US2843041A - Deep perforation of subsurface formations - Google Patents

Description

y 1958 D. M. STEWART I DEEP PERFQRATION OF SUBSURFACE FORMATIONS Filed Dec. 14. 1953 Fla. 2.

IN V EN TOR. Doug/ass M. Stewart FIG. I.

ATTO the formation.

in the channel, the channel is extended along the longi- 1 former is more sensitive to shock than the latter.

U i d M 2,843,t l41 DEEP PERFORATIONOF SUBSURFACE ,FORMATIONS Douglass M. Stewart, Houston, Tex.', assignor, by mesne assignments, to Esso Research and Engineering Company, Elizabeth, N. J., a corporation of Delaware Appli cation December- 14, 1953, Serial No. 398,053

" 3 Claims. (c1. 10221.6)

- The present invention may be briefly described as an apparatus-for perforating a subsurface earth formation which comprises a body member adapted to be lowered in awell' bore on a suitable suspending means, such'as a wi'rejline or an electrical-conductor cable. Arranged in the body member is a cannon toface. the wall of the well bore; The cannon is designed to receive and has arranged in it a hollow metal projectile which has a shaped charge arranged therein confined by a cone-shaped metal wall with the apex of the wall pointing away from the nose of the projectile. The cone has an open base which faces the nose of the projectile. Arranged in the projectile and confined by the cone-shaped wall is a coneshaped primary high explosive charge. Behind the primary 'high explosive charge is a booster charge, and behind the booster charge is a primer charge. An explosive delay element is arranged in the projectile to explode the explosive chain comprised of the several charges.

f The cannon has an explosive charge arranged in it behind the projectile for firing the projectile into the formation and to set oii the explosive delay element.

The apparatus of the present invention may suitably be used for perforating a subsurface formation through a casing or perforating a subsurface earth formation in' an open hole by firing the projectilecontaining a shaped charge into the formation to form a lateral channel in Thereafter on firing the shaped charge tudinal axis of said channel. Thus a channel deeply penetrating an earth formation from a well bore may be formed and extended in a predetermined direction.

The high explosive shaped charge employed in the present invention may suitably be pentolite, tetryl,

T. N. T.,'R. D. X., and the like. The booster charge may, for example, be R. D. X., prima cord, and the like. Tetryl may be used as a booster for pentolite since the primer charge may suitably be composed of fulminate of I mercury or black powder, and the like.

The explosive charge employed in the cannon is aconventional type of explosive used in gun perforators employing a cannon and gun barrel and may suitably be I exemplified by black powder, smokeless powder, and the like.

The invention will be further illustrated by reference to the drawing in which Fig. 2 illustrates one type of a projectile;

Fig. 3 represents amodification of Fig. 2; and

The

, structed of steel and the like.

2 Fig. '4 illustrates the effect of firing the device of Fig. 1. Referring now. to the drawing, numeral 11 designates a body member which is designed to be lowered in a well 12 by means of an electrical conductor cable 13. The well -12 has a casing 14 arrangedtherein around which isa sheath of cement 15. The well 12 penetrates an earth formation 16 containing desirable earth fluids,

such as oil, gas, and the like. The body member 11 may be provided with a plurality of cannons 17 facing the wall of the well 12. The cannons are provided with gun barrels 18 which may suitably be closed, if. desired, with cover plates 19 to prevent entry of well fluids into the gun detonating means 24 connected by electrical conducting means 25 to the earths surface which are carried to the earths surface through the electrical conductor cable 13 and to a source of electrical energy not shown.

Referring now to Fig. 2, it will be seen that the projectile 20 has a conical shaped wall 22 arranged therein with an apex 26 facing away from the nose 27 of the projectile, the wall defining a space 28. The second wall member 29 and the wall member 22 confine therein between .a high explosive shaped charge 30 of the type illustrated. Behind the high. explosive charge'30 is a booster charge 31 and behind the booster charge 31' is a primer charge 32. The primer charge 32 is connectedv to an explosive delay element 33, which, in turn, connects to the explosive charge 23. The end of the projectile 20 is suitably constructed of a frangible metal 34 such as cast iron or brass, the projectile itself being constructed of steel and the like. The wall 22 may be constructed of a metal such as copper, and the like.

