US2023831A - Torpedo and method for shooting oil wells - Google Patents

Description

` Dec. l0, 1935. `A. E. ELLIS 2,023,831

TORPEDO AND METHOD FOR SHOOTING OIL WELLS Filed may 21, 1935 that has a large oil collecting from an earlier shooting of the Patented Dec. 10, 1935 UNITED sTATEs PATENT y oFFlcE TORPEDO AvNDIIETHOD SFOR SHOOTING WELL Alfred E. Ema'rarkersburg, w. va. Application May 21, 1935, serial No. 22,604

This in'vention relates to a torpedo and method for shooting oil wells and more particularly to an improved torpedo construction and a novel method for shooting a slowly flowing or dry well cavity resulting well.

According to generally accepted practice, it is customary to shoot a well, drilled, in order to increase hen it is originally its production.- Location of the explosive charge is a simple matter at this stage in the development ofva well and may be accomplished by positioning a plug in the bore of the well charge. found Tn the United 733,492 of 1903.

so that it will support the A description of such practice may be States patent to Little, No.

` Wells frequently cease to produce, after a period of time, sufficient eration. This is true even where the well wasv shot by a method such as the original drilling. is generally due to a matter which clogs the pores in oil bearing stratum cavity. It is a particularly oil to warrant their op- Littles at the time of The reduction of oil ow deposit of paraln or other the face of the surrounding the enlarged troublesome problem in the art at the present time to remove the paraflln deposit when its mote from the bore of One method for solving the problem the well again with the move the outer layer position is relatively rethe well.

is to shoot object to tear away or reof the oil bearing stratum which is clogged with paraflin. Heretofore, the

explosve material has been bore of the well and lowered down the deposited in the oil-collecting cavity immediately below the well bore. The explosive then rested on'the bottom of the cavity which is generally composed of a soft mudiike material. In

frequently below and oil bearing stratum. vail and the explosive desirable results `structive action of tend only part of the way up this position, the explosive is at some distance from the When these conditions pre1 charge is set off, several unare obtained. First, the de- -the explosive force may exthe face of the oil producing stratum and sometimes may not even reach the clogged face. Therefore, only a small edg by part of the explosive e), if any, of the clogged the shot. Second, a large force is uselessly consumed in stirring up the soft mud-like material immediately below and sive charge. Third,

at the sides of the exploas the explosive action is from the area of the mud-like material .toward the oil bearing stratum, the disturbed mud is forcefully thrown ag ainst and into the face of avoided. According to this invention,

z2 claims. (ci. 1oz-4) the oil bearing stratum. Consequently, the clogged condition may not be appreciably relieved and in some cases may be greatly accentuated. Obviously, therefore, in many cases the increase in oil production is negligible, disap- 5 pointing, and not -worth its cost.

By the present invention, the above undesirable results may be substantially eliminated and the charge consists of buoyant torpedoes which float and 10 move in the enlarged cavity to a position at or adjacent the face of the oil bearing stratum where they are set off. To provide for this movement of the torpedoes, a body of liquid, such as water, is collected in or introduced into the oil l5 collecting cavity, and the surface or level of the liquid is preferably determined so as to lie within the upper and lower limits of the oil bearing stratum. Some advantage may be gained, however, where the liquid levelA is adjacent but not between the limits of the oil bearing stratum. 'Ihe torpedo in floating on the liquid surface will reach the clogged face and then be in the most advantageous position for tearing it away. An unbalanced torpedo having its center of gravity somewhat adjacent but to the rear of its longitudinal axis may be used as the unbalanced characteristic probably assists a torpedo in seeking out the edge of the liquid.

Important advantages are achieved in the practice of this invention. Practically all of the destructive force of the explosion is usefully employed as the torpedoes lie against or near the. clogged face when set oi. Where the liquid level is within the limts of the explosion does not cause the mud-like ymaterial to be thrown against the oil bearing stratum so as to clog the newly .exposed face. Other results flow from these achievements. The amount of explosivematerial used in shooting a well 'may 40 be substantially reduced, and at the same time the .increase in oil production will be much greater,

than the increase which might have been obtained by the old -method and known torpedoes.

This invention also relates to a novel construction for oil well torpedoes which gives them a larger factor of safety and vmaires them buoyant.

