The Macondo well blowout on April 20 was avoidable, and occurred largely because of a series of bad decisions by the companies and personnel involved that did not take into account the proper risks, according to a partial report released Wednesday by the presidential oil spill commission.

“The well blew out because a number of separate risk factors, oversights, and outright mistakes combined to overwhelm the safeguards meant to prevent just such an event from happening.”

“But most of the mistakes and oversights at Macondo can be traced back to a single overarching failure�a failure of management. Better management by BP, Halliburton, and Transocean would almost certainly have prevented the blowout by improving the ability of individuals involved to identify the risks they faced, and to properly evaluate, communicate, and address them.

“A blowout in deepwater was not a statistical inevitability,” the report says of the blowout that killed 11 men and left millions of gallons of oil spewing into the Gulf of Mexico.

The National Commission on the BP Deepwater Horizon Oil Spill and Offshore Drilling released the report — a chapter of its final report — in advance of the full report due to President Obama on Jan.11.

Halliburton, in an emailed statement, says “In general, the National Commission selectively omitted information we provided to them in response to their numerous inquiries.”

Halliburton says that it acted at the direction of BP. Transocean also put the blame on BP: “Consistent with industry standards, the procedures being conducted in the final hours were crafted and directed by BP engineers and approved in advance by federal regulators.” BP did not immediately respond to requests for comment.

The report points out several occasions when BP, Transocean and Halliburton did not conduct a thorough engineering analysis, or notice and question puzzling pressure readings coming from the well below.

The team also did not take additional care with the well, though it knew it was a difficult well that had problems almost from the beginning. Rather the crew compromised its decisions for the sake of money and time, according to the report. The crew essentially refused to see the problems in the well, chalking them up to broken gauges, erroneous readings, or coming up with other unusual explanations, according to the commission’s report.

In one example: “It appears instead they started from the assumption that the well could not be flowing, and kept running tests and coming up with various explanations until they had convinced themselves their assumption was correct,” the report says of the crews attempt to get a successful pressure test on April 20.

In another example, the commission says “BP’s team appears not to have seriously examined why it had to apply over four times the 750 psi design pressure to convert the float valves. More importantly, the team assumed that the sharp drop from 3,142 psi meant the float valves had in fact converted. That was not at all certain. The auto-fill tube was designed to convert in response to flow-induced pressure. Without the required rate of flow, an increase in static pressure, no matter how great, will not dislodge the tube.”

The commission’s report pinpoints nine decisions as examples that led to the explosion aboard the Deepwater Horizon � most of them focused on the cement job.

They included not waiting for more centralizers for the casing pipe to ensure a good cement job; not waiting for foam stability tests to ensure that the foam cement injected into the casing by Halliburton would hold; not running a cement evaluation log after the cement job; using a combination of unusual materials called spacer between the drilling mud and the seawater in order to dispose of the material; removing drilling mud from the riser before setting a surface cement plug; setting a surface cement plug 3,000 feet below the mud line in the sweater; not installing additional physical barriers to prevent flow from the well; not performer further well integrity tests in light of unexplained problems in the well; and bypassing mud pits when removing the mud to save time

“There is nothing to suggest that BP’s engineering team conducted a formal, disciplined analysis of the combined impact of these risk factors on the prospects for a successful cement job. There is nothing to suggest that BP communicated a need for elevated vigilance after the job. And there is nothing to indicate that Halliburton highlighted to BP or others the relative difficulty of BP’s cementing plan before, during, or after the job, or that it recommended any post-cementing measures to confirm that the primary cement had in fact isolated the high-pressure hydrocarbons in the pay zone,” according to the report.

Randall Luthi, president of the National Offshore Industries Association, hailed the report as a positive for the offshore industry.

“What is more important to the future of the nation’s offshore energy is the conclusion that this blowout was not a statistical inevitability. That means the human failures that led to Macondo can and will be corrected. In fact, the offshore industry has already made changes in procedures and practices based on the lessons learned thus far and in response to new regulations.”