Patent Publication Number: US-10781677-B2

Title: Pyrotechnic initiated hydrostatic/boost assisted down-hole activation device and method

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application is a U.S. National Stage Application of International Application No. PCT/US2015/036461 filed Jun. 18, 2015, which is incorporated herein by reference in its entirety for all purposes. 
     TECHNICAL FIELD 
     The present disclosure relates generally to activation of down-hole devices in subterranean formations, and more particularly, to a pyrotechnic initiated hydrostatic/boost assisted device for activating the down-hole device. 
     BACKGROUND 
     Hydrocarbons, such as oil and gas, are commonly obtained from subterranean formations that may be located onshore or offshore. The development of subterranean operations and the processes involved in removing hydrocarbons from a subterranean formation typically include a number of different steps such as, for example, drilling a wellbore at a desired well site, treating the wellbore to optimize production of hydrocarbons, and performing the necessary steps to produce and process the hydrocarbons from the subterranean formation. 
     There are a number of different methods for perforating a production tubing or casing in connection with a work-over or other post-completion well service operation. Commonly used methods employ explosive charges. There are a number of logistical issues associated with the use of explosives, however, to perforate production tubing or casing. In many instances, transport of the necessary explosives is tightly controlled making movement of the devices to the well site very difficult. 
     Mechanical perforation avoids the logistical issues of explosives. Devices for mechanically perforating a well casing without the use of explosives are also known in the art and, in fact, predate the use of explosives. Such devices include, for example, laterally movable punches and toothed wheel perforators. Mechanical perforators require sufficient motive force to be activated to operate effectively. Current systems employ large rechargeable hydraulic power sources for actuating the down-hole tools. Such systems typically employ complex valving schemes to operate the tool. An activation system which utilizes a much smaller and less complex device to perforate the tubing or casing and which is thus desired. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of the features and advantages of the present disclosure, reference is now made to the detailed description of the present disclosure along with the accompanying figures in which corresponding numerals in the different figures refer to corresponding parts and in which: 
         FIG. 1  illustrates a downhole tool employing a mechanical perforator which is activated using a pyrotechnic initiator device in accordance with the present disclosure; 
         FIG. 2  is a cross-sectional schematic view of an exemplary booster-based, force-balanced activating device according to an aspect of the present disclosure and in an initial position; and 
         FIG. 3  is a cross-sectional schematic view of an exemplary booster-based, force-balanced activating device according to  FIG. 2  in an activated position. 
         FIG. 4  is a cross-sectional schematic view of an exemplary hydrostatic-based, force-balanced activating device according to another aspect of the present disclosure; 
         FIG. 5  is a cross-sectional schematic view of a pyrotechnic initiator in accordance with the present disclosure; 
         FIG. 6  is a schematic view of down-hole tool with a button type mechanical perforator shown in the activated position; and 
         FIG. 7  is a schematic view of down-hole tool with a blade type mechanical perforator shown in the activated position. 
     
    
    
     DETAILED DESCRIPTION 
     Illustrative embodiments of the present disclosure are described in detail herein. In the interest of clarity, not all features of an actual implementation are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation specific decisions must be made to achieve developers&#39; specific goals, such as compliance with system related and business related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of the present disclosure. Furthermore, in no way should the following examples be read to limit, or define, the scope of the disclosure. 
     It is to be understood that the various embodiments of the present disclosure described herein may be utilized in various orientations, such as inclined, inverted, horizontal, vertical, etc., and in various configurations, without departing from the principles of the present disclosure. The embodiments are described merely as examples of useful applications of the principles disclosed herein, which is not limited to any specific details of these embodiments. 
     In the following description of the representative embodiments of the present disclosure, directional terms, such as “above,” “below,” “upper,” “lower,” etc., are used for convenience in referring to the accompanying drawings. In general, “above,” “upper,” “upward” and similar terms refer to a direction toward the earth&#39;s surface along a wellbore, and “below,” “lower,” “downward” and similar terms refer to a direction away from the earth&#39;s surface along the wellbore. 
