BACKGROUND
Wells are commonly drilled into a formation to recover natural resources, such as oil, natural gas, etc. After drilling the wellbore, a casing string is installed to reinforce portions of the wellbore. A casing string comprises large diameter metal tubulars that are connected end-to-end, lowered into the wellbore, and cemented in place. The casing string increases the integrity of the wellbore and provides a structure for supporting other wellbore equipment such as production tubing used for producing fluids from one or production zones of the formation to surface. When a production zone is lined with casing, the casing is perforated to allow the formation fluids to enter the wellbore. The casing is also perforated later, during plug and abandonment, after the well has reached the end of its natural life and is no longer economically producing.
Perforations are hydraulic openings that extend through the casing and into the surrounding formation. Typically, perforations are created by lowering a perforating gun string downhole and detonating a series of explosive shaped charges adjacent to the production zone. A perforating gun string is lowered into the cased wellbore on an appropriate conveyance, such as a wireline. An explosive train may then be initiated to detonate the shaped charges, e.g., in a predetermined, serial fashion. The perforating gun string is then retrieved to the surface. To maximize area of flow (AOF), perforating guns are typically densely packed with charges or else use large explosives, e.g., big hole (BH) charges. Current technology has all but reached the limit of AOF using size/number of explosives alone, and while unconventional perforating assemblies (e.g., linear perforating assemblies) capable of making wider perforations do exist, these are generally unpopular due to their awkwardness of design and incompatibility with most types of existing perforating systems.
BRIEF DESCRIPTION OF THE DRAWINGS
These drawings illustrate certain aspects of some of the embodiments of the present disclosure and should not be used to limit or define the disclosure.
FIG. 1 is a system showing a perforating gun in a wellbore in a land environment, in accordance with some examples of the present disclosure.
FIG. 2 is a system showing a perforating gun in a wellbore in a sea environment, in accordance with some examples of the present disclosure.
FIG. 3 illustrates perspective view of a single perforating gun, in accordance with some examples of the present disclosure.
FIG. 4 illustrates a cross-sectional view of a conical perforating assembly, in accordance with some examples of the present disclosure.
FIG. 5 is a top-down view of a horizontal cross-section of a conical perforating assembly to show a charge carrier having a gradually tapered thickness profile, in accordance with some examples of the present disclosure.
FIG. 6 is a top-down view of a horizontal cross section of a conical perforating assembly to show a charge carrier having a step-change thickness profile, in accordance with some examples of the present disclosure.
FIG. 7 is a top-down view of a horizontal cross section of a conical perforating assembly to show a conical liner having a gradually tapered thickness profile, in accordance with some examples of the present disclosure.
FIG. 8 is a top-down view of a horizontal cross-section of a conical perforating assembly to show a shaped charge having a gradually tapered thickness profile, in accordance with some examples of the present disclosure.
FIG. 9 is a top-down view of a horizontal cross-section of a conical perforating assembly to show a conical liner including two sections, in accordance with some examples of the present disclosure.
FIG. 10A is a schematic illustration of the trajectory of a projectile launched by a standard perforating assembly.
FIG. 10B is a schematic illustration of the trajectory of a projectile launched by a conical perforating assembly, in accordance with some examples of the present disclosure.
FIG. 11A is a schematic illustration of a perforation profile formed by the projectile of FIG. 10A.
FIG. 11B is a schematic illustration of a perforation profile formed by a projectile launched by a conical perforating assembly, in accordance with some examples of the present disclosure.
DETAILED DESCRIPTION
Disclosed herein is a perforating system including a perforating gun and, more particularly, disclosed are methods and apparatuses using a perforating assembly. More particularly, example embodiments of the perforating assembly may have an asymmetric profile that allows it to form elongated perforations in a wellbore casing without the need for making drastic design changes to existing perforating systems.
While example embodiments of the present disclosure focus mainly on conical perforating assemblies, the teachings and principles disclosed herein may be equally applicable to linear, hemispheric, cylindrical, flat front, stepped cone, etc., or other types of perforating assemblies without departing from the scope and spirit of the disclosure.
The perforating assemblies (or “perforators”) disclosed herein each have an “asymmetric profile.” Various examples of the asymmetric profile are provided herein, however, in general, this refers to structural and/or material asymmetry of the perforating assembly which allows for elongated perforations. As opposed to the more conventionally round, non-elongated perforations, these may have an improved AOF and thus reduce the need for higher shot densities and/or large explosives without needing to make significant design changes to existing guns. Also, projectiles by perforating assemblies in accordance with the present disclosure may produce jets with sufficient velocity to better clear the fluid in an annulus. Lastly, these perforating assemblies may also be especially applicable in plug and abandonment applications where the goal is to maximize fluid communication between pumped cement and the regions of the formation nearest the wellbore.
