will mark the 30th anniversary of the first field discovered in
the deepwater Gulf of Mexico province, defined here as water depth
of greater than 600 feet (183 meters).
when the first commercial field (Cognac) was discovered by Shell,
over 21.2 billion barrels of oil equivalent have been discovered
in the province and approximately 9.2 TCFG and 2,200 MMBO have been
produced between 1979 and the end of 2002.
been approximately 232 commercial fields discovered during the period
from 1975 to the end of 2003.
mean size of these discoveries is 94.3 MMBOE. The two largest fields
found to date are Mars (750 MMBOE) and Thunder Horse (1,000 MMBOE).
statistic to remember: Initial well flow rates in the deepwater
province did not exceed 10,000 BOPD until 1995 — 20 years after
the discovery of Cognac field in 1975.
short years later, individual well rates at Ram Powell and Troika
exceeded 20,000 BOPD.
been three major exploration plays in the deepwater province: the
Flex Trend play, the Mini-Basin play and the Fold Belt play (see
the "subsalt play" is simply any of these plays obscured by salt.
The Flex Trend play began in the early 1970s with the discovery
of Cognac field. It was developed just beyond the present-day
shelf edge where there is a "flex" in the sea floor profile.
Some of the larger flex trend discoveries were Lena, Zinc, Pompano
and Green Canyon 18. Wells generally targeted "bright spots"
on 2-D seismic. Most discoveries in the play were fields with
small reserves, discontinuous sands and wells with fairly low
Needless to say, this was not a very encouraging start to exploration
in the deepwater province.
The Mini-Basin play began in 1983 with the discovery of Bullwinkle.
This play targeted the flanks of structural intraslope basins
where reservoir sands pinched out and formed a combination structural/stratigraphic
Some of the larger mini-basin fields discovered are Auger, Mars,
Diana, Genesis, Troika and Europa. Ram Powell was discovered
in 1985 and is a very large, stratigraphic trap developed in
a more unrestricted mini-basin.
(Larger mini-basins also may have turtle structures developed
in their centers.)
The first mini-basin fields brought on-line (Bullwinkle in 1989,
Auger in 1994) produced at much higher than expected rates,
had better than expected aquifer support and needed fewer wells
to develop them. Many of the early production ended up being
are at least three fold belt trends: the Mississippi Fan, the
Perdido and the Port Isabel fold belt.
The Fold Belt play began in 1995 with the discovery of Neptune
in Atwater Valley 575 in the Mississippi Fan fold belt.
BAHA was the first discovery in the Perdido fold belt in 1996.
To date, there has not been a discovery in the Port Isabel fold
The largest field discovered to date (Thunder Horse) was not
discovered until 1999, a full 24 years after the first discovery
in the flex trend play (Cognac).
been consistently more than 10 discoveries per year in the period
after 1995 when the Royalty Relief Act was established, which allowed
producers to postpone paying royalties until most of the exploration
and development costs are recovered.
success rates in the deepwater Gulf have been estimated to be about
1 in 4.
the first nine years of exploration in the deepwater Gulf of Mexico,
15 fields were discovered, all with reservoirs of either Pliocene
and/or Pleistocene age. More Pleistocene reservoirs were discovered
in 1984 than in any other year, and the most Pliocene reservoirs
were discovered in 1995. The first Miocene reservoirs were not discovered
until 1984 at Tahoe, although these were gas-bearing, thin-bedded
reservoirs were later discovered at Ram Powell in 1985, Mensa, Kepler
and Coulomb in 1987, Mars in 1989, Mickey and Pompano in 1990, and
Crosby in 1991.
Paleogene age reservoirs have been discovered in the Fold Belt play.
10 companies were operating discoveries in the deepwater in the
first 13 years of exploration; in 2003, there were approximately
44 companies operating discoveries in the deep water. Shell has
been by far the most successful operator, with approximately 52
discoveries through early 2004.
is the second most successful operator with approximately 17 discoveries.
21.2 billion barrels of oil equivalent have been discovered in the
deepwater Gulf of Mexico. The most reserves were added in 2001,
when 32 fields were discovered.
of reserves greater than 1,000 MMBOE per year were added in 1989,
and during the period 1998-2002. During the period of exploration
from 1975-2003, reserves in excess of 500 MMBOE have been added
in 13 of the 29 years.
were made, and no reserves were added, during the years of 1978,
1979 and 1992.
MMBOE), discovered in 1989, was often thought to be the largest
field in the province until Thunder Horse (1,000 MMBOE) was discovered
in 1999. The sizes of these fields suggest that there is still a
possibility that several fields in the range of 750 MMBOE to 1,000
MMBOE still wait to be discovered.
oil field to start production in the province was Cognac, in 1979.
This was followed in 1980 by the first gas field (GB 236).
not until 1984 that the third field (Lena) started production, almost
10 years after the first commercial discovery.
24 fields to start production in the deep water either produced
from Pleistocene or Pliocene reservoirs.
per well production rates were disappointing during the first few
years of production from the early producing fields. Peak well rates
at Lena, which started production in 1984, were only 500 to 2,200
BOPD. It was clear from these early producing fields that higher
per well flow rates had to be achieved if the deepwater province
was to be economically viable.
that started production in the late 1980s achieved slightly higher
per well rates. The Green Canyon 18 A-8 well flowed at 7,400 BOPD
during January 1989, but that rate was short-lived. Rates of 3,000-6,000
BOPD were achieved at Bullwinkle, but these rates were reached years
after the startup of the field.
Miocene reservoirs started producing in 1994, almost 20 years after
the first discovery in the province. It was not until 1994 that
the first Miocene and early Pliocene reservoirs were brought into
production at Tahoe and Auger.
per well rates were first achieved at Auger field — four came on-line
in 1994 — but it was not until 1995 that the first well at Auger
achieved a rate in excess of 10,000 BOPD. It was then realized that
high per well rates from the Deepwater Province were possible.
years later, well rates at Troika and Ram Powell exceeded rates
of 20,000 BOPD.
end of 2003 there were 136 fields producing in the Deepwater Province.
Sixteen fields started production in 2003.