By Kristen Hays

NEW ORLEANS, Feb 27 (Reuters) - BP Plc took chances drilling its doomed Macondo well long before it ruptured in 2010, a well design and pressure expert said on Wednesday in the second day of testimony in the civil trial over the Gulf of Mexico oil spill.

Alan Huffman, chief technology officer for Fusion Petroleum Technologies Inc, said BP forged ahead with the well in 2009 outside the margin deemed safe by the industry and regulators.

He said there was a "kick" in the well during one of many intervals in drilling, which indicates pressure was unstable and there could be a rupture or other problem. Rather than stop drilling, the work went ahead with another interval.

"It is truly egregious to drill that extra 100 feet knowing you could lose the well in the process," Huffman said.

Testifying on behalf of the U.S. Justice Department, Gulf states affected by the spill, and plaintiffs suing BP and its partners, Huffman said the well was "dangerous and fragile" and "they should not have drilled ahead at all".

In this first of the trial's three phases, U.S. District Judge Carl Barbier will seek to allocate blame among well owner BP, driller Transocean Ltd, cement services provider Halliburton Co and others, unless a settlement cuts the trial short.

The April 2010 blowout caused an explosion that killed 11 men and sent more than 4 million barrels of crude spewing into the Gulf.

Huffman, a geophysicist who analyzed BP documentation of the well's condition, said BP should have at least sought permission from regulators before drilling without a safe "drilling margin" - referring to the required minimum weight of the drilling fluid compared with the rock the drill was penetrating.

He told Transocean lawyer Kerry Miller that a safe drilling margin was the "first line of defense" against a blowout for the operator, which in this case was BP. "It is the responsibility of the operator to determine those parameters and tell the drilling people what to do."

On cross-examination, BP lawyer Matt Regan challenged Huffman's expertise, noting that he was not a regulator.

"You have never been to an offshore rig that's operating in your life?" Regan asked, to which Huffman replied: "That's true."

Huffman said he was unaware of any documented violations of drilling regulations on the Macondo operation. He said he analyzed that operation at the Justice Department's request to opine on the way the well was drilled and how it applied to regulations.

After more back and forth on drilling regulations and margin, the judge interjected, seemingly to clarify Huffman's point: "Is this a weakest-link issue?" Barbier asked.

"That is the practice I've seen industry-wide, your honor," Huffman answered. "If there's a weaker zone in the well, you have to honor that zone in your drilling margin."

Earlier on Wednesday, plaintiffs played an excerpt of a videotaped deposition of Kevin Lacy, former senior vice president of Gulf drilling operations for BP, who resigned from the company a few months before the spill because of what he said were concerns about BP's safety practices.

He testified that he was under heavy pressure from top BP management in 2008 and 2009 to shave hundreds of millions of dollars in costs and received bonuses for doing so. In 2009, his team cut up to $300 million in costs and had pressure to keep it up in 2010.

"I was never given a directive to cut corners or to deliver something not safely," Lacy said. "But there was tremendous pressure on costs."

Also on tap to testify this week is Mark Bly, global head of safety and operational risk who ran BP's internal probe of the spill in 2010.

The case is In re: Oil Spill by the Oil Rig "Deepwater Horizon" in the Gulf of Mexico, on April 20, 2010, No. 10-md-02179, in the U.S. District Court, Eastern District of Louisiana.

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