WO2015126375A1

WO2015126375A1 - Co-crystal explosives for high temperature downhole operations

Info

Publication number: WO2015126375A1
Application number: PCT/US2014/017069
Authority: WO
Inventors: Daniel Francois Dorffer; James Marshall BARKER; Justine Marie DAVIDSON; David John Leidel
Original assignee: Halliburton Energy Services, Inc.
Priority date: 2014-02-19
Filing date: 2014-02-19
Publication date: 2015-08-27

Abstract

A disclosed example embodiment includes an explosive for high temperature downhole operations. The explosive includes first and second explosive components in a co- crystal structure. The first explosive component has a higher thermal stability than the second explosive component. The second explosive component has a higher sensitivity than the first explosive component. The co-crystal structure of the first and second explosive components has a higher sensitivity than the first explosive component.

Description

CO-CRYSTAL EXPLOSIVES FOR HIGH TEMPERATURE

DOWNHOLE OPERATIONS

TECHNICAL FIELD OF THE DISCLOSURE

[0001] This disclosure relates, in general, to equipment utilized in conjunction with operations performed in relation to subterranean wells and, in particular, to co-crystal explosives tailored to have desired thermal stability and desired sensitivity for high temperature downhole operations.

BACKGROUND

[0002] Without limiting the scope of the present disclosure, its background will be described with reference to perforating a cased wellbore with a perforating gun assembly, as an example.

[0003] After drilling each section of a wellbore that traverses various subterranean formations, individual lengths of relatively large diameter metal tubulars are typically secured together to form a casing string that is positioned within the wellbore. In addition to providing a sealing function, the casing string provides wellbore stability to counteract the geomechanics of the formations such as compaction forces, seismic forces and tectonic forces, thereby preventing the collapse of the wellbore wall. The casing string is generally fixed within the wellbore by a cement layer that fills the annulus between the outer surface of the casing string and the wall of the wellbore. For example, once a casing string is located in its desired position in the wellbore, a cement slurry is pumped via the interior of the casing string, around the lower end of the casing string and upward into the annulus. After the annulus around the casing string is sufficiently filled with the cement slurry, the cement slurry is allowed to harden, thereby supporting the casing string and forming a substantially impermeable barrier. [0004] To produce fluids into the casing string or inject fluids into the formation, hydraulic openings or perforations must be made through the casing string, the cement and a short distance into the formation. Typically, these perforations are created by detonating a series of shaped charges that are disposed within the casing string and are positioned adjacent to the desired formation. Specifically, one or more charge carriers are loaded with shaped charges that are connected with a detonating cord. The charge carriers are then connected within a tool string that is lowered into the cased wellbore at the end of a tubing string, wireline, slick line, electric line, coil tubing or other conveyance. Once the charge carriers are properly positioned in the wellbore such that the shaped charges are adjacent to the interval to be perforated, the shaped charges are detonated. Upon detonation, each shaped charge generates a high speed jet that penetrates through the casing, the cement and into the formation with the goal of forming an effective communication path for fluids between the reservoir and the wellbore.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] For a more complete understanding of the features and advantages of the present disclosure, reference is now made to the detailed description along with the accompanying figures in which corresponding numerals in the different figures refer to corresponding parts and in which:

[0006] Figure 1 is a schematic illustration of an offshore oil and gas platform operating a perforating system including co-crystal explosives for high temperature downhole operations according to an embodiment of the present disclosure;

[0007] Figure 2 is a cross sectional view of a perforating gun assembly in a well environment having an explosive train including co-crystal explosives for high temperature downhole operations according to an embodiment of the present disclosure; [0008] Figure 3 is a cross sectional view of a shaped charge including a co-crystal explosive for high temperature downhole operations according to an embodiment of the present disclosure;

[0009] Figure 4 is a cross sectional view of a shaped charge including a co-crystal explosive for high temperature downhole operations according to an embodiment of the present disclosure;

[0010] Figure 5 is a cross sectional view of a tubular coupling having a booster-to- booster transfer including a co-crystal explosive for high temperature downhole operations according to an embodiment of the present disclosure.

