ASYMMETRIC SHAPED CHARGES AND METHOD FOR MAKING ASYMMETRIC PERFORATIONS
There is a shaped charge for making an asymmetrical perforation into a casing. The shaped charge includes a case extending along a symmetry axis X and having a back wall and an open end; an explosive material located within the case; a liner located within the case, over the explosive material; a booster material; and an asymmetrical feature. The asymmetrical feature is selected to generate an asymmetrical perforation into the casing.
Embodiments of the subject matter disclosed herein generally relate to shaped charges and associated perforations made in the casing of a well, and more specifically, to methods and systems for generating an asymmetric jet of material for perforating the casing to obtain a desired perforation profile.
Discussion of the BackgroundIn the oil and gas field, once a well 100 is drilled to a desired depth H relative to the surface 110, as illustrated in
During the perforating step for a given stage, perforating guns 115i of the perforating gun string 114 are used to create perforation clusters in the horizontal multistage hydraulically fractured unconventional well 100. Clusters are typically spaced along the length of a stage 140 (a portion of the casing that is separated with plugs from the other portions of the casing), and each cluster comprises multiple perforations (or holes) 130. Each cluster is intended to function as a point of contact between the wellbore 104 and the formation 106. After each stage 140 is perforated, a slurry of proppant (sand) and liquid (water) is pumped into the stage at high rates and then, through the perforation holes 130, into the formation 106, with the intent of hydraulically fracturing the formation to increase the contact area between that stage and the formation. A typical design goal is for each of the clusters to take a proportional share of the slurry volume, and to generate effective fractures, or contact points, with the formation, so that the well produces a consistent amount of oil cluster to cluster and stage to stage.
In typical wells, the distribution of the slurry and proppant between the various clusters is not uniform. There can be more slurry deposited near the toe end 140A of the stage 140, resulting in a toe biased stage, or more deposited near the heel end 140B of the stage 140, resulting in a heel biased stage. Sometimes, the clusters may not take appreciable amounts of slurry at all. Size, shape, distribution, and uniformity of perforation holes may contribute to this treatment nonuniformity.
The perforation geometry is typically a round hole 130, as shown in
Constant Entry Hole or Equal Entry Hole (CEH or EEH) charges have proven to be very beneficial in this application. Baseline conventional shaped charges 150 (
One mechanism to promote a more equal distribution of the slurry into the hole is the SANDIQ system, belonging to the assignee of this application, in which the perforation charges with CEH or Constant Entry Hole design are angled toward the toe so as to create a perforation which might more readily accept fluid and sand with less erosion, and with a lower pressure drop. Field results have been promising, with lower pressure drops observed during treatment, and hinting that the discharge coefficient might be higher than with systems having shaped charges with no angle.
Shaped charges which create slots have also been used to create noncircular perforation tunnels. These charges have been used in arrangements where the slot was perpendicular to the well axis (as shown in
Thus, there is a need to form slots into the casing, to control an orientation of the slots along the casing, and to design shaped charges that would achieve these results on a consistent basis.
SUMMARYAccording to an embodiment, there is a shaped charge for making an asymmetrical perforation into a casing. The shaped charge includes a case extending along a symmetry axis X and having a back wall and an open end; an explosive material located within the case; a liner located within the case, over the explosive material; a booster material; and an asymmetrical feature. The asymmetrical feature is selected to generate an asymmetrical perforation into the casing.
According to another embodiment, there is a liner for covering an explosive material in a case of a shaped charge. The liner includes a metallic powdered material, a binder that holds together the metallic powdered material, and an insert located partially within the metallic powdered material. The liner has a concave shape.
According to still another embodiment, there is a shaped charge for making an asymmetric perforation in a casing of a well. The shaped charge includes a case extending along a symmetry axis X and having a back wall and an open end, an explosive material located at the back wall of the case, a liner located within the case, over the explosive material, and a booster material located in a channel formed in the back wall of the case. The liner includes a metallic powdered material; a binder that holds together the metallic powdered material; and an insert located partially within the metallic powdered material. The liner has a concave shape.
According to yet another embodiment, there is a gun for perforating asymmetrically a casing of a well. The gun includes a gun carrier; and a shaped charge located inside the gun carrier and having a liner placed over an explosive material, where the liner includes a metallic powdered material; a binder that holds together the metallic powdered material; and an insert located partially within the metallic powdered material. The liner has a concave shape.
