Hibernia
Jim Baroffio (Former President of Chevron Canada
Resources)
Ohio State University, Columbus, Ohio, USA
12 November 1998
See
July 1998 Geotimes on Hibernia.
Hibernia
is the name of a drilling structure. Baroffio wants to have us appreciate
the magnitude of the Hibernia project. Hibernia is the largest
construction project in North America for the last 7 years, and is the 2nd
largest project that Canada has ever had (the first for Canada, and the most
important, was the Trans-Canadian railroad, years ago). The technology
that went into building Hibernia was remarkable - there were no textbooks on
how to build this thing. Engineers and geologists broke new ground in
figuring out this project. A fascinating structure - it sits out on the
bank of Newfoundland in the Grand Banks area. It will probably last for
the next 50 years.
The
base of the structure is around 105 meters; from base to the first platform is
85 meters. Its sits in ~80 meters of water. The foundation is 28-29
stories tall, most of which will be submerged. Four risers support the main
facility. Each of the 4 risers is 17-18 stories high. The platform
itself sits on a gravity based platform, unlike platforms in the Gulf of Mexico
or the North Sea. Hibernia is a permanent structure, for all practical
purposes. Theoretically, it can be moved, but it is doubtful that it will
ever be moved. The main facility consists of supermodules that are
~100’ high and 100-200’ of derrick. The total height of the
Hibernia structure is ~74-75 stories. The water depth is only about 80
meters - not nearly as deep as people might expect.
Canadian Maritime Provinces - Newfoundland and Labrador are now joined together as 1 of the 10
provinces of Canada. Hibernia is situated 350 km southeast of the
furthest point of eastern North America (St. Johns area, Newfoundland).
The Hibernia structure was built in Trinity Bay. Hibernia is the only
structure out in the Grand Banks area. In the next 5-10 years, there will
be additional structures, but they will not be like Hibernia - they will be
floating platforms that will then tie into either Hibernia or elsewhere.
Town of St. Johns, Newfoundland - a quaint town, and the furthest tip east in North
America. The channel at St. Johns is generally filled with ice, sometimes
with polar bears on them. This was the jumping off point for early
telecommunications companies. Hibernia is named after an old name for
Ireland. A late 1800s ship that laid early cables across the Atlantic was
named Hibernia because it was mainly based in Ireland.
Geology - the Atlantic
Ocean was opening up in Aptian to Albian time (late Early Cretaceous) The
margin of the basin has extension rifts, which were aborted soon after they
started to split/rift. The source rock in the area is 1600-2000’
thick (the original water depth was probably only about 20’). The
source rock is Kimmeridgian (mid Late Jurassic), one of the greatest source
rocks the world has ever known. It is sourcing gigantic fields all over
the world, including the Middle East. The aborted rift existed only for a
short time and resulted in deposition of the only real source rock in the Grand
Banks area. Many other wells have been drilled in other adjacent basins,
but were all dry because those areas lacked source rocks. Extensional
rifting in the Late Jurassic resulted in a shallow, restricted basin for
sediment deposition - a prime criterion you need because nothing could get
oxidized and it was a reducing environment, resulting in source rock.
After
global eustatic changes occurred (sealevel drop), local highs were erosively
stripped (such as a central ridge) of much material which was redeposited
elsewhere. Got lots of sand being deposited - so the first formation is
the Upper Jurassic Jeanne d'Arc Sandstone. Afterward, another
source rock was deposited. In this case, got reservoir rocks right next
to source rocks - the best situation. It took an additional 50 my for
this stuff to be buried deep enough to generate oil. Quite a few sand
deposits occur in the section, but there 2 main sands are the key reservoirs.
The first one is the Hibernia reservoir, a fantastic sandstone reservoir.
Permeability in the reservoir is 10 darcies - often times, permeabilities are
expressed in millidarcies. It is a coastal deposit, similar to the Gulf
of Mexico where the Mississippi River is coming in, depositing sands, which had
all the fines winnowed out. The Avalon Sandstone - a coastal, lagoonal
deposit; the porosity and permeability is less in this upper sandstone
reservoir compared with the Hibernia Reservoir. Recovery in the
lower/better sandstone reservoir will be at least 35-40%, and 8-10% in the
upper reservoir. Hibernia Sandstone depth - 12,200’. Avalon
Sandstone depth - 8,000’.
Drilling
from the Hibernia platform will in some cases test both sands and have dual
completion, which will save a tremendous amount of money. They have
completed an $8 million 3-D seismic program in the area that shows all the
faults in such detail that the Hibernia structure could be mapped far better
than anyone imagined. The Avalon Sandstone, Hibernia Sandstone, and
Kimmeridgian source rocks are deformed a bit by upwelling Late Triassic-Early
Jurassic salts. Chevron discovered the Hibernia field in 1979; it only
came on line last year (1997), 18 years later. In 1981-1982, 8-9 development
wells were drilled and are now plugged because we now have the Hibernia
platform that can redrill the wells.
