US3134437A

US3134437A - Means and method of treating wells

Info

Publication number: US3134437A
Application number: US52824A
Authority: US
Inventors: Karpovich John
Original assignee: Dow Chemical Co
Current assignee: Dow Chemical Co
Priority date: 1960-08-30
Filing date: 1960-08-30
Publication date: 1964-05-26
Anticipated expiration: 1981-05-26

Description

y 1964 J. KARPOVICH MEANS AND METHOD OF TREATING WELLS Filed Aug. 30, 1960 H e age/7f reservoir 7'0 draw 0 war/as Tre a/l'ng f/u/c/ INVEN TOR. J0/7n Karpow'ch BY AGENT United States Patent MEANS AND METHOD OF TREATING WELLS John Karpovich, Midland, Mich., assignor to The Dow Chemical Company, Midland, Mich., a corporation of Delaware Filed Aug. 30, 1960, Ser. No. 52,824

, 4 Claims. (Cl. 166-42) A This invention relates to earth well treatments and particularly to so called formation fracturing treatments.

It is known to use implodable frangible vessels or capsules in :well stimulation treatments of the so-called Rock Shock type. In such treatments the vessel or capsule is disposed in a liquid column in a well bore adjacent to the formation to be stimulated and the hydraulic pressure is increased to the point where the capsule implodes. The forces resulting from the implosion often 'form fractures which were not practical to produce otherwise because of casing limitations as to the pressure it can withstand or because of limitations of surface pumping equipment. a

While the implosion produces a violent reaction in the well bore, a second reaction to supplement the implosion is desirable tomore effectively drive treating fluid into the adjacent earth formation.

- Accordingly, a principal object of this invention is-to provide an improved method of treatment of an earth well.

Another object of this invention is to provide an improved well stimulation apparatus. V

A further object of this invention is to provide an improved method of fracturing earth formations which are adjacent to the bore of an earth well.

In', accordance with this invention an implosion capsule having disposed therein materials which, when exposed to the well bore liquid or to shock, explodes. Thus, when the capsule "is imploded, the violent reaction attendant to "the implosion issupplemented by the explosion at the same point along the well bore, resulting in a more effective treatment of the adjacent earth formation. The

invention, as well as additional objects and advantages thereof, will best be understood when the following dean alternative form of implosion device which may be used in accordance with this invention.

Referring to FIG. 1, there is shown an earth well 8 having a bore wall '10 which extends from the surface 12 of the earth through

earth formations

14, 16, 18, for example. Casing 20, capped by a suitable casing head 22, extends through the

earth formations

14, 16 and into the formation 18 near the bottom 24- of the well. The casing 20 is bonded to the wall by cement 26.

A frangible capsule, indicated generally by the numeral 28, is shown suspended from a cable 30 below the casing 20 in the well 8. The cable 30 passes through the casing head 22, over a sheave 32 and to a draw works (not shown). The capsule is held in a weighted carrier (not shown) as is conventionally done where implosion capsules are used in a well treatment. Such weighted carriers are listed in the publication Dowell Technical Report on Rockshock, published in March 1960 by Dowell Div., The Dow Chemical Company, Tulsa, Oklahoma. Also, the March 1960 issue of World Oil magazine, in an article entitled Implosion Technique Improves Fracturing Performance, by Donald D. Setser, notes that capsules may be suspended from the tubing in the well.

The capsule 28 comprises a frangible body part 34 capsule. In the event the capsule 28 is to be imploded in a non-aqueous medium, a sealed container of an agent capable of oxidizing the alkali metal such as water or hydrogen peroxide is also disposed within the capsule 28.

At the surface, a source 44 of treating fluid, a source 46' of treating fluid with propping agent, and a gas reservoir 48 are coupled to the well through the

lines

50, 52, 54,

valves

56, 58, 60, 62 and

pumps

64, 66. Treating fluids and treating fluids with propping agent and their uses are disclosed in Farris Reissue Patent No. 23,733, issued Nov. 10, '1953. I

A vent valve 76 and pressure gauge 78 are coupled to the casing head 22. v

in operation, with the casing head 22 opened, the

capsule 28 is lowered into the well 8 on the cable 30 to' pling means for holding the capsule 28 belowv the'icab le 30 have been shown only schematically.

The well bore may be, if desired, at least par-tiall filled with liquid as the capsule 28 is lowered into position. 1 r

When the capsule is in position, the casing head is closed and, with valves 56, 62 closed, treating fluid from the reservoir 44 is pumped by means of pu-mp'64 into the well 8. The vent valve 76 is opened until the well bore is filled with treating fluid and is then closed while the pumping of treating fluid is continued. In some cases sufficient hydrostatic head on the capsule to collapse it may be reached without filling the well completely.

Afterthe vent valve is closed, it is sometimes desirable to open valve 56 and, by means of pump 66, inject gas from the reservoir 48 into theliquid being pumped into the'well, in accordance with the teaching of US. Patent No. 3,004,594 toF. W. Crawford, especially lines 17 through 28 of column 2., for example.

The hydraulic pressure in the well bore is increased to cause the implosion of the capsule28, causing a violent reaction in the well bore, especially adjacent to the point along the bore where the implosion occurs. This violent reaction is in itself often sufiicient to initiate fractures in the adjacent earth formations. However, in the instant invention the implosion of the capsule in turn results in an explosion in the well bore adjacent to the formation being treated. This explosion supplements the violent reaction of the implosion and causes more extensive frac turing of the formation than occurs when an implosion alone is used in the treatment.

