Foam and impedance-guided steam injection

Claim 1

In a well treating process within a reservoir in which a gaseous fluid is injected through tubing surrounded by a permeable-walled conduit in a manner tending to provide a preferential inflow into a selected portion of the reservoir, an improvement comprising: in a location near but above that at which the gaseous fluid is to be injected into the reservoir, introducing solid granules into the space between the permeable-walled conduit and the reservoir to an extent sufficient to ensure that the vertical permeability in that space is not significantly more than the permeability provided by the interstices between a mass of gravel-sized solid particles; positioning a mechanical fluid-flow-impeding means within the annulus between the tubing string and the permeable-walled conduit at a depth which is below the top of said mass of gravel-sized particles and is just above the depth at which the gaseous fluid is to be injected into the reservoir; injecting fluid which is significantly more viscous than the gaseous fluid through the annulus and into said mass of particles above the mechanical flow impeding means at a rate and pressure such that the fluid pressure near the impedance exceeds the pressure at which the gaseous fluid is to be injected into the reservoir; and injecting the gaseous fluid through the tubing string and into the reservoir below the mechanical flow impeding means.