Using bismuth based alloys to seal in downhole conditions was first tried by the Schlumberger brothers back in 1930s, using electrical heaters. It was continually tried using electrical heaters through the 1960s to 1990s, but without realistic practical implementation due to the time it takes for the heating process to take effect, as well as limitations on deployment depth and the specialist wireline equipment required to run the electrical heaters at that time.
What we do differently at BiSN is we use modified thermite heaters, which makes this a game changing technology reducing the heating time required from hours to minutes and eliminates the need for any specialist wireline equipment, with no restriction on deployment depth.