A propellant assembly for subsurface fracturing and method for using the same are provided. The assembly can include 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; and 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.