OGPSS - reaching the oil offshore Alaska

I have tried in the last two OGPSS posts to show some of the problems that are developing in the flow of oil from Alaska to the rest of the United States. Based on a falling volume of oil produced from the existing fields in the North Slope, the delivery pipeline from Deadhorse to Valdez is approaching levels of flow which will make it more difficult to deliver that oil. There are fields in the region that are still being developed. Alaska_geo has pointed to several developments that are likely to take place over the next year, mainly in exploration but including the development of the Umiat field. One of the mechanisms that the Alaskan Governor has proposed to help encourage industry was to provide a road up to Umiat. The oil reserve for the Umiat field is estimated at 250 mb, but the road may take another five years to finish.

As with the subjects of the last couple of posts not everyone knows where the different places are in Alaska, so, since one of the intents with this post is to look at off-shore deposits, let me put up a new map.

Locations along the North Shore of Alaska (USGS).

You will notice that the map shows Deadhorse rather than Prudhoe Bay, this is because that is the official name of the population center. There are a number of possible reasons for the name, I am partial to the one told by Deborah Bernard.

Once upon a time, a very famous, very rich man in New York set up a $6 million trust fund for his son. The only catch was this son couldn’t collect the money until he was 35 years old. The young heir went to Alaska . . . . met some people who owned some gravel hauling equipment (and) talked the father into co-signing a loan for this company. . . . . Things went from bad to worse and he found himself in possession of several dump trucks, pieces of equipment and a hauling company. He put the heir in charge of it and named it “Deadhorse Haulers.” (The) father, disgruntled that he was financially responsible for the ill- fortuned gravel company, said, “I hate to put money into feeding a dead horse.” Hence the name.

Which may also be why folk prefer saying that they work at Prudhoe Bay!

The major new exploration, however, will take place offshore, with Shell seeking to send two drilling rigs to the region to drill two wells in the Beaufort Sea and three in the Chukchi Sea, as I mentioned last time. (And I should perhaps have mentioned that of the $4 billion investment Shell is making some $2.1 billion went to the Federal Government in the lease sale). The total oil resource available in these seas has been estimated to be as much as 25 billion harrels of oil (bb) and 127 Tcf of natural gas . Alaska will be selling leases to an area of some 14.7 million acres this fall, though the sale has just been postponed until December.

It said the acreage involved, covering roughly the size of Massachusetts, Vermont and Connecticut combined, would include 2 million acres in the Beaufort Sea as well as leases adjacent to the federally controlled Arctic National Wildlife Refuge and the National Petroleum Reserve-Alaska.

The problems that will be encountered should the fields be this rich are not just limited to those involved in proving the presence of the hydrocarbons through drilling. Production and transportation of the fuel is a non-trivial exercise. Offshore wells will be located in the Arctic where the ice moves subject to wind and current.

Arctic Ocean circulation (NSIDC)

sea ice in the Beaufort Sea has more time to grow and reach the thermodynamic equilibrium thickness, so it is thicker. Also, because of the circular rotation of ice in the Beaufort Sea, ice floes frequently bump into each other. Ice deformation is common and leads to thicker and more ridged ice compared to other regions.

Unfortunately also the flow patterns are not consistent, and may on occasion reverse, thus making the design of systems to survive in those conditions more challenging.

In fact this the region around the North Pole, from the Beaufort Sea over to the Russian side and fields such as the Shtokman are where the some of the latest technical challenges lie. One problem is that there are not enough US Icebreakers, and one, the Polar Sea will be decommissioned at the end of the month, while its sister ship the Polar Star has been laid up since 2006. There will then be only one remaining, the Healy.

So how does one drill and produce in such an environment? Initially the exploration wells are drilled using drill ships, though these can only operate during the time that the sea is ice free, which varies from year to year.

Open Water availability Harrison Bay, Alaska (C-Core )

This limits the time of operation, and can be a much more restrictive problem closer inshore, and at times when larger and more permanent operations are planned. There is, after all, only so many places you can pull errant icebergs out of the way as the season develops. (The market for hauling icebergs to Arabia never developed). And the problems come in all sizes.

Support vessels servicing the rigs are also in danger, not from the big bergs, readily visible as they tower from the ocean, but from the small growlers and round-tops, often undetectable on radar and virtually impossible to see in the North Atlantic waves. In some areas, sheer numbers aggravate the problem. The drill ship West Navion had to deal with over 200 bergs and deflect more than seventy while drilling in the Davis Straight.

