BigOilFields.Com


Shallow, Potentially Prolific
Serpentine Plug Prospect (Travis
Mound)
Hidalgo Exploration & Production Co., Inc has acquired leases on
a magnetic anomaly in central Texas that appears to be a Travis
volcanic mound, and thus a potential undiscovered oil field.
Travis mounds are ancient volcanoes that erupted during the
Late Cretaceous (70 to 80 million years ago) and formed
mounds on the shallow sea floor. The mounds were partially
eroded and then covered with younger sediments. The mounds
in central Texas are generally referred to as “Travis volcanic
mounds” for the surface exposure of one of these mounds in
Travis County. The mounds are commonly called “serpentine
plugs” because the mineral serpentine commonly occurs in the
mounds. Some of the minerals that occur in these mounds are
magnetic, hence the magnetic anomalies over these mounds.
The mounds have formed structurally high areas in the
subsurface that provide traps for oil and gas.
Thirty-eight oil fields in central Texas are associated with Travis
volcanic mounds. These fields range in size from 3000 barrels to
11,500,000 barrels of oil recovered, and occur at depths
between 900 feet and 1800 feet. Some wells in the mound fields
have produced as much as 5000 BOPD (barrels of oil per day)
initially, but the initial production of most wells was between 25
BOPD and 100 BOPD. Most of the better wells were located near
fractures that are prevalent in the mounds. Most of the oil fields
that are associated with Travis volcanic mounds were discovered
in the 1930’s, 1940’s, and 1950’s, although six fields were
discovered between 1913 and 1929 and three fields were
discovered between 1964 and 1977. Over half of the fields are
still active including some of the early discoveries. Some of the
first oil fields found on the Travis volcanic mounds were
discovered by farmers drilling water wells.
Oil is found in at least four different geologic settings in the
mounds. Much of the oil occurs in porous areas within the
generally altered volcanic igneous rocks that form the mounds.
Some oil is found in sedimentary rocks (sandstones and
limestones) within the mounds, some oil occurs in sedimentary
rocks that overlie the mounds, and some oil is trapped in
sedimentary rocks that pinch out on the flanks of the mounds.
Thus there are non-productive areas within the confines of the
fields associated with the mounds. This prospect appears to
cover about 180 acres.
The magnetic anomaly associated with this prospect is
comparable to the anomalies associated with one million to three
million barrel fields, although the size and intensity of magnetic
anomalies is sometimes misleading. Most of the magnetic
anomalies that occur in the area are associated with Travis
volcanic mounds. The other magnetic anomalies have not been
drilled but are believed to be Travis volcanic mounds. A
geochemical survey acquired recently found significant
(anomalous) concentrations of petroleum hydrocarbons in the
soil over the prospect. This suggests minute leakage from an
accumulation of hydrocarbons at depth. Additionally, the
operator has acquired satellite data that suggest the presence of
soil within the prospect that has been altered mineralogically.
This condition has been observed in soils over known oil and
gas fields. All of these data together suggest a fairly high
probability that a commercial accumulation of hydrocarbons
(likely oil) exists under the prospect.
There is no record of a well having been drilled on the prospect.
There are few records pertaining to wells that were drilled before
1930, so it is possible that an old unrecorded dry hole has been
drilled on the prospect. A local fellow born in 1920 is not aware
of an old well having been drilled in the prospect area, however.
About seven or eight percent of the wells drilled within the Travis
volcanic mound fields are dry holes because they were drilled in
the small non-productive areas within most of the fields. We
believe that there is a fairly high probability that this prospect is a
Travis volcanic mound with a commercial accumulation of oil.
There is a five to ten percent probability, however, that the first
well would miss the oil field and be a dry hole. A discovery well
would likely find a field with 500,000 barrels to 3,000,000 barrels
of oil recoverable, although the field could be larger or smaller. A
dry hole (1300 feet deep) would cost about $80,000, and a
completed producing well would cost about $200,000 or less.
This is a very small risk when one has the potential to find
$10,000,000 to $60,000,000 net income. Additionally, Hidalgo
has two other Travis volcanic mound prospects that would be
available.