' There are a number of objectszwhich are sought and obtained by the present invention.

It is an object of this invention to provide a new method for positioning torpedoes in oil wells.

Another object of this invention is to position torpedoes in the enlarged cavities of oil wells by floating them to the face of the Aoil bearing stratum.

oil bearing stratum, the 35 -a torpedo whichis particularly adapted for positioning in an oil well by iloating to the oil bear- A ing stratum.

Still another object of the invention i to increasethe safetyfactor of oil well torpedoes.

I shot one or more A ac It is also an object. of this invention to provide a torpedo which may be positioned in oil-wells of high temperatures without the heat causing premature explosion of the torpedo.

Other objects and' advantages of the present invention "will be apparent from the accompanying drawings andfollowing description.

Referring to thedrawing, Figure 1 illustrates `an oil well to be shot in accordance with the present invention. o

. Figure 2 is a crss sectional view taken along the longitudinal axisof. one of the iioating torpedoes shownin Figurev v Figure 3 is anenlarged view of one of the iloating torpedoes ini Figure 1, and shows vthe angle of inclination. when the torpedo is floating.

Figure -1 shows a typical 'oil well which has been times and has thereafter ceased to produce oil in quantitiesl which warrant its continued operation. Frequently such a well is abandoned, as known methods have not been adequate to increase production to an extentv which wouldl justify the necessary investment.

Shaft i is the original bore fornied when the well wasl ilrst developed, and cavity 2 is the reslt ofthe 'well being shot one or more times at an earlier date. Just above a stratum of mudlike material 3 is astratum of oil bearing sand l their destructive tion may be obtained the well made Satl the time of its original developl in this operation.

or rock 4 having an exposed `surface layer 5' clogged with parailin or other material. The object oi' shooting a well by the old or the present method is to remove this layer 6.

Heretofore, the torpedoesl have-been deposited on the door of the sition of the torpedoes shown in dotted lines at 6 in Figure 1. When these torpedoes are set off, action'A may lreach only part of the way up the side of the cavity and vmay not reach the 'clogged face 5. Also the torpedoes indicated' at 6 would spend a great part of their explosive force on the stratum I and throw the mud against the oil stratum 4 so as to further clog its iace.v

In practicing the method of the present invention, the first step is to ascertain the position and limits of the oil bearing stratum 4 with reference to the depth of the cavity 2. This informaby referring to the log of ment. The log will show'the distances from the top of the well (or ground level) to the upper and 'lower limits of stratum 4 and from these measurements one can readily calculate the level of the middle of the stratum 4 For example, the upper and lower'limits of stratum 4 'being at depths of 2,000 and 2,010 feet respectively, the midpoint of the stratum'would be at a depth 'of 2,005 feet.

The next step is to provide the desired liquid level of the water. 1 in the4 cavity 2 which level may be, for example, at a point mid-way of the stratuin 4. A conventional thief havingwindows and a valve operating plunger at its The thiefis employed to determine if there is water or other liquid in the cavity 2 and the rate f flow of the liquid into the cavity. The rate `of iiow vmay be calculated by testing the liquid level in the cavity at regular intervals. In using the thief, it is lowered into the Well in the cavity. When A*cavity is dry or into the cavity,

.the level of the surface of the cavity as indicated by the polower end isused' by means of a iie and when its plunger strik the iioor ofthe cavity, it will open a valve and water will rise in the thief until the level of the liquid in the thief is the same as the liquid level the thief is wlthdrawneirom the well, the liquid level in the cavity may' be determined by viewing the height of the liquid in the thief through its windows.

If the vertical distancefrom the oor of the cavity toa point midway upthe oil bearing 10 stratum is greater than the length ofthe available'thief, rock or other materialv may be deposited into the cavity to provide a special support for the thief in its liquid level measuring operation.

' Should reading of the thief show that the well thatl only a small quantity of water is present, water is poured into the well until' it has reached the desired level, the liquid level beingvv ascertained by means of the thief.'

