INJECTION OF LIQUID INTO BOREHOLES, WITH SUCKBACK PULSING

When injecting liquids into the ground, imposing pulses on the injected liquid is effective to increase penetration and saturation of the ground. Imposing suckback onto the pulses is effective to make the liquid in the ground behave as a coherent unitary body, surging out and back each pulse, and to super-saturate the ground. The tool includes a suckback-chamber, which is timed to open to the ground formation just as the pulse-valve closes. A biasser (e.g a spring) drives the chamber open and sucks in some of the liquid from the ground. The chamber is then emptied, back to the ground, by the rising pressure as the pulsing tool is recharged. The suckback-chamber can be added to any type of pulsing tool.