Detonation module

A detonation module for a perforation tool includes a detonator, a switch circuit disposed in a fluid-sealed housing and electrically coupled to the detonator, a shielding circuit coupled to the switch circuit, an annular electrical contact electrically coupled to the switch circuit, and an annular, electrically conductive, compressive member to form a compressive electrical connection with an end of a perforation unit.

FIELD

This patent application addresses hardware for stimulating hydrocarbon reservoirs. Specifically described herein is hardware for use in perforating wells drilled into geologic formations.

BACKGROUND

Hydrocarbon reservoirs are commonly stimulated to increase recovery of hydrocarbons. Hydraulic fracturing, where a fluid is pressurized into the reservoir at a pressure above the fracture strength of the reservoir, is commonly practiced. In most fracturing practice, a well is drilled into the formation and a casing formed on the outer wall of the well. The casing is then perforated using explosives to form holes in the casing that can extend a short distance into the formation from the well wall. Perforation creates holes extending from the well wall into the formation.

Perforation tools commonly employ multiple individual perforation “guns” that can be activated to perforate different parts of a well. These guns may be activated at different depths selected to access target areas of the formation. Activation of selected guns is achieved by sending signals to the controller for each gun to activate a switch, which provides electrical connection to the detonator for the selected gun. When the switch is activated, electrical energy can then be coupled to the detonator by a separate firing circuit.

Connection of the circuit and firing the circuit are frequently performed as two separation actions in order to prevent unwanted firing of guns. The “arming” circuit and activity add complexity to the selective firing of perforation guns in a perforation tool. Simplification of the process and architecture of perforation tools, without compromising safety, is needed.

SUMMARY

A summary of certain embodiments described herein is set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of these certain embodiments and that these aspects are not intended to limit the scope of this disclosure.

Embodiments described herein provide a detonation module for a perforation tool, the detonation module comprising a detonator; a switch circuit disposed in a fluid-sealed housing and electrically coupled to the detonator; a shielding circuit coupled to the switch circuit; an annular electrical contact electrically coupled to the switch circuit; and an annular, electrically conductive, compressive member to form a compressive electrical connection with an end of a shaped charge unit.

Other embodiments described herein provide a method of activating a perforation tool, comprising electrically connecting the perforation tool to a detonation module using two annular electrical contacts, at least one of which is compressive; electrically connecting at least one of the annular electrical contacts with a switching circuit in the detonation module; electrically connecting the switching circuit to a detonator and to a shielding circuit in the detonation module, the shielding circuit comprising at least one RF mitigation component; arranging the annular electrical contacts to provide a fluid pathway for transmitting ballistic discharge from the detonator to the perforation tool; and delivering an electrical impulse from the switching circuit to the detonator.

Other embodiments described herein provide a perforation tool, comprising a perforation unit to house shaped charges; and a detonator module coupled to the perforation unit, the detonation module comprising a detonator; a switch circuit disposed in a fluid-sealed housing and electrically coupled to the detonator; a shielding circuit coupled to the switch circuit; an annular electrical contact electrically coupled to the switch circuit; and an annular, electrically conductive, compressive member to form a compressive electrical connection between the annular electrical contact and an end of the perforation unit.

DETAILED DESCRIPTION

A detonation module for a perforation tool is described herein, along with a perforation tool employing the detonation module. The description sets forth details of certain embodiments of the detonation module and perforation tool to facilitate understanding of the structure and operation of the apparatus and methods of using the apparatus, but these details should not be understood as the only way to embody the useful concepts of the apparatus and methods described herein. Variations of the apparatus and methods described herein can be readily ascertained and understood as equally embodying the concepts of the apparatus and methods described herein.

It should be noted that in the development of the embodiments described herein, certain specific choices are made to achieve specific goals, which may vary from one implementation to another. Such choices might be complex to implement but would be routing for those of ordinary skill in this art having the benefit of the description herein. Further, the apparatus and methods described herein can use other components and approaches not described herein. This description should not be read as exclusive of such other components and approaches.

Unless expressly stated to the contrary, “or” refers to an inclusive or and not to an exclusive or. For example, a condition A or B is satisfied by any one of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present). Also, “the,” “a,” or “an” are used to describe elements and components of the embodiments herein. This is done merely for convenience and to give a general sense of concepts according to the disclosure. This description should be read to include one or at least one and the singular also includes the plural unless otherwise stated.