Thus, example embodiments of the present application provide various methods and systems which may rely on the asymmetric profile to reliably form elongated perforations. These may be implemented in well systems. Accordingly, FIGS. 1 and 2 show land and sea-based well systems implementing perforating tools, in accordance with some examples of the present disclosure.
FIG. 1 is a system 100 showing a perforating system 102 in a wellbore 110 during a land-based operation. The system 100 comprises a servicing rig 108 disposed on a terrestrial surface over a wellbore 110 extending into subterranean formation 116. Wellbore 110 may be vertical, deviated, horizontal, and/or curved at one or more regions of subterranean formation 116. Wellbore 110 may be cased, open hole, contain tubing, and may generally comprise a hole in the ground, i.e., “borehole”, extending any appropriate distance into subterranean formation 116. In one or more examples, one or more regions of the wellbore 110 may be secured at least in part by cement 114. Servicing rig 108 may be a drilling rig, completion rig, workover rig, or other mast structure supporting work string 104. In some examples, servicing rig 108 comprises a derrick and rig floor through which work string 104 extends downwards into wellbore 110. As will be shown in FIG. 2, a wellbore may be alternatively positioned in a sea-based environment, such as on a semi-submersible platform or rig, or otherwise disposed above a sea floor at an off-shore location.
Work string 104 may comprise a conveyance 106 and a perforating system 102, i.e., “perforating gun string,” “gun string,” or “gun assembly,” comprising one or more perforating guns. In addition, work string 104 may comprise other downhole tools, such as one or more packers, one or more completion components, e.g., screens and/or production valves, one or more sensing components and/or measuring equipment, e.g., downhole sensors, and other equipment not shown in FIG. 1. In operation, work string 104 is lowered into wellbore 110 and one or more explosive charges disposed within the one or more perforating guns are detonated to perforate casing 112 to facilitate fluid communication between one or more production zones (“pay zones”) 118a, 118b, 118c, etc., and wellbore 110. In plug and abandonment, the perforated areas indicated at 118a, 118b, 118c, etc., may instead serve as entry points for plugging material to create a permanent plug in the wellbore 110.
Perforating system 102 may comprise a single or a plurality of perforating guns, which may be coupled together on a single gun string. While the present figures generally show a single perforating gun, perforating system 102 may comprise any suitable number of perforating guns. In some examples, perforating system 102 may further comprise a firing head for initiating a detonation train to fire each of the perforating guns, as well as tandems, spacers, or other coupling structures for coupling together the perforating guns.
FIG. 2 is a system 200 showing one or more perforating guns 201a, 201b, 201c, 201d, etc., in a wellbore 214 during a sea-based operation, in accordance with some examples of the present disclosure. As mentioned, the principles shown and described with respect to perforating during land-based operations are equally applicable to sea-based operations without departing from the spirit and scope of the disclosure. As illustrated, a wellbore 214 may extend into a subterranean formation 224 beneath a sea floor 220. A semi-submersible platform 206 is centered over a hydrocarbon-bearing formation 224 located beneath a sea floor 220. A subsea conduit 212 extends from deck 208 of platform 206 to wellhead installation 228 which may include one or more subsea blow-out preventers 230. Platform 206 has a hoisting apparatus 204 and a derrick 202 for raising and lowering tubular strings such as work string 210.
A wellbore 214 extends through various earth strata including subterranean formation 224. Casing 226 is cemented within wellbore 214 by cement 216, as with FIG. 1. Work string 210 may be substantially identical to work string 104 (e.g., referring to FIG. 1), except that it is adapted for a subsea environment. In operation, work string 210 is similarly lowered through casing 226 until one or more perforating guns of work string 210 reach a desired depth. Thereafter, the explosive charges are detonated to perforate casing 226. In either of FIG. 1 or 2, detonation may occur in either a down-going (downhole) or an up-going (uphole) fashion. As shown, work string 210 comprises one or more perforating guns 201a, 201b, 201c, 201d, etc., which may be joined together during, for example, tubular make-up of the gun string. FIG. 3 further shows, with more detail, an example of a perforating gun 300.
