Momentum trap

The present disclosure provides an embodiment of a perforating gun assembly for use in a wellbore. The perforating gun assembly, in one example includes a carrier gun body. The perforating gun assembly, in this example, further includes a plurality of shaped charges supported within the carrier gun body, wherein each shaped charge may include a case exterior, the case exterior including an outer surface, and an inner surface forming a cavity, a liner located within the cavity, and explosive material located within a gap between the inner surface of the case exterior and the liner. The perforating gun assembly, in this example, may further include one or more momentum traps positioned between one or more adjacent shaped charges.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to International Application Serial No. PCT/US2018/067222, filed on Dec. 21, 2018, and entitled “MOMENTUM TRAP,” is commonly assigned with this application and incorporated herein by reference in its entirety.

BACKGROUND

After drilling the various sections of a subterranean wellbore that traverses a formation, individual lengths of relatively large diameter metal tubulars are typically secured together to form a casing string that is positioned within the wellbore. This casing string increases the integrity of the wellbore and provides a path for producing fluids from the producing intervals to the surface. Conventionally, the casing string is cemented within the wellbore. To produce fluids into the casing string, 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 formation. Specifically, one or more perforating guns are loaded with shaped charges that are connected with a detonator via a detonation cord. The perforating guns are then connected within a tool string that is lowered into the cased wellbore at the end of a tubing string, wireline, slick line, coil tubing or other conveyance. Once the perforating guns are properly positioned in the wellbore such that the shaped charges are adjacent to the formation to be perforated, the shaped charges may be detonated, thereby creating the desired openings.

The performance of the well is dependent on the ability to easily extract hydrocarbons from the surrounding formation. Thus, improvements are needed in the art to more easily extract hydrocarbons from the surrounding formation.

DETAILED DESCRIPTION

In the drawings and descriptions that follow, like parts are typically marked throughout the specification and drawings with the same reference numerals, respectively. The drawn figures are not necessarily to scale. Certain features of the disclosure may be shown exaggerated in scale or in somewhat schematic form and some details of certain elements may not be shown in the interest of clarity and conciseness. The present disclosure may be implemented in embodiments of different forms.

Specific embodiments are described in detail and are shown in the drawings, with the understanding that the present disclosure is to be considered an exemplification of the principles of the disclosure, and is not intended to limit the disclosure to that illustrated and described herein. It is to be fully recognized that the different teachings of the embodiments discussed herein may be employed separately or in any suitable combination to produce desired results.

Unless otherwise specified, use of the terms “connect,” “engage,” “couple,” “attach,” or any other like term describing an interaction between elements is not meant to limit the interaction to direct interaction between the elements and may also include indirect interaction between the elements described.

Unless otherwise specified, use of the terms “up,” “upper,” “upward,” “uphole,” “upstream,” or other like terms shall be construed as generally toward the surface of the ground; likewise, use of the terms “down,” “lower,” “downward,” “downhole,” or other like terms shall be construed as generally toward the bottom, terminal end of a well, regardless of the wellbore orientation. Use of any one or more of the foregoing terms shall not be construed as denoting positions along a perfectly vertical axis. Unless otherwise specified, use of the term “subterranean formation” shall be construed as encompassing both areas below exposed earth and areas below earth covered by water such as ocean or fresh water.

Referring initially toFIG.1, schematically illustrated is a well system100including a plurality of perforating gun assemblies of the present disclosure operating in a subterranean formation (e.g., from an offshore oil and gas platform). A semi-submersible platform112is centered over a submerged oil and gas formation114located below sea floor116. A subsea conduit118extends from deck120of platform112to wellhead installation122including subsea blow-out preventers124. Platform112has a hoisting apparatus126and a derrick128for raising and lowering pipe strings such as work string130. As used herein, work string encompasses any conveyance for downhole use, including drill strings, completion strings, evaluation strings, other tubular members, wireline systems, and the like.

A wellbore132extends through the various earth strata including formation114. In the embodiment ofFIG.1, a casing134is cemented within wellbore132by cement136. Work string130includes various tools such as a plurality of perforating gun assemblies of the present disclosure. When it is desired to perforate formation114, work string130is lowered through casing134until the perforating guns are properly positioned relative to formation114. Thereafter, the shaped charges within the string of perforating guns may be sequentially fired, either in an uphole to downhole or a downhole to uphole direction. Upon detonation, the liners of the shaped charges form jets that create a spaced series of perforations extending outwardly through casing134, cement136and into formation114, thereby allowing fluid communication between formation114and wellbore132. In accordance with one embodiment of the disclosure, a momentum trap may be disposed between one or more adjacent charges of the perforating gun assembly. Specifics of the momentum trap will be discussed in greater detail below.