The terminology and phraseology used herein is for descriptive purposes and should not be construed as limiting in scope. Language such as “including,” “comprising,” “having,” “containing,” or “involving,” and variations thereof, is intended to be broad and encompass the subject matter listed thereafter, equivalents, and additional subject matter not recited. The word “embodiments” refers to non-limiting examples, whether claimed or not, which may be employed or present alone or in any combination or permutation with one or more other embodiments. Each embodiment disclosed herein should be regarded both as an added feature to be used with one or more other embodiments, as well as an alternative to be used separately or in lieu of one or more other embodiments. It should be understood that no limitation of the scope of the claimed subject matter is thereby intended, any alterations and further modifications in the illustrated embodiments, and any further applications of the principles of the application as illustrated therein as would normally occur to one skilled in the art to which the disclosure relates are contemplated herein.

Moreover, the schematic illustrations and descriptions provided herein are understood to be examples only, and components and operations may be combined or divided, and added or removed, as well as re-ordered in whole or part, unless stated explicitly to the contrary herein. Certain operations illustrated may be implemented by a computer executing a computer program product on a computer readable medium, where the computer program comprises instructions causing the computer to execute one or more of the operations, or to issue commands to other devices to execute one or more of the operations.

The detonation module described herein automatically, and passively, establishes electrical and ballistic connectivity and conductivity upon assembly of the various modules of the perforation tool, using the described detonation module. The detonation module described herein employs spring connections for secure electrical conductivity along with RF shielding to prevent unwanted firing signals arising from RF noise. The spring connections have open pathways for ballistic continuity.

FIG.1Ais a cross-sectional view of a perforation tool100, according to one embodiment, in a fully-assembled state. The perforation tool100has a perforation unit102connected with a detonation module104. The perforation unit102has a charge frame106to support one or more shaped charges108. The shaped charges108can all generally be the same or different, but they are usually all the same at least within one perforation unit. The perforation unit102has a housing107that houses the frame106in an interior109of the housing107. The housing107has a generally cylindrical shape with a cylindrical inner bore into which the frame106is inserted.

The detonation module104has a detonation end110, a feedthrough end112opposite from the detonation end110, and a switch portion114between the detonation end110and the feedthrough end112. The detonation end110interfaces with the perforation unit102to provide ballistic energy to activate the charges108of the perforation unit102. The detonation end110has a detonator116to initiate application of ballistic energy to activate the charges108of the perforation unit102. The perforation unit102has a ballistic transfer unit118to engage with the detonation module104for ballistic and electrical continuity. The ballistic transfer unit118transfers ballistic energy to a ballistic feed120that extends along the perforation unit102to carry ballistic energy to the charges108. In this case, the ballistic feed120is a detonation cord, but in other cases, the ballistic feed120can be a pathway, which may use booster charges to continue ballistic discharge along the perforation tool102. In this case, the charges108extend across the frame106from one side to the other, and the charges108are phased according to rotational displacements about a longitudinal axis128of the tool100. In other cases, the frame106could have a central conduit extending along the longitudinal axis128, and the charges108can be arranged around that central conduit. In such cases booster charges can be disposed within the central conduit, or detonation cord can be routed along the central conduit, to apply ballistic energy to the charges108and continue the ballistic discharge along the perforation tool102.

The detonation module104has a housing122that houses a switch unit124disposed in an interior space126of the housing122. The tool100has a generally cylindrical profile, and each unit of the tool100also has a generally cylindrical profile. The housing122has a generally cylindrical shape and the interior space126is a cylindrical bore formed along the longitudinal axis128of the tool100, which substantially coincides with a longitudinal axis of the housing122and a longitudinal axis of the perforation unit102. The switch unit124includes passive RF shielding, attenuation, or filtering to prevent unwanted electrical signals reaching the detonator116. The detonation module104has an annular, compressive electrical connector130at the detonation end110thereof to make electrical connection with an annular contact132.