       FIG. 1  is a schematic view of a well system including an embodiment of the mechanical perforator activating apparatus according to the present disclosure positioned in a subterranean wellbore. A well system  10  is depicted having a wellbore  12  extending through a subterranean formation  14 , shown having casing  16 . The devices disclosed herein can be used in cased or uncased wells, vertical, deviated or horizontal wells, and for on-shore or off-shore drilling. A tubing string  18  is shown having a plurality of tubing sections  20  and a down-hole tool  22 , which includes mechanical perforator  30 , downhole force generator (DFG) assembly  40 , and force multiplier assembly  50 . The down-hole tool  22  is inserted into a section of production tubing or casing  24 , which is installed in the well bore  12 . A mechanical linkage assembly  60  between the DFG and the downhole tool is provided for transferring the power generated by the DFG into longitudinal or rotary movement, via a shaft, piston, sleeve, etc. The DFG assembly preferably includes a processor to operate the tool, measure environmental and tool parameters, etc. The mechanical perforator  30  operable by DFG units is described generally below with reference to  FIGS. 6 and 7 , but is not described in any detail as those of ordinary skill in the art will be familiar with such devices. Indeed, the present disclosure is directed to the activating mechanism for the mechanical perforator  30  and not the mechanical perforator itself. 
       FIG. 2  is a cross-sectional schematic view of an exemplary booster-based, force-balanced down-hole tool activating device  100  according to an aspect of the present disclosure.  FIG. 3  is a cross-sectional schematic view of an exemplary booster-based, force-balanced down-hole tool activating device according to  FIG. 3  in an activated position. The Figures are discussed in conjunction. The movement most frequently used is a linear axial stroke, in either direction. The embodiment of the down-hole tool activating device shown provides an axially upward movement of a selected stroke length. As those of skill in the art will recognize, other embodiments can provide a downward activation stroke. Additionally, the down-hole tool activating device can be used to provide other types of mechanical motion, such as rotational, etc., with appropriate mechanical parts to translate motion, as will be recognized by those of skill in the art. The embodiment is discussed in terms of a down-hole tool activating device for use in linear actuation of a mechanical perforator, however, it is understood that the devices disclosed herein can be used in other types of tool assemblies and for providing non-axial motive force. 
     The down-hole tool activating device  100  has an upper connector subassembly  102 , shown configured for connection at threads  104  to a sucker rod (not shown) or similar. It is understood that the upper connector can be selected for connection to a tool string, wireline, coiled tubing, slickline, e-line etc. The upper connector  102  has lower threads at  110  which mate with the housing  108  of the control assembly  106 . 
     The control assembly  106  has a housing  108 , preferably a tubular body, connected to the upper connector sub  102  at threads  110  and connected at threads  112  to connector subassembly  130 . The control assembly  106  houses an electronic control module  114  having, in a preferred embodiment, a power source, such as batteries, an electric-powered timer or timing device, and indicators  118  for start-up and timer set values. The indicators can be LED or other indicators as known in the art. The timer and battery packs are not discussed in detail and are known in the art. An electrical connector  116  is preferably provided for e-line start. It is also possible to provide electrical power via power line from the surface for powering the actuator (pyrotechnic initiator)  154 . A hermetic connector  120  is positioned between the control module  114  and connector sub  130  to provide a hermetically sealed section for housing the control module. 
     A connector subassembly  130  has a connector body  132  with a bore  134  defined therein and extending axially there through. The bore  134  houses communication lines, such as electrical wiring, necessary for transmitting a signal from the control module to the actuator (pyrotechnic initiator)  154 . The connector sub attaches to housing  108  at its upper end and to housing  142  at its lower end. 
     A booster assembly  140  has a housing  142  attached at threads  144  to the connector sub  130  and at threads  146  to connector sub  180 . The booster assembly  140  defines a booster chamber  148  which is pre-charged with a pressurized fluid, preferably an inert gas to an actuation pressure. A charge port  151  and charging valve  150  are provided, with appropriate fluid passageways to the chamber, for supplying the pressurized gas to the chamber. In the embodiment shown, the charging valve and port are positioned in connector sub  180 , although they can be positioned in connector sub  130  or as part of the booster assembly  140 . 
