More Safety in future Rig design and operation? More cost ?

The aftermath of the Deep Horizon rig explosion in the Gulf of Mexico has left a lot of lesson to be learnt for those in the offshore industry as well as those classification socities reviewing and approving the design and construction of rigs in various region in the world. For the majority of those who are non-offshore industry people, an oil well gushing uncontrollably into the sea for over two months seems bewildering and there still is no sign that BP, having mobilised many rigs and support vessels, is able to plug the powerful gush and luckily the recent Tropical Storm Alex veered away from the Gulf of Mexico oil spill Saturday but experts warned that strong waves and winds could still upset efforts to halt the environmental disaster.

For Americans, the accident has been catastrophic and costly, and for the offshore oil industry, the reputation has taken a severe hit. US President Barack Obama and his administration are also feeling a political backlash. The widespread pollution as a result of the gushing oil is wreaking havoc on the ecosystems of the Gulf and the livelihoods of affected Americans. Entire industries across the Gulf coast, from fishing to tourism, have been devastated. This makes the issue a political hot potato on top of everything else.

The political and regulatory fallout from this disaster will be analysed and discussed for many years, as happened following the Exxon Valdez oil spill some 20 years ago. New regulations to govern the industry are already in the works, and hopefully the commissions of inquiry and Congressional hearings will produce conclusions that will be helpful and instructive for the industry. But the question remains: how is it that the world's most powerful nation - with the most sophisticated scientific and technological resources at its command - looks so helpless in the face of an oil leak? It must be asked: is leaving the job of plugging the leak to just one company a satisfactory approach? It's high time the Obama administration considered the possibility that this is something BP cannot solve on its own. There is also the danger that as the bills mount, and its run of unsuccessful attempts continue, BP may just give up the ghost.

The option of pooling global resources and tapping the collective expertise of the entire oil industry should be seriously examined.

Meanwhile, for us in Singapore, the Deep Horizon rig disaster contains a cautionary lesson. We must remember that Singapore is not just an international maritime hub, but also the world's biggest oil rig builder. Keppel Offshore & Marine and SembCorp Marine together account for around two-thirds of the rigs built in the world currently. Our port and waterways are among the busiest in the world with most of the oil tanker fleet plying this route. Woe be the day when a manufacturing fault of a Singapore-made rig becomes the cause of a disaster elsewhere. Or when a major accident of a similar nature occurs close to our own shores as seen recently, the spill occurred when the Malaysian-registered tanker MT Bunga Kelana 3 collided with the St. Vincent's and The Grenadines-registered bulk carrier MV Waily in May2010 at the Singapore Strait about 13km to the southeast of the city-state's east coast.

Such minor spill have already created much inconvenience to shore lovers, sea-going businesses,etc.

The oil industry will continue to boom for several years yet. But as the Deep Horizon disaster has made clear, it is an industry exposed to unpredictable and enormous risks. The need for safety first cannot be overemphasised. And if that calls for tighter regulation here as well, so be it and we as rig builders in Keppel O&M will have to take a further step to look at our rig designs and what kind of possible prevention or pre-empt to the future possibility of repeat incident and upholding and sustaining the reputation of "world class" rig builder in the offshore business sector.


Mid July 2010, BP has halted the Gulf of Mexico oil leak for the first time after struggling to cap the well for three months, raising hopes yesterday that the worst oil disaster in United States history may finally be ending.


In London, BP shares were up after the latest development in a disaster that has cost the company US$3.5 billion (S$4.8 billion). Compensation for damage caused by the oil spill could reach 10 times that amount.

Mr Obama, who has encouraged, cajoled and outright ordered BP to stop the leak, welcomed the news as 'a positive sign' but reminded everyone that 'we're still in the testing phase'.

BP is hoping to choke off the oil flow from the well, estimated at between 35,000 and 60,000 barrels a day. But doing so from the top could force oil out in new leaks if the wellbore has been damaged.
During the tests, engineers will take multiple readings from the 9m capping stack placed on top of the wellhead on Monday to monitor the pressure inside. High pressure readings would allow the three valves to remain shut and the well would effectively be sealed, but low readings could mean there is a hole or holes somewhere else in the casing of the well where oil is escaping. After 48 hours, the engineers will open up the system again and begin capturing the oil through two surface vessels to allow a new seismic survey to be done, said the official in charge of the US response, Coast Guard Admiral Thad Allen.

A final solution is not expected before the middle of next month, when crews will complete the first of two relief wells, allowing the oil reservoir to be permanently plugged in a 'kill' operation.

The disaster began on April 20 when the BP-leased Deepwater Horizon oil rig exploded 80km off the coast of Louisiana, killing 11 workers. Two days later, the still-blazing rig sank to the bottom of the Gulf.