DETAILED DESCRIPTION

[0011] While various system, method and other embodiments are discussed in detail below, it should be appreciated that the present disclosure provides many applicable inventive concepts, which can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative and do not delimit the scope of the present disclosure.

[0012] Referring initially to figure 1, a perforating system is being operating from an offshore oil and gas platform that is schematically illustrated and generally designated 10. A semi- submersible platform 12 is centered over a submerged oil and gas formation 14 located below sea floor 16. A subsea conduit 18 extends from deck 20 of platform 12 to wellhead installation 22 including subsea blow-out preventers 24. Platform 12 has a hoisting apparatus 26, a derrick 28, a travel block 30, a hook 32 and a swivel 34 for raising and lowering pipe strings, such as work string 36. A wellbore 38 extends through the various earth strata including formation 14. A casing 40 is secured within wellbore 38 by cement 42. On the lower end of work string 36 are various tools such as a tandem perforating gun assembly 44. When it is desired to perform a perforation operation, work string 36 is lowered through casing 40 until perforating gun assembly 44 is properly positioned relative to formation 14 and the pressure within wellbore 38 is adjusted to the desired pressure regime, for example, static overbalanced, static underbalanced or static balanced. Thereafter, a signal is sent to a detonator carried by perforating gun assembly 44 to initiate detonation of the explosive train including one or more co-crystal explosives for high temperature downhole operations which may be disposed within one or more of the detonator, the detonating cord, the boosters and the shaped charges. Upon detonation, the shaped charge liners generates high-pressure streams of metallic particles in the form of jets that create a spaced series of perforations 46 extending generally radially outwardly through casing 40, cement 42 and into formation 14, thereby allowing fluid communication between formation 14 and wellbore 38.

[0013] Even though figure 1 depicts a vertical wellbore, it should be understood by those skilled in the art that the systems and methods of the present disclosure are equally well suited for use in wellbores having other directional orientations including deviated wellbores, horizontal wellbores, multilateral wellbores or the like. 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, uphole, downhole and the like are used in relation to the illustrative embodiments as they are depicted in the figures, the uphole direction being toward the top or the left of the corresponding figure and the downhole direction being toward the bottom or the right of the corresponding figure. Also, even though figure 1 depicts an offshore operation, it should be understood by those skilled in the art that the systems and methods of the present disclosure are equally well suited for use in onshore operations. In addition, even though a single tandem tubing conveyed perforating gun assembly has been depicted, it should be understood by those skilled in the art that any arrangement of perforating guns on any type of conveyance may be utilized without departing from the principles of the present disclosure. [0014] Figure 2 is an enlarged view, partially in cross section, of a portion of the well system of figure 1. Perforating gun assembly 44 is positioned in wellbore 38 adjacent to formation 14. Casing 40 lines wellbore 38 and is secured in position by cement 42. A conveyance depicted as work string 36 is coupled to perforating gun assembly 44 at a cable head 50. A collar locator 52 is positioned below cable head 50 to aid in the positioning of perforating gun assembly 44 in wellbore 38. A fluid, such as drilling fluid (not shown) may fill the annular region between perforating gun assembly 44 and casing 40. In the illustrated embodiment, perforating gun assembly 44 has a ported carrier 60 having a plurality of port plugs 62 positioned therein that create a fluid seal and prevent any wellbore fluids from entering perforating gun assembly 44. Radially aligned with each port plug 62 is a respective one of a plurality of shaped charges, such as shaped charge 66. Each of the shaped charges includes an outer housing, such as housing 68 of shaped charge 66, and a liner, such as liner 70 of shaped charge 66. Disposed between each housing and liner is a quantity of high explosive, which may be a co-crystal explosive for high temperature downhole operations as described below.

[0015] In the illustrated embodiment, the shaped charges are retained within carrier 60 by a support assembly 72 that includes an outer charge holder sleeve 74 and an inner charge holder sleeve 76. In this configuration, outer charge holder sleeve 74 supports the discharge ends of the shaped charges, while inner charge holder sleeve 76 supports the initiation ends of the shaped charges. In explosive communication with the shaped charges and extending through inner charge holder sleeve 76 is a detonating cord 78 that contains an explosive, which may be a co-crystal explosive for high temperature downhole operations as described below. In the illustrated embodiment, the initiation ends of the shaped charges extend across the central longitudinal axis of perforating gun assembly 44 allowing detonating cord 78 to explosively communicate with the explosive within the shaped charges through an aperture defined at the apex of the housings of the shaped charges.

