US Patent 7303016 Casing with isolated annular space

The invention is comprised of (see FIG. 1) an inner pipe (2), and an outer pipe (3), and two end subs (1). An isolated circular hollowed space is contained in between these components. The isolated space can be used for transport of different medias down into the well, this can be vacuum, air, gas, acids, solids, tracers, or other well stimulating medias. The end subs (1) can be connected to the casing in the well and become an integrated part of the casing. The invention can be cemented on the outside like the casing can. The invention can be perforated after installed in the well.