FIG. 3 is a side view of a single perforating gun 300 in accordance with some examples of the present disclosure. The perforating gun 300 may be one of a plurality of perforating guns connected end-to-end to achieve a perforating gun string (e.g., perforating system 102 on FIG. 1). The perforating gun 300 may include a gun body 302 and a charge tube 304 having receptacles 308 adapted to hold respective perforating assemblies 306 (e.g., perforating assembly 400 of FIG. 4). In examples, the perforating gun 300 may also include a bulkhead 310 containing a pass-through 316 which may allow a detonation signal to pass to/from a neighboring gun. The perforating gun 300 may also include a detonator 312 to trigger detonation of the perforating assemblies 306, and end alignments 314. Gun body 302 is shown in this figure as a generally tubular body, in which the other gun components are disposed. A plurality of perforating charges may be secured to the charge tube 304 at different positions and firing orientations along the charge tube 304. Charge tube 302 may have a generally continuous tubular construction as shown, however, other suitable charge tube configurations are also within the scope of this disclosure, such as modular charge tubes formed by snapping together or otherwise interconnecting any number of charge tube segments that each hold one or more perforating charges within a perforating gun.
Where used, end alignments 314 may serve to isolate charge tube 304 and perforating assemblies 306 from gun body 302, as well as to ensure proper alignment of perforating assemblies 306 to scallops 318, in some examples. Likewise, detonator 312 may comprise housing, in some examples, which may be coupled to charge tube 304 and include various features to hold detonator 312, detonating cord, and other components. Bulkhead 310 may provide stability and structure to the perforating gun 300 as well as an interface to connect to a neighboring perforating gun.
FIG. 4 illustrates a cross-sectional view of a perforating assembly 400, in accordance with some examples of the present disclosure. Perforating assembly 400 is but one example of a perforating charge assembly 306 of FIG. 3. As illustrated, perforating assembly 400 may have a generally conical profile and includes a charge carrier 402, a liner 406 disposed in the charge carrier, and an explosive charge 404 disposed between the charge carrier 402 and the liner 406 and supported on the charge carrier 402.
As illustrated, the explosive charge 404 is disposed between the charge carrier 402 and the liner 406, and which comprises one or more explosive materials. Various factors, such as the amount of explosive material, geometry of charge carrier 402, geometry of liner 406, etc., may influence how far a projectile formed by liner 406 penetrates into formation 116 (e.g., referring to FIG. 1). In use, the build-up of hot, high-pressure expanding gases from detonation of explosive charge 404 causes the invertible liner 406 to invert, whereupon it forms a projectile and is fired through gun body 302 (e.g., referring to FIG. 3), casing 112 (e.g., referring to FIG. 1) and into the formation 116.
Charge carrier 402 is a rigid housing that supports the liner 406 and explosive charge 404, and which may comprise any suitable material sufficiently rigid to withstand the explosion of explosive charge 404. Charge carrier 402 may have a conical shape, as illustrated in FIG. 4, however alternative shapes are possible such as hemispheric, linear, cylindrical, etc. Charge carrier 402 provides a rigid structure that guides the trajectory of liner 406 in a firing direction as it is expelled from the perforating assembly 400 upon detonation of the explosive charge 404. Thickness of the charge carrier 402 at any given radial coordinate may correlate, in some examples, with the rigidity of the charge carrier 402 at that radial coordinate and thus with the normal force applied against the high pressure of the expanding gas at that radial coordinate. The high pressure is ultimately redirected against the outer surface 418 of the liner 406 which, following the path of least resistance, is launched in the firing direction out from charge carrier 402, through a gun body, wellbore casing and annulus (e.g., casing 112 and annulus 114 of FIG. 1), wellbore wall, and into the formation at some penetration depth.
In this example, charge carrier 402 has a straight section 432 and a conical section 434. The explosive charge 404 is shown occupying a space between outer surface 418 that extends along the entirety of conical section 434 and at least a portion of straight section 432. The liner 406 may rest against an inner surface 436 at a point 420 disposed a distance 440 below a mouth 438 of charge carrier 402. In some examples, increasing or decreasing this distance 440 may change the overall trajectory of liner 406 as it is expelled from charge carrier 402. For example, a longer distance 440 may result in a more direct firing direction, whereas a shorter distance 440 may allow for the asymmetry of the perforating assembly 400 to have a greater effect on the irregular (e.g., angled) trajectory, thereby leading to the slotted perforations in the casing 112 (e.g., referring to FIG. 1). Likewise, changing the degree of concavity of the inner surface 436 may similarly have an effect on the degree to which the asymmetry causes the firing direction to be more or less irregular relative to a direct, straight-line perforating angle (e.g., 1004 of FIG. 10A). For situations where conical section 434 is hemispherical rather than conical, the radius of the inner surface 436 of the charge carrier 402 (at a center point of the hemisphere) may similarly affect the influence of the asymmetry on the firing direction. Balancing the distance 440 and/or degree of concavity or sphericity of inner surface 436 with the extent of asymmetry may result in an optimized size and/or angle of perforations, resulting in maximum AOF.