     Positioned in the booster assembly are a pyrotechnic initiator  154 , actuator retainer  152 , rupture disc  160 , and pin actuator  158 . The initiator  154  is electrically connected via wire extending from the actuator retainer  152 , through a conduit which is in threaded connection to the passageway  134  of connector assembly  130 , and the control electronic control module  114 . The initiator is triggered by a small electrical charge. The actuator retainer  152  houses the initiator  154 . The rupture disc retainer and actuator guide  156  is mounted to the tool assembly, for example, to the connector assembly  180 , as shown, via threaded connection or similar. Alternately, the retainer can be mounted to the housing, etc. The initiator  154  is positioned adjacent or proximate a rupture disc  160  that initially blocks fluid flow from the pressurized chamber. 
     Small, pyrotechnic initiators  154  are available from commercial vendors known in the art, such as SDI, Inc. The pyrotechnic initiator utilizes a small amount of pyrotechnic material, triggerable by a low electrical charge, to drive a thruster pin  158  longitudinally into and rupturing the rupture disc  160 . The thruster pin  158  is preferably hollow with a relief port on the stem such that if the disc fails to rupture after the pin has pushed through the disc, a fluid path is available through the pin. Note that the pyrotechnic initiator does not provide the motive force for movement of the activating rod. The tool assembly is not a pyrotechnic activating tool. The initiator only provides motive force to move the pin actuator to rupture the rupture disc  160 . The motive force for activating the tool is provided by the release of pressurized gas in the booster chamber. Because such a low amount of force is required of the initiator, and such a small amount of chemical or pyrotechnic required to provide the force, the preferred pyrotechnic initiator is classified by DOT and BATF as a non-explosive for purposes of transportation and shipping. 
     In addition to the preferred pyrotechnic initiator, other initiators can be used, preferably low-powered and classified as non-explosive. For example, such initiators include electrical, chemical, thermal, and other initiators. The initiators can open the pressurized chamber by opening, melting, dissolving, burning, etc., a fluid barrier. Further, the initiator can be used to power or actuate a variety of available actuators, such as a thruster pin, a check-valve, other valves, etc., to open the pressurized chamber to fluid flow. 
     Power to trigger the initiator is provided from the battery pack or power source in the electronic control module  114  of the control assembly  106 . Since the preferred initiator is small and requires low power to initiate, it is ideal for low-powered battery activation. With a small power requirement, the battery can be small and low power and included within the timer module. An exemplary battery might include a single low rate “AA” primary lithium cell. The timer module can be small and used for the various tools for the different activating tools. The small timer module can thermally insulated, for example, for use in higher temperature operations within the larger housings of the bigger activating tools. The timer module is preferably switch-selectable and can include an electrical start port for either e-line or a pressure/temperature switch. Additional features could be added to the timer (pressure, temperature, motion, etc.); however, this would result in a larger electronics and battery assembly. 
     The rupture disc  160  can be selected from those known in the art and alternative discs and rupture assemblies will be apparent to those of skill in the art. The disc can be made of ceramic, metal, plastic, or other similar material. The disc can be ruptured, punctured, dissolved, melted, or otherwise penetrated, depending on the selected initiator and actuator. The preferred assembly utilizes a rupture disc which is physically punctured or broken by the extendable pin of the initiator. The rupture disc  160  initially blocks fluid flow from pressurized chamber  148  into passageway  184  of connector assembly  180 . In a preferred embodiment, the rupture disc is mounted to the housing, connector assembly or retainer  156 . The disc assembly is positioned in a bore  157  designed for that purpose in the connector assembly  180 . Seals  161  are provided as necessary to facilitate assembly and fluid isolation. The retainer  156  provides and maintains positioning of the disc. Upon rupture, fluid communication is provided between the pressurized chamber  148  and the passageway  184  through connector assembly  180 . 
     The initiator assembly may be a thruster assembly for rupturing discs, such as the actuator assemblies commercially made available by the assignee herein, Halliburton Energy Services, Inc. Additional actuator assemblies are known in the art and will be understood by persons of skill in the art. Key components are the rupture disc, an electrical power source, and an electrically-initiated method of breaching the barrier disc. In one exemplary embodiment, the electrical power source is a battery, and a thruster assembly is used to puncture the disc. 
