Ordnance – Well perforators
Reexamination Certificate
2001-01-11
2003-02-25
Carone, Michael J. (Department: 3641)
Ordnance
Well perforators
C166S297000, C166S299000, C166S063000, C175S004510, C175S004550, C175S004570, C102S310000, C102S311000, C102S312000, C102S313000, C102S320000
Reexamination Certificate
active
06523449
ABSTRACT:
BACKGROUND
The invention generally relates to a perforating gun.
For purposes of enhancing production from a subterranean formation, a perforating gun typically is lowered down into a wellbore (that extends through the formation), and radially oriented shaped charges (of the perforating gun) are detonated to form perforations in the formation. The shaped charges typically are placed at points along a helical spiral that extends around a longitudinal axis of the perforating gun. The angular displacement (with respect to the longitudinal axis) between the adjacent charges along this path defines a phasing of the gun. Typically, specified parameters, such as a shot density and the phasing, control the number of shaped charges of the gun, the angular positions of the shaped charges and the distances along the longitudinal axis between the shaped charges.
For example,
FIG. 1
depicts a carrier tube-type perforating gun
10
that includes shaped charges
14
(charges
14
a
,
14
b
and
14
c
depicted as examples) that are alternatively phased (relative to each other) at 0° and 180° about the longitudinal axis of the gun
10
, i.e., the shaped charges are phased 180° apart. In this manner, the top charge
14
a
of the perforating gun
10
in
FIG. 1
is positioned at 0° (as a reference point), the middle charge
14
b
is positioned at 180° and the bottom charge
14
c
is positioned at 0°. Thus, each adjacent pair of charges
14
is phased differently (at 0° and 180°). The charges
14
are housed inside a hollow carrier tubing
11
, and a detonating cord
12
extends between and is connected to the charges
14
to communicate a detonating wave to the charges
14
. Although a carrier tube-type perforating gun is depicted in
FIG. 1
, another structure may hold and orient the charges
14
, such as a strip (in a strip-type perforating gun) to which the ends of the charges
14
are connected.
A distance (called “d” in
FIG. 1
) between adjacent charges
14
governs the shot density of the perforating gun
10
. Thus, to increase the shot density of the perforating gun
10
, the distance d is decreased, and to decrease the shot density of the gun
10
, the distance d is increased. However, factors limit the maximum shot density of the gun
10
. For example, the closer the adjacent charges
14
are together (i.e., the smaller the distance d), the more the detonating cord
12
bends between the charges
14
, a factor that increases a cord-to-charge interference between the detonating cord
12
and the charges
14
. Furthermore, if there is interference between the charges
14
, the closer the adjacent charges
14
, the greater the charge-to-charge interference between the charges
14
. In this manner, charges
14
that have opposite phases typically significantly interfere with each other when the charges
14
are placed too close together.
Thus, there is a continuing need for an arrangement that addresses one or more of the problems that are stated above.
SUMMARY
In one embodiment, a technique includes arranging perforating charges of a perforating gun into groups of adjacent perforating charges. Each perforating charge of each group is aligned in a single direction associated with the group. The groups are oriented to form a phasing for the perforating gun.
Other embodiments and features will become apparent from the following description, from the drawings, and from the claims.
REFERENCES:
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patent: 4960171 (1990-10-01), Parrott et al.
patent: 5033553 (1991-07-01), Miszewski et al.
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patent: 5477785 (1995-12-01), Dieman et al.
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patent: 5673760 (1997-10-01), Brooks et al.
patent: 6125946 (2000-10-01), Chen
patent: 6298915 (2001-10-01), George
Fayard Alfredo
Li Haoming
Parrott Robert A.
Griffin Jeffery E.
Jeffery Briqitte L.
Schlumberger Technology Corporation
Trop Pruner & Hu P.C.
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