In the illustrated embodiment, wellbore132has an initial, generally vertical portion138and a lower, generally deviated portion140which is illustrated as being horizontal. It should be noted, however, by those skilled in the art that the perforating gun assemblies of the present disclosure are equally well-suited for use in other well configurations including, but not limited to, inclined wells, wells with restrictions, non-deviated wells and the like.

In the embodiment ofFIG.1, work string130includes a retrievable packer142which may be sealingly engaged with casing134in a vertical portion138of wellbore132. At the lower end of work string is a gun string, generally designated144. In the illustrated embodiment, gun string144has at its upper or near end a ported nipple146below which is a time domain firer148. Time domain firer148is disposed at the upper end of a tandem gun set150including first and second guns152and154. In the illustrated embodiment, a plurality of such gun sets150, each including a first gun152and a second gun154are utilized. Positioned between each gun set150in the embodiment ofFIG.1is a blank pipe section156. Blank pipe sections156may be used to control and optimize the pressure conditions in wellbore132immediately after detonation of the shaped charges. While tandem gun sets150have been described with blank pipe sections156there between, it should be understood by those skilled in the art that any arrangement of perforating guns may be utilized in conjunction with the present disclosure including both more or less sections of blank pipe as well as no sections of blank pipe, without departing from the principles of the present disclosure.

Referring now toFIG.2, therein is depicted a perforating gun assembly of the present disclosure that is generally designated200. In one embodiment, the perforating gun assembly200forms at least a portion of the gun sets150illustrated inFIG.1. Perforating gun assembly200includes a carrier gun body202, in one embodiment made of a cylindrical sleeve having a plurality of radially reduced areas depicted as scallops or recesses204. Radially aligned with each of the recesses204is a respective one of a plurality of shaped charges, only eleven of which, shaped charges206-226, are visible inFIG.2.

Each of the shaped charges, such as shaped charge216includes an outer housing, such as case exterior228, an inner housing, such as case interior229and a liner230. Furthermore, disposed between each case exterior228, case interior229and liner230is a quantity of explosive material.

The shaped charges206-226, in the embodiment shown, are retained within carrier gun body202by a charge holder232which includes an outer charge holder sleeve234and an inner charge holder sleeve236. In this configuration, outer tube234supports the discharge ends of the shaped charges, while inner tube236supports the initiation ends of the shaped charges. Disposed within inner tube236is a detonation cord240, which is used to detonate the shaped charges. In the illustrated embodiment, the initiation ends of the shaped charges extend across the central longitudinal axis of perforating gun assembly200allowing detonation cord240to connect to the high explosive within the shaped charges through an aperture defined at the apex of the housings of the shaped charges.

In the embodiment ofFIG.2, each of the shaped charges206-226is longitudinally and radially aligned with one of the recesses204in carrier gun body202when perforating gun assembly200is fully assembled. In the illustrated embodiment, the shaped charges are arranged in a spiral pattern such that each of the 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 understood by those skilled in the art, however, 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.

In accordance with the disclosure, one or more momentum traps240may be positioned between one or more of the adjacent shaped charges206-226. In the illustrated embodiment, the charge holder232may have a plurality of openings250(e.g., illustrated with dotted lines to depict the openings250are enclosed by the carrier gun body202) in the exterior thereof for receiving one or more momentum traps240therein. In the illustrated embodiment, the openings250were laser or die cut within the charge holder232at a precise location as to place the momentum traps240between the one or more adjacent shaped charges206-226. Other methods for creating the openings250are within the scope of the disclosure. In fact, certain embodiments exist wherein no openings250are used, or alternatively wherein the openings250are placed within the carrier body202, among other places.

As will be discussed herein, in some embodiments, the momentum traps240may be positioned between two adjacent shaped charges such as, e.g. shaped charges208and212, wherein the shaped charge208is fully isolated from the shaped charge212. Fully isolated, as used herein, means that there is no part of shaped charge208that is exposed to shaped charge212. In some embodiments, fully isolated may be achieved by positioning the momentum trap240such that the momentum trap240extends at least to a top end (or radially outward end) of shaped charges208and212and extend at least to a bottom (or radially inward) end of shaped charges208and212, such that no portion of one is exposed to the other. In other embodiments, the momentum trap240may extend beyond the top and bottom ends of shaped charges208and212. In other embodiments, however, adjacent shaped charges may only be partially isolated.

