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with the knowledge and understanding of the occurrence of oil in those
regions rather than in the United States.



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58 PBTBOLEXJM INDUBTBT OF TBINIDAD



Petroleum Industry of Trinidad

By Geobgb a. Macrbadt, Los Anqelbs, Cauf.

(St. Loab Meeting, September, 1920)

Tbinidad, British West Indies, is an island near the north coast of
South America, situated between latitudes 10^ and 11^ N., and opposite
the numerous outlets of the Orinoco River Delta. It is separated from
Venezuela by the Gulf of Paria (salt water) and straits over 6 mi. (8
km.) wide. The area of the island is approximately 1760 sq. mi. (463,-
260 hectares) and the population is approximately 400,000. The climate
is tropical with an annual rainfall of from 46 to 60 in. (114 to 162 cm.).

The oil fields consist of several units, or fields, located in the southern
half of the island. Approximately 90 per cent, of the total production
has been yielded by fields situated within 7 mi. (11.3 km.) of the famous
asphalt lake and on the southwest peninsula.

The most important producing fields, or units, are the following,
which are shown on the accompan3ring map:

Brighton, or Pitch Lake Field, operated by the Trinidad Lake Pe-
troleum Co., Ltd., is situated beside the famous Pitch Lake; it even en-
croaches on the lake.

Vessigny Field, operated by the Trinidad Lake Petroleum Co., Ltd.,
is situated 2 mi. (3.2 km.) south of Pitch Lake.

Lot One Field, operated by the Petroleum Development Co., Ltd.,
the United British Oilfields of Trinidad, Ltd., and StoUmeyer, Ltd.,
is situated 3 mi. south of Pitch Lake upon Lot One of Morne TEnfer
Forest Reserve and adjoining properties.

Parry Lands Field, operated by the United British Oilfields of Trini-
dad, Ltd., and the Petroleum Development Co., Ltd., is situated 3^
mi. south of Pitch Lake on Lot Three of Morne TEnfer Forest Reserve
and adjoining properties.

Point Fortin Field, operated by the United British Oilfields of Trini-
dad, Ltd., is situated at Point Fortin, 6 mi. southwest of Pitch Lake.

Fyzabad Field, operated by Trinidad Leaseholds, Ltd., is situated
several miles southwest of Fyzabad Village and 6 mi. south-southeast of
Pitch Lake.

Barracpore Field, operated by Trinidad Leaseholds, Ltd., is situated
several miles south of San Fernando and 15 mi. (24.14 km.) east of Pitch
Lake.



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GBORGB A. MACBBADT



59



Tabaqxiite Field, operated by Trinidad Central Oilfields, Ltd., is
situated 4 mi. southeast of Tabaquite Railroad Station, and 30 mi.
(48.28 km.) northeast of Pitch Lake.




Gnayaguayare Field, operated by Trinidad Leaseholds, Ltd., is situ-
ated in the extreme southeast corner of the island 46 mi. (72.42 km.)
from Pitch Lake.

From 1870 to 1900, several attempts were made to obtain oil on Trini-



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60 PBTB0LEX7M INDU8TRT OP TRINIDAD

dad but although small quantities of oil were encountered, no com-
mercial production resulted, and most of the wells were abandoned.
An attempt was also made to obtain oil from the crude lake asphalt,
probably by a cracking process, but without commercial success.

The present industry can be said to commence with wells drilled since
1900 near Guayaguayare, in the extreme southeast corner of the Island.
Several years later wells were drilled near Point Fortin, southwest of
Pitch Lake, which yielded commercial quantities of oil but not sufficient
for export.

In 1908, the New Trinidad Lake Asphalt Co., Ltd., commenced drill-
ing at the Pitch Lake and encoimtered an excellent flow of oil in its second
well. Other wells were drilled and, in 1910, this company exported the
first steamship cargo of oil from Trinidad. Since then, the quantity of
oil produced and the number of companies exporting has increased. The
production in 1908 was 169 bbl., in 1912, 436,805 bbl.; and in 1917,
1,599,455 bbl.

