Abstract: A tool and method are disclosed for injecting various treatment fluids into a formation surrounding an underground borehole. The tool comprises at least three axially spaced swab assemblies which define at least two annular spaces between the tool body and the wellbore. In use the tool is moved through the wellbore whilst a first treatment fluid such as a sand consolidation agent or production stimulation chemical, is pumped via a first annular space into the formation and a second treatment fluid, such as an overflush fluid, is pumped via a second annular space into the formation. The tool allows accurate and continuous injection of various treatment fluids over long intervals into the formation without requiring cycling to new fluids.