Referring now toFIG.3, therein is depicted one embodiment of a shaped charge system300which may be used within a perforating gun assembly such as perforating gun assembly200. The shaped charge system300may include a plurality of shaped charges310aand310b, which may be supported within the carrier gun body202. In one embodiment, the shaped charges310aand310bmay be positioned adjacent each other, and adjacent additional shaped charges. In the embodiment shown, the shaped charges310aand310bare positioned such that they are offset from each other at an angle. In some embodiments, the offset angle may be about 60 degrees, but those skilled in the art understand that the shaped charges310a,310bmay be positioned in various arrangements and offset at various angles. Each shaped charge310a,310bmay include a case exterior320, the case exterior including an outer surface330, and an inner surface340forming a cavity. A liner350may be located within the cavity and explosive material360may be located within a gap between the inner surface340of the case exterior320and the liner350. A momentum trap370may be positioned between one or more adjacent shaped charges, such as shaped charges310aand310b. The momentum trap370may reduce the interference from one shaped charge to the next adjacent charge such that each shaped charge maintains a high level of charge performance.

In some embodiments, momentum trap370may be positioned between two adjacent shaped charges such as, e.g. shaped charges310aand310b, such that the entirety of shaped charge310ais fully isolated from the entirety of shaped charge310b. Fully isolated, as used herein, means that there is no part of shaped charge310ais touching or exposed to shaped charge310b. In some embodiments, fully isolating shaped charge310afrom310bmay be achieved by positioning the momentum trap370such that the momentum trap370extends at least to all exterior edges of the case exterior320of both shaped charges310aand310b, and in other embodiments, the momentum trap370may extend beyond all exterior edges of the case exterior320of both shaped charges310aand310b.

In other embodiments, the momentum trap370may be positioned between shaped charges310aand310bsuch that shaped charge310ais only partially isolated from shaped charge310b. Partially isolated, as used herein, means that at least a part of a shaped charge (e.g., shaped charge310a) is exposed to at least a part of an adjacent shaped charge (e.g., shaped charge310b). For example, the momentum trap370may be positioned to extend radially inward from the carrier gun body to only a partial depth, less than the height of each shaped charge, such that only radially outward portions of the shaped charges310aand310bare isolated from each other by the momentum trap370. Alternatively, the exposed parts of the adjacent shaped charges (e.g., shaped charges310a,310b) could be the radially outer parts thereof.

The momentum trap370may be fabricated using various materials capable of withstanding conditions experienced by tools used within a wellbore, such as a perforating gun. The liner350may need to penetrate, in some embodiments, at least a carrier gun body, the wellbore, a fluid casing surrounding the wellbore, cement around the fluid casing, and the subterranean formation. As such, the momentum trap370may comprise a high density material sufficient to withstand the explosion and force of the explosive material360, while isolating one shaped charge310afrom the adjacent shaped charge310b. The phrase “high density material”, as used herein, means a material having a density of at least about 1.7 g/cm3. Examples of a high density material which may be used include, but are not limited to, platinum, gold, tungsten, uranium, tantalum, palladium, lead, silver, molybdenum, bismuth, copper, nickel, iron, tin, zinc, zirconium, titanium, aluminum, silicon, carbon, magnesium. In another embodiment, the momentum trap370may comprise a “very high density material” having a density of at least about 8.9 g/cm3, or in another embodiment an “extremely high density material” having a density of at least about 11.5 g/cm3. The high density material, very high density material, or extremely high density material may, in certain embodiments, be solid foam, or distended foam (e.g., foams or pressed powders, at some percentage of a possible maximum density of 100%). Other embodiments may include combinations, layers, and/or alloys of the foregoing high density, very high density and extremely high density materials.

Referring now toFIGS.4A and4B, there are shown results from two different 2-charge perforating systems400aand400b, each having two adjacent shaped charges and illustrating jet streams exploding from each charge. In the perforating system400aofFIG.4A, two adjacent shaped charges410aand410bdo not have a momentum trap between them. Shaped charge410ainitiates first and shaped charge410binitiates after a short time delay. As shown inFIG.4A, without any isolating mechanism between the shaped charges410aand410b, the performance of shaped charge410bis affected. For example, a jet stream415bexiting from shaped charge410bis shown to deviate from the central axis of shaped charge410bWhen the jet stream from each shaped charge is affected as shown inFIG.4A, the charge performance of the perforating system is negatively impacted, which may result in reduced charge performance or suboptimal well performance.

FIG.4Billustrates charge perforating system400b, wherein shaped charges430aand430bhave a momentum trap470positioned there between. Shaped charge430ainitiates first and shaped charge430binitiates after a short time delay. The presence of the momentum trap470provides isolation of shaped charge430bfrom shaped charge430aand as a result, the jet stream435bfrom shaped charge430b, is substantially perpendicular with a top surface440of shaped charge430b, indicating a high level of charge performance by shaped charge430b. Accordingly, the charge performance of shaped charge430bis only minimally impacted, if any, by shaped charge430asuch that shaped charge430bcan deliver a superior charge performance relative to the reduced charge performance illustrated inFIG.4A.