Geology
Stratigraphy

All petroleum produced by Trinidad has been yielded by strata of
Tertiary age. In general, the Tertiary strata consist of clays, shales,
marls, and sandstones; conglomerate is extremely rare and limestone is
uncommon. The sandstone is usually composed of small quartz grains
uniformly sorted. Cretaceous and metamorphic rocks underlie the
Tertiary. The most important portion of the Tertiary strata consists
of sandstone and shale, which grades upward into marl and shale con-
taining marine organic material and evidences of petroleum. The organic
material in this shale is probably the primary, or "mother," source
from which Trinidad petroleum is derived. The upper portion of the
shale contains sandy strata into which petroleum has migrated and ac-
cumulated in quantities sufficient for commercial exploitation. Eocene
fossils occur in the lower part, but the upper part may extend into the
Oligocene. This includes the Naparima clay, Cruse oil zone, and Stoll-
meyer oil zone.

The Morne TEnfer formation unconformably overlies the above-
mentioned, and consists of sandstone and clay shale in approximately
equal proportions. The lower sandstones are often heavily impregnated
with asphalt and often outcrop as "pitch sand" cliffs. The author
believes that this asphalt has migrated from the imderljring shales and
marls. Near Pitch Lake, some oil may be produced from this formation.
Strata younger than the Mome TEnfer have not yielded commercial
quantities of oil and are unimportant.

The accompanying tabulation describes the geological formations of



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OEOBOB A. MACBSADT 61

Trinidad in more detaQ. The areal distribution of the formations is
shown approximately on the map.

Structure

The areal geology of the island is separated into two parts by the
great east-west fault passing near Port of Spain and Matura, and ex-
tending from the Atlantic Ocean into Venezuela. North of the fault is
the area of Metamorphics, forming the Northern Moimtain Range.
South of the fault is a great undulating blanket of Tertiary, strata.

The dominating features of the Tertiary structure are: A synclinal
or monoclinal trough between the Central and Northern Mountain
Ranges; an anticlinal uplift along the south side of the Central Range
striking east-northeast by west-southwest, from Pointe k Pierre toNariva
Swamp; an undulating synclinal structiu-e between San Fernando, May-
oro Point, Guayaguayare Bay, and Icacos Point with an east-west strike;
the magnitude of erosion at the imconformity below the Morne TEnfer
formation. Numerous local folds, faults, kinks, anticlines, and synclines
modify the broader features and are very important in the concentration
of petroleum.

Occurrence oj Petroleum

All the producing oil fields of Trinidad (except Tabaquite Field) are
within or on the flanks of the great synclinal trough or basin of the
southern part of Trinidad. Most of them are on the southwest penin-
sula. This imdulating synclinal structure is underlain by Naparima
clays, marls, and organic shales. It forms the drainage area from which
petroleum has accumulated. This petroleum has concentrated in com-
mercial quantities near anticlinal folds.

The location and richness of each productive area are modified by
the magnitude and condition of the unconformity below the Morne
I'Enfer formation; by the channels of migration; by the local conditions
of porosity of reservoir sands; by the lenticular condition of the oil
sands; by the facility with which connate salt waters were displaced by
oil. There are three principal horizons in which petroleum usually,
but not always, is concentrated in commercial quantities.

The Cruse oil zone is persistent because its proximity to the organic
shales permits ready saturation, has permitted much time for connate
waters to be forced out, and Tertiary erosion has not attacked it as
frequently as higher strata. Its thinness and high gas pressure increase
operating cost. This condition applies at Parry Lands, Morne TEnf er
Forest Reserve, and Point Fortin.

The Stollmeyer oil zone overlies the organic shales and the sands are
lenticular. The porosity and saturation of the oil sand varies locally.



