Out the Window
of Bass Strait oil and gas activity is a fascinating chapter in
the global petroleum industry evolution -- and, ultimately, a rewarding
chapter for AAPG.
been recorded along Australia’s southern coastline since 1869, but
it wasn’t until 1960 that the offshore region was even considered.
that time former BHP executive Eric Rudd contracted Lewis Weeks,
a leading American oil field geologist who, before retiring as president
of Standard Oil of New Jersey (Exxon), had found oil seemingly everywhere
-- it was said he studied data for all of the world’s known basins
-- and was about to enjoy retirement in his Westport, Conn., home.
Weeks to help him convince BHP officials that an oil search in oil-dry
Australia should be launched.
did some studying, then met with the BHP officials and told them
he knew where oil could be found that was accessible to 90 percent
of Australia’s market.
then offered -- and accepted -- a 2.5 percent royalty deal. And
then he was asked, where’s the oil?
your window,” he replied. “It lies out there in the Bass Strait,
and most particularly off the Gippsland Coast.”
the Bass Strait was one of the world’s roughest water areas -- the
region had been passed over since after 40 years of trying the adjacent
coastline was dotted with nothing but 140 dry holes.
to take a risk, however, and following encouraging results from
an initial aerial survey, commissioned Australia’s first offshore
seismic survey that indicated several possible oil traps in the
Gippsland Basin. Prior to drilling, however, BHP went looking for
a partner and in 1964 convinced Esso Standard Oil (Australia) Ltd.
to join the venture as a 50-50 partner.
brought in from the Gulf of Mexico spudded the first well in 1964
in water 42 meters deep, and after months of battling notorious
bad weather the drill bit reached 1,318 meters and hit gas.
pay dirt on the first ever try was almost unheard of and prompted
later the joint venture partners made a second major gas discovery
at the Marlin Field and tapped the real prize -- oil.
Kingfish Field discovery soon followed, and since that time a host
of fields were uncovered in quick succession, including Halibut,
Dolphin, Perch, Flounder, Tuna, Snapper, Mackerel and Bream as well
as oil at Barracouta and West Kingfish.
peak in the mid-1980s the Bass Strait was producing over half a
million barrels of oil a day.
point the Bass Strait discoveries supplied 70 percent of Australia’s
these finds Australia was almost totally reliant on imports of petroleum
to Esso Australia, the oil and gas produced from the Bass Strait,
combined with the cost of oil that otherwise would have had to be
imported plus the tens of billions of revenue dollars paid by the
joint venture to the government, equal an enormous impact on Australia’s
AAPG, Weeks, a generous philanthropist, was able to provide the
money for the headquarters addition in Tulsa that bears his name:
the Weeks Tower. His son, geologist L. Austin Weeks, continues as
a contributor to the AAPG Foundation.
ambitious new drilling program in Australia's offshore Gippsland
Basin is set to kick off in February based on new state-of-the-art
3-D seismic data.
however, is not the only driver in this province, located in the
Bass Strait off southeast Australia.
natural gas market in Australia and nearby Tasmania also is fueling
renewed efforts to find and produce both oil and natural gas.
and BHP Billiton (50-50 joint venture partners) late last year announced
plans for what is expected to be the basin's largest combined exploration
and production drilling program since the 1980s.
in discussions to contract a rig capable of drilling wells from
either existing platforms or in new locations.
the success of the initial wells, the program is expected to extend
into 2005, according to the companies.
is based on 3-D seismic data acquired in 2002 as part of the largest
proprietary 3-D seismic survey ever undertaken in Australia. The
survey, which covered over 3,900 square kilometers, was designed
to identify new exploration prospects, provide data to better plan
for the depletion of producing fields and to assist in bringing
small, undeveloped discoveries into production.
will target both oil and gas opportunities, and all the planned
wells will be located within existing production license areas.
there are new oil and gas resources still to be found in the Gippsland
Basin," said Doug Schwebel, Esso Australia exploration director.
