Hydrocarbon Seals: Importance for Exploration and Production

249 Pages·1997·37.953 MB·1-250\249

by  P. Møller-Pedersen and A.G. Koestler (Eds.)

Preface
In January 1996 a total of 270 conference participants gathered for 3 days in Trondheim, Norway,
to focus on and to discuss the complex topic of hydrocarbon seals particularly related to deformation
zones and to caprocks. All together 32 oral papers and 9 poster were presented. There was also a ple-
nary discussion and informal gatherings.
The conference was the first in Norway and one of the first in Europe to exclusively address this
very important subject. The purposes of the conference were to present some of the most recent re-
search results, to establish state-of-the-art with respect to understanding hydrocarbon seals and to dis-
cuss where to go from here to find some of the keys to successful future exploration and enhanced oil
and gas recovery. Out of the presented papers and posters, 71 are compiled and published in this vol-
ume. These provide a good overview of and an introduction to the numerous aspects covered during
the fruitful days in Trondheim.
In the introductory paper by K.J. Weber, a wide-ranging and well illustrated historical overview,
the development of theories and methods to predict and quantify trapping mechanisms is presented.
The paper covers the period from the early days of the oil business around 1850 up to now and it
contains a significant amount of previously unpublished historic material.
The section on fault seals comprises a total of 01 papers ranging from case studies to in-depth
studies of specific sealing mechanisms. R.J. Knipe et al. provide an introduction to fault seals and
processes, describe how properties and evolution of seals within fault zones can be evaluated and sug-
gest ways forward to improve fault seal risk evaluation. F.K. Lehner and W.F Pilaar document some
previously unpublished observations from a study of clay smears in synsedimentary normal faults dis-
played in lignite mines at Frechen in Germany. Although several earlier studies covered these beauti-
ful outcrops, a new approach to the well documented observations confirm that substantial clay
smears can occur if ductile shale source beds are faulted at slow displacement rates. J.R. Fulljames
with co-authors present a method to systematically analyse fault seals and to quantitatively approach
the prediction of two types of fault seals, namely juxtaposition seals and fault gouge seals. C. Childs
et al. provide a description of the complexity of fault zones based on outcrop studies. They outline a
model for the development of the complex internal structures which seem to be important for the
evaluation of the sealing potential. The way forward in fault seal prediction is in the authors' opinion
by refinement of current empirical and comparative methods through more detailed characterisation of
sub-surface faults.
A study of fracture systems and rock mechanical properties of the cap rocks of the Late Jurassic
Fuglen and Hekkingen Formations in the south-western Barents Sea, Norway, is presented by R.H.
Gabrielsen and O.S. Klcvjan. They propose that leakage of hydrocarbons to the surface caused by the
Tertiary uplift and erosion could be related to one of four fracture groups associated with major fault
zones. To predict deformation mechanisms and cementation of faults in sandstones, E. Sverdrup and
K. BjCrlykke developed models by studying cores and outcrops. Timing of faulting relative to the di-
agenetic processes is critical and fault characteristics and cementation can be predicted by relating
fault episodes to the diagenetic history of the basin. T. Fristad et al. describe a methodology to predict
fault-seal behaviour from analysis of a detailed depth model in conjunction with detailed lithological
mapping. The case study concentrates on the Oseberg area in the North Viking Graben, Norway. An-
other case study done by A.I. Welbon et al. documents a fault seal analysis of the Greater Heidrun
area in Mid-Norway. The study assesses the control of fault seal on migration, trap integrity and fill-
ing history, which serves as a basis for assessment of risk parameters for exploration prospects and
their subsequent ranking. A. Makurat et al. present results from laboratory tests to study flow behav-
iour associated with fractures. They conclude that five factors in addition to the fracture orientation
affect the flow along and across fractures. These are uniaxial compressive strength, permeability and
porosity of the intact rock, fracture roughness, shear displacement and the ratio between effective
iv ecaferP
stress on the fracture and the compressive strength of the intact rock. T.R. Harper and E.R. Lundin
review the predictability of juxtaposition and deformation seals, describe the mechanisms of shear
bands and clay smear, estimate the sealing capacity of shear bands and assess the influence of present-
day stress on the sealing capacity of faults.
