Abstract: A modular propellant assembly for fracturing wells has a propellant charge with a detonating cord extending along its length to ignite the propellant. Each propellant module also has end caps with male and female connectors that enable propellant modules to be connected in an end-to-end relationship to any desired length. These connectors align the ends of the detonating cords in adjacent propellant modules and are sealed with O-rings so that the detonating cords remains dry while submerged at high pressures. This enables the detonating cords to be ignited in series.