An
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.
New technology,
however, is not the only driver in this province, located in the
Bass Strait off southeast Australia.
A growing
natural gas market in Australia and nearby Tasmania also is fueling
renewed efforts to find and produce both oil and natural gas.
Esso Australia
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.
They are
in discussions to contract a rig capable of drilling wells from
either existing platforms or in new locations.
Pending
the success of the initial wells, the program is expected to extend
into 2005, according to the companies.
The program
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.
The program
will target both oil and gas opportunities, and all the planned
wells will be located within existing production license areas.
"We believe
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."
Steve Bell,
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."
Yesterday,
Today and Tomorrow
Australia's
first offshore well was spud in 1964 in the Bass Strait , discovering
the Barracouta gas field.
But that
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.
The Barracouta
Field was followed two years later by the Kingfish discovery, Australia's
first offshore oil field that remains its largest oil find.
The Kingfish
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.
Esso Australia
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.
The Gippsland
Basin fields supply around 20 percent of Australia's crude oil requirements
and nearly all of Victoria's natural gas.
"We can
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.
In 2002
the new Tasmanian gas pipeline was opened and Bass Strait gas also
began flowing south into Tasmania for the first time.
With nearby
markets established it is no wonder Esso Australia and BHP Billiton
are working hard to buoy reserves and production from the Bass Strait
region.
"Despite
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."
Seismic's
Impact
It was
that remaining potential that prompted the joint venture to under
take a massive 3-D seismic program to search for additional reserves.
In 1999
the firms conducted two small 3-D surveys, one at Barracouta and
one at Kipper Field.
"Our target
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
gas-bearing sand."
This success
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.
"We had
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."
The project
(October 2001-July 2002) covered about 3,900 square kilometers in
the area surrounding the northern fields in the Bass Strait.
The genesis
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.
Seismic
imaging in the Gippsland Basin can be challenging. Diverse geologic
features tend to complicate the images.
"Take,
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
indicators below."