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OUR FIELD IS THE EARTH
OFTEN, when informed of the fact that you are a geologist, the layman responds with, "Oh, so you are one of
those people who deals with rocks?!!" But, what is it about geology and "rocks" that is so important
to Trinidad and Tobago or any country for that matter? 'Me definition of geology, Is the study of the Earth as
a whole, its origin, structure, composition, and history (including the development of life) and the nature of
the processes which have given rise to its present state.
Many of the elements of man's existence on this planet such as energy minerals including petroleum, metallic ore,
water, construction materials (e.g., clay for bricks, sand and gravel, limestone for cement) are obtained from
the earth's crust. These elements exist in unique conditions that only the student of the crust can predict. In
addition, intangibles such as earthquakes, volcanic eruptions (both of which are potentially hazardous to civilization)
and rock strength, which are all linked to the
dynamics within the crust, fall under the umbrella of the professional geologist. The history of geology in Trinidad
and Tobago Is a relatively short one, and, to a large extent, is linked to the development of the oil industry.
This has been so because, apart from those investigations carried out on behalf of the Government, most of the
geological work has been done by the oil companies. As far back as the 16th Century, when Sir Walter Raleigh and
others, used asphalt from the Pitch Lake for repairing their ships, some small value was seen in petroleum. Petroleum
(including manjack) was the first natural resource of economic importance.
The developing awareness of the importance of petroleum as a source of energy, an awareness which became significant
in the 19th Century, prompted the first geological investigation in the island. The first of well ever drilled
anywhere in the world was drilled near the Pitch Lake in 1857. The other earliest wells were drilled at Guayaguayare,
Aripero and Point Fortin, and were sited close to the numerous oil seepages present in the southern part of the
island, or were just drilled on a hunch. These first attempts at oil exploration met with both success and
failure. It was the success at some of these early wells, coupled with the worldwide increasing demand for energy
resources that led, among other things, to the preparation of the Geological Survey of Trinidad with special reference
to Economic Geology by Wall and Sawkins in 1885 and to the appointment of the fast Government geologist, Mr. CunninghamCraig
in 1982. Wall and Sawkins were seconded from the Geological Society of Great Britain.
Their work provided Information on the structure and mineral resources of that country.
Cunningham-Craig's job involved execution of extensive geological surveys, in both Trinidad and Tobago, which would
assist in appraising oil prospects and encourage investors in oil exploration. Between 1910 and 1914, commercial
oil production was established and was based on much of this early geologic mapping. At that time, the favoured
areas for oil accumulation were based on the crest of the anticline theory. By that time, it was recognized that
successful exploration for oil depended on geologists to identify the anticlinal structures and to advise on favourability
for drilling. Success was accomplished by drilling favourable crestal structures in Guayaguayare, Point Fortin,
Tabaquite, and Forest Reserve.
Most of the early oilfield pioneers were private individuals and/or concerns who obtained leases from Government
and private owners. Names such as Rust, Darwent, Lee Lum, and Mac Kennich, featured prominently in these early
exploitations. These men started what, today, is our most valuable industry.
In 1913, a number of foreign geologists, including Swiss Geologist Dr. Fortunat Zyndel, began arriving in Trinidad.
These men figured prominently in the continued growth of geological thought both in Trinidad and around the world.
At that time Swiss schools of geology had the highest reputations in the world. Consequently, many of these Swiss
geologists were sought after by the oil companies operating in the country at that time.
Between 1913 and 1967, these geologists laid the foundation for petroleum geology
in Trinidad. 'Their work, much as it is today, though not as sophisticated, included geologic field mapping, examination
of cores and drill cuttings, analysis of electric well logs, paleontology, geophysics, and aerial photography.
Their maps and analytical reports formed the basis for continued and more successful oil exploration throughout
the years. Some of the highlights of that period are as follows:
- Dr. Fortunat proposed the discovery well of the Forest Reserve Field in 1914. This well was called 'Helena-I.'
This field has become one of the most prolific oilfields to date (production from Trinidad in 1914 was 1,000,000
barrels of oil per year).