[0016] Each of the shaped charges is longitudinally and radially aligned with a port plug 62 in carrier 60 when perforating gun assembly 44 is fully assembled. In the illustrated embodiment, the shaped charges are arranged in a spiral pattern such that each shaped charge is disposed on its own level or height and is to be individually detonated so that only one shaped charge is fired at a time. It should be noted, however, by those skilled in the art that alternate arrangements of shaped charges may be used, including cluster type designs wherein more than one shaped charge is at the same level and is detonated at the same time, without departing from the principles of the present disclosure. Perforating gun assembly 44 includes a detonator subassembly 80. Disposed within detonator subassembly 80 is a detonator 82 that contains an explosive, which may be a co-crystal explosive for high temperature downhole operations as described below. In the illustrated embodiment, detonator 82 is coupled to an electrical energy source via electrical wire 84. Detonator 82 is coupled to a lower end of detonating cord 78. In operation, perforating gun assembly 44 is attached to a conveyance and run downhole to the desired location. To detonate the shaped charges, an electrical signal is sent to detonator 82 via electrical wire 84 that initiates a detonation within detonating cord 78. The detonation wave progresses through detonating cord 78 to initiate the detonation of the shaped charges, thereby perforating the well.

[0017] Figure 3 is a cross sectional view of a shaped charge 100 according to the present disclosure. Shaped charge 100 has a generally cylindrically shaped housing 102 that may be formed from a metal such as steel, zinc or aluminum or other suitable material such as a ceramic, glass or plastic. A quantity of high explosive powder depicted as main explosive 104 is disposed within housing 102. Main explosive 104 may be a co-crystal explosive for high temperature downhole operations as described below. In the illustrated embodiment, main explosive 104 is part of an explosive train including detonator 82 and detonating cord 106, each of which may contain a co-crystal explosive for high temperature downhole operations as described below. A liner 108 is positioned toward the discharge end 110 of housing 102. As illustrated, main explosive 104 is positioned between a lower surface of liner 108 and the initiation end 112 of housing 102. Main explosive 104 may fill the entire volume therebetween or certain voids may be present if desired. Liner 108 may be formed by sheet metal or powdered metal processes and may include one or more metals such as copper, aluminum, tin, lead, brass, bismuth, zinc, silver, antimony, cobalt, nickel, molybdenum, tungsten, tantalum, uranium, cadmium, cobalt, magnesium, zirconium, beryllium, gold, platinum, alloys and mixtures thereof as well as mixtures including plastics, polymers, binders, lubricants, graphite, oil or other additives.

[0018] Figure 4 is a cross sectional view of a shaped charge 120 according to the present disclosure. Shaped charge 120 has a generally cylindrically shaped housing 102. A quantity of high explosive powder depicted as main explosive 104 is disposed within housing 102. A liner 108 is positioned toward the discharge end 110 of housing 102. As illustrated, main explosive 104 is positioned between a lower surface of liner 108 and the initiation end 112 of housing 102. In the illustrated embodiment, main explosive 104 is a secondary explosive that is detonated using a primer depicted as booster 122 that contains a primary explosive, which may be a co-crystal explosive for high temperature downhole operations as described below. Main explosive 104 and booster 122 are part of an explosive train including detonator 82 and detonating cord 106.

[0019] Figure 5 is a cross sectional view of a tubular coupling 150 having a booster-to- booster transfer according to the present disclosure. As illustrated, an upper tubular 152 is threadably and sealing coupled to a lower tubular 154. Upper tubular 152 and lower tubular 154 house an explosive train including detonating cord 156, booster 158, booster 160 and detonating cord 162. Detonating cord 156 contains an explosive 164, booster 158 contains an explosive 166, booster 160 contains an explosive 168 and detonating cord 162 contains an explosive 170. Each of the explosives 164, 166, 168, 170 may be a co-crystal explosive for high temperature downhole operations as described below.

