It is still unclear what factors unquestionably caused the explosion on Deepwater Horizon, but this event brings to light many flaws in professionalism. A few factors will be touched on here that may have influenced the explosion. More importantly, these factors give a glimpse into the unethical rational of the professionals involved and let you, as the reader, decide whether you define this incident as a mere accident or a failure to act in a professional manner.

The objective of oil companies is to locate and extract hydrocarbons or fossil fuel miles within the earth. Particularly over water, large vessels known as deep sea semi-submersibles are sent to tap into this hydrocarbon filled rock miles below the seafloor known as payzones. The $560 million ^[1] semi-submersible drilling rig named Deepwater Horizon, contracted by BP and owned by Transocean, was sent in late January 2010 to drill the Macondo well in the Gulf of Mexico ^[2].

Deep sea semi-submersible

The Explosion

Drilling for oil is a delicate and dangerous process because of the high pressure in these payzones. This business of drilling utilizes mud, steel casings, and cement to create an equilibrium without releasing the high pressure within the earth. As a path is drilled, pipe is used to transport high density mud to counter balance the high pressures within the earth. If the weight of the mud is too low, oil and pressure can enter the pipe and cause a kick and potentially destroy all the drilling equipment used. If the weight of the mud is too high, the mud pressure may fracture the payzone and the oil will be irretrievable. Steel casings are used to line the well hole for stability. Devices called centralizers are used to keep the casings in place. The whole system is sealed with cement to prevent fluid and pressure leakage. Continuous readings of the pressures and volumes of fluid in the system are monitored. In an emergency, especially if the pressure is too high, the crew drilling can shut off the well and sever the connection to the rig via a blowout preventer before a disaster ensues. ^[2]

Deepwater Horizon offshore drilling unit on fire

Deepwater Horizon struck their intended payzone but unfortunately the pressure of the mud fractured the area around the hydrocarbon filled rock. The new plan was to pump the area with high viscous fluid in hopes to seal the fracture, then to install a final steel casing for future oil and gas extraction. The final casing was placed and stabilized with centralizers and cemented by Halliburton subcontractor. ^[2]

On April 20th, 2010 between 9:40 pm and 9:43pm evidence of a kick occurred when mud spewed from the rotary onto the rig deck ^[3]. At 9:49 the first explosion occurred on Deepwater Horizon. A Transocean representative, during government hearings, compared the explosion to “a 550-ton freight train hitting the rig floor,” followed by what he described as “a jet engine’s worth of gas coming out of the rotary” ^[4].

After this initial explosion, the crew immediately tried to seal the well however their control of the blow out preventer failed ^[2]. The following moments included more explosions and eventually led to 11 deaths, 17 injuries ^[5], and after months of leakage from the Macondo well, 4.9 million barrels of oil in the Gulf ^[6]. BP suffered an estimated $40 billion in losses from this disaster ^[7].

Negative Pressure Test Overlooked

A negative-pressure test is a measure of checking the strength of the cement seal. Hours before the explosion, a negative-pressure test was performed and there was evidence of fluid buildup and increased pressure in the well. However, the drilling crew continued on with their routine even though there was a clear sign of danger ^[8]. Were the individuals responsible in monitoring the pressures trained correctly in determining the readings displayed by a negative-pressure test? While it may still be unclear, it is certain that if the crew was aware of the warning signs from this test, the well could have been shut down in time and the disaster fully prevented.

Decision to Use Fewer Centralizers

One possible source of the explosion comes from the inadequate use of centralizers. Centralizers are key components in ensuring a good cement job; they help keep the steel casings centered when cementing a solid barrier ^[2]. BP contacted their supplier, Weatherford, for more centralizers in order to plug their well for future oil production. Their original design called for sixteen centralizers^[9], but on April 1, Weatherford had only six “sub” centralizers in stock^[10]. The alternative to using “sub” centralizers was to use “slip on” centralizers. These would slide onto the casing, rather than screw in like the “subs”. The BP team leader, John Guide, was not in favor of using these because they risk catching on other equipment while the casing is lowered^[11].

BP made no effort to request new modeling from Halliburton to predict the effect of using only six centralizers, nor did they inform them of their decision^[12]. One Halliburton engineer, Jesse Gagliano, happened to overhear a discussion on the rig concerning the use of only six centralizers^[13]. He ran computer simulations using proprietary modeling software, which led him to conclude that they would need more than six centralizers to prevent leakage of pressure and fluid^[2].

