US Patent 7819193 Parallel fracturing system for wellbores

Downhole fracturing tools comprise upper and lower isolation devices and a housing disposed in between. The housing comprises a housing bore that is divided into two chambers isolated from each other within the housing bore. The upper bore is in fluid communication with a fluid injection line through which a fracturing fluid is pumped into the upper bore. The fracturing fluid flows down the upper bore, substantially parallel to a longitudinal length of the tool, and exits the tool through at least one port. The fracturing fluid then travels down the wellbore annulus. Returns from the fracturing fluid flow through a screen in the tool and up a return line that empties into the wellbore annulus above the upper isolation device.