[0020] The various explosive devices discussed herein such as detonator 82, detonating cords 78, 156, 162, boosters 122, 158, 160 and shaped charges 66, 100, 120 include explosive components that are used to enable the formation of high speed jets that penetrate through the casing, the cement and into the formation with the goal of forming an effective communication path for fluids between the reservoir and the wellbore. More specifically, the explosive components form an explosive train that may be initiated, for example, electrically. Upon initiation, the explosive with a detonator detonates. The detonation of the explosive within the detonator causes detonation of the explosive within a detonating cord. As the denotation progresses through the detonating cord one or more booster-to-booster transfers may be required. The denotation of the detonating cord then causes the explosive within the shaped charges to detonate directly or via an intermediate explosive in booster, if present. In general, each of the explosives with the explosive train are selected based upon factors such as power, thermal stability, sensitivity to external stimuli such as impact, friction, shock or electrostatic charge as well as other factors known to those skilled in the art. For example, the explosive in a detonator or a booster may typically have higher sensitivity and therefore detonate more reliably than the explosive in a shaped charge, while the explosive in a shaped charge may have more explosive power than the explosive in a detonator or a booster. Example of explosives used in conventional detonators, detonating cord, boosters and shaped charges may include PYX, ONT, NONA and BRX. Each of these explosives has known properties relating to power, thermal stability, sensitivity and the like that allow an operator to select suitable explosive component for particular operations. [0021] In downhole operations, one of the primary factors to consider in selecting an explosive is thermal stability. Many explosives that have high thermal stability, such as PYX and ONT, have low sensitivity and therefore detonate less reliably, while more sensitive explosives, such as NONA and BRX, may not possess the desired thermal stability. In the present disclosure, by forming a co-crystal structure with a thermally stable explosive component and a more sensitive explosive component, the resultant co-crystal explosive may be tailored to have more desirable properties than either of the component explosives. Preferable co-crystal explosive structures include at least one explosive having high thermal stability selected from the group consisting of PYX, TPT, ONT, TNN, PENCO, TAP, DAAF, DAAzF, TATB, DATB, Tacot, PATO, TNAZ, BTATNB, DANTNP, LLM-105, cubanes, nitrocubanes, polynitrocubanes, homocubanes and adamantanes and at least one explosive having high sensitivity selected from the group consisting of NONA, BRX, DODECA, HMX, HNS, HNO, CL-20, HNAB and DAHNS. The ratio the thermally stable explosive component to the more sensitive explosive component is determined based upon the desired properties of the resultant co-crystal explosive. Suitable ratios are between about 20: 1 and about 4: 1, between about 4: 1 and about 2: 1, between about 2: 1 and about 1 : 1, between about 1 : 1 and about 1 :2, between about 1 :2 and about 1 :4 and between about 1 :4 and about 1 :20.

[0022] The process of co-crystallization involves forming a multiple component crystal between compounds that are solid under ambient conditions. Co-crystallization enables the organization of various chemical species by non-covalent interactions without changing the chemical composition of the compounds. In co-crystallization, the chemical species are repositioned based upon interactions including as hydrogen bonding, pi-stalking, electrostatic interactions, ionic interactions, halogen bonding, coordinative bonding, van der Waals forces and the like. The repositioning may be achieved by weaken existing bonds using a variety of processes including mechanical agitation, solvent chemistry or the like including liquid- assisted grinding. The co-crystallization process generally yields a resultant co-crystal having an optimal geometry in a unique crystalline structure having unique properties. Through use of the co-crystallization process, the resultant co-crystal explosives of the present disclosure may be tailored to have desired thermally stability and desired sensitivity.

[0023] In a first aspect, the present disclosure is directed to an explosive for high temperature downhole operations. The explosive includes first and second explosive components in a co-crystal structure. The first explosive component has a higher thermal stability than the second explosive component. The second explosive component has a higher sensitivity than the first explosive component. The co-crystal structure of the first and second explosive components has a higher sensitivity than the first explosive component.

