US3912560A

US3912560A - Thin layer propagating slurry explosive

Info

Publication number: US3912560A
Application number: US434754A
Authority: US
Inventors: Charles D Forrest
Original assignee: TELEDYNE MCCORMICK SLEPH
Current assignee: TELEDYNE MCCORMICK SLEPH
Priority date: 1974-01-31
Filing date: 1974-01-31
Publication date: 1975-10-14
Anticipated expiration: 1992-10-14

Abstract

A cap-sensitive slurry explosive capable of propagating a high order detonation in thin layers and which has a high degree of safety for a cap-sensitive explosive. The slurry consists of an ultra-fine solid explosive suspended in an energetic, but nonself-explosive liquid matrix and contains no liquid explosive ingredient. The slurry resists dispersion in a variety of liquids including water and crude oil. In a preferred embodiment, the slurry includes penetaerythritol tetranitrate (PETN).

Description

United States Patent Forrest Oct. 14, 1975 [54] THIN LAYER PROPAGATING SLURRY 3,676,234 7/1972 Schwoyer 149/93 X EXPLOSIVE [75] Inventor: Charles D. Forrest, Hollister, Calif. Primary Examiner S tephen Attorney, Agent, or firm-David H. Semmes [73] Assignee: Teledyne McComiick Sleph,

H II' t C l'f.

0 1S er a1 C [22] Filed: Jan. 31, 1974 Appl. No.: 434,754

References Cited UNITED STATES PATENTS 7/1969 Griffith et al. 149/93 A cap-sensitive slurry explosive capable of propagating a high order detonation in thin layers and which has a high degree of safety for a cap-sensitive explosive. The slurry consists of an ultra-fine solid explosive suspended in an energetic, but non-self-explosive liquid matrix and contains no liquid explosive ingredient. The slurry resists dispersion in a variety of liquids including water and crude oil. In a preferred embodiment, the slurry includes penetaerythritol tetranitrate (PETN).

1 Claim, No Drawings THIN LAYER PROPAGATING SLURRY EXPLOSIVE BACKGROUND OF THE INVENTION As is known, certain explosives such as penetaerythritol tetranitrate (PETN) for example, are hazardous when subjected to modest physical abuse from impact or friction forces. Such compounds additionally do not have desired inertness toward crude oil and brine and dilute forms of many other well environmental material. Such materials additionally are hazardous in being highly inflammable and in many formulations are toxic.

BRIEF DESCRIPTION OF THE INVENTION The slurry of the present invention is a new type of cap-sensitive slurry explosive capable of propagating a high order detonation in thin layers. The invention provides a safe explosive in slurry form which may be used in oil well and gas well formation fracturing, rock fracturing for in situ ore leaching, non-nuclear fracturing of oil shale formations, and explosive formation of fire lanes in terrain inaccessable to motorized equipment.

The slurry of the present invention is formulated to resist accidental initiation by adiabatic compression of gas bubbles which may be introduced during loading and handling, and due to the good chemical stability of the explosive formula, the slurry gives a high degree of inertness toward crude oil and brine and dilute forms of most other well environmental materials. The material of the presentinvention in fires is difficult to ignite, and once ignited, burns quietly with no explosion. The ingredients comprising the slurry are non-toxic prior to detonation.

Additional advantages, objects and features of the invention will be more readily apparent from the following detailed description of an embodiment thereof.

Example by weight) Sensitive Fine Particle PETN 50 6071 Ammonium Nitrate Solution 0 80 Diethylene Glycol O Guar Gum or Poly-acrylamide 0.1 3.0 Water Balance Cross-linking Agent As required The sensitive fine particle PETN is disclosed in greater detail in my co-pending application, Ser. No. 434,753, filed Jan. 31, 1974 entitled SENSITIVE FINE PARTICLE PETN.

The ammonium nitrate solution may, in certain instances, be replaced largly by potassium, barium or sodium nitrate solution. The diethylene glycol may be replaced largly by other soluble organic fuels such as formamide, diethyl formamide or other glycols and certain alcohols. Also, some portion of solid fuel may be included, i.e., fine coal, sulfur, gilsonite, or aluminum, ferro-phosphorous, ferro-silicon, etc.

