A device for drilling a hole in a well tubular and for subsequent injection of a fluid or fluid mixture into an annular space or formation surrounding the well tubular. The device comprises a housing and a drill bit assembly arranged inside the housing. In the drill bit assembly, a drill bit with cutting edges and grooves extending along its outside surface, is arranged. The device further comprises rotation means being capable of rotating the drill bit assembly and a fluid supply for supplying a fluid or fluid mixture to the grooves of the rotating drill bit. A seal is surrounding the drill bit and capable of sealing the device against the inner surface of the well tubular.