- Continuing detailed geological studies led to further drilling and development of the Forest Reserve, Fyzabad,
Tabaquite,
Parrylands and Barrackpore fields from 1919 through 1924. By that -time, the fault-trap theory for oil accumulation
was in vogue.
- Dr. Hans Kugler, regarded by many as the 'father of Trinidad geology' arrived in Trinidad in 1920. Among his
many contributions over his 44 years in Trinidad were extensive field mapping of the island, participation in the
introduction of electric well-logging by Schlumberger in 1932, establishment of the micropaleontology laboratory
at Pointe-a-Pierre, compilation of the Geological Map and Cross-sections of Trinidad, theory of the mechanics and
origin of mud volcanism and submarine slumping, and the theory of lenticular sand-bodies. Perhaps, it would
be best to break away from a chronological report and briefly examine why Dr. Kugler's contributions were so important.
Let us examine each one briery:
(1) ELECTRIC WELILOGGING
This was pioneered by Schlumberger of France in the 1020's and introduced to Trinidad in 1932 on Kugler's and others'
insistence. The subsurface lithology through which the early oil wells were drilled was difficult to determine.
The electric log gave a graphical plot of precise lithology and fluids with depth. With electric logs, it became
easy to know where your oil reservoirs were in the subsurface and to correlate reservoirs from one well to the
next. Ibis invention was one of the most significant contributions to subsurface geological mapping.
(2) THE PALEONTOLOGY LABORATORY AT POINTE. A-PIERRE:
The paleontology laboratory at Pointe-a-Pierre possesses the best type-collections of planktonic (open sea) foraminifers
(microfossils) In the Western Hemisphere. Foraminifer, which are abundant in Trinidad sediments, provide
one of the best means for subdivision and correlation of formations. Dr. Kugler was instrumental in upgrading the
then small laboratory into one which was well equipped for the study of microfossils. He was able to attract a
strong team of competent paleontologists among whom were V.C. Ming, W.F.L. Nuttall, R.J.L. Guppy, F.W. Penn, J.A.
Bullbrook, P.W. Jarvis, J.A. Cushman, H. Naegeli, K. Schmid, H.A. Renz, B. Caudri, R.M. Stainforth, P. Bronniman,
H. Bolli, P.A. Martin-Kaye, J. Saunders, W.H. Blow and J. Beckman, to carry out studies at the laboratory.
Dr. Kugler influenced management to immediately publish the results of their work, results which were of considerable
economic value. The Publication of these
results began to stimulate the study of planktic foraminifera around the world. Thus, it was the work by this team
of eminent micropaleontologists at Pointe-a-Pierre resulted in worldwide application of microfossils in the understanding
of the earth's history.
(3) THE RE-COMPILATION OF THE GEOLOGICAL MAP OF TRINIDAD WITH SECTIONS
This re-compilation began in 1950, completed in 1959 and published in 1961, all with the support of the Petroleum
Association of Trinidad. This map brought together the results of work by a series of committed geologists who
had been working the length and breadth of Trinidad engaged in field mapping and subsurface studies (using well
logs, paleontology and drill cuttings). This was a monumental task. The map is presently the comer-stone of geological
study in Trinidad today.
(4) GEOPHYSICAL INVESTlGATIONS
Geophysics is another tool for subsurface investigations. This was introduced in 1931 when magnetic refraction
was used in the Brighton area. Major gravity and seismic exploratory efforts and a short electrical resistivity
survey began in 1937 in south Trinidad and later continued in the Central Range and the Northern Basin.
(5) INTRODUCTION OF EXPLORATION FROM THE AIR (AERIAL PHOTOGRAPHY)
This tool allowed the definition of some of the major geologic structures and stratigraphic features from the air.
In this regard, Kugler solicited the expertise of Dr. K. Rohr, as photo-geologist who explored and mapped geological
features from the air. Dr. Rohr's aerial survey of Trinidad was one of the most important contributions to subsequent
oil exploration.