A satisfactory cross-linking agent consists of Tyzor LA, which is a trademark preparation of E. I. DuPont de Nemours & Company, Inc. and which is known generally as Titanium-antimonium lactate, as illustrated in US. Pat. No. 3,622,408.

In the above example, the concentration of ammonium nitrate solution is not critical. A 60% solution is convenient to use because the ammonium nitrate stays completely in solution above 54F, which means that handling is simplified over, for example, an solution which has a solidification temperature of about 136F, which would require expensive heated storage. After blending withanti-freeze agent, such as diethylene glycol, the solidification temperature is decreased.

This cap-sensitive explosive is capable of propagating a high order detonation in thin layers, i.e., one-thirty second inch when confined between masonite, able to detonate completely in thin layers simultaneously exposed to a hydrostatic pressure of 10,000 psi or above and a temperature of approximately 200F, does not cause headache during handling, and contains no liquid explosive ingredient. Further, slurry explosive is unaffected when penetrated by British 303 ammunition from a distance of 75 to feet, even when backed by steel or aluminum. Slurry explosive will slowly decom pose in a bonfire when unconfined, but by itself will not support combustion.

The purpose of this invention is to provide a safe explosive in slurry form which may be used in l the explosive fracturing of oil and gas reservoirs in order to increase formation permeability and thus increase rate of flow to wellbore; (2) the explosive fracturing of oil shale formations to permit thermal recovery of petroleum products therefrom in an economical manner; (3) various military applications; and (4) non-incendiary line charges for the rapid construction of fire lanes to fight forest fires, particularly in terrain inaccessable to mechanized equipment.

Ordinarily, PETN (penethaerythritol tetranitrate) is considered a hazardout explosive which is known to explode when subjected to modest physical abuse from impact or friction forces. For example, in a drop test apparatus in which a small (i.e., approximately onetwentieth gram) sample of sensitized small particle PETN is placed on a hard tool steel anvil and impacted by a free fall hammer, also made of hard tool steel and weighing 2.143 kg, detonations of the PETN occur when the drop height is only 2 cm. In other words, the impact sensitivity of the pure, dry PETN is 4.3 kg-cm. When this same PETN is compounded into this slurry explosive in the proportions of 40% PETN/50% of a 60% AN solution/9.5% DEG/0.5% guar and cross linked (5 drops/100g slurry) with a 50% solution of Tyzor LA in deionized water, the resulting explosive mixture is unaffected by repeated hammer drops from a drop height of 63/5cm. Thus, in slurry form, the PETN is not exploded by an impact of 136.3 kg-cm, which is more than 30 times the energy at which the PETN alone explodes. The slurry formula given in the above example detonates completely at high velocity under a hydrostatic pressure of 10,000 psi in a layer one-sixteenth inch thick by 2- /2 inches wide confined between two sheets of A inch thick masonite.

The consistency of the slurry can be varied to suit the needs of a particular requirement. The slurry can be provided in viscosity ranges from a thin milkshake to bread dough consistency. Rather thick slurry has the amazing property of passing readily through a small (l/32 inch diameter) orifice under low pressure and then reconsolidating with itself. This high degree of thixatrophy allows it to readily adapt to a variety of applications. It has been found that the detonation rate of the slurry is 21,400 feet per second in a layer thickness of 0.032 inches (one-thirty second) with mild confinement. Atpressures up to 10,000 psi, the slurry explosive with a thickness of 0.063 inch (one-sixteenth) detonates completely.

Manifestly, minor changes can be effected in the above-described examples without departing from the spirit and the scope of the invention as defined in and limited solely by the appended claims.

I claim:

' l. A thin layer propagating slurry explosive compris-

Claims

1. A THIN LAYER PROPAGATING SLURRY EXPLOSIVE COMPRISING A MIXTURE CONSISTING OF, BY WEIGHT: A. 40% SENSITIVE FINE PARTICLE PENETAERYTHRITOL TETRANITRATE (PETN), B. 50% OF A 60% AMMONIUM NITRITE SOLUTION, C. 9.5% DIETHYLENE GLYCOL, D. 0.5% GUAR, AND E. 5 DROPS/100G SLURRY OF A 50% SOLUTION OF TITANIUM ANTIMONIUM LACTATE IN DEIONIZED WATER AS A CROSS-LINKING AGENT.