Deepwater Horizon: The Largest Marine Oil Spill in History

The Deepwater Horizon disaster is the most recent of the great industrial catastrophes in this archive, and in some ways the most fully documented, investigated in exhaustive detail by official commissions whose findings left little doubt about what went wrong and why. It was not, those investigations concluded, an unforeseeable accident but a preventable one — the product of decisions that prioritized cost and speed over safety, of a failed safety culture across the companies involved, and of regulation too weak and too cozy with the industry to prevent it. Eleven men died, the largest marine oil spill in history fouled the Gulf of Mexico, and an ecosystem and an economy were gravely harmed. And it happened, the record shows, because a series of warnings were missed or ignored and a series of risky choices were made to save time and money. Deepwater Horizon is the modern face of an old pattern: the disaster that was not bad luck but bad choices.

This is the story of the largest oil spill ever.

The well and the rig

By 2010, the search for oil had moved into the deep ocean. As shallower and more accessible reserves were depleted, the petroleum industry pushed into ever deeper waters, drilling wells through thousands of feet of sea and then thousands more feet of rock to reach oil and gas trapped far below the seabed. It was difficult, expensive, and dangerous work, at the technological frontier, and it depended on managing enormous pressures deep underground where any failure was hard to reach and harder to fix. The Deepwater Horizon, a state-of-the-art rig owned by the drilling contractor Transocean and working under contract for BP, was engaged in exactly this kind of frontier operation at the Macondo well.

The well had been troublesome and was behind schedule and over budget, and that pressure of time and money would loom over the decisions that followed. The crew was in the process of temporarily sealing the well, which had finished its exploratory drilling, so that the rig could move on and the well could later be brought into production. This phase involved cementing the well to seal it against the high-pressure oil and gas in the reservoir below — a delicate and critical operation, because a faulty seal could allow the hydrocarbons to escape up the well in an uncontrolled blowout.

The blowout

On the evening of 20 April 2010, that is exactly what happened. The cement seal at the bottom of the well failed to hold, and oil and gas under immense pressure began to flow up the well bore toward the rig. A critical safety test — the negative-pressure test, designed to confirm the well was properly sealed — had given worrying readings, but these were misinterpreted, and the crew proceeded in the belief that the well was secure. It was not. The hydrocarbons surged upward, expanding violently as they rose and the pressure dropped, until gas erupted onto the rig and found an ignition source.

The explosion tore through the Deepwater Horizon, followed by a furious fire fed by the oil and gas still flowing up from the well. Of the 126 people aboard, 11 were killed — workers who had been at or near the center of the blast and never escaped — and many others were injured. The survivors evacuated as the rig burned out of control. The last and ultimate line of defense, the blowout preventer — a massive assembly of valves on the seabed designed to seal the well in an emergency, even by shearing through the drill pipe and crushing it closed — failed to function and did not seal the well. The Deepwater Horizon burned for about thirty-six hours and then, on 22 April, sank to the bottom of the Gulf, leaving the well open and gushing oil a mile below the surface.

Eighty-seven days

What followed was a national ordeal played out, unprecedentedly, on live television. BP, responsible for stopping the leak, mounted a succession of increasingly desperate attempts to cap the gushing well a mile beneath the surface, in conditions of crushing pressure and total darkness that pushed the limits of the technology. A containment dome was lowered and failed; an effort to clog the well by pumping in heavy drilling mud, the "top kill," failed; and meanwhile a remotely operated camera broadcast a continuous live feed of oil billowing from the broken wellhead, a maddening image of an unstoppable wound that transfixed and infuriated the public for weeks.

As the oil spread, so did the damage, and the response became a vast emergency operation. Booms were strung to protect shorelines; skimmer ships worked to collect oil from the surface; portions of the slick were set alight in controlled burns; and enormous quantities of chemical dispersants were sprayed and injected to break up the oil — a measure that itself became controversial, since the dispersants' long-term effects were uncertain and they did not remove the oil so much as spread it through the water column. Tens of thousands of people were mobilized in the response, but against a leak of that magnitude, flowing unchecked for nearly three months, the efforts could only mitigate, not master, the disaster.

The crisis became a political and public-relations catastrophe as well as an environmental one. The administration of President Barack Obama faced intense criticism over the adequacy of the federal response and its reliance on BP to stop a leak only BP had the technology to reach. BP's own handling of the disaster's public face became a case study in how not to manage a crisis: its chief executive, Tony Hayward, made a series of damaging remarks, most infamously complaining that no one "wanted this thing over more than I do — I'd like my life back," a self-pitying comment from the head of the responsible company while eleven families grieved and the Gulf filled with oil. The remark crystallized public fury at a corporation seen as having caused an enormous disaster through its own negligence and then bungling its response, and Hayward was soon removed from his role overseeing the spill and ultimately replaced.