One function served by charge carrier 402 is that it supports the explosive charge 404, providing a receptacle that ensures, in some examples, the explosive charge 404 has the appropriate shape when it is compacted between outer surface 418 of liner 406 and inner surface of charge carrier 402.
Explosive charge 404 is a packed explosive that rests between liner 406 and inner surface 436 of charge carrier 402. Explosive charge 404 may comprise any suitable explosive material suitable to perforate the casing, annulus, and wellbore. For example, explosive charge 404 may comprise a single explosive, or multiple explosives. As will be discussed later, explosive charge 404 may comprise multiple sections having varying concentrations or amounts of one or more types of explosives. For example, a first section with a first recipe and a second section with a second recipe. A first recipe may have a first explosivity and a second section, a second explosivity different from the first. “Different” in this context means that either the heat of reaction, the difference between number of moles of products/reactants of the detonation reaction, or both, differ by at least 5%. This may result in an uneven detonation profile which may be, or contribute to, the asymmetry of perforating assembly 400 that results in the irregular firing direction that leads to elongated perforations, to be discussed in greater detail. Explosive charge 404 may be a shaped charge, meaning that it is compactly formed in a particular shape that may, in some examples, be sufficiently cohesive as to maintain a steady shape during assembly prior to introduction to charge carrier 402. Where explosive charge 404 is a shaped charge, it may have any suitable shape, e.g., conical, disk, oblong, round, hemispheric, etc. As mentioned, the shape of inner surface 436 and/or outer surface 418 may ensure that explosive charge 404 retains its shape upon introduction to the perforating assembly 400. For example, an inner surface 436 may be designed to conform with the shape profile of explosive charge 404, or vice versa. In examples, explosive charge 404 may be a solid, such as a tightly packed powder arranged to contact a detonating cord disposed on the other side of aperture 442.
Upon arrival of the ignition through aperture 442 (e.g., from a detonating cord situated near aperture 442), the ignition spreads through aperture 442 to ignite shaped charge 404, which rapidly undergoes a chemical reaction. In some examples, an explosive initiator, e.g., comprising a parcel of a more highly explosive material, may be disposed in or near aperture 442 to activate the chemical reaction. The chemical reaction may be highly exothermic and form a high amount of volume of the expanding gas that results in an extreme pressure between the inner surface 436 and outer surface 418 of liner 406, which ultimately forces the liner to invert, whereby it launches through the casing 112, annulus 114, wellbore wall, and into the formation 116 (e.g., referring to FIG. 1). As mentioned, the one or more asymmetries that may be characteristic of at least one of the explosive charge 404, charge carrier 402, liner 406, or combination thereof, may result in there being a difference in pressures at different radial coordinate regions of perforating assembly 400. “Different” in this context means radial coordinates of at least one of the explosive charge 404, charge carrier 402, or liner 406 separated by at least 5 degrees. Thus, the amount of pressure at a first radial location (e.g., at side 412) may differ from the pressure at a second radial location (e.g., at side 414) following detonation of the explosive charge 404. First and second radial locations may be spaced apart by 180 degrees but may alternatively be from about 5 degrees to about 180 degree, or any ranges therebetween. Moreover, while these radial locations are shown as being disposed in an area occupied by shaped charge 404, they may in addition, or alternatively, refer to other areas of the perforating assembly. For example, different internal and/or surface regions of the liner 406, regions of the void space preliminarily occupied by the shaped charge 404 prior to the detonation, and by internal and/or surface regions of the charge carrier 402.
Another function of explosive charge 404 is that is supports the liner 406. The liner 406 may rest against an inner surface of explosive charge 404. Distance 440 may depend on the size and/or amount of explosive material used for the explosive charge 404.
Liner 406 is an invertible structure that forms the projectile used to perforate the casing 112 and wellbore 120 (e.g., referring to FIG. 1). Liner 406 may comprise any suitable material sufficiently ductile to invert yet having sufficient cohesiveness and strength to resist shattering upon impact with gun body 302, casing 112 (e.g., referring to FIG. 1), and wellbore 120. Liner 406 may have any suitable shape or profile, such as the generally conical profile shown in FIG. 4. Alternatively, a hemispheric, round, multifaceted, etc., or other suitable profile. The function of liner 406 is to temporarily absorb the explosive energy of the detonation of the explosive charge 404 and transfer that energy to the casing 112 and formation 116 to create the perforation that allows for increased AOF, as discussed.