FIGS.1B1,1B2,1B3,1C1,1C2, and1C3show the cross-sectioned perforation tool100in progressive disassembly. FIGS.1B1,1B2, and1B3are a partial disassembly cross-sectional view of the perforation tool100ofFIG.1Awith the detonation module104separated from the perforation unit102. A cap133used for closing an end of the perforation unit102is shown in disassembly, as well, for context. The housing122has an exterior interface surface134at the detonation end110of the detonation module104that engages with an interior interface surface136of the perforation unit102. The interface surfaces134and136can be threaded or engaged according to any convenient method. An overlap portion138of the housing107of the perforation unit102extends over the detonation end110of the detonation module104until the interface surfaces134and136can be engaged. An end140of the housing107reaches to a first external shoulder142of the housing122of the detonation module104adjacent to first fastening bores144formed in the housing122adjacent to the detonation end110thereof. When the detonation module104is coupled to the perforation unit102, first fasteners146are installed into the first fastening bores144to secure the detonation module104to the first perforation unit102. One or more first grooves148are provided in an exterior wall150of the housing122between the first fastening bores144and the exterior interface surface134. Each first groove148receives a seal member152to seal the interface between the detonation module104and the first perforation unit102.

The housing122has a second exterior interface surface154at the feedthrough end112of the housing122to engage with an interior interface surface of another unit, such as another perforation tool (not shown), which can also be threaded or can use any convenient method of engagement. The housing122has a second external shoulder156near the feedthrough end112. An overlap portion of another unit can extend over the feedthrough end112to reach the second external shoulder156, and can be secured by second fasteners158disposed in second fastening bores160adjacent to the second external shoulder156. One or more second grooves162are provided in the exterior wall150of the housing122between the second exterior interface surface154and the second fastening bores160to receive seal members164to seal the interface between the detonation module104and another tool.

FIGS.1C1,1C2, and1C3are a further partial disassembly cross-sectional view of the perforation tool100showing separation of internal components from the housing122. The ballistic transfer unit118is separated from the housing122to the right, and a feedthrough unit166is separated from the housing122to the left. To assemble the detonation module104, the ballistic transfer unit118is inserted into the housing122at the detonation end110of the detonation module104, and the feedthrough unit166is inserted into the housing122at the feedthrough end112. The ballistic transfer unit118is press-fit into the housing122, while the feedthrough unit166can be press-fit or threaded into the housing122. The feedthrough unit166has a fitting168that engages with the housing122and with switch electronics170to position the switch electronics170within the interior space126of the housing.

FIG.2Ais a detailed cross-sectional view of the detonation module104. In this case, the detonation module104has an extra feedthrough adapter202attached at the feedthrough end112of the detonation module104. The feedthrough adapter202can be used to interface the detonation module104with another unit.

The fitting168has a central bore204that accommodates a conductive member206, which extends substantially from end to end of the fitting168to provide electrical connectivity at either end of the fitting168. At a first end208of the fitting, proximate to the switch electronics170when assembled, the conductive member206engages with a cartridge210that houses the switch electronics170and provides electrical connection with the switch electronics170. At a second end212of the fitting, opposite from the first end208, the conductive member206emerges into a plug end214that can interface electrically with another unit. In this case, a feedthrough member216of the feedthrough adapter202engages with the conductive member206.

The fitting168has an outer body218that, in this case, is conductive, so an insulator219is disposed around the conductive member206within the central bore204of the fitting168. The insulator219is, in this case, overmolded onto the conductive member206, but an insulator can be used according to any convenient design. At a midpoint of the insulator219, a seal member221is disposed around the insulator219, between the insulator219and an inner wall of the central bore204. The seal member221seals the central bore204and secures the conductive member206within the central bore204by friction with the inner wall.

The switch electronics170is located in the interior126of the housing122between the fitting168and the detonator116. The switch electronics170and the detonator116are enclosed in the cartridge210which extends from the fitting168to the ballistic transfer unit118. The switch electronics170includes a switch circuit220and a shielding circuit222. The switch electronics170is electrically coupled to the detonator116at a first end224of the switch electronics170and to the connector cartridge210at a second end226of the switch electronics170opposite from the first end224. The cartridge210features an inner casing228that encloses the switch circuit220, which extends in the longitudinal direction of the detonation module104. The inner casing228can be plastic. The cartridge210also features a plurality of prongs230that support the shielding circuit222in a spaced-apart orientation substantially parallel to the switch circuit220. The shielding circuit222generally has capacitive components, such as spark gaps, switches, and capacitors, that absorb and attenuate RF noise in electrical leads electrically connected to the detonator to minimize the opportunity for unwanted electrical impulses to activate the detonator. The switch electronics170also includes RF attenuators232, in this case ferrite beads, disposed on electrical leads connecting to the shielding circuit222to enhance attenuation of RF noise. The capacitive components and RF attenuators function as RF mitigators, so that the switch electronics170includes a first RF mitigation component and a second RF mitigation component to provide broad shielding against RF noise.