According to another embodiment, there is a method for making a shaped charge that is capable of making an asymmetric perforation into a casing. The method includes providing a case that extends along a symmetry axis X and has a back wall and an open end; making a channel through the back wall; installing a booster material into the channel; adding an explosive material to the back wall of the case; forming a liner; and placing the liner within the case, over the explosive material. The shaped charge has an asymmetrical feature selected to make the asymmetric perforation into the casing.
According to another embodiment, there is a gun for perforating a casing in a well. The gun includes a gun carrier and an asymmetric shaped charge located inside the gun carrier. The shaped charge has an asymmetrical feature selected to make an asymmetric perforation into the casing.
According to another embodiment, there is a casing that was perforated with an asymmetrical shaped charge. The casing includes a round wall; and an elongated perforation formed in the round wall with the shaped charge. A longitudinal axis x2 of the elongated perforation extends along a desired direction as a result of using the asymmetrical shaped charge.
According to another embodiment, there is a method for making an asymmetrical perforation in a casing. The method includes lowering a gun into the casing of a well; firing an asymmetric shaped charge located inside a gun carrier of the gun; and forming the asymmetrical perforation in the casing due to the asymmetric shaped charge.
The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate one or more embodiments and, together with the description, explain these embodiments. In the drawings:
The following description of the embodiments refers to the accompanying drawings. The same reference numbers in different drawings identify the same or similar elements. The following detailed description does not limit the invention. Instead, the scope of the invention is defined by the appended claims. The following embodiments are discussed, for simplicity, with regard to a perforating gun used for perforating a casing in a well. However, the embodiments discussed herein may be used for guns in another context.
Reference throughout the specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with an embodiment is included in at least one embodiment of the subject matter disclosed. Thus, the appearance of the phrases “in one embodiment” or “in an embodiment” in various places throughout the specification is not necessarily referring to the same embodiment. Further, the particular features, structures or characteristics may be combined in any suitable manner in one or more embodiments.
According to an embodiment, a shaped charge includes a case, an explosive material, a liner, and a booster material. The explosive material is sandwiched between the case and the liner and the booster material is in contact with the explosive material, at one edge of the explosive material. At least one of these elements of the shape charge is made to be asymmetrical regarding a longitudinal axis (symmetry axis) of the shaped charge. In one variation, although all the above elements of the shaped charge are symmetrical relative to the symmetry axis, one or more inserts are added to one or more of these elements and the insert is made asymmetrical. For example, the insert may be asymmetrical in shape relative to the longitudinal axis. However, in one application, the insert may have a symmetrical shape, but asymmetrical properties, i.e., different physical properties as, for example, a melting point, impedance, etc. In one application, the insert is made of an inert material, i.e., a material that does not explode, ignite, or burns under natural conditions. These possible implementations of an asymmetrical shaped charge are now discussed.
A shaped charge 400 is illustrated in
An explosive material 410 is placed inside the cup shaped case 402. The explosive material 410 is typically packed inside the case 402 by micro-forging or other methods. The explosive material may be a high explosive material, like NONA, ONT, RDX, HMX, HNS, BRX, PETN, CL-20, HNIW, PYX, TATB, TNAZ, HNIW, or other known explosive. The liner 420 covers the explosive material 410 and keeps it inside the case 402. The liner 420 may be made of a reactive or an inert material, e.g., metal particles mixed with a light glue, so that the liner appears like a metallic sheet.
The booster material 430 is placed at the bottom of the case 402, in the channel 406. The booster material 430 is connected to a detonation cord 440, which initiates the detonation of the booster material 430. The booster material includes a detonation material, which may be the same as the explosive material 410 or different. When the gun is fired, the gun detonator is first detonated, which initiates the detonation cord 440. The detonation cord 440 initiates the booster material 430. The detonation of the booster material 430 starts the explosion of the explosive material 410. Thus, in the embodiment of
However, in the embodiment of
In another embodiment illustrated in
As previously discussed, the booster material 430 constitutes the initiation point for the explosive material. Due to the asymmetry of the booster material, the propagation of the detonation front becomes also asymmetrical inside the explosive material 410 while inside the case 402, which results in the expelled jet being non-symmetrical. As will be discussed later, by controlling the asymmetry of the shaped charge, the expelled jet is expected to form a key hole shape in the casing or a slot with a desired orientation relative to a longitudinal axis of the casing of the well.
