Deep Water Horizon
Deep water Horizon: Dissecting a catastrophe
I know that many, if not all of you have been watching the development of the Gulf of Mexico oil spill There are few issues, such as transportation and retail consumables, that are not currently affected and, consequently, the real price not reflected yet.
But my true object today, is to talk about an issue that I have been intricately trained in, and with Fathers Day looming as the forecasted day Deep Water Horizon will surpass the Exxon Valdez environmental release, I can promise there are few options; and most; for the near future, are insurmountable.
April 20th is a fateful day; when eleven platform drill workers lost their lives. A tragic end to be sure and also the epistaxis of a hydrocarbon release of approximately 210,000 gallons ( 794,936 litres or 4,667 Barrels) a day, an estimate that should be considered as lowballed in my experience.
To understand the environmental release, we will look at the main piping systems in an oil production well, where we will find our release point.
Production well and associated support groups including well head, well casing, pump and aggregate filter with production supply lines to the well head are the areas of our attention.
It is a simple process, in application that is, when one is drilling for oil. First a well head is drilled and installed; this encompasses an initial bore hole of approximately 36 inches, from which a system of well casing extends to the bottom of the well and generally their circumference starts at 32” and will taper to near 7” at the bottom. This process takes 60 to 90 days to accomplish.
The casing is an important component in the production well. It is a flexible iron and steel combination that tapers at certain depths and is suspended into each taper with intricate hangers to shore the transition points. The flexibility of the casing is paramount in cases of directional drilling and its tinsel components change as needed.
We find that the casing protects the production well by providing a stable borehole to the target depth, and is at all points larger than the well production line. This is done to allow drill mud to fill the area between the casing and the well production line that usually is 1” high pressure steel or composite.
It is here that we will find the driving force of the Deepwater Horizon release. Drill mud is utilized internally in the casing system and at regular intervals its specific gravity and viscosity are changed to maintain a greater pressure than that of the surrounding strata. If this pressure is not controlled, the oil is free to move to find the path of least equilibrium, or simply said flow to the low pressure area until the pressure equalizes at both ends.
A key note here, if the casing fails or looses it continuity, the drill mud will be forced out of the borehole and the casing itself becomes an auxiliary delivery system to help stabilize the substrata pressure of the hydrocarbon.
In all aspects of discovery or maintenance drilling the well head is connected to a blowout preventer, which is a sideline diverter that uses hydraulic oil to increase well head pressure in the event of a pressure peak originating in the well production line. It attempts to stabilize the well system and if it is unsuccessful, diverts pressure to crimp and seal the well head.
This blowout preventer, or BOP as known in the industry, is a temporary construction and is removed at the end of service work when the well is stable and can be secured at other areas of the production line.
However in cases of deep water production, during service and active drilling, the BOP is the only safety device and it sits beneath drill casing, most times over a mile long reaching from the sea floor to the surface and the drive components of a floating drill rig. It is in essence a match head supporting a tinder straw.
There are no clear reasons for the explosion that tragically killed the eleven rig workers, but suffice to say the BOP failed to meet the crucial timeline to exert more force than it was being assailed with and could not bypass or engage primary safeties.
In the words of Rep. Henry Waxman (D-Calif.), “the BOP failed as a result of a leak in a crucial hydraulic system”. Waxman further added that the well had failed a negative pressure test just hours before the April 20th explosion.
In essence, Deepwater Horizon was in a state of instability and the entire well source was exerting more force than the invasive borehole. A sudden or acute pressure spike circulating bottoms up in the well structure can present the well head with rogue force capacity and compromise the well integrity completely.
This being the case, most likely the entire well pipe support heaved upwards from the borehole and snapped the production line at the BOP. A flash explosion would terminally destabilize the Deepwater Horizon drill rig, pulling the entire casing structure and days later, the Deepwater Horizon itself to settle on top of and near the protruding well structure; a source of random structural debris amidst an uncontrolled hydrocarbon release, seeking to equalize the pressure of the substrata source.
Properties of crude oil
There are other scenarios that could be hypothesized, and we could go on ad verbatim, but that is not my focus. My focus is, now that we have a rudimentary understanding of the release and conditions of the release, what are the properties of the released hydrocarbons, and how can they be stopped?
The first order of business is to determine the grade, or the sweetness of the hydrocarbon. Crude from the Alaskan North Slope production field of Milne Point possesses low fuel oil content and concurrently has large quantities of paraffin and sulfur that bind it together, it is poorer grade crude oil that is difficult to extract and its odor is of heavy tars and sulfur.