Examples of materials which may be disposed within the vessel 28 to cause an explosion when the vessel implodes are metal hydrides, metallo-organic compounds, alkali metal, e.g. sodium in a form which presents a large surface area per unit weight, and shock sensitive explosives.

Metal hydrides which may be used include aluminum hydride. Metallo-organic compounds which may be used include metal alkyls such as trimethyl aluminum, triethyl aluminum, triethyl magnesium, and Grignard type compounds.

The addition of a capsule which may readily be ruptured and which may be made of polytrifluorochloroethane, for example, containing hydrogen peroxide will cause the explosive reaction to occur on implosion. of the vessel 28 even when water is not present in the well bore adjacent to the capsule. 28. The capsule 37 of hydrogen peroxide, of course, ruptures when the capsule 28 is irnploded.

When shock sensitive explosives are provided in the capsule 28, however, there is no need to provide peroxide or water as the force resulting from the implosion detonates the explosive regardless of the nature of the surrounding liquid medium in which the capsule 28 is disposed. V

7 FIG. 2 shows a sealed vessel or capsule 80 which is similar to the vessel or capsule 28 except that it has a pair of electrical leads 8 2, 84 extending from the exterior to the interior thereof, the leads having an electrically energizable filament 86 connected across them.

The capsule ,80 has readily oxidizable material such as magnesium, aluminum or zirconium foil, wool, or ribbon 88 disposed therein in physical contact with the filament a 86; An oxygen atmosphere exists in the capsule 80'. The capsule 80 is suspended in any suitable manner from a cable 90 which has electrical conductors connected to the

leads

82, 84 and, as 'further shown schematically by the

leads

92, 94 and switch 96, to a battery 98 or other sourcefor energizing the filament 86. The battery may be disposed at the surface 12 of the earth, for example.

In operation the filament 86 is energized by closing the battery circuit while the capsule is in place in the well bore adjacent to the earth formation to be treated and the liquid medium in the bore is under an appropriate pressure. Energizing the filament, causes the foil, wool or ribbon 88 to fire,-causing thermal stresses which, with the pressure of the liquid medium in the well bore, cause the capsule to collapse suddenly. The explosion of the material 36 then is initiated as described in connection with the capsule 28 in FIG. 1.

-"Following the implosion and explosion, it is usually desirable to close the valve 60 and open valve 62 in the line 52 leading to the reservoir 46 of treating fluid with propping agent. Thus, propping agent is pumped down the well bore and into the newly created or extended fractures 100' (see FIG. 1).

From the above description it is apparent that the instant invention provides a novel, safe means and method of fracturing or otherwise stimulating an earth well. For

example, this invention is also applicable to acidizing and other treatments where the formation must be broken 4 What is claimed isi 1. A method of treating an earth well which comprises: V

(a) loading into a hollow frangible walled vessel explodable material from the class consisting of metal hydrides, metallo-organic compounds, alkali metals,

' and shock sensitive explosives,

(b) sealing said vessel,

(c) lowering said sealed vessel position in said earth well,

(d) covering said sealed vessel with liquid,

(e) subjecting said vessel to sufiicient hydraulic pressure to compress fluid in said well bore and to implode and shatter said vessel, and

(f) on shattering said vessel, exposing said explodable material to ambient Well bore conditions which inito a predetermined tiate detonation of said explodable material, .thereby' vessel, when sealed, has an internal pressure which. is

a minor fraction of the pressure at which it iinplodes.

4. A method in accordance with claim 1, wherein treatingagent is pumped into said earth formation. following said detonation.

References Citedin the file of this patent UNITED STATES PATENTS Re. 23,733

Farris Nov. 10, 1953 2,361,558 Mason Oct. 31, 1944 2,756,826 Ebaugh July 31, 1956 7 2,785,633 Ewing et al Mar. [19, 1957 2,887,954 Swed May 26, 1959 2,911,046 Yahn Nov. 3, '1959 2,932,251 Hamilton Apr. 12, 1960 Chestnut Oct. 3, 1961

Claims

1. A METHOD OF TREATING AN EARTH WELL WHICH COMPRISES: (A) LOADING INTO A HOLLOW FRANGIBLE WALLED VESSEL EXPLODABLE MATERIAL FROM THE CLASS CONSISTING OF METAL HYDRIDES, METALLO-ORGANIC COMPOUNDS, ALKALI METALS, AND SHOCK SENSITIVE EXPLOSIVES, (B) SEALING SAID VESSEL, (C) LOWERING SAID SEALED VESSEL TO A PREDETERMINED POSITION IN SAID EARTH WELL, (D) COVERING SAID SEALED VESSEL WITH LIQUID, (E) SUBJECTING SAID VESSEL TO SUFFICIENT HYDRAULIC PRESSURE TO COMPRESS FLUID IN SAID WELL BORE AND TO IMPLODE AND SHATTER SAID VESSEL, AND (F) ON SHATTERING SAID VESSEL, EXPOSING SAID EXPLODABLE MATERIAL TO AMBIENT WELL BORE CONDITIONS WHICH INITIATE DETONATION OF SAID EXPLODABLE MATERIAL, THEREBY INDUCING THE FORMATION OF FRACTURES IN THE WALL OF SAID EARTH WELL ADJACENT BY MEANS OF THE SHOCK WAVE OF SAID IMPLOSION AND THE DETONATION OF SAID EXPLODABLE MATERIAL.