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62 PETR0LEX7M INDUSTR7 OF TRINIDAD

It may or may not, locally, be conformable below the Home PEnfer
formation or it may be entirely missing. Where apparently conformable
below the Morne TEnfer formation, conditions are simple and anticlinal
structures may prove very rich, as in the Morne I'Enfer Forest Reserve.
As the unconformity increases, modifications occur. Part of the Stoll-
meyer sand may have been removed by erosion and the remainder sealed
by the clayey base of the Morne TEnfer formation. One flank of an
anticline may prove richer due to better drainage area on that side, as
may be the case at Lot One. A flank of the anticline may be enriched but
the apex barren because the sand is missing; such may be the case at
Point Fortin, Barracpore, and possibly at Brixton. Connate salt water
has not been completely forced out of all the sand lenses but usually
remains only in the lowest lenses.

The Morne TEnfer formation is enriched by oil migrating from the
underlying organic shales. Where the organic shales lie close below as a
result of Tertiary erosion and the Morne TEnfer sands are not too thick
or too clayey at the base, saturation may be sufficient for conmiercial
production; such may be the condition in fields near Pitch Lake. Where
the sand is too thick and petroleum has migrated slowly, saturation may
not be sufficient for commercial production; such may be the condition
of pitch sands in the Forest Reserve.

Near Tabaquite, petroleum has concentrated in sands closely associ-
ated with organic shales but too distant from other fields for correlation.

Technology
DrtUing

The rotary system of drilling has proved most successful in the produc-
tive fields. Cable tools are usually confined to some, but not all, isolated
test wells, to special work, and to repairing damaged wells; but in the
early days many wells were drilled and finished with them. Portable
drilling machines have been successful for shallow wells in the central
and extreme southern portions of Trinidad. Some wells have been
drilled with Canadian and Galacian outfits.

Some difficulty is encoimtered in penetrating pitch strata. If sandy,
they are hard and wear off rotary bits. If clayey, they are plastic and
squeeze slowly but persistently into the hole and grip the drill pipe above
the bit; this has been overcome by using hot water circulation and driving
casing through the pitch.

For wells expected to be over 1000 ft. (305 m.) deep, it is conmion
practice to drill with rotary and set 15^^ in. 70-lb., 13-in. 54-lb., or 12J^-
in. 50-lb. screw casing as the outside string. Either this or the succeeding
one is used to shut off water preferably, but not always, by cementing.
Wells are usually drilled into the oil sand using 6-in. (15.24-cm.) or 8-in.



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QEOBGB A. MACBBADT 63

perforated drill pipe equipped with a blow-out preventer on an outer
string. With all in readiness to receive a big flow of oil, drilling proceeds
until the oil sand is drilled through or the flow of oil and gas prevents far-
ther progress. Then the drill pipe is left as it is and the wash pipe
recovered when convenient. In shallow fields, a common practice is to
set about 100 ft. (30.5 m.) of 12^-in. (31.76-cm.) casing as a conductor
and then to drill through the oil zone. Perforated casing is substituted
for drill pipe and the well tubed to pump or flow as the case may be.

Casing is not perforated in the well if it can be avoided; the usual
practice is to set shop perforated casing. Screen casing has not been
successful because of clogging with clay. Explosives are never used to
increase production and rarely to break up junk.

For a well 1500 ft. (457.2 m.) deep, 60 days is a fair average time from
first actual drilling until production begins. This includes usual delays,
casing setting, changing crews, waiting, etc. The actual number of
days in which hole is dug may be as low as fourteen. In 1918, $15,000
was a fair average cost to the depth of 1500 feet.

Production

Wells in the thin deep sands usually begin production with a large
initial flow or gust under great gas pressure, yielding up to 100,000 bbl.
in the first few days and later choking with sand or shale. During the
first year, the production is dependent largely on spasmodic flows aided
by bailing or tubing agitation, but after the first year few wells yield
over 100 bbl. daily. The shallower wells with thicker oil sands begin
production sometimes as pumpers and sometimes by flowing. The
initial flow averages much less than for the deeper weUs, but is less
spasmodic and less costly to control. Few wells flow for over a year.