As mentioned, one or more of the perforating charge assemblies 306 of FIG. 3 may have an asymmetric profile. The asymmetric profile may be a structural and/or a material asymmetry in one or more components of the perforating charge assemblies 306. Thus, the charge carrier 402, explosive charge 404, liner 406, or any combination thereof, may be characterized by asymmetry. Various non-limiting examples of asymmetric profiles are disclosed in the following figures. It should be understood that while these various asymmetries are shown and described individually, a perforating charge assembly 306 may include a combination of these various asymmetries. This may have the added benefit, in some examples, of ensuring that the elongation (e.g., width 1108 of FIG. 11B) is more reliably and/or further increased. Likewise, while the various asymmetries are shown, they are meant to be exemplary and are not intended to limit the perforating assembly 400 to any particular embodiment.
Thus, the geometric profile of charge carrier 402 may be asymmetric. This may be achieved in a number of ways, for example, by increasing the thickness of the charge carrier 402 on one side relative to the other. For example, first side 413 of charge carrier 402 may have a first thickness 410 while a second side 414 opposite the first side 413 may have a second thickness 412 different from the first. As used herein, “different” means a percent difference by at least 5%. In examples, a change in thickness between first and second thicknesses 410, 412 may be from about 5% to about 50%. Alternatively, from about 5% to about 25%, about 25% to about 75%, about 75% to about 150%, about 150% to about 250%, or any ranges therebetween. In another example, the distances shown and indicated at L2 and L4 may each be greater than those at L1 and L3, respectively, by an amount from about 5% to about 50%. Alternatively, from about 5% to about 25%, about 25% to about 75%, about 75% to about 150%, about 150% to about 250%, or any ranges therebetween. It should be noted that while the charge carrier 402 is shown as having a conical profile in this figure, it may alternatively have other suitable profiles as well, such as hemispheric, cylindrical, flat front, stepped cone, etc. Thus, the ranges disclosed for comparing L2 and L4 with L1 and L3, as well as first and second thicknesses 410, 412, may apply to these other types of charge carriers. However, in this figure, L1 is the distance between outer surface 416 of charge carrier 402 and outer surface 418 of conical liner 406 in the direction perpendicular to the outer surface 418 at a point 420 where conical liner 406 contacts charge carrier 402. L3 and L4 in this figure are distance between the outer surface 416 and outer surface 418 at a point 422 where a curvature of outer surface 418 of liner 406 transitions from a straight portion to a curved portion 416, in the direction perpendicular to linear portion 416. Due to the asymmetry, charge carrier 402 (or other components of a perforating charge assembly 306, e.g., referring to FIG. 3), may cause there to be a misalignment between the actual axis of rotation and the central axis 408 of perforating assembly 400, in some examples.
In addition, or as an alternative to, geometric asymmetry of a perforating charge assembly 306 (e.g., referring to FIG. 3), the material properties of a perforating charge assembly 306 may be varied. “Material properties,” as used herein, may include, without limitation, density, tensile strength, Young's modulus of elasticity, hardness, ductility, toughness, combinations thereof, or the like. For example, a material property (e.g., density) at one side of the charge carrier 402 may be increased by about 5% to about 250% with respect to the other side, or any ranges therebetween, in some examples. Similarly, the material properties of select regions of liner 406 may be reinforced or weakened, such that the stress-strain response to the detonation is varied. This may be achieved, for example, by using more than one material, as shown later in FIG. 9, or by pressing one side of liner 406 to a higher density, e.g., with or without maintaining the axis-symmetry of the liner 406. Material properties may also include the explosivity of explosive charge 404 at select regions. For example, higher concentration and/or additional (e.g., more explosive) explosive materials may also be used at select regions of the perforating charge.