The ballistic transfer unit118has a conductive nose234that at least partially surrounds an end of the ballistic feed120. The conductive nose234has a generally cylindrical shape with an axial opening236at a first end238of the conductive nose234and a flange240at a second end242of the conductive nose234opposite from the first end238in an axial direction of the conductive nose234. An end of the ballistic feed120is disposed within the conductive nose234in contact with the first end238so the axial opening236exposes an end region of the ballistic feed120at the first end238. The flange240is captured within an annular capture space244of a connection structure246of the ballistic transfer unit118.

The capture space244of the connection structure246is at a first end248of the connection structure246. The connection structure246also has a sleeve250at a second end253of the connection structure246opposite from the first end248in an axial direction of the connection structure246. The sleeve250of the connection structure246is a cylindrical extension that extends into an end of the charge frame106to position the ballistic feed120to carry ballistic energy to the charges108. As noted above, in this case the ballistic feed120is disposed at a periphery of the charge frame106. In cases where the charge frame106has a central conduit, with charges arranged around the central conduit and pointing away from the central conduit, and the ballistic feed is the central conduit with booster charges disposed therein (i.e. no detonation cord is used), the connection structure246may be omitted.

FIG.2Bis a close-up cross-sectional view of a portion of the detonation module104at the feedthrough end112thereof. Here, the feedthrough end112of the detonation module104is shown engaged with a perforation unit such as the perforation unit102at a distal end thereof opposite from the end of the perforation unit102engaged with the ballistic transfer unit118of the detonator module104.FIG.2Billustrates the multi-unit connectivity of the detonator module104. The fitting168engages with the detonation module104using a bushing252. The bushing252fits into an annular space254defined between the conductive member206and the interior wall of the fitting168at the second end208thereof. The bushing252connects with the end of the cartridge210and provides a pathway, through a central passage of the bushing252, for the conductive member206to extend into the cartridge210and make contact with a wire contact256that connects to a wire from the switch electronics170(not shown).

The cartridge210, which abuts the second end208of the fitting168, is in two pieces that divide in a longitudinal direction (meaning that the division between the two pieces extends in a longitudinal direction) and have snaps or clasps (not shown) that hold the two pieces together when assembled. The cartridge210has a wide end258adjacent to the second end226of the switch electronics170(FIG.2A) to facilitate correct installation of the cartridge210. The wide end258of the cartridge210has a plurality of stand-offs260that, when the cartridge is installed in the housing122, contact an interior wall of the housing122to provide centering and stable positioning of the cartridge210within the housing. The stand-offs260can also absorb some shock and can help prevent unwanted disconnection of the switch electronics170. The pieces of the cartridge210can be plastic, and can be molded.

FIG.2Cis a close-up cross-sectional view of a portion of the detonation module104at the detonation end110thereof. As noted above, an RF attenuator232is disposed around a wire leading to the detonator116. The detonator116is disposed in a receptacle262formed by the two pieces of the cartridge210. The receptacle262positions the detonator116in a central location of the cartridge210, the detonator module104, and the perforation tool100, so that ballistic discharge from the detonator116can be transmitted to the charges108.

An annular, electrically conductive, compressive member264is disposed between the detonator116and the conductive nose234of the ballistic transfer unit118. An annular electrical contact266is disposed between the detonator116and the compressive member264to provide electrical connectivity between the switch electronics170and the conductive nose234, which in turn provides electrical connectivity to the perforation unit102through the flange240.

