Patent Application
20090078144
The present invention relates to a liner for a shaped charge where the liner comprises a plurality of portions and where at least one portion comprises a powder material.
When the shaped charge 10 is detonated a portion of the liner 12 forms a jet portion of the liner. The jet is propelled away from the jacket 11 in a direction 17 toward a target. Another portion of the liner 12 is propelled away from the jacket 11 and forms what is known as a slug or carrot portion of the liner. The slug or carrot portion is not propelled to the same extent as the “jet”. When the shaped charge 10 is used in a perforating gun, the target is normally a cased downhole formation. Upon detonation, the jet portion of the liner 12 is propelled through the casing and penetrates the downhole formation to enhance recovery of downhole hydrocarbons. The slug portion, on the other hand, is designed to break up upon contact with the casing.
Only about 25-30 percent of the shaped charge liner mass is converted into the jet. The jet density, velocity profile, jet material, jet straightness, and target properties determine the ability of the jet to penetrate a given target. While the slug portion does not contribute much to the penetration of the shaped charge, the slug should have certain properties that contribute to system performance. For example, the slug should break up and not plug the perforation tunnel in the target.
Liners for shaped charges have been fabricated using pure metals, alloys and/or ceramics. The metals used to form the liners can be powder materials, which may, for example, comprise tungsten, lead or copper. When the latter liners have been used, about 75 percent of the tungsten, i.e. that portion of the tungsten in the slug portion, is not converted into the jet. Since tungsten comprises the bulk of such powder and since tungsten is quite expensive, a substantial amount of money is wasted by fabricating the slug portion of a shaped charge with tungsten.
Liners for shaped charges have been fabricated using different solid materials for the jet and the slug. One such example of a liner utilizing solid copper for the jet and solid zinc for the slug.
In accordance with the present invention, a liner is provided for a shaped charge which comprises at least two portions where at least one of the portions is composed of powder materials. One of the portions approximate the jet segment and the other portion approximate the segment of the liner.
In one embodiment, a liner according to the present invention comprises three portions, where two of these three portions comprise the slug, and the third portion comprises the jet. In another embodiment, two of the three portions comprise the jet while the third portion comprises the slug.
In a further embodiment, a liner according to the present invention comprises four portions, and each portion of these liners may be composed of the same or different powder materials, in order to optimize the perforation or enhance the perforation tunnel.
In one embodiment, any one portion of a liner in accordance with the present invention may be formed with a powder composed of a single material or any combination of the materials selected from the group consisting of aluminum, copper, lead, tin, bismuth, tungsten, iron, lithium, sulfur, tantalum, zirconium, boron, niobium, titanium, cesium, zinc, magnesium, selenium, tellurium, manganese, nickel, molybdenum, and palladium. The particle sizes of the powder materials for the slug and jet segments of the liner may be selected to achieve a more uniform detonation wave front through the slug and/or jet, while the particle sizes of the powder materials from the jet segment may be selected to achieve a more stable (reduced transverse velocity) jet.
In another embodiment of the present invention, one portion of the liner may be fabricated from a solid material, e.g. copper, zinc, aluminum or lead, while the remaining portions of the liner are fabricated from powder materials.
In accordance with the present invention, a perforating gun is provided comprising a plurality of shaped charges, wherein each shaped charge comprises a jacket, a liner, and an explosive material disposed between the jacket and the liner. The liner for each of the shaped charges comprises at least two portions, as described above.
In the accompanying drawings:
a is an elevation drawing in cross-section in an embodiment of a liner in accordance with the present invention which comprises two portions.
b is a pictorial drawing illustrating the jet and slug portions of the two portion liner of
c is an elevation drawing in cross-section of another embodiment of a liner in accordance with the present invention which also comprises two portions.
d is a pictorial drawing illustrating the jet and slug portions of the liner of
a is an elevation drawing in cross-section of an embodiment of a liner in accordance with the present invention which comprises three portions.
b is a pictorial drawing illustrating the jet and slug portions of one embodiment of a three-portion liner upon detonation.
c is a pictorial drawing illustrating the jet and slug portions of another embodiment of a three-portion liner upon detonation.
a is an elevation drawing in cross-section of a further embodiment of a liner in accordance with the present invention which comprises four portions.
b is a pictorial drawing illustrating the jet and slug portions of one embodiment of a four-portion liner upon detonation.
It will be appreciated that the present invention may take many forms and embodiments. In the following description, some embodiments of the invention are described and numerous details are set forth to provide an understanding of the present invention. Those skilled in the art will appreciate, however, that the present invention may be practiced without those details and that numerous variations and modifications from the described embodiments may be possible. The following description is thus intended to illustrate and not to limit the present invention.
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a illustrates another embodiment of a liner 20 in accordance with the present invention. Liner 20 comprises three portions 21, 22 and 23. Each of the three portions 21, 22 and 23 has a composition that is different from the others. Each portion 21-23 of liner 20 may, for example, be composed of different powder materials. In one embodiment, for example, portion 21-23 of liner 20 may each be formed with a powder composed of a single material or any combination of the materials selected from the group consisting of the materials specified in paragraph [0026]. Liner 20 may be fabricated by using a die set. As illustrated, the different portions 21-23 can be configured in layers so that the portion 23 is an outer layer, portion 22 is an inner layer, and portion 21 is between portions 23 and portion 22. Other configurations are possible too, for example, one portion could be distal to an end of the liner and one portion could be proximal to the end of the liner.
b illustrates the jet portion and slug portions of the liner 20 upon detonation of the shaped charge in which liner 20 is installed. In
Those skilled in the art who have the benefit of the present disclosure will appreciate that a three layer liner could also produce: (a) a one portion jet segment 24 and a two portion slug segment 25, 26 (
a illustrates a liner 30 comprising four different portions 31-34. Each of the four portions has a composition that is different from the others. Each portion of the liner 30 may be fabricated from one or more materials, in order to optimize the penetration or enhance the perforating tunnel. Each portion may, for example, be fabricated from a single powder material or any combination of powder materials selected from the group consisting of the materials specified in paragraph [0026] above. Liner 30 may also be fabricated by using a die set.
Reactive materials may also be utilized in either the jet or slug portion of the liner. The use of reactive materials in a liner is disclosed in U.S. Patent Application Publication No. 2006/0266551, which is incorporated herein by reference.
