Abstract A liquid explosive is described which has a small critical diameter, is safe to handle, is capable of use in cold climates and yet is compatible with the higher temperatures commonly present in subterranean formations, which includes a nitroparaffin compound having dissolved therein a nitramine explosive, a ballistic modifier and a detonation aid in such proportions that the critical diameter of the explosive is on the order of 1/32 inch. Other constituents may also be added for controlling the consistency and ballistic properties as well as the manufacturing and handling properties of the explosive. A thickening or gelling agent is also preferably added to retain the ballistic modifier as well as any other suspended solids in a uniform dispersion. A method of fracturing well formations for enhancing their productivity, using such liquid explosives, is described.
A method of fracturing the productive formation of a water, oil or gas well containing a network of geological fissures to increase the permeability of said formation and thereby enhance the productivity of the well, utilizing a viscous, pourable liquid explosive consisting essentially of between about 65 and 75 percent by weight of a nitroparaffin explosive having dissolved therein between about six and 10 percent by weight of a nitramine explosive, between about eight and 12 percent by weight of a detonation aid, between about five and 20 percent of a ballistic modifier, between about one and five percent by weight of a thickening agent for maintaining an even dispersion of any particulate solids in said explosive and an acid scavenger, comprising: injecting said liquid explosive through an injection tube into the well bore at the level of the productive formation to be fractured; forcing said liquid explosive back into the productive formation to be fractured at a rate low enough to prevent undue heating of the explosive and yet high enough to maintain the flow without continually having to overcome static friction, and leaving a sufficient amount of said explosive in the well bore to initiate the explosive in the formation; and detonating the explosive in the well bore to fracture the formation, the amount of acid scavenger being sufficient, at said rate, to prevent auto-ignition through buildup of nitrogen oxide.
Claim 2
Dependent Claim
30 words
A method as defined in claim 2 wherein said nitramine explosive and said thickening agent are selected to have decomposition temperatures above the temperature of the explosive at said rate.
Claim 3
Dependent Claim
22 words
A method as defined in claim 3 wherein the amount of acid scavenger is between about 1.5 and 2.5 percent by weight.
Claim 4
Dependent Claim
30 words
A method as defined in claim 3 wherein said rate at which the explosive is forced back into the productive formation is between about four and 13 gallons per minute.