G.M. Ingram and M.A. Naylor introduce the section on migration and top seal integrity totalling 6
papers by presenting an approach to top seal assessment. They review the physics of capillary sealing
and flow barriers, discuss static versus dynamic sealing and present a technique for assessing the ef-
fect of sub-seismic fault populations within the top seal. A model for gas migration is developed by D.
Kettel based on history matches of gas flow by diffusion and Darcy flow through nine known gas
fields sealed by salt. The model can be used to derive permeability/depth functions for rock salt that
may be used in the prediction of the degree of gas fill for a prospect. N.C. Dutta describes a technique
to predict pore pressure before drilling based on seismic velocity data. Examples from deep water ar-
eas of the Gulf of Mexico are shown. The technique allows seal failure risk assessment for prospects.
R. Olstad et al. has studied the porewater flow and petroleum migration in the SmCrbukk area, Nor-
way. They found that a major sealing fault zone has affected lateral migration and has caused the de-
velopment of high overpressure cells. The authors conclude that petroleum migration cannot be in-
ferred from the pressure distribution because the permeability changes continuously due to diagenetic
processes. The Njord Field, Norway, is an interesting case of reservoir compartmentalization as dem-
onstrated by T. Lilleng and R. Gundesr Formation pressure data confirms the presence of sealing
faults creating hydraulic compartments. A dynamic model of active hydrocarbon migration coupled
with vertical leakage through breaching of the reservoir top seal is discussed. D.M. Hall et al. review
the processes for top seal failure in the greater Ekofisk area, Norway. There is no evidence that a sig-
nificant amount of leakage has occurred as a result of hydraulic breaching, tectonic breaching or cap-
illary leakage. The authors argue that pressure-inhibit charge is an alternative explanation for the lim-
ited extent of the hydrocarbon columns in some structures.
The editors hope that this volume will make a contribution towards a better understanding of hy-
drocarbon seals and that it may stimulate further research and studies. The aim would be to improve
understanding and promote proper application for the numerous cases where sealing prediction might
be the key for enhanced recovery or more effective exploration. We would like to thank all the con-
tributors for their interest in the topic and their cooperation during the preparation of this volume. The
important work done by reviewers of the papers is highly acknowledged. Thanks are given to NPF,
who made this conference possible. Finally, we would like to encourage further research within this
field of geology and engineering to make creative steps towards unraveling the true potential of seal
evaluation and predictions to improve hydrocarbon exploration and production.
Per MOller-Pedersen
The Norwegian Oil Industry Association, P.O. Box 547, N-4001 Stavanger, Norway
Andreas .G Koestler
Geo-Recon A/S, Munkedamsveien 59, N-0270 Oslo, Norway
vii
List of Contributors
L. BACKER Norwegian Technical Institute, P.O. Box 3930 Ullevaal Hageby, Sogns-
veien ,27 N-0806 Oslo, Norway
A. BEACH Alastair Beach Associates Ltd., 11 Royal Exchange Square, Glasgow, 1G
A3 ,J UK
K. BJORLYKKE Department of Geology, University of Oslo, P.O. Box 1047, N-0316 Oslo,
