The recent oil well disaster in the Gulf of Mexico has raised some serious questions in the minds of many as to whether offshore oil drilling is a viable means of securing new oil supplies. Immediately prior to this spill, even the President was advocating more offshore drilling in Federally-controlled areas. Since we already have producing offshore wells in the Santa Barbara Channel, and since we have already had a serious oil spill here, the question arises: Could what happened in the Gulf happen here? In this week’s column, I will discuss the spill, and compare the BP rig and well with our local wells to show how a Gulf of Mexico-type spill simply could not occur here. I realize for those who oppose expanding offshore drilling in the SB Channel, there will never be an effective argument for more drilling, but hopefully I can at least allay any fears locals may have about a similar accident happening here.
The Deepwater Horizon oil spill (also referred to as the BP oil spill, the Gulf of Mexico oil spill, the BP oil disaster or the Macondo blowout) is a massive, ongoing oil spill in the Gulf of Mexico, now considered the largest offshore spill in U.S. history. Some estimates placed it among the largest oil spills in the world with tens of millions of gallons spilled to date. I have seen estimates stated that between 60,000 and 200,000 barrels per day are being discharged from the well. The spill stems from a sea floor oil gusher that resulted from the April 20, 2010 Deepwater Horizon drilling rig explosion, which killed 11 platform workers and injured 17 others.
The spill is originating from a deepwater wellhead 5,000 feet (1,500 m) below the ocean surface. The exact spill flow rate is uncertain due to the difficulty of installing measurement devices at that depth and is a matter of ongoing debate. The resulting oil slick covers a surface area of at least 2,500 square miles (6,500 km2), with the exact size and location of the slick fluctuating from day to day depending on weather conditions, currents, etc. Scientists have also reported immense underwater plumes of oil not visible at the surface.
There have been a variety of ongoing efforts to stem the flow of oil at the wellhead, including a “Top Kill” where drilling “mud’ was pumped into the well to try to plug the flow (it failed), and a concrete dome was built (twice) and placed over the well to try to collect at least some of the oil (it seems to be working a little). There is also a relief well being drilled, which is expected to be completed in August (head of schedule they claim as of this week), which could be used to reduce pressure at the leak, or to plug the well with concrete or some other substance (we will have to wait and see if this will work, assuming they haven’t stopped the leak before the relief well is completed).
Crews have been working to protect hundreds of miles of beaches, wetlands and estuaries along the northern Gulf coast, using skimmer ships, floating containment booms, anchored barriers, and sand-filled barricades along shorelines. The U.S. Government has named BP as the responsible party in the incident, and officials have said the company will be held accountable for all cleanup costs resulting from the oil spill. Just this week, Tony Hayward, BP’s CEO testified before Congress, and also pledged $20 billion for clean-up and compensation for those impacted by the spill.
The best way to analyze what happened (as is still happening) in the Gulf, and to compare it to our local wells, is to review the structure of the BP drilling rig and characteristics of the well, and then compare that information with our local wells. First, let’s compare the BP drilling rig with our current platforms operating in the Santa Barbara Channel today. The Deepwater Horizon, as the BP rig was known, was a very large and extremely complex floating rig (some experts have compared it to the Space Shuttle.) It was a floating, dynamically-positioned rig (no anchors), which means that it used a sophisticated computer control system and Satellite GPS navigation, making constant adjustments, to maintain its position over the well head.
More specifically, the Deepwater Horizon was a 9-year-old semi-submersible Mobile Offshore Drilling Unit (MODU), a massive floating, dynamically positioned drilling rig built by Hyundai Heavy Industries that could operate in waters up to 8,000 feet (2,400 m) deep and drill down to 30,000 feet (9,100 m). It was owned by Transocean, operated under the Marshalese flag of convenience, and was under lease to BP until September 2013. At the time of the explosion, the Deepwater Horizon was drilling an exploratory well at a water depth of approximately 5,000 feet (1,500 m) in the Macondo Prospect located in the Mississippi Canyon Block 252, in the United States exclusive economic zone about 41 miles (66 km) off the Louisiana coast in the Gulf of Mexico. This exploratory well was at roughly an 18,000 foot depth when the explosion occurred.
Production casing was being run and cemented by Halliburton Energy Services. Once the cementing was complete, it was due to be tested for integrity and a cement plug set to temporarily abandon the well for later completion as a subsea producer. BP is the operator and principal developer of the Macondo Prospect with a 65% of interest, while 25% is owned by Anadarko Petroleum Corporation, and 10% by MOEX Offshore 2007, a unit of Mitsui. BP purchased the mineral rights to drill for oil in Macondo at the Minerals Management Service's lease sale in March 2008.
During March and April, 2010, multiple platform workers and supervisors expressed concerns with well control. At approximately 9:45 p.m. CDT on April 20, 2010, methane gas from the well under high pressure shot up and out of the drill column marine riser, expanded onto the platform, and then ignited and exploded. Fire then engulfed the platform. Most of the workers were evacuated by lifeboats or were airlifted out by helicopter, but eleven workers were never found despite a three-day Coast Guard search operation, and are presumed to have died in the explosion. Efforts by multiple ships to douse the flames were unsuccessful. After burning furiously for approximately 36 hours, the Deepwater Horizon sank on the morning of April 22, 2010.
On the afternoon of April 22, 2010, a large oil slick began to spread at the former rig site. Due to the extreme depth of the water (and this is a key point of difference between this well and our local wells), the only way to even see what is happening at the well head, much less do anything about the spill is with ROV’s (Remotely Operated Vehicles). Two ROV’s attempted to cap the well initially, but were unsuccessful.
The well head had an automatic shut-off that as a failsafe is supposed to stop the flow of oil, should anything happen to the rig, including the pipe being pulled off of the well head. Unfortunately, when the explosion occurred, all of the sophisticated navigation equipment and GPS positioning computers blew up, so there was no way to maintain the rig’s position over the well. Unlike our local platforms that are permanently anchored to the ocean floor, the Deepwater Horizon’s only connection to the sea floor was the pipe that had oil flowing through it. Also, that failsafe shutoff apparently also needed to be activated from the rig, and since the rig was engulfed in flames, and the equipment was destroyed in the explosion, there was no way to activate the shutoff.
As stated above, the depth to the BP well head (ocean floor) is about 5,000 feet, which our wells are only about 700 feet to the well head. The BP well is over 18,000 feet deep (to where the oil reservoir is), as compared to our wells, which are only about 5,500 feet deep to the oil. In addition to the depth of the well and the resulting limited access (only with ROV’s), the other key difference is the enormous pressure. The BP well is under 12,000 psi (pounds per square-inch), while our local wells are at about 1,500 psi (about 12.5% of the pressure of the BP well). This extreme pressure is forcing the oil out of the break in the pipe at a high velocity, which is why the Top Kill operation failed.
There are at least 10 graduated pipe diameters and casing strings and cement jobs needed to get to the 18,000 foot depth. The overall complexity, depth, pressure, limited access, floating rig design, and the failure of the failsafe cutoff, all contributed to the BP spill. In stark contrast, our wells are under low pressure, and not deep, so we can access them (and do regularly for inspections) in the event of a spill. Most importantly, our platforms are permanently attached to the bottom, so there is no chance that they could get torn from the well head, causing a leak in this manner.
While there can be many causes of an oil spill, and the consequences are severe, at least we can have confidence that the type of mistakes that were made and the characteristics of the rig and well that contributed to the BP spill cannot happen here.