In one embodiment, it is possible to combine the asymmetric features shown in
According to another embodiment, as illustrated in
According to another embodiment, which is illustrated in
In another embodiment, as illustrated in
In one variation of the embodiment of
In another variation of the embodiment of
For any of the above discussed embodiments, if two inserts 1200 and 1210 are used, they may be distributed inside the case 402 so that an angle β between the two inserts is in the range of 165 to 195°, as illustrated in
In still another embodiment, as illustrated in
The liner 420 has a smaller part 422 that corresponds to the smaller volume of explosive material hold by the part 408A of the lateral wall 408 and a larger part 424 corresponding to the part 408B. Thus, for the embodiment shown in
A method for manufacturing an asymmetrical shaped charge 400 (as shown in any of the
In step 1404, the booster material 430 is placed into the channel 406 by any known method. If more than one channel 406 is formed, the channels may be distributed as illustrated in
In step 1408 the liner 420 is formed. The liner may be formed by injection mold, 3D print, machined, cast, extrusion, stamping, mold, microforge, etc. The liner 420 may be made to be symmetric relative to the symmetry axis X or not. In one embodiment, one side of the liner is made larger than the other side of the liner, as illustrated in
In the above discussed embodiments, the asymmetry of the shaped charge has been added to one of the elements of the shaped charge. However, it is possible to introduce an asymmetry into the structure of the liner itself. Thus, the next embodiments discuss these possibilities.
The liner 1500 (and other liners illustrated in other figures) may have a generally concave shape. The concave shape may be symmetrical or not relative to the symmetry axis X. The concave shape may be implemented in many ways, for example, as a trumpet, cone, bell, hemispherical, etc. The liner 420 includes at least one type of powdered metal 1502. The metal may be copper, tin, nickel, tungsten, lead, molybdenum or a combination of these materials. The metallic powder is held together with a binder 1504. The binder can be a glue, polymer or other material. In one application, the liner is machined from a solid piece of material. In another application, the liner is printed, forged, or molded.
In another embodiment illustrated in
The embodiment of
The embodiment illustrated in
Any of the configurations discussed above achieves a jet of material that is not symmetrical. Based on experiments performed by the inventors, one or more of these asymmetrical configurations may generate the following holes in a casing.
By changing the orientation and/or location of the asymmetry in the shaped charge, it is possible to control the position of the longitudinal axis X2 of the slot 1910 or key hole 1920. For example, as shown in
For all the embodiments discussed herein, while the asymmetric shaped charges may be attached to the gun carrier to be perpendicular to the longitudinal axis of the casing, it is also possible to have the shaped charges installed with a non-zero angle relative to the axial direction of the casing. In one embodiment, it is possible that some asymmetrical shaped charges are perpendicular to the longitudinal direction of the casing while the other asymmetrical shaped charges are tilted to the axial direction. Further, in one application it is possible to combine traditional, symmetrical, shaped charges with one or more of the novel asymmetrical shaped charges discussed above.
One advantage of making key hole perforations is that it can be made in a consistent manner. Traditional slot charges are very sensitive to the water gap and pressure, and will produce suboptimal results in downhole conditions. The key hole perforation produced with the asymmetrical shaped charge discussed above has a consistent hole size, with the key hole extending the opportunity for sand placement.
Another possible advantage is that the traditionally eroded holes tend to be shaped like a key hole, so that by directly producing a key hole perforation, it is likely to be less eroded by the sand placement.
In one embodiment, the perforations will be a tapered slot, generated by a slot producing charge being held at an angle within the gun body (generally tilted toe-ward, but could be either way) so that the travel distances for the various parts of the jet are not symmetric, which will result in a narrowing slot.
A method for making the liner shown in
A gun having one or more of the shaped charged discussed with regard to
The disclosed embodiments provide methods and systems for generating a slot or key hole perforation into a casing of a well, by using at least a shaped charge that has an asymmetrical feature. It should be understood that this description is not intended to limit the invention. On the contrary, the exemplary embodiments are intended to cover alternatives, modifications and equivalents, which are included in the spirit and scope of the invention as defined by the appended claims. Further, in the detailed description of the exemplary embodiments, numerous specific details are set forth in order to provide a comprehensive understanding of the claimed invention. However, one skilled in the art would understand that various embodiments may be practiced without such specific details.
