depicted as a disk member and is preferably formed from a metal but could alternatively be made from a plastic, a composite, a glass, a ceramic, a mixture of these materials, or other material suitable for initially containing fluid  70  in chamber  72  but failing in response to an output signal as described below. 
     Positioned within housing member  54  is a control system  84  that includes numerous components that cooperate together to receive and process a predetermined input signal and to generate an output signal that creates a failure of barrier  76 . For example, control system  84  includes a signal detector such as a pressure sensor, a strain sensor, a hydrophone, an antenna or any other type of signal detector which is capable of receiving the predetermined input signal, which may be in the form of a wireless signal such as an acoustic signal, pressure pulses, electromagnetic telemetry or the like. Alternatively, the signal detector could be hard wired to the surface and operable to receive the predetermined input signal in the form of an electrical signal, an optical signal or the like. As another alternatively, the signal detector may communicate with other downhole devices which may be internal or external to housing assembly  52  such as a timer, a downhole sensor or the like that generates the predetermined input signal. 
     The signal detector may include or be in communication with a control circuit that interprets the input signal, for example, by digitally decoding the input signal, and that determines whether actuator  50  should be operated. The control circuit is preferably an electronic circuit including various components such as a microprocessor, a digital signal processor, random access member, read only member and the like that are programmed or otherwise operable to recognize the predetermined input signal and to determine whether actuator  50  should be operated. Control system  84  also includes a downhole power supply operable to provide the required power to the other elements of control system  84 . Preferably, the power supply is in the form of one or more batteries, however, other types of power supplies may alternatively be used without departing from the principles of the present invention. Control system  84  may also include timing devices to delay or control the time period between receipt of the predetermined input signal and the generation of the output signal. 
     Control system  84  further includes an output signal generator or trigger depicted in  FIG. 2A  as a chemical jet nozzle assembly  86 . Chemical jet nozzle assembly  86  includes a chemical element or energetic material  88 , an ignition agent  90  and a nozzle  92 . Chemical element  88  is preferably formed from a composition of a metal powder and a metal oxide that produces an exothermic chemical reaction at high temperature known as a thermite reaction. The metal powder used in the composition may include aluminum, magnesium, calcium, titanium, zinc, silicon, boron and the like. The metal oxide used in the composition may include boron(III) oxide, silicon(IV) oxide, chromium(III) oxide, manganese(IV) oxide, iron(III) oxide, iron(II, III) oxide, copper(II) oxide, lead(II, III, IV) oxide and the like. For example, a composition of aluminum and iron(III) oxide may be used which has a reaction according to the following equation:
 
Fe 2 O 3 +2Al−&gt;2Fe+Al 2 O 3 +Heat
 
     Use of chemical element  88  that produces a thermite reaction is advantageous in the present invention as the reactants are stable at wellbore temperatures but produce an extremely intense exothermic reaction following ignition. Chemical element  88  may also include a binder material to hold the included chemicals together, including, for example, TEFLON™, VITON™, PBAN (polybutadiene acrylonitrile copolymer), HTPB (hydroxyl-terminated polybutadiene), epoxy and the like. 
     In the illustrated embodiment, ignition agent  90  is connected to the control circuit via an electrical cable  94  so that, when it is determined that actuator  50  should be operated, the control circuit supplies electrical current to ignition agent  90 . Ignition agent  90  is preferably a metal burning fuse such as a magnesium fuse which is activated by the electrical current. Metal fuses are preferred as metals burn without releasing cooling gases and can burn at extremely high temperatures. Magnesium fuses are most preferred due to the reactive nature of magnesium and the temperature at which magnesium burns which is sufficiently high to ignite chemical element  88 . Alternatively, a nichrome wire such as a NiCr60 wire, may be used to directly ignite chemical element  88 . As another alternative, a nichrome wire may be used in an ignition train to ignite a metal burning fuse which in turn ignites chemical element  88 . In this case, both the nichrome wire and the metal burning fuse may be considered to be ignition agent  90 . 
     In the illustrated embodiment, nozzle  92  is designed to focus the heat and molten materials created in the thermite reaction into a hot jet that is directed towards barrier  76 . The hot jet causes a focused hot spot on barrier  76  resulting in the desired failure of barrier  76 . It is noted that the mode of failure of barrier  76  may including penetrating, melting, combustion, ignition, weakening or other degradation of barrier  76 . 