Slightly over a hundred miles from Milne Point is the Kuukparuk Field, where you will find the Alpine Satellite field at its westernmost frontier. Alpines crude is so sweet you can run a diesel generator with well tapings, or unrefined crude. It is very light and similar to coffee in color and viscosity, toluene and other methyl sulfates, solvents and natural gasses compose its odor.
Were it to be any combination of the two, I would have to say that the Deepwater Horizon’s chemical components are a mixture of high end hydrocarbons, natural gasses and crude oil with a high viscosity. These combinations of hydrocarbons are a nightmare in the Environmental Response fields and to have this scenario unfold from an Industrial Hygienists outlook earmarks an environmental time bomb has just been armed.
It should be considered as well that the hydrocarbon release site at the sea floor is heated by the deeper substrata pressure and may enter the aquatic environment at temperatures nearing 220 degrees Fahrenheit.
From the very inception of Spill Response tactics, it has been the preference to control environmental releases in water scenarios through the use of water Boom, or boom if you will. This particular tactic uses 33 foot sections of heavy wrought foam encased in a durable vinyl sleeve. Each unit of boom slip locks to other sections of boom and are stringed together in different ways. There is also absorbent boom, but it is in limited quantity and not a viable first response tool.
I was at a M.A.D. drill (mutual aid drill) in Prudhoe Bay years ago, and as there was considerable conference table time, we would throw around prior response scenarios and analyze the incident for other means of recovery. That day, during our round tables, a man named Harvey Whitehead arrived with representatives of the major oilfield producers within Prudhoe Bay.
These men were not regular oil executives; they were the driving force of the North Slope Health, Safety and Environmental (HSE) Departments, many of them were first responders in the Exxon Valdez release.
They were there to assess our team’s ability to be on scene command personnel in the event of a large scale environmental incident, and to teach us their experience and techniques of incident command. In short order they had us on topic, and in this retrospect we will examine the Deepwater Horizon.
It is not the best use of time or resources to attempt to contain large or active hydrocarbon releases in open seas with boom. The waters and winds are not reliable consorts and the boom requires stable calm waters to optimize its ability to quarantine and herd hydrocarbon releases.
At current there is a slick that measures 48 miles by 60 miles, or 3840 square miles (6179.880 kilometers), and NOAA reports that there are more than 517 response vessels and that 1.5 million feet of boom have been deployed with an additional 1.4 million feet of regular and absorbent boom in reserve.
So in essence there is only enough booming material to effectively quarantine about a square mile, and we see that water booms really are a minor control tool, and in a feasible essence, not an acute release containment contingency preference.
Tactics of recovery
As we see the limited ability of boom to be a source of initial containment in large scale release scenarios, it is wise to consider the use of this instrument and marry it to other recovery vehicles to best minimize the initial and continued environmental release.
Tactics currently in use have medium sized boats towing extended sections of boom in tandem to encompass calm and stable hydrocarbons in larger areas of the drifting slick. Amidst the trapped hydrocarbons, a recovery vessel is attached to weir recovery system and is automated in processes.
Weir skimmers bob in the water and collect hydrocarbons off the surface in a conical buoy and pump the collected oil and water slurry to an external recovery vessel.
Most of the associated boom will be utilized this way in the days and weeks to come as a frontline defense contingency and the best scenario would have them intercept, contain and recover hydrocarbons while they are still drifting in large formations.
To date these tactics have recovered by some reports issued by NOAA to be near four million gallons of hydrocarbon releases and contaminated water, but there are other response options out there and it past time we looked at them.
Immediate gains remedies
After several test burns in the past week, large scale burn operations remain elusive due to weather and unfavorable conditions, a scant few thousand gallons have been mitigated in this fashion.
Drawbacks of large scale burn remedies introduce a toxic cloud during extended scale burn operations and permeate the atmosphere with tremendous greenhouse gasses, further raining toxic ash leeward in the prevailing winds to invade whatever environment it encounters.
Also during the burn process, toxic remains of the burn begin to sink in the water and become suspended in the water table itself.
Since May 6th, to date 436,246 gallons of dispersant have been used and this is in essence, window dressing.
Dispersants are a surfactant or detergent and are usually mixed with organic solvents or alcohols to help them adhere to the hydrocarbon releases and reduce the surface tension of the oil components.
Surfactants encapsulate the oil and both form fine particles that are then dispersed throughout the entire water table where water movement agitates the mixture and allows it to sink to the sea floor.