FIG. 5 is a horizontal cross section 410 of the perforating assembly 400 of FIG. 4, in accordance with some examples of the present disclosure. This view shows the charge carrier 402, explosive charge 404, and liner 406 concentrically disposed about the central axis 408. While the central axis 408 in this figure is shown as being the center-point of the liner 406 and outer surface 416, other configurations are possible, such as where the central axis 408 is the center-point of an outer surface 416 of charge carrier 402, inner surface 428 of charge carrier 402, outer surface 424 of liner 406, inner surface 426 of liner 406, combinations thereof, or the like. This figure shows a first thickness 410 at side 413 being less than a second thickness at side 414. Second thickness 412 may be about twice that of first thickness 410. Alternatively, from about 1.2 to about 4 times as thick, or any ranges therebetween. The thickness in this figure gradually tapers from the first side 413 to the second side 414. This gradual change in the thickness about the central axis may be characterized by mathematical formulas, such as linear, polynomial, trigonometric, sinusoidal, statistical, step-change (any suitable number of steps, e.g., between 1 and 100, or any ranges therebetween), etc., equations, or combinations thereof. This concept of gradually tapered profiles may be applied, without limitation, to the other types of asymmetry discussed by this disclosure.
FIG. 6 shows an alternative horizontal cross section of a perforating assembly 400 to that shown in FIG. 5, in accordance with some examples of the present disclosure. This figure is identical to FIG. 5, except that rather than gradual tapering, the transition from the first thickness 410 to the second thickness 412 occurs at step changes 602a and 602b. While only two step changes 602a, 602b are shown in this figure, more step changes are possible, e.g., 4, 6, 8, etc. The step changes 602a and 602b are shown as being disposed at 12 o'clock and 6 o'clock positions, respectively, so that first side 413 having first thickness 410 encompasses half the profile of charge carrier 402 and second side 414 having second thickness 412 encompasses the other half. Alternatively, first side 413 having a first thickness 410 may encompass from about 5% to about 95%, or any ranges therebetween, of the profile of charge carrier 402, with second side 412 encompassing the remainder. In embodiments where more than two step changes 602a, 602b are used, the percentage of the profile of charge carrier 402 encompassed by any one or more thicknesses may encompass these same ranges, with other portions comprising the remainder. For example, a first thickness type may occupy 40%, a second thickness type may occupy 30%, and a third thickness type may occupy the remaining 30%, to use a non-limiting example. Any number of step changes at any suitable radial position(s) about a central axis 408 may be used to influence the profile of a trajectory formed by liner 406. In some examples, a combination of gradual tapering and step changed profiles may be used.
FIG. 7 shows another alternative horizontal cross section of a perforating assembly 400 to that shown in FIG. 5, in accordance with some examples of the present disclosure. This figure is identical to FIG. 5, except that rather than an asymmetric charge carrier 402, conical liner 406 is asymmetric. As shown by the figure, the first thickness 702 of conical liner 406 may be less at first side 413 than second thickness 704 at second side 414. The percent difference between first and second thicknesses 702, 704 may include any of the same ranges as those disclosed for first and second thicknesses 410, 412 of FIG. 4. As with a charge carrier 402 (e.g., referring to FIG. 6), a conical liner 406 may have a stepped profile or other suitable asymmetric profile.
FIG. 8 shows another alternative horizontal cross section of a perforating assembly 400 to that shown in FIG. 5, in accordance with some examples of the present disclosure. This figure is also substantially identical to FIG. 5, except that rather than an asymmetric charge carrier 402, explosive charge 404 is asymmetric. As shown by the figure, the first thickness 802 of explosive charge 404 may be less at first side 413 than a second thickness 804 at second side 414. The percent difference between first and second thicknesses 802, 804 may include any of the same ranges as those disclosed for first and second thicknesses 410, 412 of FIG. 4. As shown by FIG. 6, a conical liner 406 may have a stepped profile.
FIG. 9 shows another alternative horizontal cross section of a perforating assembly 400 to that shown in FIG. 5, in accordance with some examples of the present disclosure. This figure shows a liner 406 which comprises a first section 902 and a second section 904. First section 902 may comprise a first type of material, e.g., having a first material property, and second section 904 may comprise a second type of material, e.g., having a second material property. As illustrated, the distance between the inner surface 426 and the interface 910 at side 412 may be less than the respective distance at the other side 414. Likewise, because the distance 912 between the interface 910 and the outer surface 424 may make up the remainder of the body of the liner 406 for a given cross section 410, this latter distance 912 at a given radial coordinate may be equal to the difference between the conical liner's 406 outer diameter and the radial distance of the interface 910 from the central axis 408 at the respective angle of that radial coordinate. As illustrated, the geometric profiles of the first and second sections 902 and 904 are offset in this figure such that the interface 910 does not concentrically align with either the inner surface 426 or the outer surface 424 of the liner 406. Also, the percent change in the distances indicated at 906 and 908 may include any of the same ranges as those disclosed for first and second thicknesses 410, 412 of FIG. 4. In examples, having an asymmetric conical liner may be used in combination with, or instead of, other forms of asymmetry. Where combined, however, the effects on the elongation (e.g., width 1108 of FIG. 11B) may be compounded to further improve the AOF.