FIG.2Dis an oblique view of the cross-section ofFIG.2C. This view shows the annular electrical contact266and the annular conductive compressive member264between the conductive nose234and the detonator116. Central openings of the annular members264and266provide ballistic continuity from the detonator116to the ballistic feed120while the periphery of the annular members264and266maintain electrical continuity within the tool100. Wires270are electrically connected to the annular contact266and to the switch electronics170passing by the detonator116within the cartridge210. The detonator discharge moves through the central openings of the annular contact266, the annular compressive member264, and the annular end of the conductive nose234to activate the ballistic feed120, in this case a detonation cord, while electrical connectivity is maintained (prior to detonator discharge) by the peripheral conductive portions of the annular compressive member264, the annular contact266, and the annular end of the conductive nose234.

As described above, certain embodiments of the present disclosure include a detonation module for a perforation tool. The detonation module includes a detonator; a switch circuit disposed in a fluid-sealed housing and electrically coupled to the detonator; a shielding circuit coupled to the switch circuit; an annular electrical contact electrically coupled to the switch circuit; and an annular, electrically conductive, compressive member to form a compressive electrical connection between the annular electrical contact and an end of a perforation unit.

In certain embodiments, the shielding circuit combines a first RF mitigation component and a second RF mitigation component, and the first RF mitigation component is different from the second RF mitigation component. In certain embodiments, the detonator is electrically coupled to the shielding circuit by a wire, and the first RF mitigation component is a ferrite bead disposed around the wire.

In certain embodiments, the annular, electrically conductive compressive member is a wave spring. In certain embodiments, the detonator, the annular, electrical contact, and the annular, electrically conductive, compressive member are substantially coaxial. In certain embodiments, the annular contact and the annular electrically conductive, compressive member together form a fluid pathway to fluidly couple the detonator to ballistic members of a perforation unit when the perforation unit is connected to the detonation module. In certain embodiments, the detonation module also includes a housing that positions the housing of the switch circuit to connect to a feedthrough unit.

In addition, as described above, in certain embodiments of the present disclosure, a method of activating a perforation tool includes electrically connecting a perforation unit to a detonation module using two annular electrical contacts, at least one of which is compressive; electrically connecting at least one of the annular electrical contacts with a switching circuit in the detonation module; and electrically connecting the switching circuit to a detonator and to an shielding circuit in the detonation module, the shielding circuit including at least one RF mitigation component. The method also includes arranging the annular electrical contacts to provide a fluid pathway for transmitting ballistic discharge from the detonator to the perforation unit; and delivering an electrical impulse from the switching circuit to the detonator.

In certain embodiments, the shielding circuit includes a first RF mitigation component and a second RF mitigation component, and the first RF mitigation component is different from the second RF mitigation component. In certain embodiments, the first RF mitigation component is a ferrite bead and the second RF mitigation component is a capacitive component. In certain embodiments, the annular electrical contacts comprise a compressive member. In certain embodiments, the compressive member is a wave spring. In certain embodiments, the switching circuit and the shielding circuit are housed in a fluid-sealed housing located adjacent to the detonator.

In addition, as described above, in certain embodiments of the present disclosure, a perforation tool includes a perforation unit to house shaped charges and a detonator module coupled to the perforation unit. The detonation module includes a detonator, a switching circuit disposed in a fluid-sealed housing and electrically coupled to the detonator, a shielding circuit coupled to the switching circuit, an annular electrical contact electrically coupled to the switching circuit, and an annular, electrically conductive, compressive member to form a compressive electrical connection between the annular electrical contact and end of the perforation unit.

In certain embodiments, the perforation unit includes a ballistic transfer device arranged at the end of the perforation unit, and the end of the perforation unit includes a conductive nose disposed over an end of the ballistic transfer device, the conductive nose having a central opening that exposes the end of the ballistic transfer device. In certain embodiments, the annular, electrically conductive, compressive member is a wave spring, and the annular electrical contact, the wave spring, and the conductive nose together define a fluid pathway from the detonator to the ballistic transfer device and electrically connect the perforation unit with the detonation module. In certain embodiments, the annular electrical contact and the annular electrically conductive, compressive member together form a fluid pathway to fluidly couple the detonator to ballistic members of the perforation unit. In certain embodiments, the shielding circuit includes a capacitive component and a ferrite bead. In certain embodiments, the ferrite bead is disposed around a wire connecting the shielding circuit with the detonator.

While the foregoing is directed to embodiments of the present invention, other and further embodiments of the present disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.