     Connector assembly  180  is attached to a vent chamber assembly  190 , preferably by threaded connection to a vent chamber housing  192 . The vent chamber  194  defined within the vent chamber assembly contains fluid at hydrostatic pressure as it is open to fluid flow between the chamber and the exterior of the tool (the wellbore). One or more ports  196  provide fluid communication between chamber and exterior. A thick-walled tube  198  extends from the passageway  184  to a force-balance piston rod  216 , providing communication of the released pressurized gas from the pressurized chamber  148  to the piston passageway  218 . As piston rod  216  moves upward into the vent chamber, pressure is equalized in the vent chamber  194  as fluid flows out of the chamber through ports  196 . Note that the activation section is force balanced by hydrostatic pressure acting on the power rod  230  from below, so the activation action is independent of hydrostatic pressure. 
     A flow restrictor  164  is preferably positioned across an upper portion  162  of the passageway  184  in body  182  of the connector assembly  180 . The speed of activation is controlled by the flow restrictor. The flow restrictor can be positioned elsewhere along the flow path from the pressurized chamber to the piston head. Flow restrictors and use thereof to control activation speed is known in the art. The flow restrictor can be a flow nozzle, orifice, plate, inflow control device, autonomous inflow control device, tortuous path, as known in the art. 
     A connector assembly  200  provides flow connection between the vent chamber assembly  190  and the force-balance piston assembly  210 . The connector assembly body  202  is threadedly attached to the vent chamber housing  192  and to a piston housing  212 . An axial passageway  204  is defined through the connector body, the piston rod  216  axially slidable therein. Seals  206  are provided for sealing engagement between passageway wall and piston. Further, rod-wipes  208 , or similar, are mounted to wipe the exterior surface of the piston as it moves through the passageway  204 . 
     A piston assembly  210  is attached to the connector assembly  200  at housing  212 . The housing defines a piston chamber  214  which is divided into two spaces by piston head  220 . The chamber  214  is preferably at atmospheric pressure initially. Piston rod  216  defines an axial passageway  218  therein providing fluid communication from the tube  198  to a passageway  222  through the piston head  220 . The piston rod  216  is mounted to the piston head  220 . A power rod  230  is attached to the lower end of the piston head  220 . Port  224  provides fluid communication from the passageway  218  of the piston rod to the chamber  214  below the piston head  220 . When pressurized gas is released from pressurized chamber  148 , the gas flows through the various passageways and tubes, through passageway  218  of the piston rod, through passageway  222  of the piston head  220 , and through port  224  to the chamber  214  below the piston head. The pressurized gas forces the piston head upward. Upward movement of the piston head causes piston rod  216  to slide upwardly through the connector assembly  200  and into vent chamber  194 . Movement of the piston head also pulls power rod  230  upwardly through a bore  232  defined in the lower end of the piston housing sub  210 . Appropriate seals  234  and wipers  236  may be employed. 
     Movement of the power rod, axially, provides the necessary motion to activate the mechanical perforator positioned below the activation device. The activation force is supplied by the pre-charged fluid in the booster chamber. Carrying the activation force with a gas pre-charge means a large motor and battery arrangement, typical in many downhole force generators, is not required. 
     The entire assembly is compact, reducing the overall length of the tool assembly. This can be important in negotiating long, deviated or horizontal wellbores. Preferably, the length of the activation tool assembly is on the order of six feet for every eight inches of stroke. Greater activation force can be provided by utilizing a force-multiplying piston having varying surface areas on either side of the piston head, as is known in the art. 
       FIG. 4  illustrates a hydrostatically-based, force-balanced down-hole tool activating device  400  according to another embodiment of the present disclosure. The down-hole tool activating device  400  may have many of the same components of the device illustrated in  FIGS. 2 and 3 . The main difference between the embodiment in  FIGS. 2 and 3  and that of  FIG. 4  is that rather than having a pressurized booster chamber which fills the chamber containing the piston assembly  210 , the chamber containing the piston assembly is filled with wellbore fluid at wellbore pressure.  FIG. 4  shows the piston assembly  410  as a simple piston having a head  420  and power rod  416 . The piston assembly  410  however may alternatively have the same construction as piston assembly  210 . The main feature of this embodiment is that is uses the wellbore fluid to act on the piston assembly, which in turn via the power rod  416  activates the mechanical perforator or other down-hole device  418 . 
