Abstract: In a drill stem test, a packer is set in the well bore to isolate a potential producing zone. A drill pipe with a down hole valve is fitted through the packer. The pipe is usually partially filled with a liquid column prior to commencement of the test, which essentially comprises opening the valve so that formation fluids can flow into the drill pipe and measuring various parameters associated with the fluid transfer. A method for estimating porosity and/or permeability includes the steps of setting up such a drill stem test wherein flow of formation fluid to a drill pipe may be controlled by a down hole valve, opening the valve to establish a flow, recording flow parameters, and analyzing oscillatory transients in the flow to compute therefrom estimates of porosity and permeability.