Is the criminal plea agreement Halliburton struck with the Justice Department on Thursday a good deal for the company?

The terms seemingly marked a setback for the Houston-based oil services giant, which had asserted its innocence in the 2010 Gulf of Mexico oil spill that killed 11 people and poured nearly 5 million barrels of oil offshore. Now Halliburton concedes that employees twice erased computer simulations that undercut the company’s argument about the causes of the disaster.

But investors on Friday shrugged off that admission. After the announcement Friday of a share buyback program of up to $3.3 billion, Halliburton’s stock closed at $45.98, up 3.7 percent.

And the terms of the company’s settlement with Justice also could be viewed less harshly:

●Halliburton will pay the maximum fine for a misdemeanor, but the $200,000 is equal to just under four minutes’ revenue for the company.

●The company will pay $55 million to the National Fish and Wildlife Foundation, but that payment might be considered tax deductible since the foundation, a conservation grant-making organization created by Congress in 1984, is a nonprofit group.

●The “cementing technology director” who instructed two colleagues to destroy computer simulations that would have been evidence in the investigation of the oil spill has retained his anonymity and continues to work for the company, officials said. That, some legal experts say, undercuts whatever deterrent the case might have against future misdeeds.

“Given the scale of the harm caused by the oil spill, it seems surprising that the government would accept a plea to a relatively minor charge,” said J. Kelly Strader, a law professor at Southwestern Law School. Destruction of evidence often leads to multiple felony counts, he said, including obstruction of justice, as it did in the case of Enron’s market ma­nipu­la­tion a decade ago.

Halliburton said Justice agreed to not pursue any charges beyond the misdemeanor in return for cooperation. And its fine and payment to the National Fish and Wildlife Foundation is tiny compared with settlements made earlier by TransOcean and BP.

Justice could still pursue criminal charges against individuals involved in destroying evidence, but company spokeswoman Susie McMichael said, “We have no reason to believe that the DOJ intends prosecution of any of them.”

Strader said that if Halliburton’s cooperation leads to criminal charges against others “then the plea to a relatively minor crime might make sense from the government’s perspective.” If not, “then this looks like a slap on the wrist that would do little to deter such obstructive behavior in the future,” he said.

“One might read this as a deterrent in the reverse sense, in that it strongly encourages future corporate defendants to admit guilt, make separate unconditional payouts and cooperate like crazy, with the ‘carrot’ being a mere misdemeanor conviction,” said Robert Weisberg, law professor and director of Stanford Law School’s criminal justice center.

That way, Halliburton “buys immunity from the potential disaster of an Arthur Andersen outcome,” Weisberg said. Andersen, the auditing firm, went out of business and was convicted of obstruction of justice over the demise of the energy firm Enron just over a decade ago.

People familiar with the thinking of officials at Halliburton said the company believes that the deal with Justice might not be harmful in its civil litigation. A wide variety of plaintiffs — including states, businesses and individuals — have brought suit against Halliburton, the drilling-rig owner TransOcean and the well operator BP.

The destruction of evidence took place after the accident and did not directly implicate problems with the cementing job that Halliburton performed on BP’s Macondo well, which blew out April 20, 2010, destroying the Deepwater Horizon drilling rig.

But other analysts say that the destruction of evidence could signal trouble for the company.

“The problem that the plea agreement might produce for Halliburton in the civil cases is that obstructive acts tend to show consciousness of wrongdoing: Why would you cover up something if you believed you weren’t culpable?” said Strader, who has litigated a number of cases. “That could be very persuasive to a jury in a civil case.”

Halliburton has agreed to three years of probation. Lawyers involved with white-collar criminal cases say that means a later offense could have more severe consequences. And Halliburton’s record is not unblemished; the Securities and Exchange Commission charged in 2009 that the company had bribed Ni­ger­ian government officials in violation of the Foreign Corrupt Practices Act.

The computer simulations Halliburton destroyed would have defused one of the allegations against BP, which Halliburton publicly said had failed to use enough centralizers in the well. Centralizers are metal collars that help keep the steel drill pipe in the center of the well bore. The simulations might have turned more attention toward whether Halliburton’s cement job was flawed.

“The question of cement integrity has from the start been central to finding out what caused the blowout and what the industry might do differently to prevent a similar disaster going forward,” said Frances Beinecke, president of the Natural Resources Defense Council and member of the National Commission on the BP Deepwater Horizon Oil Spill and Offshore Drilling. “The deliberate and willful destruction of information that could help lead to answers is a deeply disturbing reminder of the need for effective public oversight of this industry.”