The distribution and migration ability of weak gel directly affect its profile control and flooding performance. Conventional plugging experiments using core models cannot intuitively observe gel distribution，and rarely reflect the influence of reservoir heterogeneity on migration process. In this paper，weak gel profile control and flooding as well as CT scanning experiments were carried out in long sand filling model，large-size visual heterogeneous model and heterogeneous core model，respectively，to systematically study the spatial distribution and migration depth of weak gel. The results of long sand filling model showed that before reaching final setting time （12 . 0 — 14 . 0 h），the dynamic injection pressure of the gelling fluid had increased significantly to a maximum of 37 . 5 MPa. On the one hand，this confirmed the occurrence of dynamic gelation；on the other hand，it indicated that the migration resistance of gelling fluid increased sharply and flow became difficult before final setting in porous media，so final setting time could not accurately reflect the fluidity of gelling fluid in porous media. During gelling fluid injection and subsequent water flooding，weak gel could migrate，but the migration distance was very limited. The total length of the model was 21 . 5 m；weak gel only was squeezed to 0 — 4 . 2 m section in the gelling stage，and subsequent water flooding could only push it to 4 . 2 — 8 . 5 m section for plugging requiring an extremely high displacement pressure of 15 . 0 — 37 . 5 MPa. The results of visual heterogeneous model showed that the plugging depth of the first round of weak gel was about 27 . 0 cm. During subsequent water injection and the injection of the second and third rounds of gelling fluid，the injected fluid had obvious bypass flow，the injection pressure only increased slightly，the gel of previous rounds did not migrate significantly，and it would also block the migration of subsequent rounds of gelling fluid. After three rounds of injection，the total plugging depth was only 43 . 3 cm，which was far less than the total length of the model （200 . 0 cm），confirming that weak gel had very poor migration ability or even basically could not migrate under heterogeneous conditions. The fluid distribution results of heterogeneous core model further verified that weak gel could basically not achieve effective deep migration after gelation under heterogeneous conditions，and it played more role of “ profile control ” rather than “ profile control and flooding ” .