(6) Finally, Dr. Kugler's
firm conviction of the trapping of oil in lenticular sand-bodies not present at anticlinal crests, led to the drilling
of wells off the crest and on the' thinks of anticlinal structures. His theory was proven to be correct, and led
to the successful development of the Apex Fyzabad and Forest Reserve Fields into the biggest oilfields on land
in Trinidad. In addition, he was also convinced that Outcropping sands need not have lost all their oil by seepage
to surface, but could have retained their oil with the help of a bitumen seal.
This theory was proven correct, and encouraged drilling for this type of sand.
These two theories, the lenticularity of sands and the bitumen seal, were responsible for the successful drilling
operations by the Apex Company, and Trinidad Leaseholds Ltd., and ensured the future of the oil industry.
- Meanwhile, in 1926, the Palo Seco Field which was the first major discovery since the Apex Fyzabad and Forest
Reserve Fields, was becoming a prolific producer. 'Ibis field, first drilled in 1920 benefited from Kugler's theory
of sand lenses developing down an anticlinal flank with little indication of existence in the crestal area. The
north flank of the structure which was first drilled, ultimately became the best producing area of the field.
- Between 1919 and 1924, Trinidad Petroleum Development Company carried out an islandwide geological survey under
the direction of G.A. Waring who published a paper on the geology of Trinidad. Based on the results of this survey,
fifteen exploration wells were drilled Islandwide between 1922 and 1924. Throughout this period, and later,
a number of private companies were in operation and leases often changed hands.
- Throughout the 1930s and 19408, geological efforts continued and oil production exceeded 22 million barrels in
1940. The geological theories then in vogue here the stratigraphic trap and of the layering of oil reservoirs one
on top of the other. Thus, one well could tap more than one reservoir at a time. Previously, the wells produced
from the first oilsand encountered while drilling. The Cruse, Coora, Barrackpore and Herrera Fields had been discovered.
The Coora Field discovery of this field was significant in that its situation far away from an anticlinal crest
encouraged drilling further away from known crests. Thus, it was that synclinal fields of Apex and Barrackpore/
Penal were discovered.
- In the 1950s the Balata, Cat's Hill, Soldado, Trinity-Inniss and Rock Dome Fields were discovered. And marine
exploration began with the major success at Soldado in the southern Gulf of Paria.
- From the 1960s to present, the emphasis has been on continued geological investigations aimed at the same goal
- finding that next barrel of oil. The goal and many of the basic methods are the same. However, many of the scientific
tools which were used in the early part of this century have become extremely advanced. This advancement
of technology has provided today's geologist with an abundance of vital information, so necessary for the production
of the perfect subsurface map.
- In the 1980s, geological theory in vogue is that of Wrench Tectonics, and srtratigraphic
modeling is also being emphasized. Wrench tectonics, an offshoot of the Plate Tectonic Theory, deals in structures
associated with strike-slip faulting. Stratigraphic modeling in Trinidad is related to deltas, and more
specifically, the Orinoco Delta which formed at the mouth of the Orinoco River approximately 10 million years ago.
- Among some of the other advances in the 1980s are: Diversification in electric
logging products, new theories of earth dynamics including the Plate Tec. tonic theory, research in rock Properties,
advancements in seismic processing, new models for sediments deposition, and refinement of the theories of formation
and migration of petroleum. The early electric log has been replaced by more advanced induction tools. Other tools
have been developed and are now used to indicate subsurface bed dips, to differentiate between oil and gas in subsurface,
read porosity, differentiate clay constituents, and in many other applications.
The emphasis on active drilling in the Southern Basin of Trinidad has resulted in
the compilation of extremely, detailed geological maps which trace the geological history of the basis from its
earliest beginnings approximately 150 million years ago. These detailed maps are the property of private
companies and generally classified as confidential. They continue to be developed, fine-tuned --or modified through
the years. However, publication of geological reports and maps occurs from time to time. In summary, the
oil industry fueled geological investigation at the beginning of the century. These investigations were aided by
the work of a succession of committed and enthusiastic geologists, who through an extensive exploration effort
using all the tools available to them including field mapping, geophysics, paleontology and electric log interpretations
created a comprehensive picture of Trinidad's geology.
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