Gagliano went to BP with this information on April 15^[14]. With John Guide not present, drilling engineer, Gregory Walz, ordered fifteen additional “slip on” centralizers, which was the most they could immediately obtain from Weatherford^[2]. Gagliano reconfirmed that using fifteen additional centralizers along with the original six would provide greater protection from leakage. Walz emailed John Guide, telling him they should honor Gagliano’s model and use the “slip on's” despite Guide's concern with them. Also, he ensured that these centralizers were custom built for a previous BP rig; therefore, it was a safe option^[15].

When the “slip on” centralizers arrived, BP engineer Brian Morel identified them as being conventionally designed instead of custom built like they expected. Morel voiced his concern about this in an email to BP Operations Drilling Engineer Brett Cocales, where he questioned the need for the additional centralizers^[16]. Cocales disagreed with his opinion, but ended by saying: “But, who cares, it’s done, end of story, [we] will probably be fine and we’ll get a good cement job. I would rather have to squeeze [remediate the cement job] than get stuck above the WH [wellhead]^[17]. John Guide also identified the centralizers as being the wrong type. The last minute addition of these centralizers concerned him and he ultimately decided to use only six^[18].

The BP investigation reported that the 15 additional “slip on's” were in fact the custom built type they had ordered, and the team had mistaken them for the wrong kind. To this day, there are conflicting accounts from BP whether they were or were not the correct type^[19].

If BP had sought help from Halliburton, rather than waiting for them to catch one of their mistakes, they could have determined whether additional centralizers would be needed. They could have then based their decision on a full examination of potential risks, so they could order the correct number and type of centralizers needed. Instead, they were stuck making a misguided last minute decision. It is uncertain whether the failure to use six instead of an additional fifteen centralizers was a direct cause of the blowout, but the process BP took to arrive at the decision to use only six shows some of the critical flaws in their management, as well as poor communication practices between BP and Halliburton.

Mismanagement

Choices made by management leading up to the explosion played a role in the safety and integrity of Deepwater Horizon. In management, some decisions have to be made for safety reasons which may compromise other technical functions. Some compromising decisions had unclear motivations, and some decisions were made with insufficient resources.

Minerals Management Service

The Mineral Management Service (MMS) is a federal agency who is responsible for leasing, safety and environmental compliance with offshore drilling. They approve drilling permits and inspect drilling rigs. There is evidence that they were more relaxed in regulations in cases including the Deepwater Horizon. One example of mismanagement occurred when there were more applications coming in for drilling than there were engineers qualified to approve them. So the MMS hired engineers who would be willing to approve the overload of applications coming in. However, MMS did not have specific qualification requirements for the engineers. ^[20]

Many regulations promote safety in design and maintenance of offshore drilling rigs. The Oil Pollution Act of 1990 and Oil Spill Response Plans are a couple examples of regulation which require vessels to have plans set up in worst-case-scenario situations. ^[21] When looking back through reports, BP did not use the required detail to show real preparation in a worst-case-scenario situation, and MMS did not challenge it, inspect the rig appropriately, or have the capacity for running high risk analysis on the report. ^[22]

There were instances in the months leading up to the explosion that management decisions were made which may have compromised the integrity of the full operation as well as in compromising the effectiveness of the project in order to provide more safety. In drilling, BP had a goal of reaching 20,200 feet ^[23], but stopped at 18,360 due to issues of well integrity and safety. The Transocean crew made a judgment call when determining whether the mud circulation pressure they found was valid. The drilling mud subcontractor determined that 570 pounds per square inch (psi) would be required and the crew reading only obtained 340 psi. In testing a different circulating pump they determined the gauge was broken. It is unclear as to exactly why they decided this value was due to a broken gauge. ^[24]

BP made compromises on different issues, taking risks in some areas to provide safety in others. Another example is when they decided to reduce the amount of cement they pumped into the well to reduce the pressure on the well. The amount they pumped provided for a column 500 feet above the payzone, even though their own requirements called for the column to reach 1000 feet above. The purpose of the cement is to reduce contamination risk such as leakage and helps protect against placement errors. ^{[25] [26]}

Conclusion

Drilling for oil is a complex system. Many parties are involved and must interact efficiently in order to accomplish their goals in a safe and efficient manner. Management failed in their abilities to prevent such a disaster as shown by all this evidence. The negative-pressure test was clearly overlooked. If guidelines and protocol were enacted for pressure testing this disaster would not have occurred. The decision to use too few centralizers conveys the quick decision of leadership without taking the time to look into every scenario. This could have very well contributed to the high pressure build-up and cement failure. Finally, the broader management of oil companies via government organizations became lax in enforcing safety regulations. This may have caused a trickledown effect which ultimately led the Deepwater Horizon explosion. Can future disasters in complex systems be prevented after examining this event? Yes they can as long as professionals in management do not let factors sway them away from making ethically rational decisions.

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