Downhole drill-inject & plug tool

A drill bit assembly comprising:

• a drill bit having a drill point and a drive shaft;
• a conical swage formed on the drill bit between the drill point and the drive shaft, the conical swage having a conical shape sloping down toward the drive shaft;
• and
• a seal plug removably coupled to the threaded drill bit, the seal plug comprising an outer surface having a self-cutting thread.

A method comprising:

• rotating a drill bit assembly against a casing, the drill bit assembly having a drill bit with a seal plug and a conical swage;
• penetrating an inner surface and an outer surface of the casing with a drill point of the drill bit thereby forming a hole;
• engaging an outer surface of the seal plug with a hole wall defining the hole via a thread;
• threadingly engaging the seal plug with the hole wall;
• disengaging the seal plug from a drive shaft of the drill bit assembly when the seal plug is threadingly engaged with the hole wall;
• retracting the drill bit assembly through the seal plug threadingly engaged with the hole wall;
• and
• engaging an outer surface of the conical swage with an inner surface of the seal plug and radially expanding the seal plug as the conical swage is retracted through the hole wall, thereby sealing the hole.