[0024] In a first embodiment, the co-crystal structure of the first and second explosive components may have a ratio of the first explosive component to the second explosive component of between about 20: 1 and about 4:1. In a second embodiment, the co-crystal structure of the first and second explosive components may have a ratio of the first explosive component to the second explosive component of between about 4: 1 and about 2:1. In a third embodiment, the co-crystal structure of the first and second explosive components may have a ratio of the first explosive component to the second explosive component of between about 2: 1 and about 1 :1. In a fourth embodiment, the co-crystal structure of the first and second explosive components may have a ratio of the first explosive component to the second explosive component of between about 1 : 1 and about 1 :2. In a fifth embodiment, the co- crystal structure of the first and second explosive components may have a ratio of the first explosive component to the second explosive component of between about 1 :2 and about 1 :4. In a sixth embodiment, the co-crystal structure of the first and second explosive components may have a ratio of the first explosive component to the second explosive component of between about 1 :4 and about 1 :20.

[0025] In any of the above embodiments, the co-crystal structure of the first and second explosive components may have a thermal stability equal to or about equal to that of the first explosive component. In any of the above embodiments, the first explosive component may be selected from the group consisting of PYX, TPT, ONT, TNN, PENCO, TAP, DAAF, DAAzF, TATB, DATB, Tacot, PATO, TNAZ, BTATNB, DANTNP, LLM-105, cubanes, nitrocubanes, polynitrocubanes, homocubanes and adamantanes and the second explosive component may be selected from the group consisting of NONA, BRX, DODECA, HMX, HNS, HNO, CL-20, HNAB and DAHNS. The co-crystal structure of the first and second explosive components of any of the above embodiments may form at least a portion of the explosive in a downhole component such as a shaped charge, a booster, a detonator or a detonating cord.

[0026] In a second aspect, the present disclosure is directed to a shaped charge for high temperature downhole operations. The shaped charge includes a housing having a discharge end and an initiation end, a liner positioned with the housing and a main explosive positioned within the housing between the liner and the initiation end of the housing. The main explosive includes first and second explosive components in a co-crystal structure, wherein the first explosive component has a higher thermal stability than the second explosive component, the second explosive component has a higher sensitivity than the first explosive component and the co-crystal structure of the first and second explosive components has a higher sensitivity than the first explosive component.

[0027] In a third aspect, the present disclosure is directed to a booster for high temperature downhole operations. The booster includes a housing and a primary explosive positioned within the housing. The primary explosive includes first and second explosive components in a co-crystal structure, wherein the first explosive component has a higher thermal stability than the second explosive component, the second explosive component has a higher sensitivity than the first explosive component and the co-crystal structure of the first and second explosive components has a higher sensitivity than the first explosive component.

[0028] It should be understood by those skilled in the art that the illustrative embodiments described herein are not intended to be construed in a limiting sense. Various modifications and combinations of the illustrative embodiments as well as other embodiments will be apparent to persons skilled in the art upon reference to this disclosure. It is, therefore, intended that the appended claims encompass any such modifications or embodiments.

Claims

What is claimed is:

1. An explosive for high temperature downhole operations comprising:

first and second explosive components in a co-crystal structure;

the first explosive component having a higher thermal stability than the second explosive component; and

the second explosive component having a higher sensitivity than the first explosive component,

wherein, the co-crystal structure of the first and second explosive components has a higher sensitivity than the first explosive component.

2. The explosive as recited in claim 1 wherein the co-crystal structure of the first and second explosive components further comprises a ratio of the first explosive component to the second explosive component of between about 20: 1 and about 4:1.

3. The explosive as recited in claim 1 wherein the co-crystal structure of the first and second explosive components further comprises a ratio of the first explosive component to the second explosive component of between about 4: 1 and about 2: 1.

4. The explosive as recited in claim 1 wherein the co-crystal structure of the first and second explosive components further comprises a ratio of the first explosive component to the second explosive component of between about 2: 1 and about 1 :1.

5. The explosive as recited in claim 1 wherein the co-crystal structure of the first and second explosive components further comprises a ratio of the first explosive component to the second explosive component of between about 1 : 1 and about 1 :2.