After wells cease flowing they are usually pumped by the walking
beam. Sand and mud must be cleaned out frequently for two years or
more. None of the southwest fields have been successful in
pumping from a central power or jack. Few wells have produced over
eight years and many cease producing in the second or third year. The
production of individual weUs is greatly influenced by the local porosity
of the oil sand and the size of individual oil-sand lenses.

Character oj Petroleum

Trinidad petroleum varies greatly in specific gravity, not only in
different fields, but also within the same field. It is (with one exception)
of asphaltic base. Oil from the Trinidad Central Oil Fields, Ltd., near
Tabaquite has little asphalt but some paraffine, and yields much gaso-
line and kerosene by distillation. The average specific gravities for



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64



PETROLETTM INDUSTRT OP TRINIDAD



Geologic Column of Trinidad



Age


Name
of

Por-
matioii


Thick'
new.
Feet


LitbdoRy

Petroleum Evidence

Foldins


MiaceUaneona Remarki


^


a
1


40


PrinripaUy eoft cUy. eilt. vegetable
remaine. Lcm tand. Rarely eon-
glomeritio.

Asphalt oonet and eeepafes and mud
▼olcanoee occur by breaking through
from underlying formation!.

Never tUted.


Contiata of stream alluvium and
swamp deposits.



Unconformity



100 Ferruginous sands, clays and con- |
I glonierates.

, Evidences of an>halt occur b^ break-
ing through m>m underlying for-
mations.
Usually nearly flat; rarely tilted to 5*.



_ I



I



! i

! %

a

I ^



The Llanos formation consists of ma-
terial deposited in the basin of which
the present Orinooo Vallejr was a
portion. Large areas occur in Vene-
sucla. particularly in the Uanos, or
plains, of the Orinoco River Valley,
but in Trinidad where the formation
appears thinner, erosion has dissected
it until only hill-top remnants and a
few larger areas remain.

When seen from the Gulf of Paria, the
topography of southern Trinidad has
the appearance of a former flat
surface, such as a sea bottom, up-
Ufted to a pUteau 100 to 300 ft.
above sea level through which
** islands'* or peaks of older resistant
rocks project. (Erin Peak. Mome
I'Enfer. Soldado Rock. Naparima
Hill for example.) The present
drainage system has dissected this
plateau Into a low, but steep topo-
graphy gentler than canyon topo-
graphy.



Unconformity



400



s



b4



Porcellanite, lignitic clay, lignite,
partly altered wood, shale, dav, and
sandstone exhibiting great lateral
variation in character. Conglomer-
ates not known.

Rarely eontains asphalt and has no
commercial oil honions.

Usually found tilted but rarely over
35'.



Usually occurs within syndines flanked
by the TEnfer formation. It may
be of fresh-water origin of material
derived from the older tertiary
rocks. In troughs, or syndines, de-
position may have been uninterrupted
between this and the Llanos forma-
tion.

This formation corresponds to the

upper tertiary strata in reports of

E. H. Cimningham-Craig.

I Porcellanite has not been proved to

I exist in other formation in Trinidad.



Unconformity Oocally)






'I ^



2500 Sandstones of uniform small auarti

grains separated by bands of day

shale and rarely by lignite.

I No conglomerate known.

The lowest sands are commonly

saturated with asphalt. Near Mome

* I'Enfer 300 ft. of "tar sand" has

I been observed in the lowest 700 ft.,

some of which was very rich.
I Some of the oil fields nearest the Pitch
I^ke may derive production from
sands of thiii formation.
Tilting is commonly over 20* but
rarely as much as 00*.



The following thicknesses have been
measured: 2500 ft. at Erin Bay,
1200 ft. at Guapo Bay, 000 ft. at
Vessigny Bay, 800 ft. at Mome
I'Enfer.