Although the features and elements of the present exemplary embodiments are described in the embodiments in particular combinations, each feature or element can be used alone without the other features and elements of the embodiments or in various combinations with or without other features and elements disclosed herein.
This written description uses examples of the subject matter disclosed to enable any person skilled in the art to practice the same, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the subject matter is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims.
Claims
1. A liner for covering an explosive material in a case of a shaped charge, the liner comprising:
- a metallic powdered material;
- a binder that holds together the metallic powdered material; and
- an insert located partially within the metallic powdered material,
- wherein the liner has a concave shape.
2. The liner of claim 1, wherein the insert is fully immersed within the liner.
3. (canceled)
4. The liner of claim 1, wherein the insert is asymmetric relative to a symmetry axis of the liner.
5-7. (canceled)
8. The liner of claim 1, wherein one face of the insert is flush with a surface of the liner and the remaining of the insert is fully embedded into the liner.
9. (canceled)
10. A shaped charge for making an asymmetric perforation in a casing of a well, the shaped charge comprising:
- a case extending along a symmetry axis X and having a back wall and an open end;
- an explosive material located at the back wall of the case;
- a liner located within the case, over the explosive material; and
- a booster material located in a channel formed in the back wall of the case,
- wherein the liner includes:
- a metallic powdered material;
- a binder that holds together the metallic powdered material; and
- an insert located partially within the metallic powdered material,
- wherein the liner has a concave shape.
11-27. (canceled)
28. A shaped charge for making an asymmetrical perforation into a casing, the shaped charge comprising:
- a case extending along a symmetry axis X and having a back wall and an open end;
- an explosive material located within the case;
- a liner located within the case, over the explosive material;
- a booster material; and
- an asymmetrical feature,
- wherein the asymmetrical feature is selected to generate an asymmetrical perforation into the casing.
29. The shaped charge of claim 28, wherein the asymmetrical feature is the liner being tilted relative the symmetry axis X so that one side of the liner touches the case at a first height and the other side of the liner touches the case at a second height, different from the first height.
30. The shaped charge of claim 29, wherein the channel and the booster material are symmetrically distributed relative to the symmetry axis X.
31. The shaped charge of claim 28, wherein the asymmetrical feature is that the symmetry axis X and an axis of symmetry X′ of the liner make a non-zero angle.
32. The shaped charge of claim 28, wherein the asymmetrical feature is that the channel has a longitudinal axis X″, which makes a non-zero angle with the symmetry axis X.
33. The shaped charge of claim 32, wherein the case, the explosive material and the liner are symmetrical relative to the symmetry axis.
34. The shaped charge of claim 32, wherein the channel is offset relative to the symmetry axis.
35. The shaped charge of claim 28, further comprising:
- another channel formed in the back wall of the case.
36. The shaped charge of claim 35, wherein the another channel and the channel are asymmetrically located relative to the symmetry axis X.
37. The shaped charge of claim 28, wherein the asymmetrical feature is that the booster material fires along an axis that is not the symmetry axis X.
38. The shaped charge of claim 28, wherein the asymmetrical feature is that the booster material fires toward a side wall of the case.
39. The shaped charge of claim 28, wherein the asymmetrical feature is that a first volume of the explosive material has a characteristic that is different from a second volume of the explosive material.
40. The shaped charge of claim 39, wherein the characteristic is a density.
41. The shaped charge of claim 39, wherein the characteristic is a chemical composition.
42. The shaped charge of claim 28, wherein the asymmetrical feature is an insert placed inside the case.
43. The shaped charge of claim 42, wherein the insert is fully embedded into the explosive material.
44-68. (canceled)
Type: Application
Filed: Dec 20, 2019
Publication Date: Mar 17, 2022
Inventors: David WESSON (Ft. Worth, TX), Phil SNIDER (Houston, TX), Nathan CLARK (Mansfield, TX), Wenbo YANG (Kennedale, TX), John HARDESTY (Fort Worth, TX)
Application Number: 17/424,668