Norway
P.J. BROCKBANK Alastair Beach Associates Ltd., 11 Royal Exchange Square, Glasgow, 1G
A3 ,J UK
C. CHILDS Fault Analysis Group, Department of Earth Sciences, University of Liver-
pool Liverpool L69 3BX, UK
M.R. CLENNELL Rock Deformation Research Group, Department of Earth Sciences, Uni-
versity of Leeds, Leeds, LS2 9JT, UK
B.A. DUFF PetroFina ,as Rue de l'industrie ,25 B-1040 Bruxelles, Belgium
N.C. DUTTA BP Exploration Inc., 200 Westlake Park Boulevard, Houston, TX 77079,
ASU
M. ELIAS Fina Italiana, Viale Premuda ,72 1-20129, Milano, Italy
A.B. FARMER Rock Deformation Research Group, Department of Earth Sciences, Uni-
versity of Leeds, Leeds, LS2 9JT, UK
Q.J. FISHER Rock Deformation Research Group, Department of Earth Sciences, Uni-
versity of Leeds, Leeds, LS2 9JT, UK
O. FJELD Phillips Petroleum Company Norway, P.O. Box 220, 4056 Tananger,
Norway
R.C.M.W. FRANSSEN Shell Oil Company, OPA, P.O. Box 4704, Houston, TX 77210-4704, ASU
B. FREEMAN Badley Earth Sciences Ltd., North Beck House, North Beck Lane,
Hundleby, Spilsby, Lincolnshire, PE23 5NB, UK
T. FRISTAD Norsk Hydro, P.O. Box 200, N-1321 Stabekk, Norway
J.R. FULLJAMES Shell International Exploration & Production BV., P.O. Box ,06 2280 AB
Rijswijk, ehT Netherlands
R.H. GABRIELSEN Department of Geology, University of Bergen, All~gaten ,14 N-5007 Ber-
gen, Norway
A. GROTH Norsk Hydro, P.O. Box 200, N-1321 Stabekk, Norway
R. GUNDESO Norsk Hydro Produksjon a.s., N-5020 Bergen, Norway
M. GUTIERREZ Norwegian Technical Institute, P.O. Box 3930 Ullevaal Hageby, Sogns-
veien ,27 N-0806 Oslo, Norway
S.R. GYTRI Fina Exploration Norway, SkOgstostraen, P.O. Box 4055, Stavanger, Nor-
way
D.M. HALL PetroFina ,as Rue de l'industrie ,25 B-1040 Bruxelles, Belgium
iiiv List of Contributors
T.R. HARPER Geosphere Ltd., Netherton Farm, Sheepwash, Beaworthy, Devon EX21
5PL, UK
A. HARRISON Rock Deformation Research Group, Department of Earth Sciences, Uni-
versity of Leeds, Leeds, LS2 9JT, UK
G.M. INGRAM Shell International Exploration and Production, Research & Technical
Services, P.O. Box ,06 2280 AB Rijswijk, ehT Netherlands
G. JONES Rock Deformation Research Group, Department of Earth Sciences, Uni-
versity of Leeds, Leeds, LS2 9JT, UK
D.A. KARLSEN Department of Geology, University of Oslo, P.O. Box 1047, N-0316 Oslo,
Norway
D. KETTEL Kettel Consultants, Ch~tellon de Cornelle, 01640 Boyeux .tS Jgr6me,
ecnarF
B. KIDD Rock Deformation Research Group, Department of Earth Sciences, Uni-
versity of Leeds, Leeds, LS2 9JT, UK
O.S. KLOVJAN Norsk Hydro U&P Research Centre, N-5020 Bergen, Norway
R.J. KNIPE Rock Deformation Research Group, Department of Earth Sciences, Uni-
versity of Leeds, Leeds, LS2 9JT, UK
S.D. KNOTT 3 Creagbat Avenue, Quarriers Village, Bridge of Wear, UK
F.K. LEHNER Institute for Geodynamics, Bonn University, Nussalle ,8 D-53115 Bonn,
Germany
T. LILLENG Norsk Hydro Produksjon a.s., N-5020 Bergen, Norway
E.R. LUNDIN Statoil Research Centre, Postuttak, 7005 Trondheim, Norway
A. MAKURAT Norwegian Technical Institute, P.O. Box 3930 Ullevaal Hageby, Sogns-
veien ,27 N-0806 Oslo, Norway
E. MCALLISTER Rock Deformation Research Group, Department of Earth Sciences, Uni-
versity of Leeds, Leeds, LS2 9JT, UK
M.A. NAYLOR Petroleum Development Oman LLC, PDO Office, Mina al Fahal, Muscat,
Oman
R. OLSTAD Esso Norway ,SA PO Box ,06 N-4033 Forus, Norway
T. PEDERSEN Conoco Norway Inc., Randberg, PO Box 488, N-4001 Stavanger, Norway