Fossils of doubtful Oligocene age have
been found near this formation. In
the Centra] Rani^e mountains. Mio-
cene fossils occur in what may be the
equivalent formation Because of
the great unconformity bdow this
formation, the author prefers to
regard it as Miocene.

The name of this formation is sdected
because of its occurrence in the
Morne I'Enfer Forest Reserve.



500 Blue and gray clay often very sticky.



wo,



This forms the impervious cover over
the Stollmeyer oil tone.

The author is convinced that there is a
great unconformity below the Moma
rEnfer formation, but owing to the
clayey non-resistant nature of tha



VOL. LXV. — 5



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OaOBOB A. ICACBBADT



65




■trata the ezftet horiion it diffioult
to identify. It probably ocoun in
these elaye, below the loweet Morne
inSnfer umd.

This condition was obeenred by the
author on a muoh smaller scale at a
small island which rose oTemight
from the sea near Trinidad in 1911.
A few weeks later waves had eroded
it oompletely and deposited toe
material on similar adjacent clayey
material.



I Unconformity




500



Orerlappinc p anca k e-shaped lenses of I This is the most profitable oil forma-
nnd and shale alternating. .....



I The sands contain oil and salt water,
. the best saturation of c^ being in the
I upper part of toe sons and not far
; from an anticlinal axis.
Salt water is usually confined to the
lower lenses, but has been found at
I the top of the tone.



tion on Trinidad.

It is difficult to correlate individual
lensss from well to well but the group
or sone can easily be traced through a
field.




600 Prindpally day shales with occasional
lenses of sand. Foraminifera occur
in the lower part of these shales.
Some of the sand lenses are highly
I saturated with petroleum and gas '

under great pressure.
Lenses occasionally contain salt water, i



Several oil wells srield production from
restricted sand lenses in this forma-
tion.



40 , Sand.

' Often saturated with petroleum and

gas under great pressure.
. Salt water may occur. I



This is the most persistent oil horison
on Trinidad, but its thinness, depth,
and violent gas pressure increases the
cost of exploiUtton. It is identified
over a large area in the northern
portion of the Morne i'Enfer Forest
Reserve where it occurs 1000 to 1200
ft. bdow the top of the Stollmeyer oil
sone. Many of the gaa-mud vol-
canoes of Trinidad may occur near
the outcrops of this horumi.



4000



I



Clay, shale, and marl containing
marine organic matter.

Outcrops often with a perceptible
odor of kerosene and where an
irridescent film of oil covers poob
of water. Manjak veins occur near
San Fernando.

Conunonly tilted to vertical with
abrupt changes and overturns.



Large areas outcrop nsar San Fer*
nando. Folding is so complex and

I abrupt that it is diflicult to obtain a

reliable measurement of thickness.

This formation may be the "mother

, rock" from which the petroleum of

! Trinidad is derived.

, Some of the light oil from Trinidad

I may come from wells in this forma-

I tion.



, Clay and shale and hard gritty sand-
stone.



Eocene foesils occur in or bdow the
Naparima day. The author has not
made extensive studies of the
Tertiary strata below the Naparima
day.



< Unconformity



is



Dark, black or brown shale and lime-
stone.



Cretaceous strata have been reported
in limited areas in the Central Range
of Trinidad and doubtfully farther
south. Large mountainous areas
of Cretaceous occur in Venetuda.



Unconformity



81



I Schist, gniess (Pre-Cretaceous vol-
I canics near Toco).



The Northern Range of Trinidad con-
sists of a metamorphoeed complex
bounded on the south by an east-
west fault passing near Port of Spain
and Nature Bay, and extending Into
the Atlantic Ocean and Venesuda.



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66 PBTBOLXUH INDU8TBT OF TRINIDAD

different fields are: 0.9524, 0.9722, 0.9589, 0.9459, 0.9333, 0.9211, and
0.8092; or, 17% 14% 16% 18% 20% 22% and 43^ Baurn^,.

