Patent ID: 7861785

Claim:
A downhole tool for subsurface fracturing, comprising: two or more propellant assemblies connected in series, each assembly comprising: a first tubular member having an annulus formed therethrough; a second tubular member at least partially disposed within the annulus of the first tubular member; one or more tubular propellants housed within the first tubular member, between an inner diameter of the first tubular member and an outer diameter of the second tubular member; one or more detonating cords housed within the second tubular member, wherein the second tubular member has one or more portions thereof having a reduced wall thickness, wherein the first and second tubular members are substantially concentric to one another; and a first end connector and a second end connector disposed at opposite ends of the first tubular member, wherein the second tubular member has threaded ends adapted to threadably engage the first and second end connectors; a male coupler having a first side and a second side that is adapted to be received into the first end connector of one of the two or more propellant assemblies; a female coupler having a first side and a second side that is adapted to receive the second end connector of one of the two or more propellant assemblies; and a transfer sub housing disposed between the two or more propellant assemblies, the transfer sub housing having first and second ends, wherein the first sides of the male and female couplers are adapted to be received into either of the first and second ends of the transfer sub housing.