Gasflow distribution device, gas distributor, pipe string and method for separate-layer gas injection

A gasflow distribution device, the gasflow distribution device comprising:

• an outer pipe, a gland, a filter screen, and a filling block with a pore structure;
• wherein the outer pipe is a hollow outer pipe with an open upper end and a lower end with a bottom of which the center part is provided with a bottom hole, and wherein the filling block with a pore structure is contained in the outer pipe and sealed to an inner wall of the outer pipe;
• wherein the gland has a bottom end provided with a circular groove for setting the filter screen which is sealed to the inner wall of the circular groove, and a top end distributed evenly with a plurality of top holes through the gland;
• and
• wherein the gland is connected to the outer pipe via an inner screw thread.