If there is an appreciable natural flow of water its rate should be'takeninto consideration so that the level of water at the time of shootingl the it may be necessary to remove surplus water in the well to obtain the desired level. Fig. 1 shows water'l midway of the oil bearing stratum 4. f l

The explosive charge for shooting the well preferably consists of buoyant torpedoes, for example, about 8 or 10. Each torpedohas its weight'so distributed that the center of gravity-is adjacent but rearward of the center of its torpedoes, therefore, when nearly horizontal position; but with their longitudinal axis slightly inclinedI in a vertical plane. T'he angle of inclination might be on the order of three and one-half degrees, but an 'angle of approximately two and one-third degrees is preferred. 'I'his preferred, angular position is illustrated by the floating torpedoes in Figs. 1 and 3.

'I'he unbalanced buoyant torpedoes I are lowered into the well one at a time by means of a line 9, having a hook i0 which engages the bale Il of the torpedo. As each torpedo 8 enters the -water andline 9 continues to be paid out, hook l0 slipsout of engagement with bale Ii. The torpedo, now free, risesin the water at an angle to the liquid-level and with its nose or pointed end leading seeks out a position similar to that of the torpedoes shown iloating at the side oi' the cavity in Fig. 1.

After the desired number of torpedoes have been placed in the well and they have arranged themselves around the cavity in close proximity to the face of the oil be set oil by any suitable means. In some cases, it may be desirable to use a conventional squib, which is dropped down the well. A squib usually has an explosive. charge and a time fuse. In other cases, one may use a conventional bumpjack which is lowered on a line down the well. The bump-lack has an explosive charge and a cartridge which is iired by a weight sliding down the line. The explosion produced by the squib `or bump-jack is suilicient to set oil' the torpedoes a. plurality of unbalanced longitudinal axis. These floating `assume a bearing stratum, they may will float on the supporting liquid (generally water) but not in the tamping fluid.

The torpedo supporting liquid is preferably n water and the tamping preferably oil as the two a relatively small part above the top surface of.

the water so that the water around the torpedo will prevent burning or'charring of the' oil bearing sands due to the heat of the explosion.

The torpedoes of this invention are preferably constructed in accordance with the Fig. 2 illustration.- The torpedo has inner and outer shells I2 and I3 of tin or other suitable material. At their lower orfront ends, shells I2 and I2 are pointed or cone-shaped as shown in Illg.- 2 and are held in relatively fixed spaced relation by a brace Il. The ends of the brace Il are formed to snugly fit the pointed ends of the shells as shown in Fig. 2. This'brace may be secured in place by soldering, welding or the like. 'Ihe rear wall I 5 of the torpedo is of cone-shape and serves to space the shells I2, I2 at that end of the torpedo. Wall I5 Ais also formed of tin, though, oi"

course, other material may be used. This construction provides a central liquid-proof chamber I6 for the' explosive material, such as nitroglycerine; 'and an outer` concentric sealed air chamber I 1, which may hold the air under a pressure, for example, of one pound. A

A tube I8 secured to the end wall I5 provides a filling opening for the explosive containing chamber I6, which opening may be closed by a` stopper I9. Two wires 20, secured at their inner ends to the torpedo. when brought together over the stopper and then twisted as shown in Fig. 2, prevent accidental displacement of the stopper.

The torpedo of this invention has two quite distinct but importar/ii characteristics achieved by a relatively simple and inexpensive structure. The instant torpedo is buoyant and has a large factor of safety. These characteristics are due to the following features: The outwardly spaced shell I5 eliminates rupturing of the shell I2 while the torpedo is being lowered down a 'weil casing. A chamber I'I is provided for collecting any leakage coming from explosive containing chamber I5. Accidental explosion is avoided as the ductile characteristic of tin shell I3 permits it to yield to temporary deforming forces and shocks c without the force and shock being wholly transmitted to shell I2. Accidental explosions are to a great extent also' avoided as brace Il and end wall I5 will tend to maintain shells I2 and I3 in vspaced relation and out of frictional contact' even when shell I3 is temporarily or permanently deformed'while being placed in a well. Furthermore, the ductile characteristic of shell Il and the underlying air cushion will provide for absorption of shocks without their being communicated to shell I2. The air cushion and brace Il will also tend to restore shell I3 to original shape after it receives a blow, as in striking the side of a well casing. The outer air chamber II not only imparts a buoyant characteristic to the torpedo but also insulates the explosive in chamber` I6 against heat. The insulating feature is quite important as it permits the use of the torpedo in wells having high temperatures without risking a premature explosion. y

Wall I5 is preferably thin in cross section and brace J4 .preferably small in 'cross section, so that there will belittle heat flow from shell I5 to shell I2 by conduction and the heat insulating effect of air chamber .I1 will not be nullified.