Towing Iceberg ( Hibernia Management and Development )

As a result ice islands are built that can give more protection to the site, and these can, if needed, be reinforced with concrete.(Though it is cheaper just to spray on more water).

The Mars Ice Island off Alaska (BOEMRE )

A number of wells can then be drilled from each island, using horizontal drilling techniques to reach out into the reservoir surrounding the island. The islands themselves can be built using a spray technology to build up the ice, since this seems to give a cost advantage over using gravel or flooded bays to form the structure. The islands can either be build over land or from a floating platform.

Builiding an ice island (US Patent 4,699,545, 1987)

The Mars Island took 898 hours to construct over 46 days, using over a million cu m of water. This island is 26 ft thick and 700 ft in diameter.

Technologies such as these will allow development of the reservoirs, though it should be remembered that the fuel has then to be brought into some sort of transport system that can move it to processing and future customers. That issue is of even greater concern with the reserves of natural gas found in the Arctic regions, and so I will move on to talk about it next. But for now I will leave you with the thought that even though there may be considerable oil reserves in Alaska that remain untapped at this time, their ability to significantly change the current and near term global supply in a positive way is realistically almost non-existent.

Drilling Rigs and Drilling Ships

The debate about how much oil is left and recoverable in the world has brought increasing attention to the recovery of oil and natural gas from offshore. And while I suspect that most of those who comment on this site are very familiar with all the terms, some of the more general readership may not be. Let me, therefore, explain just a bit about some of the different words that are being used here - with references and videos, where I can find them - to pictures of the different types of structures that are being used. And if I miss some, please chip in either to ask or answer.

Just as on land, we need some form of drilling rig if we are going to drive a bit down through the rock and find us some oil. But, unless we are working somewhere like the North Slope where we can wait until the sea freezes over and drive ice roads out to build islands to drill from, we are going to have to find a different way of providing the infrastructure support for that bit. And here is the first distinction - because a drilling rig, in the offshore sense, is more of an exploratory tool, going out to find oil, rather that developing the known fields and bringing in production. That latter task is left more to production platforms, which can be sited where best to drain the field, and may not even use the initial holes drilled by the exploration rig.

As you may have read the Minerals Management Service keeps track of production offshore (as well as on Indian lands) and lest you think that it is not that significant a bunch of folks, they have just handed out $10.68 billion in 2009.

Of the $10.68 billion, $1.99 billion was disbursed directly to states and eligible political subdivisions such as counties and parishes. Another $5.74 billion was disbursed to the U.S. Treasury; $449 million was disbursed to 34 American Indian Tribes and 30,000 individual American Indian mineral owners; $1.45 billion was contributed to the Reclamation Fund for water projects; and $899 million went to the Land & Water Conservation Fund, along with $150 million to the Historic Preservation Fund.

As with many departments of the Administration the MMS is focusing on

the importance of renewable energy and job creation, climate impact and adaptation, and efforts to support and maintain the treasured landscapes of America in the emerging clean energy economy.

Since it also controls (for the Secretary of the Interior) lease sales – with a large upcoming one in the Gulf it is a good site to check on periodically. Now to get back to what we’re going to do to get the oil/gas out if we are fortunate enough to get one of those leases.

In really shallow water, or the bayous, you might launch your bit from a drilling barge, where the derrick can be assembled once the barge has been towed to the right place. Barges can be flooded to rest on the seabed in relatively shallow operations.

Drilling barge

However they are very susceptible to bad weather, and last April one had to be raised after being sunk during Hurricane Gustav.

Raising a sunken drilling barge

So, as one moves further offshore, then one might use a self-erecting tender from a barge, but would more likely move to something which could get the drilling floor stabilized and up above the waves. These are the jack-up rigs.

Model of a jack-up rock (Stavanger Oil Museum)

Typically they have three legs, that are raised as the rig moves around. Then when it has reached the desired site, the legs are lowered to rest on the sea floor and the entire structure jacks itself up out of the sea, and, hopefully, above the waves. (You can get a paper model to cut out and assemble for this rig). There is also an animated video showing the installation of a rig at a site.

They can do this to work in depths to around 500 ft. The discussion about damaged rigs gave links to the different rigs that have been damaged, and some of these have photos of the rigs in better days.