FIGS. 10A and 10B show a comparison between the trajectory profile of a projectile launched by the perforating assembly 400 of FIG. 4 and the trajectory profile of a standard projectile, in accordance with some examples of the present disclosure. As illustrated, a first trajectory profile 1002 of a standard conical perforating assembly is a simple straight line, as indicated by a single arrow at 1004. In contrast, a second trajectory profile 1006 of a perforating assembly 400 according to the present disclosure may be more complex and may be characterized in some examples as having one or more deviations from a simple straight line, shown at 1008a, 1008b. In some examples, second trajectory profile 1006 may be angled and/or curved. Deviated firing angle 1008a may be offset from about 5° to about 85°, or any ranges therebetween, with respect to an initial firing direction 1008c.
As high-temperature, high-pressure gases formed by the detonation expand and push outward on the projectile, the asymmetry of perforating assembly 400 (e.g., referring to FIG. 4) may cause the actual trajectory of the projectile to deviate from the initial firing direction 1008c. This may ultimately cause the projectile to curve, as shown, resulting in a non-linear entry angle that forms the slotted perforations (e.g., width 1108 of FIG. 11B). As discussed, this allows for wider perforations and thus maximizes AOF.
FIGS. 11A and 11B show a comparison between perforation created by the first and second projectile profiles 1002 and 1006, respectively, of FIGS. 10A and 10B, in accordance with some examples of the present disclosure. As illustrated, a first width 1104 of a first perforation 1102 formed by a projectile launched in the straight-line trajectory profile 704 of FIG. 10A is non-elongated. In contrast a second width 1108 of a second perforation 1106 formed by a projectile launched according to one or more examples of the present disclosure may be elongated, and may be greater than first width 1104, in some examples. For example, holding all else equal between a symmetric and asymmetric conically shaped perforating assembly, this figure shows an increase from first width 1104 to second width 1108 of about 240%. Alternatively, a percent increase from about 10% to about 20%, about 20% to about 40%, about 40% to about 60%, about 60% to about 80%, about 80% to about 90%, about 90% to about 100%, about 100% to about 120%, about 120% to about 150%, about 150% to about 175%, about 175% to about 200%, about 200% to about 250%, about 250% to about 300%, about 300% to about 500%, or any ranges therebetween, depending on the type and amount of asymmetry. In some examples, the various types of asymmetry and/or amounts thereof (e.g., including the various dimensional parameters and ranges) herein disclosed may be incorporated into a perforating assembly individually, or combined together, which may compound the effects of the asymmetry on the elongation shown by FIG. 10B and thus maximize the AOF.
Accordingly, the present disclosure may provide methods and systems for perforating a wellbore casing using asymmetric perforating assemblies to increase area of flow without needing to increase shot density and charge size or make large-scale design changes to existing perforating guns. The methods and systems may include any of the various features disclosed herein, including one or more of the following statements.
Statement 1: A perforating assembly, comprising: a charge carrier; a liner disposed in the charge carrier; and an explosive charge disposed between the charge carrier and the liner and supported on the charge carrier, wherein the liner is supported on the explosive charge, wherein the perforating assembly has an asymmetric profile.
Statement 2: The perforating assembly of statement 1, wherein the perforating assembly is a conical perforating assembly or a hemispheric perforating assembly.
Statement 3: The perforating assembly of statements 1 or 2, wherein the asymmetric profile comprises a structural and/or material asymmetry in the charge carrier, the liner, the explosive charge, or combination thereof.
Statement 4: The perforating assembly of statement 3, wherein the structural and/or material asymmetry comprises a difference in thickness of the charge carrier, liner, or explosive charge by at least 5% for two radial coordinates spaced apart by at least 30 degrees about a central axis of the perforating assembly.
Statement 5: The perforating assembly of statement 4, wherein a transition between a first thickness and a second thickness comprises gradual tapering and/or step change.
Statement 6: The perforating assembly of statement 3, wherein for a given horizontal cross-section of the perforating assembly, a first thickness of the charge carrier at a first radial coordinate is different by at least 5% from at least a respective second thickness of the charge carrier at a second radial coordinate.