6. The explosive as recited in claim 1 wherein the co-crystal structure of the first and second explosive components further comprises a ratio of the first explosive component to the second explosive component of between about 1 :2 and about 1 :4.

7. The explosive as recited in claim 1 wherein the co-crystal structure of the first and second explosive components further comprises a ratio of the first explosive component to the second explosive component of between about 1 :4 and about 1 :20.

8. The explosive as recited in claim 1 wherein the co-crystal structure of the first and second explosive components has a thermal stability about equal to that of the first explosive component.

9. The explosive as recited in claim 1 wherein the first explosive component is selected from the group consisting of PYX, TPT, ONT, TNN, PENCO, TAP, DAAF, DAAzF, TATB, DATB, Tacot, PATO, TNAZ, BTATNB, DANTNP, LLM-105, cubanes, nitrocubanes, polynitrocubanes, homocubanes and adamantanes and the second explosive component is selected from the group consisting of NONA, BRX, DODECA, HMX, HNS, HNO, CL-20, HNAB and DAHNS.

10. The explosive as recited in claim 1 wherein the co-crystal structure of the first and second explosive components forms at least a portion of a downhole component selected from the group consisting of a shaped charge, a booster, a detonator and a detonating cord.

11. A shaped charge for high temperature downhole operations comprising:

a housing having a discharge end and an initiation end;

a liner positioned with the housing; and

a main explosive positioned within the housing between the liner and the initiation end of the housing, the main explosive including first and second explosive components in a co-crystal structure, the first explosive component having a higher thermal stability than the second explosive component, the second explosive component having a higher sensitivity than the first explosive component and the co-crystal structure of the first and second explosive components having a higher sensitivity than the first explosive component.

12. The shaped charge as recited in claim 11 wherein the co-crystal structure of the first and second explosive components further comprises a ratio of the first explosive component to the second explosive component of between about 20: 1 and about 1 : 1.

13. The shaped charge as recited in claim 11 wherein the co-crystal structure of the first and second explosive components further comprises a ratio of the first explosive component to the second explosive component of between about 1 :1 and about 1 :20.

14. The shaped charge as recited in claim 11 wherein the co-crystal structure of the first and second explosive components has a thermal stability equal to that of the first explosive component.

15. The shaped charge as recited in claim 11 wherein the first explosive component is selected from the group consisting of PYX, TPT, ONT, TNN, PENCO, TAP, DAAF, DAAzF, TATB, DATB, Tacot, PATO, TNAZ, BTATNB, DANTNP, LLM-105, cubanes, nitrocubanes, polynitrocubanes, homocubanes and adamantanes and the second explosive component is selected from the group consisting of NONA, BRX, DODECA, HMX, HNS, HNO, CL-20, HNAB and DAHNS.

16. A booster for high temperature downhole operations comprising: a housing; and

a primary explosive positioned within the housing, the primary explosive including first and second explosive components in a co-crystal structure, the first explosive component having a higher thermal stability than the second explosive component, the second explosive component having a higher sensitivity than the first explosive component and the co-crystal structure of the first and second explosive components having a higher sensitivity than the first explosive component.

17. The booster as recited in claim 16 wherein the co-crystal structure of the first and second explosive components further comprises a ratio of the first explosive component to the second explosive component of between about 20: 1 and about 1 : 1.

18. The booster as recited in claim 16 wherein the co-crystal structure of the first and second explosive components further comprises a ratio of the first explosive component to the second explosive component of between about 1 : 1 and about 1 :20.

19. The booster as recited in claim 16 wherein the co-crystal structure of the first and second explosive components has a thermal stability equal to that of the first explosive component.

20. The booster as recited in claim 16 wherein the first explosive component is selected from the group consisting of PYX, TPT, ONT, TNN, PENCO, TAP, DAAF, DAAzF, TATB, DATB, Tacot, PATO, TNAZ, BTATNB, DANTNP, LLM-105, cubanes, nitrocubanes, polynitrocubanes, homocubanes and adamantanes and the second explosive component is selected from the group consisting of NONA, BRX, DODECA, HMX, HNS, HNO, CL-20, HNAB and DAHNS.