Alan... depends on the pressure on the pig (balloon). If the pressure was too great, the force exerted on the pig would have to be stemmed by the tube.... might be like trying to push a party balloon with a pin???

Unless it was a big pin? Then, grout the void around the "pin"?

Still, it boils down to holding the pig in place which depends on the force of the oil. I still see the only way to do that is with a collar over the pipe to attached threaded rods or cables to PULL whatever into place.