Statement 7: The perforating assembly of any of statements 1-6, wherein the asymmetric profile comprises at least one material asymmetry in the liner selected from the group consisting of different density, different tensile strength, different hardness, different ductileness, different toughness, different elasticity, different stress-strain response, and any combination thereof.
Statement 8: The perforating assembly of any of statements 1-7, wherein the liner comprises: a first section comprising a first material; and a second section comprising a second material, wherein the first material has a different density than the second material.
Statement 9: The perforating assembly of any of statements 1-8, wherein the explosive charge comprises: a first section comprising a first explosive; and a second section comprising: a second explosive different from the first explosive, and/or a higher concentration of the first explosive.
Statement 10: A perforating system, comprising: a perforating gun, comprising: a gun body; a charge tube disposed in the gun body; and a plurality of assemblies arranged in the charge tube, wherein at least one of the perforating assemblies has an asymmetric profile, wherein each of the perforating assemblies individually comprises a charge carrier, an explosive charge supported on the charge carrier, and a liner supported on the explosive charge.
Statement 11: The perforating system of statement 10, wherein the perforating system further comprising an additional perforating gun that comprises an additional gun body, an additional charge tube and a plurality of additional perforating assemblies, each additional perforating assembly also individually comprising a charge carrier, a conical liner, and an explosive charge.
Statement 12: The perforating system of statements 10 or 11, wherein the asymmetric profile comprises a structural and/or material asymmetry in at least one charge carrier, conical liner, explosive charge, or combination thereof.
Statement 13: The perforating system of any of statements 10-12, wherein the perforating gun comprises at least one conical or hemispheric perforating assembly.
Statement 14: The perforating assembly of any of statements 10-13, wherein for a given cross-section of the at least one perforating assembly, a first thickness of the liner of the at least one perforating assembly at a first radial coordinate is different by at least 5% from at least a respective second thickness of the liner of the at least one perforating assembly at a second radial coordinate.
Statement 15: A method, comprising: introducing at least a perforating gun into a wellbore extending into a subterranean formation, wherein the perforating gun comprises one or more perforating assemblies having an asymmetric profile and comprising a charge carrier, an explosive charge supported on the charge carrier, and a liner supported on the explosive charge; lowering the perforating gun to a target depth in the wellbore; and firing the at least one perforating assembly to perforate casing disposed in the wellbore, thereby forming one or more slot perforations.
Statement 16: The method of statement 15, wherein the asymmetric profile causes an actual trajectory of a projectile to vary from its initial firing direction, whereby a profile of the perforation is elongated with respect to that which would be expected for the same perforating gun without the asymmetric profile.
Statement 17: The method of statement 16, wherein a central axis of the at least one perforating assembly is aimed directly perpendicular to the casing during firing, wherein the projectile enters the wellbore casing at an angle relative to the central axis.
Statement 18: The method of any of statements 15-17, wherein the at least one perforating assembly has a substantially conical or hemispheric profile.
Statement 19: The method of any of statements 15-18, wherein for a given cross-section of the at least one perforating assembly, a first thickness of the liner at a first radial coordinate is different from at least a respective second thickness of the liner at a second radial coordinate.
Statement 20: The method of any of statements 15-19, wherein the asymmetric profile comprises a structural and/or material asymmetry in the liner, and wherein the one or more slot perforations are generally elongated by about 10% to about 500%.
For the sake of brevity, only certain ranges are explicitly disclosed herein. However, ranges from any lower limit may be combined with any upper limit to recite a range not explicitly recited, as well as, ranges from any lower limit may be combined with any other lower limit to recite a range not explicitly recited, in the same way, ranges from any upper limit may be combined with any other upper limit to recite a range not explicitly recited. Additionally, whenever a numerical range with a lower limit and an upper limit is disclosed, any number and any included range falling within the range are specifically disclosed. In particular, every range of values (of the form, “from about a to about b,” or, equivalently, “from approximately a to b,” or, equivalently, “from approximately a-b”) disclosed herein is to be understood to set forth every number and range encompassed within the broader range of values even if not explicitly recited. Thus, every point or individual value may serve as its own lower or upper limit combined with any other point or individual value or any other lower or upper limit, to recite a range not explicitly recited.
Therefore, the present embodiments are well adapted to attain the ends and advantages mentioned as well as those that are inherent therein. The particular embodiments disclosed above are illustrative only, as the present embodiments may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Although individual embodiments are discussed, all combinations of each embodiment are contemplated and covered by the disclosure. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. Also, the terms in the claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined by the patentee. It is therefore evident that the particular illustrative embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the present disclosure.
Patent Application
20250237122