As previously described, the center of gravity of the present torpedo is displaced, so that the torpedo will -iioat at an angle as shown in Figs. 1 5 and 3. The degree of displacement may be varied by changing the distance between the -coneshaped lower ends of shells I2 and Iltoalter the size of the air pocket at 2I, and/or b'y changing the size of the indentation provided by endlo wall I5.

It will nowbe seen from the foregoing ldescription that this invention provides a novelmethod i for shooting oil wells and an improved construction for oilwell, torpedoes. l5

While the foregoing description gives .-a preferred example of how this invention may be practiced, other forms and modifications may be devised within the spirit and scope` of nthe invention, as defined in the following claims. .20

I claim: V 1. A torpedo for shooting 'oil collecting cavities at the bottom of oil wells wherein liquid is provided'for floating the torpedo to thewall of the cavity, comprising an explosive-containing ves- 25 sel, the ratio of the displacement of the torpedo to the combined weight of the vessel and `its charge of explosive being suchtliat the charged torpedo will oat in said liquid, and the weight of the vessel and its explosive being so distributed '30 that the center of gravity is rearward ofthe center of thelongitu axis of the torpedo.' whereby the torpedo when freed in said liquid will assume an inclined position adjacent the surface of said liquid.

2. A torpedo for shooting large oil `collecting cavities at the' bottom cf oil wells wherein liquid Y is provided for floating the torpedo to the wall of of the cavity comprising a closed, explosive-containing 'vessel having a central elongated and 40- s'ubstantially cylindrical portion, a'substantially cone-shaped nose,r and a substantially coneshaped depression in its rear end, the ratio of the displacement of the torpedo to the 'combined weight of the vessel and its charge of explosive 45 being such that the charged torpedo will float in said liquid, and the weight of thevessel and its explosive being so distributed thatl the center 'of gravity is rearward of the center of the longitudinal axis of the 'vessel so that the torpedo 50 when floating assumes a position such that its longitudinal axis is inclined in a vertical plane.

3. A torpedo for shooting large oil collecting cavities at the bottom oi' oil wells whereiny liquid is provided for floating the torpedo to the wall of 56 the cavity, comprising an elongated, buoyant, ex-

of the torpedo at a higher elevation than'the rear 70' end. f

5. A torpedo for shooting oil wells comprising spaced concentric shells to provide a centralchamber for liquid explosive material andan outer concentric closed air pressure' chamber, and u means at each end of the torpedo for maintaining said shells in spaced relation, the outer of said shells being oi' ductile metal `so that it will yield to temporary deiorming forces without disturb- 'ing said inner` shell andl be returned to its original shape under the influence of the air under y pressure and the action of said spacing means.

6. A torpedo for shooting oil wells comprising spaced concentric shells to provide a central chamber for liquid explosive material and an outer concentric closed airpressure chamber, /said shells being spaced apart at one end bya transverse wall which serves to close both of said chambers at said end, and a brace member extending longitudinally of the torpedo and interposedbetween the other endsof said shells to maintain them in the spaced relation, the outer of said shells being of ductile metal so that it will yield to temporary deforming forces without vdisturbing said inner shell and be returned to its between said shells.

8. Ina method of shooting oil wells in which an enlarged cavity has been Iformed at-the oil bearing stratum, the steps comprising determining the iluid level in the cavity such that its upper surface is at the level of the oil bearing stratum,l

using the iluid having such level to position a torpedo adjacent the face of the oil bearing stratum, and firing the torpedo when in such position.

9. In a method of shooting oil wells in which an enlarged cavity has been formed at the oil bearing stratum, the steps comprising determining the liquid level in -the'cavity such that its v14. A method for sheeting emerged ou eeilecting cavities in deep wells, comprising the steps oi.' determining the liquid level in the cavity such that its upper surface is at substantially the level of the oil bearing stratum, positioning an explosive charge by iloating the charge to the face of the oil bearing stratum, and ilring said explosive charge when in such position.