As the ratio of dispersant to hydrocarbon is 1:20 and although a mixture 1:40 is possible, a response in this fashion would require just over 500,000 gallons of surfactants a day and NOAA reports a dispersant reserve on scene to be 120,000 gallons as of May 12th.
Continued Executive Control measures
On scene control operations still persist in the use of unmanned miniature submarines to place a production collar over the well production line and gain control of the line at the well head. However after multiple attempts a viable entry vector for the submersible could not be achieved.
Should this be accomplished, a major component in the Deepwater Horizon hydrocarbon release would be secured, but the failure of the support casing at the well head remains a means of continued environmental release and its instability could begin to introduce higher volumes of hydrocarbons into the deep sea well area over time, once again advancing the hydrocarbon release.
After a failed attempt to place a three story containment vessel over the Deepwater Horizon, a new smaller version labeled a Top Hat has, as of May 12th, been placed near the active release site on the sea floor. This new vessel has been submerged during issues that still mire the placement of the unit.
The initial barrier to overcome is when the containment vessel is placed over the pressurized hydrocarbon release lines at the well head. Escaping natural gasses, heated from the well source, entering into the confined area combined with deep water pressures and associated low temperatures and form ice crystals that eventually seize the recovery lines.
If the top hat can be placed, the well head and the borehole transition area at the sea floor will be contained and a temporary control system will divert the crude oil to awaiting barges and transport vessels to be transported to secondary containment facilities.
During the initial days of the Deepwater Horizon’s environmental release, Executive Controls mandated that a secondary relief (well) be drilled. This is a tricky process and it seeks to intercept the compromised well structure at a deeper part of the substrata than the well head.
Relief well operations initiate the same as exploration and prospect drilling and a new well head and casing system is installed. Directional drilling provides the means for intersection, and with today’s technologies this new well head can be more than 5 miles away, although distance equates time.
Currently it could be 30 to 45 days before the relief line intersects the damaged Deepwater Horizon well casing, and before it becomes invasive it will have armed its drill mud properties to hold back more pressure than the compromised well it is attempting to assimilate.
When the Deepwater Horizon’s well structure is intersected by the relief operations, one of two options will prevail. First off, if the relief well is successful with the intersection and can seal off the target lines above it, the relief well would begin to control its compromised counterpart and circulate drill mud into the casing structure and inject it all the way to the bottom of the well; creating stable well pressure and bypassing the former disabled well structure and can install a new production line.
If the relief well is unable to contain the compromised lines it would then seal all well structures at the point of intersection and terminate the well at the juncture.
After 23 days the Deepwater Horizon continues to deploy 210,000 gallons of hydrocarbons. Booming efforts show forward momentum, but reserves must be maintained for when the oil slick nears sensitive coastal areas.
Overall conditions for the Deepwater Horizon recovery have remained, time over duration of release, favorable and forecasters are optimistic about the near future. There is talk, however, amongst international Regulatory Agencies that the Gulf of Mexico current may soon reverse its seasonal current.
Should the current change, the main body of the oil slick could destabilize and the entire accumulated mass of the release would be free to seek landfall in a near 360 degree circumference. There is further speculation as to the role of Hurricane season, now in its near single digit week countdown, and the long term ability to sustain a unified release mass is in question.
Despite hydrocarbon landfalls north of the disaster site, in general the entire release dynamics of the oil slick have sidestepped their worse case scenarios and appear to remain lethargic to large scale, quick movement.
Although burn techniques are a viable option, it will only address the initial spill transition at the surface. High end hydrocarbons and natural gases evaporate readily in the open air and render the crude oil noncombustible mere hours after introduction to the open atmosphere.
Further sources of environmental contamination mire burn practices, and condition specific necessities hinder its application.
Dispersants are needed in quantities that are unobtainable, and their long term impacts, even after 20 years of study resulting from the Exxon Valdez environmental release, are not fully understood.
Executive Control measures continue to attempt to contain the Deepwater Horizons’ release at the source, but results remain elusive.
With months of directional drilling still anticipated before a relief well will intercept with the damaged undersea production lines, we must live with one concept.
It is not deemed a cleanup site until the rogue source is under control or terminated. Deepwater Horizon remains a containment effort and how we address it will determine the extent of the release.
Most of the containment response remains highly dependent on the environmental conditions of the disaster area in its entirety, and the Deepwater Horizon release has been graced with relatively mild environmental conditions; a fact that is about to see seasonal changes, and resulting conditions have the potential to carry out catastrophic results over widespread ecosystems.
By: Thomas Littlechief- in oilman’s language, explains the difficulties of containing the Mexico Gulf Coast spill.