Transportation and Utilization

The Trinidad Lake Petroleum Co., Ltd., and the Petroleum Develop-
ment Co., Ltd., together operate a 6-mi. (9.66 km.) pipe line from the
Morne I'Enfer FcHrest Reserve to a tank farm at Brighton near Pitch
Lake beginning as 4 in. (10.16 cm.) and increasing to 10 in. (25.4 cm.).
At Brighton pier are facilities for docking and loading steamers up to 35,-
000 bbl. in 24 hr. Much of this ofl has been exported to the United
States for industries using asphalt and its products.

The Trinidad Leaseholds, Ltd., operates approximately 28 mi. (45
km.) of 6-in. (15.24 cm.) pipe line from the Morne PEnfer Forest Reserve
to Pointe k Pierre, with a short side branch from Barracpore. At Pointe
k Pierre is a tank farm and pipe trestles to a loading station 1 mi. (1.6
km.) from shore where full-size tank steamers can be loaded. Most of
this oil has been taken by the British Admiralty, although considerable
has been disposed of as bunker fuel to steamships and some has been
refined at Pointe k Pierre.

The United British Oilfields of Trinidad, Ltd., operates a 6-in. (15.24
cm.) pipe line 6 mi. (9.66 km.) in length from the Morne FEnfer Forest
Reserve to Pcnnt Fortin, with an additional branch contemplated. At
Point Fortin, oil is loaded in barges and towed to tankers anchored in
the Gulf of Paria. Loading a tanker requires several days. A refinery
at Point Fortin produces " navy fuel." Most of this oil has been taken by
the British Admiralty, but some of it has been disposed of as bunker fuel
oil to steamships and some early shipments went to various places.

The Trinidad Central Oilfields, Ltd., operates a 3-in. (7.62 cm.)
pipe line from the Tabaquite oil field to a loading pier at Claxtons Bay.
This oil is very high in gasoline and is nearly all refined for petrol, kero-
sene, and fuel residue.

StoUmeyer, Ltd., operates a 2-in. pipe line 2 mi. (3.22 km.) in length
from near the Morne I'Enfer Forest Reserve to Guapo Bay where saQ
lighters can be loaded.

Future Possibilities

The future of the petroleum industry of Trinidad depends on the
discovery of new oil fields or units as much as on complete exploitation
of the known fields. The most obvious oil fields are already in exploi-
tation. The writer is confident that a thorough search will result in
the discovery of other oil fields which will compare favorably with the
known fields.



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DISCUSSION 67

The discovery of new oil fields necessitates the drilling of isolated test
wells of which most will be barren. Exploratory drilling should be guided
by a thorough geological study of a broad area with special attention to:
The magnitude and trend of the unconformity below the Home TEnfer
formation, character of strata below this imconformity, and geologic
folding. Such geological study will reduce the number of barren wells,
which is the greatest expense of exploration. In the known fields a
continuous drilling program will be necessary to maintain the production
with declining wells.

DISCUSSION

Ralph Abnold, Los Angeles, Calif. — The Trinidad field has been the
graveyard of the reputation of many drillers and production men. Ap-
parently the effort to hold back this clay and sand by the use of strainers
is unsuccessful because the well will gradually plug up to such a point that
every known method will fail to loosen the pores and allow the oil to come
in. As wells put down near old producers will show large initial produc-
tion, the ultimate yield of oil will be increased by putting down secondary
wells.

In one field, a perfect dome, the sand is in lenticular form. At first
the wells showed considerable water but now the oil pumped is free
from wat-er.

E. DbGolyer, New York, N. Y.— I have imderstood that the chief
difficulty in Trinidad operations was to find any strainer that would hold
back the sand, which is of uniformly fine grain. The ordinary sand is
composed of grains of assorted sizes. The strainer lets the fine sand pass



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