The
Hibernia platform is around $5.9 billion dollars Canadian. A tremendous
cost (=~$4.6 billion US). Only big companies could handle this. All
this delayed the project many times. Icebergs were actually a bigger
problem to consider. This area has been called Iceberg Alley. 85%
or so of an iceberg is underwater. A 750,000 ton iceberg hit the Titanic.
It was believed that if such an iceberg hit Hibernia, it would destroy
it. What politicians didn’t understand about this concern was that
the Titanic incident occurred in 1.5 mile deep water, and Hibernia is
located in ~80 meters of water. Never has an iceberg been seen crossing
the Grand Banks that was >0.5 million tons. Yet, for environmental and
safety reasons, they would construct a feature that could withstand a 6 million
ton iceberg. The odds of that happening is something like 1 in 20,000
years. Even if a 6 million ton iceberg hit the structure, it would
probably move it a few inches, but would not destroy it, according to all the
engineering studies done. This structure will hold 1.3 million barrels of
oil, and we think that the environment will be safe.
Where
to build it? Rather than in Norway, where most of these types of
structures were being built, the government decided that they would have to
build it in Newfoundland. Hibernia was constructed at Trinity Bay, at two
sites, one for the gravity based platform, and one for construction of one of
the supermodules. Had to build two dams - an inner one and an outer one,
and they drained part of the bay to construct these structures. The
gravity based platform is ~345’ across. It needed a 15 meter icewall
and 16 teeth sticking out that would break up any iceberg that would even come
near it. This engineering had never been done before, but they needed a
structure that would withstand a 6 million ton iceberg, so plans were changed
several times as construction started. Ten times that amount of iron as
steel that went into making the Eiffel Tower went into making the platform
(95,000 tons of iron as steel). Then, added concrete. After it had
been built up about 12 meters, the drydock was flooded (they broke the dam) to
see if it would float - it did. Then, they had to float it out to deeper
water, in order to keep building it up - it would sink deeper as they built
upward. They built it up to ~85 meters, then they added 18 stories of
columns that went all the way to the bottom. Supermodules (~100’
high) were mostly built overseas (Korea, Italy, Newfoundland). They had
to fit together just right. They welded the supermodules together and
added communications. Then, they tugged the structure offshore.
Mating the top side with the gravity based platform - came within 1.5” of
where it was supposed to fit together; it is not welded together, but is bolted
with giant bolts. 35% of the finished structure is submerged. They
tugged it out to the Grand Banks drilling site - took a 300 mile trip, although
the straight distance is only 200 miles from shore. Had to get it in deep
water in order to bring it to the ~80 meters of water depth of the drilling
site - only had 3.5 meters of clearance for siting it there. If Hibernia
got grounded, they were in deep trouble. It traveled for 10 days, and
then a storm came up, despite the best forecasts and predictions by the best
European and American experts. They spent 10 days just bopping
around. Lots of people were concerned, especially Lloyd’s of
London, who insured a $4 billion structure. Positioning - came within
5’ of where it should have been (phenomenal!). Then, to ensure it
stays in place forever, they brought in additional ships to put iron ore into
some of the holes. 470,000 tons of iron ore were put in. Already
had a 600,000 ton structure - now have a million point one ton structure of
steel and iron ore.
Once in place, have to drill
wells. A total of 87 wells will be drilled. ~56 of these will be
oil wells. ~26 will be water injection wells. Others will be gas
injection wells. Have already started this - want to maintain the
original reservoir pressure so the rate at which reserves are produced
doesn’t go down. There are 3 billion barrels of oil in place in
these sands. 750,000 barrels of oil recovery is projected.
Actually, we’ll probably see well over 1 billion barrels of oil
recovery. The original projection was 500,000; the projection has been
modified since drilling only two oil wells to confirm what we had. The
first well was so prolific that it was twice anything ever hit in Canada.
It came in at 55,000 barrels of oil a day, with a capability of 80,000 barrels
of oil a day. But, they will be scaling this back to maintain reservoir
pressure. These wells are just fantastic. Will definitely have a
billion barrel field. 1.3 million barrels of oil can be held/stored in
Hibernia. An offshore oil loading system has been positioned far enough
away that in case any icebergs or icesheets come along that could scour the
bottom (there are some 16-18’ deep iceberg gouges in the area), the oil
conduit could be disconnected, flushed out, and the tankers moved to a safe
position. Two special tankers have been built; they are 1.25 thousand ton
tankers, double-hulled, capable of smashing bergybites - anything of 10,000
tons. Tankers will hold 850,000 gallons of oil. The oil is moved
from Hibernia onto tankers, and back into the St. Johns area to a ship
terminal. There, a 1.3 million barrel storage facility is present.
Then, the oil will be shipped out to anywhere in the world. Other fields
have been discovered in the area. $12.95 a barrel is the break-even point
for Hibernia. Hibernia will be producing easily for the next 25 years,
and will probably be there for the next 50 years, once the other fields are
tied in. Want a high rate of return (want to make more money than what
you would in the bank or stock market). Would like 15% rate of
return. In the end, a 20% rate of return is expected. Hibernia is
performing better than expected. A success story.
