The head of the USGS just did a press conference to announce the government’s official estimate of how much oil is flowing into the Gulf. The official estimate is that the flow rate is 12,000-19,000 BBL/day.

To get the estimate, the team used two different methodologies, then adopted the rate of overlap between the two methodologies: One team calculated how much oil is on the surface of the Gulf of Mexico, using data collected from NASA on May 17. It estimated that between 130,000 – 270,000 BBL of oil were on the surface on May 17. In addition to what is on the surface, the team calculated that a similar volume has been burned, skimmed, or evaporated. It’s initial estimate based on the estimate of how much oil was on the surface gave a rate of release of 12,000-19,000 BBL/day.

The second team developed an estimate by observing the flow video and estimating the fluid velocity and volume. This methodology was limited because it had a limited window of data to choose from (and it sounds like they didn’t get good quality video until the last week and a half). This team then estimated how much was oil, gas, hydrates and water. It’s lowerbound estimate was 12,000-25,000 BBL/day.

The team as a whole then checked these results by estimating what was coming out of each leak, which came up with the 12,000-19,000 range.

McNutt made two caveats before announcing the amount.

  • Administration response has been based on worst case scenario (she seemed to want to suggest that the response wasn’t hindered by bad estimates from BP).
  • The numbers are still preliminary–the scientists are getting new data.

Interestingly, one thing McNutt noted is that about 75% of the volume coming out of the pipe was gas.