     The down-hole tool activating device  400  of the embodiment of  FIG. 4  also utilizes a pyrotechnic initiator  454 , actuator retainer  452 , rupture disc  460 , and pin actuator  458 , all of which operate in the manner described above. Upon activation of the pyrotechnic initiator  454  and puncturing of the rupture disc  460 , wellbore fluid from the wellbore  12  enters upper chamber  462  containing the pin actuator  458  via port  466 . The wellbore fluid may optionally flow through a flow restrictor  464  as it enters intermediate chamber  468 , which may optionally be at atmospheric pressure. One or more seals  470  hermetically seal intermediate chamber  468  from lower chamber  472 , which may also optionally be at atmospheric pressure. A one-way relief valve  474  may optionally be disposed in the housing of the assembly  400  to relieve pressure from the lower chamber  472  as the piston assembly  410  is driven downward by the pressure of the wellbore fluid entering intermediate chamber  468  and acting on piston head  420 . As those of ordinary skill in the art will appreciate, the hydrostatically-based and boost-assisted forces on the piston assemblies  210 ,  410  may be combined to enhance the overall actuation force on those assemblies. 
     The details of the pyrotechnic initiators shown in  FIGS. 2-4  are shown in  FIG. 5 . The assembly is referred to generally by reference numeral  500 . The pyrotechnic initiator  500  is defined by a housing  510  which contains a pin actuator or piston pin  512 . The piston pin  512  is sealed to an interior surface of the housing  510  by a pair of O-ring seals  514 ,  516 . The piston pin  512  has a base disposed within the housing and a tip disposed outside the housing. The pyrotechnic initiator  500  further includes a pressure cartridge igniter  518 , which is disposed adjacent to, and below, the piston pin  512  and upon activation acts upon the piston pin. One of the O-rings is disposed adjacent the tip of the piston pin  512  and the other O-ring is disposed adjacent the pressure cartridge igniter  518 . A pair of connector pins  520 ,  522  connects the pressure cartridge igniter  518  to the battery pack or power source in the electronic control module  114  of the control assembly  116 , shown in  FIGS. 2-3 . The pyrotechnic initiator  500  further includes an end cap  524  which enables the initiator to connect to the actuator retainer  152  or other similar housing member. 
       FIGS. 6 and 7  show two exemplary mechanical perforators which may be connected to and activated by the down-hole tool activating devices described herein. In the embodiment illustrated in  FIG. 6 , the mechanical perforator  600  is defined by two pairs of plugs or inserts  602 ,  604 , which are shown in the activated position. The plugs or inserts  602 ,  604  perforate the production tubing  24  upon activation. The plugs or inserts are connected to a series of mechanical linkages which are activated by the piston assemblies described above upon firing of the pyrotechnic initiator described herein. In the embodiment illustrated in  FIG. 7 , the down-hole tool  700  is defined by two pairs of blade-type mechanical perforators  702 ,  704 , which are also connected to via various linkages to the piston assemblies described above upon firing of the pyrotechnic initiator. As explained above, while the present disclosure describes two different types of mechanical perforators, the present disclosure is not directed to the mechanical perforators themselves, but rather that down-hole tool activating device which activates these perforators. As those of ordinary skill in the art will appreciate, the down-hole tool activating device disclosed herein can be used to activate any type of mechanical perforator. 
     A person skilled in the art would, upon a careful consideration of the above description of representative embodiments, readily appreciate that many modifications, additions, substitutions, deletions, and other changes may be made to the specific embodiments, and such changes are contemplated by the principles of the present disclosure. Accordingly, the foregoing detailed description is to be clearly understood as being given by way of illustration and example only, the spirit and scope of the present disclosure being limited solely by the appended claims and their equivalents.