On Work: New project, AGIP KCO Cantilever Barge Rig (CBR)
Today I am starting to help the lead engineer on this project which is a cantilever barge rig for AGIP KCO, which will be operating on the Caspian Sea. Two of these will be built by my company.
This is a really interesting project. When we think of drilling rigs, there are tons of them but in Keppel FELS, we are only doing jackups and semisubmersibles. The Koreans corner the drillship market and that's that. Other drilling stations like TLP, gravity platforms, etc, don't really come up, either because they are older or because it's not commonly used.
However, a drilling barge? That's something entirely new to me and I haven't come across it in any of the literature that I have read extensively before coming here. What does it look like?
Not very impressive, to think of it. It's basically a barge, with provision of a moving cantilever allowing it to drill holes in the ground. The engineer told me the size of the hull is about that of a semisubmersible, meaning it's pretty huge. The way it drills is also similar to a semi, by taking in ballast water and letting the entire barge rest on the bottom of the sea to provide a stable drilling platform. The sea isn't very deep to begin with.
Naturally, one would wonder...why is something so mundane looking so terribly expensive?? Well the answer lies in the conditions of the Caspian Sea, of which a little National Geographic lesson is required. The Caspian Sea has been referred to as the largest lake in the world. It is a landlocked body of water supplied primarily by the river Volga, and it is surrounded by Kazakhstan, Azerbaijan, Russia, Iran and Turkmenistan. All the -stans. The unique thing geographically about this lake is that the northern area is shallow, about 5 to 6 meters, but drops off to about 190 meters near the middle (so the top part forms the 'shelf'). In the south, the depths go on to about 1000 meters and more! As such, the northern part only accounts for about 1% of the total water contained in the lake.
This area is particularly important because that's where the drilling barge will operate in. Typically jackups operate in water depths of up to 300 feet (about 100 meters), while the drilling barge will have an operating depth of where around 10 meters, sufficient for these waters.
Initially I thought the reason for such high costs is due to high salinity of water there, but apparently unlike the Black Sea, the Caspian sea only has an average salinity of 1/3 that of normal seawater, or 1.2%. The reason why it is so expensive is due to the harsh environmental conditions, with temperature of seawater ranging from -35 degrees in winter to 40 degrees during summer. The cyclic thermal stress and embrittlement presents a challenge for any man-made structure to operate here, let alone for years on end. On top of this, the water will actually freeze during winter, so there is a provision for an IBEEV, or Ice Breaking Emergency Evacuation Vessel.
The field to be developed is the Kashagan field, heralded as one of the greatest finds of this century. The harsh conditions however meant that the recoverable oil might not be as high as initially thought.
Bringing it in.
The second question that occurred to me was...how are they going to build this thing? The Caspian Sea is landlocked...but not completely. It is still possible to access using canal routes but it would mean the size of the rig is limited. But not completely. The analogy here would be like assembling a ship-in-a-bottle. Sections will be build (like the cantilever, living quarters, etc) then transported into the Caspian Sea to be assembled and commissioned. In this way, fabrication can be carried out off-site in places like Keppel FELS.
All the big oil companies like Shell, Exxonmobil and Conocophillips have a stake in this project. The drilling itself will probably be performed by AGIP KCO, with professionals brought on board since there is no dedicated drilling company like Seadrill or DDI for these waters.
So far the project is still in the FEED stage (Front End Engineering & Design) because it's a technicaly challenging project involving people from more than 50 countries. The initial planning stage started back in 2004 (the field is discovered in 2000), so people have been sitting around and thinking for a long while now.
Use and function of glycol injection
The project also allowed me to explore the use of glycol in gas production. It is used mainly to prevent the formation of hydrates in water-saturated gas once it is drilled out. Hydrate formation can cause the lines to become plugged and introduce all sorts of problems, so it can be elimited by either heating the lines or to introduce drying agents into the gas to remove the water; one of them is glycol, the other methanol.
The drying agents do not completely dry the gases though, that job is done in a central location. What they do do is prevent formation of hydrates long enough for the gas to reach the drying station.