     Even though control system  84  has been described as being positioned within housing member  54 , those skilled in the art will recognize that certain elements of control system  84  could alternatively be positioned outside of actuator  50  including the signal detector, the control circuit and the power supply, without departing from the principle of the present invention. For example, one or more of these components could be located within the well tool that is to be actuated by actuator  50  or could be located in other tools that are coupled to actuator  50 . For the purposes of the present invention, it is only relevant that the output signal generator is positioned sufficiently proximate to barrier  76  to cause the desired failure. 
     In operation, the signal detector of control system  84  receives the predetermined input signal and the control circuit processes the predetermined input signal to verify the signal. If the control circuit determines that actuator  50  should be operated, electrical power is supplied from the power supply to ignition agent  90  to initiate the chemical reaction in chemical element  88 . The chemical reaction causes barrier  76  to fail, creating opening  96  therethrough, as best seen in  FIG. 2B . Fluid communication is thus established between chamber  72  and chamber  82  through opening  96 , which allows fluid  70  to exit chamber  72  as piston  66  is urged to the left by pressure from high pressure region  64  acting on differential piston area  68 . Communication is now permitted between pressure regions  64 ,  66  via ports  60 ,  62 , as best seen in  FIG. 2B . 
     Referring now to  FIGS. 3A-3B , a downhole actuator apparatus for controlling fluid communication between pressure regions in the well is depicted in first and second operating positions and is generally designated  150 . Actuator  150  has an axially extending generally tubular body or housing assembly  152  including two housing members  154 ,  156  that are securably coupled together at a threaded coupling  158 . Housing member  156  includes ports  160 ,  162  that are respectively in communication with different pressure regions  164 ,  166 . Slidably and sealingly disposed within housing member  156  is a piston  166  that initially blocks communication between ports  160 ,  162 , as best seen in  FIG. 3A . Piston  166  is biased to the left by pressure acting on a differential piston area  168 . Initially, displacement of piston  166  to the left is substantially prevented a fluid  170  disposed within a fluid chamber  172 . Preferably, while fluid  170  prevents piston  166  from moving sufficiently to the left to open communication between ports  160 ,  162 , piston  166  is able to float as pressure differences between pressure region  164  and fluid chamber  172  are balanced. 
     Securably and sealingly positioned between housing member  154  and housing member  156  is a barrier assembly  174  that includes a barrier  176  and a support assembly  178  having a fluid passageway  180  defined therethrough. Barrier  176  initially prevents fluid  170  from escaping from chamber  172  into a chamber  182  of housing member  154 . Positioned within housing member  154  is a control system  184  that includes a signal detector, a control circuit, a power supply, optional timing devices and an output signal generator or trigger depicted in  FIG. 3A  as a chemically initiated piercing assembly  186 . Chemically initiated piercing assembly  186  includes a chemical element or energetic material  188 , an ignition agent  190  and a piercing element  192  slidably disposed within a cylinder  194 . Chemical element  188  is preferably a combustible element such as a propellant that has the capacity for extremely rapid but controlled combustion that produces a combustion event including the production of a large volume of gas at high temperature and pressure. 
     In an exemplary embodiment, chemical element  188  may comprises a solid propellant such as nitrocellulose plasticized with nitroglycerin or various phthalates and inorganic salts suspended in a plastic or synthetic rubber and containing a finely divided metal. Chemical element  188  may comprise inorganic oxidizers such as ammonium and potassium nitrates and perchlorates such as potassium perchlorate. It should be appreciated, however, that substances other than propellants may be utilized without departing from the principles of the present invention, including other explosives, pyrotechnics, flammable solids or the like. In the illustrated embodiment, ignition agent  190  is connected to the control circuit via an electrical cable  196  so that, when it is determined that actuator  150  should be operated, the control circuit supplies electrical current to ignition agent  190 . 
     In operation, the signal detector of control system  184  receives the predetermined input signal and the control circuit processes the predetermined input signal to verify the signal. If the control circuit determines that actuator  150  should be operated, electrical power is supplied from the power supply to ignition agent  190  to initiate the chemical reaction in chemical element  188 . The chemical reaction causes piercing element  192  to move to the right piecing barrier  176 , as best seen in  FIG. 3B . Fluid communication is thus established between chamber  172  and chamber  182  through opening  196 , which allows fluid  170  to exit chamber  172  as piston  166  is urged to the left by pressure from high pressure region  164  acting on differential piston area  168 . Communication is now permitted between pressure regions  164 ,  166  via ports  160 ,  162 , as best seen in  FIG. 3B . 
