US2362829A - Explosive screen cleaner - Google Patents

Description

Patented Nov. 14, 1944 6 Claims.

This invention relates to screen cleaners and more particularly to screen cleaners of the explosive type and particularly adapted to remove clogging material or debris from the openings in a screen in deep wells.

The primary object of the invention is to provide an explosive cleaner that will open the passages in. a clogged screen while it is in the well bore.

Another object is to provide a cleaner that will effect the desired cleaning operation without damage to the screen liner.

A further object is to provide a cleaner which will effectively clean either slotted or perforated screens.

Still another object is to-provide an explosive screen cleaner made up of frangible material so that such material is reduced to a form that will not hamper the operations of producing the I wells after the screen has been cleaned.

Still another object is to provide a cleaner which includes means for maintaining the cleaner assembly centrally of the screen to be cleaned at the time of detonation of the explosive carried by the cleaner.

Another object is to provide a novel method of cleaning well screens through the use of an explosive which is so positioned as to give rise 'to an explosive impact which emanates from a plurality of spaced centers.

A more specific object is to provide a screen cleaning assembly which includes a central tubular member containing an igniting explosive to discharge the main body of explosive which is carried within spaced frangible cups mounted upon such member.

The foregoing objects are primary objects and will, together with additional objects, be more fully apparent from the following description taken in connection with the accompanying drawing in which:

Fig. 1 is a sectional view through a well screen and the upper portion of a cleaner assembly embodying the invention;

Fig. 2 is an elongated view showing an-assembly within a screen and also illustrating one construction and manner of discharging the explosive.

The well cleaning device as illustrated in the drawing is lowered upon a cable I which may be a conductor cable so that electrical means may be utilized to set off the explosive. Such cable may be an ordinary wire cable attached to the lowering head 2 which is provided with a firing pin 3 having a head 4 for engagement by a memher such as a go-devil 5 (Fig. 2) which is dropped over the cable I from the mouth of the well bore after the assembly, hereinafter described, has been lowered to the desired position within the screen 6. Alternately it is apparent that the explosive used with the device may be discharged by means of an ordinary time bomb.

In the embodiment as shown, the lowering head is of relatively sturdy construction and it is intended that such head may be repeatedly usable with explosive assemblies such as that hereafter described. This construction of the lowering head 2 assists in the rapid lowering of the assembly to the desired position within the well.

The lowering head is threaded internally at 'I to receive the upper end of a small tube 8 of frangible material such as a frangible synthetic,

aluminum and the like. A cap member ID such as an ordinary type ofblasting cap containing fulminate of mercury or like material is placed on the upper end of the tube 3 and is engageable by the firing pin 3 to initiate combustion of an explosive such as the rod or string of cordite which is a stick of explosive to some extent, similar to a fuse H which, together with a plurality of blasting caps l2, fills the interior of the tube. While an alternate arrangement of the explosive cordite and the blasting caps has been shown these elements are merely for the purpose of conducting the fire from charge to charge of explosive. The cordite is found to cause detonation of the explosive it somewhat better under the existing conditions than does the blasting caps so that a section of cordite is disposedin each charge of explosive.

At spaced intervals along the tube 8 are provided a plurality of annular cups l5 of a frangible material such as a frangible synthetic or aluminum. These cups are of materially smaller diameter than the screen 6 but are of a size to contain a proper amount of explosive It such as dynamite that the detonation thereof is effective in producinga desirable explosive force to clean openings l'l adjacent thereto. The cups l5 are so spaced longitudinally of the tube 8 that their combined effect is such as to effectually clean all of the openings l1 throughout the length of screen within which the assembly is located. The fire initiated by the firing pin 3 will travel along the cordite and blasting caps l2 as a fuse to set ofi the cups of explosive IS in sequence.

To facilitate uniformity in results the invention also contemplates the provision of a plurality of sets of spring fingers 20 which are attached to the tube 8 by means of collars 2|. It seems apparent that through the use oftwo or more of these sets of fingers the explosive as sembly is maintained concentric with the screen 6 and hence the explosive force produced thereby acts'uniformly in all directions.

The operation of the device of the invention is believed apparent from the foregoing description. By way of summary it may be stated that the assembly including the tube 8, cups I and the fingers 20 are attached to the lowering head 2 and lowered by means of the cable I to the desired position within the screen 6. The desired explosion is. then initiated as by means of the go-devil 5 engaging the head 4 of the firing pin 3. The resulting explosion of the cordite I l, the blasting caps l2 and the explosive charges l4 within the cups I5 is substantially instantaneous,

and sets up a high pressure area in the screen adjacent the cleaner assembly which creates a cleaning the length of screen for which the assembly is designed. While the explosive charges have been shown and described as individual spaced charges, a continuous charge approximatingthe length of the area to be cleaned may be used.

Attention is directed to the fact that the use of frangible material for the tube 8 and the cups I5 is instrumental in providing a minimum of debris from the-assembly. This debris may, if

' desired, be removed from within the well but it has been found that such debris offers no difficulty if allowed to remain at the lower end of the well bore.

What is claimed is:

1. An explosive screen cleaner assembly comprising a lowering head, a tube of frangible material attached to said head, alternate units of an explosive and blasting caps arranged end ing head to discharge said caps and the explosive in the containers whereby detonations at a plurality of spaced points are created.v

2. An explosive screen cleaner assembly comprising a tube of frangible material, a plurality of containers of frangible material surrounding said tube in spaced relation, an explosive in said tube and said containers, means for igniting the explosive in said tube proximate one end thereof whereby the detonation travels along the tube and the explosive in the containers is detonated, and means for guiding said assembly centrally of the wallsof a surrounding screen to be cleaned by the gas pressure generated by the series of,

spaced detonations. I

3. The combination of an assembly for positioning in a well bore including a loweringline,

an explosive assembly including a firing mechanism attached to said line, said assembly including a tubular member having ignition means I therein, a plurality of annular containers atattached to and surrounding said member at spaced intervals, and an explosive insaid containers so that operation of the firing mechanism operates said ignition means to discharge the explosive'whereby an explosive impact emanates from a plurality of spaced centers to set up a high pressure area in the well which extends the length of said assembly.

4. An explosive device for lowering into a screen including an assembly comprising a lowering line, a lowering head attached thereto, a tubular member attached to said head and extending downwardly therefrom, spaced cups attached to said member, an explosive in said cups, and means within said member for firing said 'explo'sive whereby an explosive impact is imparted to end within said tube, a plurality of frangible containers surrounding said tube and secured thereto in spaced relation, guiding springs ex tending outwardly from said tube to engage surroundi g cylindrical walls to guide the assembly centrally of such walls, and means for igniting the explosive in the tube proximate the lowerto 'thescr'e'en surrounding the assembly.

5. An explosive screen cleaner including an assembly comprising a lowering line, a lowering head attached thereto, a tubular member of frangible material attached to said head and extending downwardly therefrom, spaced cups of frangible material attached to said member,

an explosive in said cups, and means within said member for firing said explosive whereby an explosive impact emanating from a plurality of spaced centers is imparted to the screen surrounding the assembly.

6. An explosive screen cleaner comprising a tubular member," alternate quantities of an explosive and blasting caps filling said member, means for igniting the'explosive atone end of the member, a plurality of frangible containers surrounding said member in spaced relation, and an explosive in said containers whereby an explosive impact emanating from a plurality of spaced points is created upon the operation of said Igniting means.

. .MYRON M. KINLEY.

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