W.F. PILAAR J.F. Kennedy plantsoen ,36 2252 EV Voorschoten, ehT Netherlands
J.R. PORTER Rock Deformation Research Group, Department of Earth Sciences, Uni-
versity of Leeds, Leeds, LS2 9JT, UK
E. SVERDRUP Saga Petroleum ,sa P.O. Box 490, N-1301 Sandvika, Norway
S. THOMAS Statoil a.s., 4035 Stavanger, Norway
J.L. URAI Geologie-Endogene Dynamik, RWTH Aachen, Lochnerstrasse4-20, D-
52056 Aachen, Germany
J.J. WALSH Fault Analysis Group, Department of Earth Sciences, University of Liver-
pool Liverpool, L69 3BX, UK
J. WATTERSON Fault Analysis Group, Department of Earth Sciences, University of Liver-
pool, Liverpool, L69 3BX, UK
K.J. WEBER Faculty of Applied Earth Sciences, Delft University of Technology, P.O.
Box 5028, 2600 AG Delft, ehT Netherlands
tsiL of srotubirtnoC xi
A.I. WELBON Alastair Beach Associates Ltd., 11 Royal Exchange Square, Glasgow, G1
3A ,J UK (now at Statoil a.s., Stavanger, Norway)
E.A. WHITE Rock Deformation Research Group, Department of Earth Sciences, Uni,
versity of Leeds, Leeds, LS2 9JT, UK
G. YIELDING Badley Earth Sciences Ltd., North Beck House, North Beck Lane,
Hundleby, Spilsby, Lincolnshire, PE23 5NB, UK
L.J.J. ZIJERVELD 21 Oxford Street, Edinburgh EH8 9PQ, UK
A historical overview of the efforts to predict and quantify
hydrocarbon trapping features ni the exploration phase
and ni field development planning
K.J. Weber
The story of the development of theories and methods related to trapping mechanisms is a fascinating succession of brilliant observations, ludi-
crous misconceptions, empirical trials, and eventually the breakthrough of sound geological and physical principles. It took some 30 years from the
start of the oil industry before petroleum geology began to have an impact. The period from 1885 to 1915 was very fruitful although the pendulum
swung too much the other way and exploration focussed on anticlinal traps only. However, by 1915 considerable progress had been made and most
trapping configurations had been recognised. Also the basic physical principles of trapping were understood in a qualitative sense.
The years from 1915 to 1935 saw the development of most of the important exploration tools and also the invention of wireline logging and
many petrophysical analysis methods. Consequently, the structural control on traps and the petrophysical characterisation improved significantly.
By 1935, so much oilfield data had become available that several geologists in succession designed detailed classification systems for trapping
configurations.
After 1935, the physics of rock mechanics, flow in porous media and interfacial tension formed the subject of important studies that put petro-
leum geology and engineering on a much more scientific footing. This led in turn to more quantitative analysis of trapping capacity and trap integ-
rity. After 1955, there was another upsurge in technical sophistication with respect to seismic quality, wireline logging, geochemistry and labora-
tory equipment.
More recently, the understanding and quantification of trapping has improved steadily through sophisticated well test analysis, reservoir per-
formance monitoring, borehole imaging logs and, in particular, the detailed images provided by 3D-seismic. Outcrop studies have been undertaken
to learn more about fault zones. Research is by no means finished and there is still a wide variety of uncertainties and controversies concerning
trapping phenomena.