The well was finally brought under control in stages. A new, tighter containment cap was installed in mid-July 2010 that at last stopped the flow of oil into the sea after 87 days, and the well was then permanently sealed from below by a relief well that intercepted it, completed that September. The hemorrhage was over — but the oil already in the Gulf, and its consequences, would remain for years.

The toll

The ecological damage was vast and varied. Oil coated the marshes and beaches of the Gulf Coast, smothering the wetlands that are nurseries for marine life and fouling shorelines from Louisiana to Florida. It killed wildlife on a large scale — seabirds whose feathers were destroyed by the oil, sea turtles, dolphins, fish, and the countless smaller organisms at the base of the food web. Dolphins in the most heavily oiled areas suffered elevated deaths and illness for years afterward, and the spill's effects rippled through the Gulf ecosystem in ways that scientists would study for a long time.

The full extent of the ecological harm proved difficult to measure and slow to resolve, and some of it was effectively invisible. A great deal of the oil never reached the surface or the shore but remained suspended in the deep water or settled onto the sea floor, where its effects on deep-sea ecosystems were hard to observe and would unfold over years. The heavy use of chemical dispersants, intended to break up the surface slick, drove still more oil down into the water column, trading a visible problem for a less visible one whose long-term consequences remained uncertain. Scientists would spend years studying the spill's effects on fish populations, deep-sea corals, and the broader food web, and the Gulf's recovery, though real, was neither quick nor complete — a reminder that the damage from such a disaster extends far beyond the oiled beaches that the cameras could show.

The human and economic toll was severe as well. Beyond the eleven workers killed, the disaster devastated the economies of the Gulf Coast that depended on the sea. The fishing industry — shrimpers, oystermen, and fishermen whose livelihoods came from Gulf waters now closed and contaminated — was hit hard, as was the tourism that drew visitors to the region's beaches, now stained with oil or shadowed by the fear of it. Communities that lived from the Gulf saw their way of life thrown into crisis, and the psychological and economic wounds of the spill compounded the ecological ones.

Why it happened

The picture that emerged from the investigations was of a series of decisions, made under the pressure of a well that was behind schedule and over budget, that repeatedly favored saving time and money over maximizing safety, and of a culture across BP and its contractors in which warning signs were not given the weight they deserved. No single mistake caused the blowout; rather, several barriers that should each have prevented disaster failed in sequence, a pattern characteristic of major industrial accidents, in which catastrophe requires multiple safeguards to fail together. That so many failed at once pointed to something systemic — a weakness not just of equipment but of the organizations and the oversight meant to keep such operations safe.

The regulation of offshore drilling came in for heavy criticism as well. The federal agency responsible, the Minerals Management Service, was found to have been too close to the industry it regulated, compromised by conflicts of interest and inadequate to the task of overseeing the risks of deep-water drilling. And BP's own oil-spill response plan for the Gulf proved to be largely a boilerplate document, notoriously including provisions to protect species such as walruses that do not live in the Gulf of Mexico — a sign of how little serious preparation had been made for the catastrophe that occurred.

The reckoning

The accountability that followed was, by the standards of corporate disasters, substantial. BP faced an avalanche of liability — for the cleanup, for economic damages to the people and businesses of the Gulf, for natural-resource damages, and for civil and criminal penalties under environmental law. The company ultimately agreed to and incurred costs, fines, and settlements estimated to exceed sixty billion dollars, an enormous sum even for one of the world's largest oil companies. In 2012, BP pleaded guilty to criminal charges, including charges related to the deaths of the eleven workers, and paid record criminal penalties; and in 2015 it reached a settlement of around $20.8 billion to resolve the civil claims, the largest environmental settlement in American history. Transocean and Halliburton also paid to settle their roles in the disaster.

In the end, Deepwater Horizon stands as the most thoroughly documented proof of an old and bitter truth: that the worst industrial disasters are usually not accidents in the sense of bad luck, but the predictable results of choices that placed cost and speed above safety. A well behind schedule, a cement seal that failed, a safety test misread, a blowout preventer that did not work, a regulator too close to the industry, a response plan that protected imaginary walruses — each was a link in a chain that the investigations found could and should have been broken. Eleven men died, the Gulf of Mexico suffered the largest oil spill in history, and a region's waters, wildlife, and livelihoods were gravely harmed, because the safeguards that should have prevented it were allowed to fail together. The tens of billions BP paid and the reforms that followed were a real reckoning, rarer and larger than most industrial disasters produce. But the deepest lesson is the one the commission stated plainly: it did not have to happen, and the only reliable way to keep such things from happening is to maintain, in good times and under every pressure to cut them, the margins of safety whose erosion is the true cause of catastrophe.