Why Do The Oil Estimates Keep Going Up?

The Oil Drum provides one answer:

Gas flows more easily through cracks than oil, and the disaster wasfirst evident when leaking gas reached the drilling rig, and thenignited. The BOP then, at least partially, functioned. After the rigsank, the riser also sank, bending the pipe just above the BOP. At thattime there were reports that a Coast Guard ROV examined the underwaterassembly and did not see any obvious oil leaks. A couple of days laterthe flow was suggested at about 1,000 bd, and...