Flow rate dust-up shows discomfort with imprecision

Bob Tippee

Of all the concerns raised by the Macondo blowout in the Gulf of Mexico, imprecision of the flow rate should rank low on a scale of urgency.

Yet the flow rate has become one more controversy.

BP, operator of the ill-fated well, initially estimated the rate at which oil was leaking from the wellhead and damaged riser at 1,000 b/d. Later, it raised the estimate to 5,000 b/d.

This week, though, it disproved its own estimate with a remediation success.

The insertion tube tool with which it is siphoning fluids out of the riser collected 5,000 b/d on May 19, and oil still entered the water.

Obviously, the 5,000-b/d estimate was low. This item of simple logic launched much of the news media into attack strategies typical of political coverage.

Had BP deliberately underestimated the flow rate to make the crisis seem less severe? Was it covering up the real flow rate? What did it know about the flow, and when did it know it?

To some reporters, the apparent underestimation legitimized a scientist’s estimate made days earlier that the rate could be 70,000 b/d or more.

Can a vertical exploratory hole in the Gulf of Mexico really produce that much oil through crimped pipe? Almost certainly not. But no one bothered to ask.

The problem is a combination of understandable anxiety and discomfort with imprecision.

Like most blowouts, the Macondo well doesn’t have a meter. BP has to estimate the flow rate based on what it knows from test results and what it observes on video of natural processes exerting themselves with natural irregulatory under 5,000 ft of water.

The company can’t be right except within a wide range of uncertainty. Still, it’s getting nailed for having been proven wrong.

That’s regrettable. The experience will make BP’s representatives less open than before with best-available information about the catastrophe. They’ll assume that saying nothing beats communicating before events are rock-solid certain.

Not that the company was setting new standards for openness before. It wasn’t.

And the silent strategy makes reporters wonder all the more what’s being covered up.

This feature will appear next on June 4.

(Online May 21, 2010; author’s e-mail:

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