Referring now toFIG.5, there is shown one embodiment of a momentum trap570which may be used between two shaped charges, such as shaped charges310aand310b. The momentum trap570may be saddle shaped and in some embodiments, be positioned between two shaped charges such that the shaped charges are fully isolated from each other.

Referring now toFIG.6, there is shown another embodiment of a momentum trap670which may have a triangular or wedge shape. In some embodiments, the momentum trap670may be positioned between two adjacent shaped charges such as to only partially isolate one shaped charge from the adjacent shaped charge. Different embodiments of momentum traps may have a variety of geometries and sizes other than shown and described herein. For examples, a momentum trap may be include but not be limited to the following shapes: a disc, wafer, plate, saddle, wedge, and other possible geometries. In some embodiments, the momentum wafer may be a symmetrical shape, but other embodiments may include momentum shapes that are not symmetric.

While the momentum traps shown in the embodiments herein have been shown substantially centered (equidistant) between the adjacent shapes charges, the momentum trap may be placed at any position between the two adjacent shaped charges and have a varying amount of spacing between the shaped charges. In one embodiment, the momentum trap may be positioned closer to a downhole shaped charge, such that there is a larger spacing between the momentum trap and an adjacent uphole shaped charge and a smaller spacing between the momentum trap and the adjacent downhole shaped charge. In other embodiments, the momentum trap may be positioned closer to the uphole shaped charge, such that there is a larger spacing between the momentum trap and an adjacent downhole shaped charge and a smaller spacing between the momentum trap and the adjacent uphole shaped charge. In some embodiments, there may be free space between the momentum trap and the adjacent shaped charges, and said free spacing may vary according to the configuration of the shaped charges and the application for which the shaped charges are configured. And in some embodiments, there may be little or no free spacing between the momentum trap and the adjacent shaped charges. In this embodiment, the momentum trap could be touching, or very close to touching, one or both of the adjacent shaped charges.

Aspects disclosed herein include:

A. A perforating gun assembly for use in a wellbore, the perforating gun including: 1) a carrier gun body; and 2) a plurality of shaped charges supported within the carrier gun body, wherein each shaped charge includes a case exterior, the case exterior including an outer surface, and an inner surface forming a cavity, a liner located within the cavity, and explosive material located within a gap between the inner surface of the case exterior and the liner, and one or more momentum traps positioned between one or more adjacent shaped charges.

B. A well system, the well system including: a wellbore; and a perforating gun assembly positioned within the wellbore, the perforating gun held in place by a conveyance and comprising; 1) a carrier gun body; 2) a plurality of shaped charges supported within the carrier gun body, wherein each shaped charge includes a case exterior, the case exterior including an outer surface, and an inner surface forming a cavity, a liner located within the cavity, and explosive material located within a gap between the inner surface of the case exterior and the liner; and 3) one or more momentum traps positioned between one or more adjacent shaped charges.

C. A method for perforating a wellbore, the method including: positioning a perforating gun assembly at a desired location within a wellbore, the perforating gun assembly including; 1) a carrier gun body, 2) a plurality of shaped charges supported within the carrier gun body, wherein each shaped charge includes a case exterior, the case exterior including an outer surface, and an inner surface forming a cavity, a liner located within the cavity, and explosive material located within a gap between the inner surface of the case exterior and the liner; and 3) one or more momentum traps positioned between one or more adjacent shaped charges; and further including detonating the explosive material within the plurality of shaped charges to form a plurality of jets that penetrate the wellbore and form a plurality of openings therein.

Aspects A, B, and C may have one or more of the following additional elements in combination: Element 1: further including a charge holder disposed within the carrier gun body, the charge holder supporting the plurality of shaped charges, wherein the charge holder includes one or more openings for receiving the one or more momentum traps therein. Element 2: wherein the one or more momentum traps comprise a high-density material. Element 3: wherein the one or more momentum traps are positioned between the one or more adjacent shaped charges such that the adjacent shaped charges are fully isolated from each other. Element 4: wherein the one or more momentum traps are positioned between the one or more adjacent shaped charges such that the adjacent shaped charges are partially isolated from each other. Element 5: wherein the one or more momentum traps are positioned such that there is free space between the one or more momentum traps and the one or more adjacent shaped charges. Element 6: wherein one of the one or more momentum traps is positioned closer to one shaped charge than the adjacent shaped charge.