Oilwell Plugged

Horizon on Fire

The Deepwater Horizon drilling rig which caught fire few days back, lasted two days, then sank in 5,000 ft of water in the Gulf of Mexico. The rig belongs to Transocean. The rig was originally contracted through the year 2013 to BP and was working on BP’s Macondo exploration well when the fire broke out. The day rate for the rig costs about US$500K per day to contract. The complete drilling day cost, with helicopters and support vessels and other services, will cost closer to US$1 mil per day to operate drilling for oil and gas. The rig building cost about US$350 mil in 2001 and would probably double that if order one today with steel prices, material cost rising. The rig represents the cutting edge of drilling technology. It is a floating rig, capable of working in up to 3000m water depth. The rig is not moored as it would be too costly and too heavy to suspend this mooring load from the floating structure. There should be a cost study done to compare options of moored or DP and long term operational cost viability. This rig has a triple-redundant computer system uses satellite positioning to control powerful thrusters that keep the rig on station at all times. From web information, seems like the rig had apparently just finished cementing steel casing in place at depths exceeding 18,000 ft. The next operation was to suspend the well so that the rig could move to its next drilling location, the idea being that a rig would return to this well later in order to complete the work necessary to bring the well into production. Initial speculation news that was thought that somehow formation fluids –oil /gas –got into the wellbore and were undetected until it was too late to take action. Usually a “kick” would have been detected from the cabin monitoring controls. With a floating drilling semi-submersible, because it moves with the waves, currents and wind, the main pressure control equipment sits on the sub-seabed –the bottom point in the well is only part unmoved. There is a setup of ‘BOP’s” and controlled with redundant systems from the rig being laid just above the seabed. In the event of a serious emergency, this BOP tree will be shut and close against the well preventing back flow of the gas from seabed. Investigation will take some months before all of the reasons are known. The well still is apparently flowing oil, which is appearing at the surface as a slick. They have been working with remotely operated vehicles, or ROV’swhich are essentially tethered miniature submarines with manipulator arms and other equipment that can perform work underwater while the operator sits on a vessel. They have been trying to close the well in using a specialized port on the BOP and a pumping arrangement on their ROV’s. Seems to be unsuccessful so far. Specialized pollution control vessels have been scrambled to start working the spill, skimming the oil up. In the coming weeks there is another plan to move in one other rig ( could be from DD3 built by us ) to drill a fresh well that will intersect the blowing one at its pay zone. They will use technology that is capable of drilling from a floating rig, over 3 miles deep to an exact specific point in the earth –with a target radius of just a few feet plus or minus. Once they intersect their target, a heavy fluid will be pumped that exceeds the formation’s pressure, thus causing the flow to cease and rendering the well safe. Probably will take months to get this done, bringing all available offshore drilling technology to fruition. It will soon be an ecological and environment hazard if the well flows continuously and not stopped.

Subsea systems challenges :

Other challenges facing the rig operator of this kind of deep water drilling vessel relating to deepwater depth in several ways:

•The temperature at the seafloor is such that hydrate formation in any gas migrating to the BOP can freeze the system closed. Provision must be made to flush the connectors routinely with BOP operating fluid (which contains glycol) or as a last resort to inject methanol remotely from the ROV.

•The well pressure at approx 7,500 feet is 230 bar or 3,333 psi. All of the subsea BOP equipment must work in cold, dark, high pressure environment around one and a half miles from the vessel drill floor.

•The long column of drilling fluid in the riser exerts a pressure on the formation. In shallow water this pressure is usually far enough from the fracture pressure of the formation that cuttings can be transported out of the hole without exceeding the fracture pressure and invading the formation. This allows longer sections of hole to be drilled before second casing. As water depth increases the difficulty of keeping mud weights between fracture gradient and pore pressure causes an effective well design to include multiple casing strings driving up both the complexity and the cost of the well

•The marine riser itself must be strong enough to support choke and kill lines, boost lines, hydraulic lines, dual gradient lines and MUX cables and yet light enough to allow a combination of top tension and buoyancy to support it for a defined range of mud weights and vessel offsets.

•The time to run any piece of equipment to the seafloor is a significant part of the total operational time. It can take days to round trip the BOP in 7,500 feet of water and the rig is vulnerable to environmental extremes while the BOP is suspended below the rig

Below typical schematic of the subsea BOP control system which should be able to shut the well once activated. With so many cables and tubings going down the seabed, probably anything can go wrong during the Horizon emergency and Murphy's law set in, anything wrong goes.

Well Control

As a result, the design of the riser, its buoyancy, the BOP and sub-sea system is the most critical element of the overall design of the rig. The size and weight of a 21” riser and 18 ¾” 15K BOP system that dictates the overall size and therefore cost of the rig. Most deepwater operators are well aware of this and extensive research has been undertaken by them to find ways to allow smaller and less capable rigs to drill safely and effectively in the ultra deep water. These technologies include :-

•Dual density drilling – to solve the pressure differential problem referred to above.

•Slimbore wells to allow the use of 16” riser and a 13 5/8” BOP

•Expandable tubing to facilitate slim bore wells

•Free standing riser systems

•Artificially buoyant seabeds bringing the wellhead closer to the surface

All of these technologies hold future promise but they also represent compromises in the primary objective which is to deliver a quality high production well to the operator.