15. A method for shooting enlarged oil collecting cavities in deep wells, comprising the steps of determining the liquid level in the cavity such that its upper surface is at substantially the level of the oil bearing stratum, positioning an explosive charge by iloatingvthe charge to the face of the oil bearing stratum, introducing into the cavity a tamping liquidof less speciilc gravity thanA said ilrst mentioned liquid and immiscible therewith, and tiring said explosive charge.

' 16. A method for shooting enlarged oil collecting cavities indeep wells, comprising the steps of determiningthe liquid level within the cavity such thatl it is within the upper and lower limits upper surface is at the level of the oil bearings..

stratum, using the liquid having such level to position a torpedo adjacent the face of the oil bearing stratum, and iiring the torpedo when in such position.

10. In a method for shooting enlarged oil collecting cavities in oilwells, the steps comprising iloating an explosive charge to a position adjacent the face oi the oil bearing stratum in said cavity, and iiring the charge when in such posi` tion.

11. In a method for shooting enlarged oil co1- lecting cavities in oil wells, the steps of positioning an explosive charge by iioating the charge to the wall of the cavity. and firing the charge when in such position.

12. In a method for shooting enlarged oil c ollecting cavities in' oil wells, the steps of obtaining a body offliquid on the door of said cavity, positioning an explosive charge by iloating the charge in said body oi liquid to the wall of said cavity, and liiring said explosive material when in such position. Y 13. In a method for shooting enlarged oil Icollecting cavities in deepwells, the steps oi' determining the liquid level in the cavity such? that -its upper surface is at substantially the level of the oil bearing stratum, and positioning an explosive "charge by floating the charge to the face ofthe oil bearing stratum.

of the oil bearing stratum, lowering a buoyant explosive torpedo into "the well, releasing the torpedo as itenters the liquid, using the liquid having said level to position a torpedo adjacent theface of the oil bearing stratum and ilring said torpedo when it is ir such position.

17. A methodfor shooting enlarged oil col lecting cavities in deep wells, comprising the steps 0f determining the liquid level within the cavity such that it is within the upper and lower limits of the oil bearing stratum, lowering buoyant explosive torpedoes into the well, releasing each ,torpedo as it enters the liquid, using the liquid having said level to position the torpedoes adjacent the face of the oil bearing stratum and ilring said torpedoes together when they are in such position.

18.v A method for shooting enlarged oil col- 4o lecting cavities -in deep wells, comprising the steps of determining the liquid level within the cavity such that it is within the upper and lower limits of the oil bearing stratum, lowering into the well an elongated buoyant explosive torpedo having its center of gravity adjacent but above its longitudinal center, releasing'the torpedo as it enters the water, using the liquid having said level to position a torpedo adjacent the ,face of the oil bearing stratum and iiring said torped'ooo when it is in such position. l 19. A method for shooting enlarged oil collecting cavities in deep wells, comprising the steps of obtaining a body of liquid'in said cavity, lowering buoyant torpedoes into the cavity one at a 66 time, using said body of liquid to position said torpedoes adjacent the wall -oi' the cavity and ilringthe torpedoes when theyare in such position.

20. A method for shooting enlarged oil collect- 00 ing cavities in deep wells, comprising Athe steps of obtaining a body ofiliquid. in said cavity, inserting buoyant torpedoes into the cavity, using' said body of liquid to position lsaid torpedoes adjacent the wall oi the cavity, introducing into u the cavity liquid tamping of lower specific gravity than the ilrst mentioned liquid. and iiring the torpedoes while in said position.

21. A method for shooting enlarged oil lcollecting cavities lin deep wells, comprising thelsteps of inserting buoyant torpedoes into the cavity, determining the liquid level in the cavity such that 'it is between the upper and lower limits of oil bearing stratum, using the liquid having u said level to position said torpedoes adjacent the face of the oil bearing stratum and firing said torpedoes when they are so positioned.

22. A method for shooting enlarged oil co1- lecting cavities in deep wells, comprising the steps of obtaining a body of liquid in the cavity,

lintroducing an unbalanced buoyant torpedo into said liquid, using said body of liquid to position said torpedo adjacent the wall of the cavity, and ring the torpedo when it is in such position.

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