Systems and methods for delivering mechanically-gassed explosives

Abstract

Systems and methods for delivering explosive mixtures with gas bubbles that are resistant to in-borehole migration or coalescence are disclosed herein. Such explosive can be sensitized by mechanically introducing gas bubbles into the explosive matrix in a number of gassing stages. Resistance to gas bubble migration and coalescence without the need for bubble stabilization agents can be achieved by homogenization in a number of homogenizing stages.

1 . An explosives delivery system, comprising:
 a flow path configured to receive a stream of an energetic material and comprising:   one or more injection ports configured to deliver a stream of a gas from a gas source into the flow path;   a plurality of modules configured to combine the gas with the energetic material and to produce a sensitized explosive;   a homogenizer fluidically connected to the plurality of modules and configured to homogenize the sensitized explosive to produce a homogenized explosive, wherein the homogenizer comprises at least one homogenizing stage; and   a delivery conduit comprising a hose fluidically connected to the homogenizer and configured to convey the homogenized explosive to a borehole.   
     
     
         2 - 6 . (canceled) 
     
     
         7 . The explosives delivery system of  claim 1 , wherein the plurality of modules includes an annular gas injector, comprising:
 a body assembly having an inner surface defining the flow path for the stream of energetic material; and   an injector assembly disposed coaxially within the flow path and comprising:   an axial channel configured to receive the stream of gas from an injection port; and   one or more radial channels in fluid communication with the axial channel and configured to direct the stream of gas outward to converge with the flow path.   
     
     
         8 . The explosives delivery system of  claim 7 , wherein the injector assembly comprises a first zone and a second zone having an increased diameter, such that the flow path around the second zone is constricted relative to the flow path around the first zone. 
     
     
         9 . The explosives delivery system of  claim 1 , wherein the plurality of modules includes a gas injection cassette comprising a plurality of channels configured to divide the stream into fractions, wherein each of the plurality of channels includes a constriction configured to impart shear on the fraction of the stream flowing through the channel. 
     
     
         10 - 12 . (canceled) 
     
     
         13 . The explosives delivery system of  claim 9 , wherein the channels are configured to admit flow of the stream in each of two opposite directions and wherein the channels are disposed in a valve that is rotatable so as to reverse an orientation of the channels relative to the flow path. 
     
     
         14 . (canceled) 
     
     
         15 . The explosives delivery system of  claim 1 , wherein the plurality of modules includes a pre-shear valve comprising a plurality of holes situated across the flow path so that the stream is divided and directed through the plurality of holes, and wherein the holes are configured to impart shear on the stream. 
     
     
         16 - 17 . (canceled) 
     
     
         18 . The explosives delivery system of  claim 15 , wherein the holes are disposed in a valve that is rotatable so as to reverse an orientation of the holes relative to the flow path. 
     
     
         19 . (canceled) 
     
     
         20 . The explosives delivery system of  claim 1 , wherein the at least one homogenizing stage comprises a shear set comprising a first shear member and a second shear member, each including at least one shear edge,
 wherein the at least one shear edge of the first shear member is opposite at least one shear edge of the second shear member across a gap; and   wherein the homogenizer is configured to direct the stream through the gap.   
     
     
         21 . The explosives delivery system of  claim 20 , wherein the first shear member and the second shear member each include a plurality of shear edges thus opposed across the gap. 
     
     
         22 - 24 . (canceled) 
     
     
         25 . The explosives delivery system of  claim 20 , wherein a width of the gap in the shear set is adjustable. 
     
     
         26 . The explosives delivery system of  claim 1 , wherein the homogenizer comprises 2 to 5 homogenizing stages, and wherein a total length of shear edge in the homogenizer is about 1 cm to about 810 cm. 
     
     
         27 . (canceled) 
     
     
         28 . The explosives delivery system of  claim 1 , wherein the homogenizer further comprises at least one mixer, and wherein the at least one mixer comprises a plurality of holes arranged in a series, wherein each hole in the series is unaligned with an adjacent hole in the series. 
     
     
         29 - 30 . (canceled) 
     
     
         31 . The explosives delivery system of  claim 1 , wherein the delivery conduit further comprises a nozzle fluidically connected to the hose and configured to eject the homogenized explosive into the borehole, wherein the nozzle includes a homogenizer comprising a first shear member and a second shear member, each including at least one shear edge,
 wherein at least one shear edge of the first shear member is opposite at least one shear edge of the second shear member across a gap; and   wherein said homogenizer is configured to direct the stream through the gap.   
     
     
         32 - 36 . (canceled) 
     
     
         37 . A method of delivering a bulk explosive material, comprising:
 obtaining an unsensitized energetic material;   gassing the energetic material, comprising mechanically introducing a gas into the energetic material;   combining the gas and the energetic material to produce a sensitized explosive material;   homogenizing the sensitized explosive material to form a homogenized explosive material; and   delivering the sensitized explosive material into a borehole.   
     
     
         38 . (canceled) 
     
     
         39 . The method of  claim 37 , comprising gassing the energetic material in 2 to 7 gassing stages. 
     
     
         40 . (canceled) 
     
     
         41 . The method of  claim 39 , wherein one of gassing stages is coincident with the delivering step. 
     
     
         42 . (canceled) 
     
     
         43 . The method of  claim 37 , comprising homogenizing the explosive material in 2 to 5 homogenizing stages. 
     
     
         44 . (canceled) 
     
     
         45 . The method of  claim 37 , wherein the energetic material is an emulsion matrix comprising a discontinuous phase of oxidizer salt solution droplets in a continuous phase of a fuel and wherein the homogenized explosive material is devoid of a bubble stabilizing agent. 
     
     
         46 . The method of  claim 45 , wherein the emulsion matrix has an initial viscosity of about 4,000 cP to about 60,000 cP. 
     
     
         47 . The method of  claim 45  wherein homogenizing increases a viscosity of the sensitized explosive material by about 30,000 cP to about 50,000 cP. 
     
     
         48 - 49 . (canceled)