Early struggles, 1850-1885 and oil production on anticlinal structures in the Ye-
nang Yaung field in Burma already in 1855. That
In nearly all oil-producing basins, numerous seeps other types of accumulation existed also was clear
exist. Early usage of petroleum goes back to biblical from studies of the Pechelbronn field along the Rhine
times in the Middle East. The fact that seeps are often graben in the Alsace, where oil production from mine
related to faults and fractures was noted, and it was shafts was started in 1735.
even observed that seepages along the Dead Sea were In Indonesia, the oil seeps on Java were studied by
activated during earthquakes. a group of mining engineers from the Delft Univer-
The beginnings of petroleum production are al- sity who started to inventorise the mineral resources
ways around seeps. Some petroleum was collected as in 1850. In 1865 they had located 52 seeps in the
medicine, for example, near Modena (Fig. .)1 In this parts of Indonesia accessible at that time. Interest-
case, the seep is along a thrust fault and nearby oil ingly, the famous naturalist Junghuhn advised against
fields are not situated directly underneath the seep. drilling on Java. He argued that the strongly disturbed
However, many seepages take place along crestal and faulted beds were likely to be incapable of hold-
fractures of anticlinal structures. The earliest mention ing sizeable accumulations. Nevertheless, present
of this fact was made by William Logan, the first di- maps show that the recorded seeps overlie nearly all
rector of the new Geological Survey of Canada, in oil provinces that have since been located.
1842. He observed the coincidence of oil seeps with Drilling wells was already common practice by the
anticlinal crests in the Gasp6 peninsula near the time the first oil wells were planned. Particularly the
mouth of the St. Lawrence. drilling of brine wells for the production of salt was
Prior to drilling for oil, some oil was produced carried out in many places. In Pennsylvania this had
from hand dug pits in places like Burma and along occasionally led to the inadvertent penetration of oil
the Caspian Sea. Thomas Young of the Geological accumulations, which rendered the wells useless. Se-
Survey of India reported the occurrence of oil seeps neca Indians in this region used petroleum scooped
nobracordyH Seals: ecnatropmI for noitarolpxE and noitcudorP edited by P. M~ller-Pedersen and A.G. Koestler.
NPF Special Publication 7, pp. 1-13, Elsevier, Singapore. (cid:14)9 Norwegian Petroleum Society (NPF) 1997
2 K.J. Weber
ilblrlu liI lililolllr Ilul~lf:, Ioqiit:llc lltII;illilill cI ploiifllillllr
Fig. 1. Oil seep near Modena, Italy, used since medieval times to prepare medicines.
from pools to impregnate torches. Thus, the first oil Elsewhere, drilling for oil started at about the same
company was named Seneca Oil Company (Fig. 2). time, for instance, in Germany, at Wietze, in 1857,
In 1859, Drake drilled the first well which penetrated near a well-known seep. In Rumania, after starting
a productive oil accumulation at about 12 m depth. with hand dug wells, drilling started in 1882. In Baku
Production amounted to 25 barrels per day, soon and Grosny, in Russia, hand dug wells were followed
dropping to .51 by drilling in 1869. In Galicia, which at that time was
~
~ ' __ 4
~ j ~ " /de.hd:.'~
f .i. / ,. C,,.l ..... / # # #
~, e,
tgtRl ; rre~<.
"~ .Lith by ~'undeilioa/r Cris,~nd lqewll~.veRl~t , r,-_~--. .k
......
Fig. 2. Share of the first American oil company that undertook the first dedicated drilling campaign for oil.
1. HISTORY 3
was basic to those plans. He interested a number of people, human primates, including work on yellow fever and a variety
including the staff of Harvard's Museum of Comparative Zool- of encephalitis viruses through the 1930s.
ogy, the faculty of Columbia University's College of Physicians The Nobel prizewinning achievement of Landsteiner and
and Surgeons, and the Columbia University/University of Popper in isolating poliovirus in Vienna (1908, 1909) provided
Puerto Rico's School of Tropical Medicine (later to become a the real beginning of serious and widespread use of nonhuman
component of the University of Puerto Rico School of Medi- primates in biomedical research, using rhesus monkeys, ba-
cine), in the planning effort. He selected Cayo Santiago, a 15.2- boons, and chimpanzees in their work. The unique susceptibil-
ha (approximately 38 acres) island 1 mile off Puerto Rico's ity of nonhuman primates to a relatively new and frightening
eastern coastal town of Humacao, as the site for the colony. disease threat clearly established their special importance in
With the help of a $60,000 grant from a private foundation, research.
