Patent Application
20240142203
The present invention relates to perforating gun systems having penetrating shaped charges to generate perforations through a wellbore casing.
In oil and gas operations, it is a known practice to install a well casing into a borehole that has been drilled into a geologic formation. A gun string is then lowered into the wellbore on a wireline, slickline or coiled tubing, opposite a hydrocarbon formation. The gun string includes shaped charges that, when fired, are formed into high-velocity jets that penetrate through the wellbore casing. The resulting perforations allow a fluid (oil or gas) to flow into the wellbore.
A gun string will typically include multiple perforating guns, each with opposing box ends having female threads. Tandems having male threads are threaded to one or both ends of each perforating gun in the gun string. In this fashion, multiple perforating guns can be connected end-to-end and sequentially detonated within the wellbore via an electrical signal sent from the surface.
The internal shaped charges are typically detonated by a detonating cord, which in turn is ballistically connected to a detonator that typically is triggered by an addressable switch, which is electronically actuated from the surface. The detonating cord is coupled to the apex of each shaped charge. In this arrangement, a single detonator at one end of the perforating gun will detonate all of the shaped charges in the perforating gun.
Despite their widespread acceptance for wellbore operations, there remains a continued need for improved perforating gun systems. In particular, there remains a continued need for improved perforating gun systems that selectively arm each gun in a gun string and requires less time to be loaded and armed at the wellsite.
In one embodiment, an arming tandem is provided. The arming tandem includes an internal arming pin that is biased in a retracted position. Detonating the last perforating gun in a gun string forces the arming pin in the immediately adjacent arming tandem into contact with a grounding plate in the next perforating gun, thereby arming the next perforating gun. In this respect, each perforating gun in a gun string can be sequentially armed, optionally without the need for an addressable switch in each such perforating gun. As explained herein in greater detail, the arming pin is biased in the retracted position by a helical compression spring that is contained within a counterbored opening in the arming tandem. An adjacent bulkhead includes a grounding plate that surrounds a contact pin. The grounding plate provides a flat surface for contacting the arming pin and creating a secure connection to ground upon detonation of the up-string perforating gun.
In another embodiment, a locking collar is provided. The locking collar is adapted to secure a perforating gun so that its shaped charges are locked into a set firing position. The locking collar includes upper and lower axial surfaces that are joined by an inner sidewall and an outer sidewall. The inner sidewall is cylindrical, and the outer sidewall is sloped along a major section of its length. The outer sidewall includes a plurality of threaded openings that extend at an angle toward the lower axial surface. Each threaded opening extends entirely through the locking collar at an angle relative to the lower axial surface. In use, the locking collar extends around a top sub and receives set screws within each of the internally threaded openings. The set screws engage a perforating gun to radially align the gun ports of the perforating gun and are more reliable than conventional locking nuts.
These and other features and advantages of the present invention will become apparent from the following description of the invention, when viewed in accordance with the accompanying drawings and appended claims.
Before embodiments of the invention are explained in detail, it is to be understood that the invention is not limited to the details of operation or to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The invention may be implemented in various other embodiments and of being practiced or being carried out in alternative ways not expressly disclosed herein. In addition, it is to be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use of “including” and “comprising” and variations thereof is meant to encompass the items listed thereafter and equivalents thereof as well as additional items and equivalents thereof. Further, enumeration may be used in the description of various embodiments. Unless otherwise expressly stated, the use of enumeration should not be construed as limiting the invention to any specific order or number of components. Nor should the use of enumeration be construed as excluding from the scope of the invention any additional steps or components that might be combined with or into the enumerated steps or components.
The following detailed description is merely exemplary in nature and is not intended to limit the oilfield perforating systems and methods as described herein. Furthermore, there is no intention to be bound by any theory presented in the preceding background or the following detailed description. The description is not in any way meant to limit the scope of any present or subsequent related claims.
As used here, the terms “above” and “below”; “up” and “down”; “upper” and “lower”; “upwardly” and “downwardly”; and other like terms indicating relative positions above or below a given point or element are used in this description to more clearly describe some embodiments. However, when applied to equipment and methods for use in wells that are deviated or horizontal, such terms may refer to a left to right, right to left, or diagonal relationship as appropriate.
A section of a gun string in accordance with an exemplary embodiment is illustrated in
As more specifically shown in
The shaped charge positioning tube 22 is formed from an electrically conductive material, for example steel, further optionally stainless steel or carbon steel. Each end portion of the shaped charge positioning tube 22 defines a plurality of longitudinal slots, such that the shaped charge positioning tube 22 includes castellated or segmented end portions 24. The shaped charge positioning tube 22 also includes a cylindrical body having multiple shaped charge openings 26 that receive a corresponding number of shaped charges. The openings 26 are angularly offset from each other in the current embodiment, but can be in angular alignment in other embodiments.
A bulkhead 30 is positioned at each end of the shaped charge positioning tube 22 and is separately shown in
The up-hole bulkhead 30 includes a grounding plate 40 that is electrically isolated from the contact pin 36 by an electrically insulating sleeve 42. The grounding plate 40 is formed from an electrically conductive material and is disk-shaped. The grounding plate 40 provides a bearing surface for the arming pin 16 contained within the adjacent arming tandem. Each arming pin 16 is received within a counterbored opening having a small diameter portion 44 and a large diameter portion 46 joined by an annular shelf. A compression spring 48 is seated against the shelf and biases the arming pin 16 away from the grounding plate 40.
The first arming tandem 12 also includes a first pass-through element 50 and the second tandem 16 includes a second pass-through element 50. Each pass-through element 50 is surrounded by an insulating sleeve 52. The insulating sleeve 52 is formed from a non-conductive material to electrically isolate the pass-through element 52 from the tandem body 54, which is formed from a non-conductive material or is electrically grounded. At least one O-ring surrounds the insulating sleeve 52 to create a seal with the tandem body 54.
The present embodiment enables the sequential arming of a series of perforating guns in a gun string, optionally without the need for an addressable switch in each such perforating gun. In operation, a firing signal is received at the first perforating gun in the gun string, causing the shaped charges within that perforating gun to detonate, thereby creating a plurality of perforations through the wellbore casing. Pressure from this detonation moves the arming pin 16 in the immediately adjacent arming tandem into contact with the grounding plate 40 in the next perforating gun, as shown in
Though not shown, the gun string can include diodes inline to control polarity, thereby preventing a stray voltage from causing a cascade event. Each perforating gun in the gun string would include a diode with the opposite polarity of the adjacent perforating gun(s). In this configuration, each perforating gun in the gun string is detonated with a firing signal having an alternating positive or negative voltage. This configuration guards against the accidental detonation of the next perforating gun in the gun string due to the large capacitance on the wireline cable, which could otherwise fire the next detonator in the gun string.
In another embodiment as shown in
As noted above, the locking collar 60 is used to secure a perforating gun so that the shaped charges are locked into a set firing position. As shown in
The above description is that of current embodiments of the invention. Various alterations and changes can be made without departing from the spirit and broader aspects of the invention as defined in the appended claims, which are to be interpreted in accordance with the principles of patent law including the doctrine of equivalents. Any reference to elements in the singular, for example, using the articles “a,” “an,” “the,” or “said,” is not to be construed as limiting the element to the singular.
This application claims the benefit of U.S. Provisional Application 63/420,901, filed Oct. 31, 2022, the disclosure of which is hereby incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| 63420901 | Oct 2022 | US |