     Referring now to  FIGS. 4A-4B , a downhole actuator apparatus for controlling fluid communication between pressure regions in the well is depicted in first and second operating positions and is generally designated  250 . Actuator  250  has an axially extending generally tubular body or housing assembly  252  including two housing members  254 ,  256  that are securably coupled together at a threaded coupling  258 . Housing member  256  includes ports  260 ,  262  that are respectively in communication with different pressure regions  264 ,  266 . Slidably and sealingly disposed within housing member  256  is a piston  266  that initially blocks communication between ports  260 ,  262 , as best seen in  FIG. 4A . Piston  266  is biased to the left by a biasing member depicted as a spiral wound compression spring  268 , however, those skilled in the art will recognize that other types of biasing member, including other types of mechanical spring or fluid spring, could alternatively be used without departing from the principle of the present invention. Initially, displacement of piston  266  to the left is substantially prevented a fluid  270  disposed within a fluid chamber  272 . 
     Securably and sealingly positioned between housing member  254  and housing member  256  is a barrier assembly  274  that includes a barrier  276  and a support assembly  278  having a fluid passageway  280  defined therethrough. Barrier  276  initially prevents fluid  270  from escaping from chamber  272  into a chamber  282  of housing member  254 . Positioned within housing member  254  is a control system  284  that includes a signal detector, a control circuit, a power supply, optional timing devices and an output signal generator or trigger depicted in  FIG. 4A  as a chemical jet nozzle assembly  286 . Chemical jet nozzle assembly  286  includes a chemical element or energetic material  288 , an ignition agent  290  and a nozzle  292 . 
     In operation, the signal detector of control system  284  receives the predetermined input signal and the control circuit processes the predetermined input signal to verify the signal. If the control circuit determines that actuator  250  should be operated, electrical power is supplied from the power supply to ignition agent  290  via electrical cable  294  to initiate the chemical reaction in chemical element  288 . The chemical reaction causes barrier  276  to fail, as best seen in  FIG. 4B . Fluid communication is thus established between chamber  272  and chamber  282  through opening  296 , which allows fluid  270  to exit chamber  272  as piston  266  is urged to the left by spring  268 . Communication is now permitted between pressure regions  264 ,  266  via ports  260 ,  262 , as best seen in  FIG. 4B . 
     Referring now to  FIGS. 5A-5B , a downhole actuator apparatus for controlling fluid communication between pressure regions in the well is depicted in first and second operating positions and is generally designated  350 . Actuator  350  has an axially extending generally tubular body or housing assembly  352  including two housing members  354 ,  356  that are securably coupled together at a threaded coupling  358 . Housing member  356  includes ports  360 ,  362  that are respectively in communication with different pressure regions  364 ,  366 . Positioned within port  360  is a barrier  376  that is operable to initially prevent fluid communication between pressure regions  364 ,  366 . Positioned within housing assembly  352  is a control system  384  that includes a signal detector, a control circuit, a power supply, optional timing devices and an output signal generator or trigger depicted in  FIG. 4A  as a chemical jet nozzle assembly  386 . Chemical jet nozzle assembly  386  includes a chemical element or energetic material  388 , an ignition agent  390  and a nozzle  392 . 
     In operation, the signal detector of control system  384  receives the predetermined input signal and the control circuit processes the predetermined input signal to verify the signal. If the control circuit determines that actuator  350  should be operated, electrical power is supplied from the power supply to ignition agent  390  via electrical cable  394  to initiate the chemical reaction in chemical element  388 . The chemical reaction causes barrier  376  to fail, as best seen in  FIG. 5B . Communication is now permitted between pressure regions  364 ,  366  via ports  360 ,  362 , as best seen in  FIG. 5B . 
     While this invention has been described with reference to illustrative embodiments, this description is not intended to be construed in a limiting sense. Various modifications and combinations of the illustrative embodiments as well as other embodiments of the invention will be apparent to persons skilled in the art upon reference to the description. It is, therefore, intended that the appended claims encompass any such modifications or embodiments.