Carpenter set off for Indochina and India in 1938. He fared well The intense efforts to develop a vaccine against polio that
in collecting rhesus monkeys but not gibbons. Survival of the followed was unprecedented. It spanned the next 45 years, was
47-day voyage from Calcutta as deck cargo was a testimonial international in scope, and involved a host of major investiga-
to the enduring qualities of the rhesus monkeys and the care tors. However, it was a complex process that experienced seri-
that they received. By early 1939, 409 rhesus monkeys, 41 gib- ous setbacks. There were some promising early findings based
bons, and 3 pig-tailed macaques were released on Cayo Santi- on nonhuman primate studies using inactivated, or partially in-
ago. Eventually only the rhesus monkeys remained. activated, vaccines. However, those findings led to disastrous
Maintenance of the island and breeding were not without results when cases of paralytic polio occurred following vacci-
problems. Local fruits and vegetables did not provide an ade- nations in human clinical trials (Horstmann, 1985).
quate diet and malnutrition was overcome only by feeding fox Nevertheless, nonhuman primates played an important role
chow, the early precursor to monkey chow. Wells were dug, but in helping to put polio research back on track. In 1931, throat
the water was brackish. Cisterns and a system for collecting washings from patients were inoculated into monkeys and re-
rainwater had to be constructed. A number of monkeys were sulted in infection (Paul and Trask, 1932). Later work showed
lost through fighting or simply through being crowded out in that poliomyelitis was an enteric and not an olfactory infection.
the establishment of a stable social structure. Some escaped by The discovery by Enders and co-workers (1949) that poliovirus
swimming the channel to the mainland. Various diseases also could be grown in human tissue culture was a major scientific
took their toll and there were few opportunities to limit spread. advance which brought them the Nobel Prize for Medicine in
However, persistent efforts did finally result in eliminating 1954. It also provided a means to reduce the need for nonhuman
tuberculosis. primates. However, like the promise computers initially offered
Another problem was the lack of dependable financial sup- for reduction of paperwork, any reduction in the use of nonhu-
port for the project. In 1944, the University of Puerto Rico man primates was soon masked by a vastly expanded dn~: ac-
assumed full responsibility for support of the colony. Opera- celerated research effort which required even more animals.
tions languished until 1948 when efforts to attract badly needed Salk's report of a formalin-inactivated polio vaccine grown
outside support were successful. At that time, the National In- in monkey kidney cell culture paved the way for extensive and
stitutes of Health (NIH) awarded the first of a number of federal successful field trials (Salk et al., 1953). Unfortunately, this
awards to the University of Puerto Rico to help support Cayo dramatic achievement was clouded by uncertainty when im-
Santiago. Eventually, the island operation was incorporated as properly inactivated vaccine caused a number of cases of polio
a component of the University's Caribbean Primate Research in 1955 (Horstmann, 1985).
Center. At about the same time, Sabin was working on the develop-
Cayo Santiago has been a valuable resource through the years ment of a polio vaccine from another direction. Depending
for both the production of monkeys and for biomedical and greatly on the use of monkeys and chimpanzees, he searched
behavioral research. The experiences with Cayo Santiago have for attenuated strains of naturally occurring poliovirus. His
also shown that outside support, primarily federal government painstaking work reportedly used 9000 monkeys and 150 chim-
support, is essential for the long-term maintenance of nonhu- panzees (Sabin, 1985). The result was the development of an
man primate resources. oral polio vaccine that remains in widest use today.