Horizon


With the Horizon rig going “under”, oil began gushing to the surface at an ever-increasing rate. In the worst case scenario, the daily outflow of oil is projected to reach as many as 60,000 barrels (2.5 million gallons) per day.

Some methods have been used for cleaning up the Gulf of Mexico, Louisiana coastline mess, both through working beneath the waves at 5,000 feet and atop, as the oil surfaced :-

Blowout preventer (Drilling term : BOP ) — In offshore oil industry, it’s an accepted fact that oil drilling rigs and platforms must be protect and prevent well kicks from the well beneath. Despite all safety precautions, there’s always the possibility of an accident that could potentially destroy the entire rig, just as happened with the Deepwater Horizon. But when that does happen, a separate device is supposed to prevent an oil leak at the bottom: the blowout preventer ( Maker like Cameron, Schaffer, Hydril are some of famous ones). For deepwater, subsea BOP is used and for shallow water like drilling jackup, surface BOP is used.

It was a bad luck that the BOP failed to activate. Other semi-submersible have been deployed to try to fix the device with help of ROVs ( remote operated vehicle ) or install a new BOP to stop the flow of oil at its lowest point, but have failed so far. It is not simple task to do it at deepsea where controls underwater are not easy with the temperature and current beneath.

Containment domes – These devices, also called coffer dams, are the second of the three major methods BP hopes will eventually stop or contain the leak by transferring the oil into FPSO. Starting with one this week, BP will lower three 40-foot tall containment “domes” over the leaking sections of pipe on the seabed. Some oil will still escape, but the plan is to suck most of it up through the dome (which is actually more of a rectangle). This idea also reveals the essential crudity of our deep-ocean technology: there’s nothing subtle about dropping just under a hundred tons of concrete onto a leaking pipe.

However, the effort to place a massive containment dome over a gushing underwater wellhead in the Gulf of Mexico was dealt a setback when a large volume of hydrates -- icelike crystals formed when gas combines with water -- accumulated inside the vessel, The dome was moved off to the side of the wellhead and is resting on the seabed while crews work to overcome the challenge

Relief wells — Even if the above two methods are successful, BP will still work on a relief well over the coming months that, when finally completed, will divert oil away from the spill site. Drilling the relief wells is a more involved process than the original well, because the drill bit must work at an angle once it penetrates the seabed. The company estimate its relief well will likely cost in the region of US$100 million.

Oil skimmers — Since some oil sits on top of the water, a clever skimming system can separate the oil to be siphoned away (and potentially even sold on the market like normal oil). Skimming devices can range from small to massive, but despite advances in the technology, none are large enough to deal with a Gulf-sized spill, at least without months of work.

Fire — One of the oldest technologies at least for gasoline, will burn off quickly and even explode. But the “sweet crude” welling up is actually a thick, heavy substance that doesn’t always burn easily or evenly. The Coast Guard attempted to burn enough oil to prevent it from reaching the Louisiana coastline, but failed.

Name: Deepwater Horizon

Reading & Bates Falcon RBS-8D
Owner: Transocean
Port of registry: Majuro
Marshall Islands
Route: Gulf of Mexico

Ordered: December 1998
Builder: Hyundai Heavy Industries

Cost: US$560 million [1][2]
Completed: 2001

Acquired: February 23, 2001

Maiden voyage: Ulsan, South Korea – Freeport, Texas
Out of service: April 21, 2010 (exploded)
Identification: ABS class no.: 0139290

Call sign: V7HC9
IMO number 8764597
General characteristics
Class and type: ABS +A1 DPS-3 Column Stabilized MODU
Tonnage: 32,588 t (32,073 LT; 35,922 ST)
Displacement: 52,587 t (51,756 LT; 57,967 ST)

Length: 112 m (367 ft)
Beam: 78 m (256 ft)
Height: 97.4 m (320 ft)
Draught: 23 m (75 ft)
Depth: 41.5 m (136 ft)

Installed power: 42 MW
Main Power 6 x Wartsila 18V32 rated 9775 hp each, driving 6 x ABB AMG 0900xU10 7000 kW 11,000 volts AC generators

Emergency Power 1 x Caterpillar 3408 DITA driving 1 x Caterpillar SR4 370 kW 480 volts AC generator
Power Distribution 8 x ABB Sami-Megastar Thruster Drives, 5.5 MW and 6 x GE Drilling Drive Lineups 600 V 12 MW
Deck Cranes 2 x Liebherr, 150 ft boom, 80 mt @ 35 ft
Thrusters 8 x Kamewa rated 7375 hp each, fixed propeller, full 360 deg azimuth
Speed: 4 kts
Crew: 146
Notes: 8202 tonne Variable Deck Load, DP Class 3, 8 thrusters, 10,000 ft drilling water depth

Video with courtesy of BP