"From an exploration viewpoint, the program is all about finding
new potential in a mature basin."
president of exploration and development for BHP Billiton Petroleum,
added, "In particular, the joint venture will be looking to leverage
its ability to commercialize smaller resources due to their proximity
to existing infrastructure. This also will help extend the productive
life span of the existing platforms and pipelines."
Today and Tomorrow
first offshore well was spud in 1964 in the Bass Strait , discovering
the Barracouta gas field.
wildcat found more than just a gas field: It set the stage for a
development that has seen the discovery of multiple large fields
and important reserves for Australia. Since the country's first
production commenced from the Gippsland Basin 34 years ago, more
than 3.5 billion barrels of oil and five trillion cubic feet of
gas have been produced.
Field was followed two years later by the Kingfish discovery, Australia's
first offshore oil field that remains its largest oil find.
and subsequent world-class discoveries led to massive infrastructure
costing more than $12.5 billion. Today there are 21 offshore platforms
and installations in Bass Strait with a network of 600 kilometers
of pipelines. The most recent addition was the Blackback subsea
facility, which at a depth of almost 400 meters is one of Australia's
deepest oil developments.
and BHP Billiton are currently producing approximately 160,000 barrels
of oil and 570 million cubic feet of gas per day, although the joint
venture has the capacity to produce gas at a peak daily rate of
more than 1,000 million cubic feet of gas daily.
It is obvious
both firms remain upbeat about the region's remaining potential.
In the past five years, overall capital expenditures associated
with the joint venture's Gippsland Basin operations, including onshore
facilities, have exceeded A$400 million annually, making it one
of Australia's largest ongoing oil and gas investment programs.
Basin fields supply around 20 percent of Australia's crude oil requirements
and nearly all of Victoria's natural gas.
also supply up to 50 percent of New South Wales' gas requirements
through the Eastern Gas Pipeline," Nick Heath, director of gas marketing
for Esso Australia, said at a recent oil and gas conference.
the new Tasmanian gas pipeline was opened and Bass Strait gas also
began flowing south into Tasmania for the first time.
markets established it is no wonder Esso Australia and BHP Billiton
are working hard to buoy reserves and production from the Bass Strait
the massive production to date, we believe that Bass Strait remains
highly prospective," Heath said, "and there are still significant
discovered reserves, at least five trillion cubic feet of gas, much
of which has been developed and more which is still to be exploited."
that remaining potential that prompted the joint venture to under
take a massive 3-D seismic program to search for additional reserves.
the firms conducted two small 3-D surveys, one at Barracouta and
one at Kipper Field.
was specifically the Golden Beach formation, which lies up to 1,000
meters beneath the LaTrobe formation, which is the primary host
of Bass Straits' current oil and gas production," Heath said. "We
used this data to identify East Pilchard, which we drilled in August
of 2001. It was to a total depth of 3,138 meters and discovered
gas in several intervals, with a total of more than 100 meters of
and the quality of the data obtained from those two small 3-D surveys
provided the joint venture with insight into the potential of 3-D
seismic technology in the Gippsland Basin -- and convinced the firms
that additional data would be valuable.
never before deliberately explored the deep part of the section,
nor had we deliberately explored for gas in the basin," Heath said.
"With this in mind we completed the largest ever 3-D seismic survey
in Bass Strait."
(October 2001-July 2002) covered about 3,900 square kilometers in
the area surrounding the northern fields in the Bass Strait.
of the huge 3-D seismic program came from ExxonMobil's massive regional
approach at Sakhalin off the eastern coast of Russia, which was
designed to develop an integrated structural and stratigraphic picture
of the basin.
imaging in the Gippsland Basin can be challenging. Diverse geologic
features tend to complicate the images.
for example, the major coal seams within the Upper LaTrobe section,
which distort the image below," he said. "However, using the new
regional 3-D seismic approach and the wealth of experience that
we have built up over four decades in the Gippsland Basin, we are
now using advanced algorithms to take out the seismic 'noise,' or
'shadowing,' generated by the coal to identify direct hydrocarbon