The present invention belongs to the field of heavy oil exploitation, and discloses a multi-layer injection and graded controllable
injection device and method for injecting hot fluid. The device comprises a
steam injection column and a graded
injection device, the latter comprising a shell, the bottom wall of which is sealedly connected to the bottom wall of the
steam injection column, the top wall of which is sealedly connected to the outer
peripheral wall of the
steam injection column, a distance is formed between the outer
peripheral wall of the shell and the outer
peripheral wall of the steam injection column to form a gas / steam injection chamber, which is axially divided into a plurality of independent sub-gas / steam injection chambers, adjacent sub-gas / steam injection chambers can be selectively connected, each sub-gas / steam injection chamber corresponds to a different oil layer, each sub-gas / steam injection chamber can be selectively connected to the corresponding oil layer, so as to inject gas / steam into a certain oil layer alone, or inject gas / steam into multiple oil
layers at the same time, or inject gas / steam into oil
layers distributed from bottom to top from bottom to top or from top to bottom in sequence, and a gas hole is formed in the area of the sub-gas / steam injection chamber located at the bottom of the steam injection column.