As one goes out to deeper depths, then one will look for a more substantial vessel and so one comes to the Semi-submersible.

Semi-submersible drilling rig (Stavenger Oil Museum)

These are built to either sail themselves, or to be towed out to the site, with the assembly floating, and then fluid is pumped into the bottom tanks to partially submerge the vessel and thus stabilize it. One can get some idea of the size of these from some of the photos shown where, (thanks to Ed Ames), wikipedia covers the subject.

Semi-submersible rig off Brazil (Wikipedia)

Since these are floating there has to be a way of holding them in place. One way is to have them dynamically positioned, using thrusters to hold them in position, such as these.

Thrusters that go under the pontoons to stabilize a semi-submersible (Wartsila)

Note that it takes about 3 years to build such a unit. The alternative is to have the rig attached to anchors on the sea bed using cables, or tethers. (And for those interested in natural gas production, note that the same rigs are used for both).

Cables with controlled winches to stabilize a semi-submersible rig (Stavanger Oil Museum)

The connection between the well and the platform now becomes more flexible and special connecting pipes called risers are designed to reach from the blow-out preventer (BOP) at the top of the well, but on the seabed, and the platform. These must allow the rig to rise and fall with the tides and so models of behavior have to be written to design ways of allowing this.

An alternative is to use a drillship to do the exploration. The drillship has the rig mounted in the middle of the ship, and can thus move around somewhat more easily than the others. It is generally held in position by dynamic positioning while drilling. (Video here).

Drill ship (Stavanger Oil Museum)

Once the field has been established, then a larger production platform can be brought out and placed where it can, using directional drilling, reach the best places to extract oil from the field. It is these large structures, such as that the Orlan platform from which Sakhalin Island oil finally began to flow recently, or the Thunder Horse, or Mars platforms. Although the former was due to produce by 2005, it was delayed by damage from Dennis and did not get up into major production until the end of last year, while the Mars platform was extensively damaged by Katrina. it is now back in production.

One of the problems with using these large platforms for Deepwater recovery is that they focus collection and so when these two are disabled, for example, they take about 400,000 bd out of production. And once they are damaged they are not so easily replaced. Back when I first wrote on this subject, in 2005 demand for rigs so strong that, as the International Herald Tribune reported

"If a customer comes today with an order, he'll have to wait until 2009 for delivery," Choo said in an interview last week. "That's how busy we are. If he's willing to pay more, he can get a rig by 2008 from our American shipyard."

By 2008 demand was such that prices had risen to half a billion dollars for a drill ship.

The original article noted that while it may only take 2 years to build a rig, the yard could only work on 8 at a time, and thus current deliveries were for 2009. The more recent story notes:

As a result, drilling costs for some of the newest deepwater rigs in the Gulf of Mexico — the nation’s top source of domestic oil and natural gas supplies — have reached about $600,000 a day, compared with $150,000 a day in 2002.

These record prices have spurred a new wave of drill-ship construction. This boom could lead to renewed offshore oil exploration that would eventually bring more supplies to the oil market, and push down prices.

Already, 16 new drill-ships are scheduled to be delivered to oil companies this year — more than double the number delivered over the last six years combined. In fact, 75 ultra-deepwater rigs should be delivered from 2008 to 2011, according to ODS-Petrodata, a firm that tracks drilling rigs.

The Chinese have also introduced a new design which is circular.

The Sevan Driller is the world’s first of its kind, with the most advanced deep-water drilling capabilities that allow it to drill wells of up to almost 13,500 metres (40,000 feet) in water depths of up to nearly 4,200 metres (12,500 feet) and an internal storage capacity of up to 150,000 barrels of oil.

The owner is Sevan Marine. The construction of this rig started at COSCO Nantong Shipyard in May 2007 and was relocated to COSCO’s Qidong Shipyard in April for derrick erection and final commissioning activities. The rig is due for delivery in the third quarter of this year and will be deployed by Petrobras in the Santos Basin, off the Brazilian coastline.

As of last week it was on its way to Brazil (which takes about 75 – 80 days) where it will drill in the Campos Basin in just over a mile of water.

Again this is a very, very brief and simplified look at some of the ways oil and gas can be produced from under the sea. It barely touches on some of the difficulties that are encountered, however. The sinking of the one barge shown at the top of the post could have been also repeated with pictures of other rigs in storms, and in battered condition.