Referring to Fig. 3, it will be seen that the projectile 20 has a nose 27 and a conical wall 22 enclosing the space 28. A high explosive shaped charge 21 is arranged in the projectile and confined by the wall 22. As with respect to Fig. 2, a booster charge 31 and a primer charge 32 is arranged, respectively, behind the'shap'ed'charge21 while an explosive delay element 33 connects to the primer charge and to the explosive charge 23 andp-rojectile 20 is suitably constructed of a frangible metal 34',

such as cast iron or brass, the projectile itself being con- In the embodiment of Fig. 3, the projectile is provided with boattail 35. both embodiments of Figs. 2 and 3, frangible members 34 and 34', respectively, readily fracture upon explosion of charge 30 thereby blowing open both ends of the projectile and providing an unobstructed passage from the point of deepest penetration of the formation to the borehole, as shown in Fig. 4.

Referring now to Fig. 4 particularly, the body' member 11 is indicated generally adjacent a casing 14 and formation 16.

has been exploded. In the lower portion of Fig. 4, the projectile 20 has been detonated to cause the channel or perforation 40 to be extended by the searing jetting action of the shaped charge as indicated by thev narrower lateral channel 41, the projectile 20 having been disintegrated Thus, in accordby detonation of the shaped charge. ance with my invention, it is possible to form lateral channels which are extended deeply into a formation by firing a projectile into the formation which contains a shaped charge and then firing the shaped charge to extend the channel along its longitudinal axis.

2,843,041. Patented July 15 1958 In Fig. 4 inthe top part of the figure one of; the cannons 17 has been fired to form a perforation 40 p I with the. projectile 20 shown before the shaped charge cient amount of the shaped charge 21 to extend the channel 40 to form the extension 41 as shown. As an example of the size of the shaped charge, the projectile 20 should have dimensions of approximately 3 inches long and 1% inches in diameter to enclose about 8 grams of the high explosive; lesser or greater amounts of the high explosive may he used.

While I have shown caps 19 to cover the barrel 18, these may be dispensed with, if desired. Although I have shown a plurality of gun barrels, it is possible to practice the present invention with only a cannon or gun barrel arranged in the body member 11. It will be preferred, however, to provide a plurality of cannons to perfo'rate the well simultaneously at a plurality of points.

The nature and objects of the present [invention having been completely described and illustrated, what I wish to claim as new and useful and to secure by Letters Patent is:

1. Apparatus for perforating a subsurface earth formation which comprises, in combination; a body member adapted to be lowered in a well bore; at least a cannon disposed in said body member to face the wall of said well bore; a hollow metal projectile in said cannon for firing by said cannon into said formation comprising a cone-shaped metal wall member arranged in said projectile having an open base facing the nose of said projectile; a cone-shaped primary high explosive charge confined behind and by said wall member in said projectile; a booster charge arranged in said projectile behind said shaped charge; a primer charge behind said booster charge in said projectile, a frangible projectile end member behind said primer charge, said charges comprising an explosive chain; an explosive delay element connected to said pnimer charge for firing said explosive chain, and

an explosive projectile propelling charge in said cannon to fire said projectile into said formation and to set off said explosive delay element.

2. Apparatus in accordance with claim 1 in which the projectile has a boattail.

3. Apparatus for perforating a subsurface earth formation which comprises, in combination, a housing member adapted to be lowered into a. well bore, at least one cannon disposed in said housing to face the wall of said well bore, a hollow metal projectile in said cannon for firing by said cannon into said formation, a shaped charge contained in said projectile facing the nose of said projectile whereby when said shaped charge is exploded, the jet pressure created thereby is in the same direction as the path of said hollow projectile, a booster charge arranged in said projectile behind said shaped charge, a primer charge arranged in said projectile behind said booster c'harge, said charges comprising an explosive chain, a frangible projectile end member behind said primer charge, an explosive delay element connected to said primer charge and extending through said frangible end member for firing said explosive chain and a projectile propelling charge in said cannon for firing said projectile into said formation and to set off said explosive delay element.

References Cited in the file of this patent UNITED STATES PATENTS 2,408,419 Foster Oct. 1, 1946 2,426,997 Gray et al. Sept. 9,- 1947 2,667,836 Church et a1. Feb. 2, 1954

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