While relatively modest in the early years, the use of mon-
keys increased dramatically following Salk's discovery of an
C. Virological Research and Nonhuman Primates
effective vaccine. The high point of this usage was in 1957 and
1958 when about 200,000 monkeys were imported annually
Technically, the modern use of nonhuman primates in bio- into the United States (Lecornu and Rowan, 1979). According
medical research had its origins in Pasteur's work with rabies to Lecornu and Rowan, the greatest single use of the more than
and the studies of others with smallpox and vaccinia in the late 2.1 million rhesus monkeys that were imported into the United
1800s. Kalter and Heberling (1971) and Gerone (1974) have States during the 20 years that followed Salk's discovery was
provided comprehensive reviews of virological research in non- for producing and testing polio vaccine.
4 K.J. Weber
he had already made several discoveries and his ideas petroleum) is covered by a protective layer, which has
began to have influence (Landes, 1951). From this been bent to a so-called saddle or anticline. The saddle
time onwards petroleum geology was clearly on the axis runs about parallel to the longitudinal axis of Su-
matra and a section perpendicular to the axis is shown in
way up in the USA, although one can say that the
the adjacent figure (Fig. 4); a-b is the petroleum soaked
anticlinical theory got too much attention to the det-
layer, which si encountered at 021 m below the surface
riment of consideration of other trapping configura-
at ,c and produces the large amounts of gas and oil; .d
tions. Later geologists have criticized some of
era fissures in the coveting rock, in which the oil rises
White's publications (White, 1885) and pointed out
by the pressures of the gasses in the oil layer to the sur-
serious discrepancies with the much more compli- face locally. Some of the covering layers that era more
cated reality. However, his influence was what or less porous have been fed by the fissures and have in
counted and we must remember the saying: "A pe- that way become secondary locations. (From the special
troleum geologist's life is a never-ending struggle commemorative book A Century of ,noitarolpxE 1885-
between brilliant concepts and inconvenient facts!" 1985, Shell Internationale Petroleum Maatschappij
(Lament of a Shell exploration guru). B.V., The Hague.)
Start of petroleum geology, 1885-1915 It is obvious from the above that the basic trapping
conditions were well understood. Surface mapping of
As an example of the state-of-the-art in petroleum structures also started at this time and on the section
geology around 1885, it is interesting to follow the of the Telaga Said field, the surface dips measured
history of exploration on the island of Sumatra in around the field are indicated (Fig. 5), This structure
Indonesia. The initial story is rather similar to the is situated on the same axial trend as the Telaga To-
enggal anticline at a distance of about 1 km towards
Pennsylvanian situation.
In 1880, a Dutch tobacco planter, A.J. Zijlker, the NW). In the USA this surface mapping became
popular after the famous Spindletop discovery in the
sheltering on a rainy night, noticed the long-burning
torches of the natives and found that these were anticlinical structure overlying a salt dome in 1901.
soaked in petroleum scooped from a nearby pool. He However, it would take 25 years before the oil reser-
managed to obtain a concession from the Sultan of voir trapped against the flanks of the dome would be
Langkat. To obtain capital for his venture, Zijlker found.
Good fieldwork and continued drilling near seeps
needed the assurance of a competent geologist that an
economic volume of oil might be present. For this he resulted in numerous discoveries in the USA but also
in Argentina, Venezuela, Trinidad, Mexico, Indonesia
had to turn to the government mining department.
and very importantly in the Middle East, in Iran.
Initially, he only received help in the form of a drill-
Typically, the discovery well in Iran at Masjid-i-
ing engineer and the first well was spudded near an
Suleiman is only a stone's throw away from a large
oil-covered pool. The well encountered some oil at a
depth of about 100 m, but deepening only led to wa- seep.
The first book on pertroleum geology appeared in
ter production. However, a second well, placed by
pure luck on the crest of an anticline, resulted in sig- 1915 (Hager, 1915) and in it, several types of trap are
described (Fig. 6). Production geological problems
nificant oil production at about 30 m and a blow-out
such as the gap in a reservoir as a result of a normal
of gas, oil and water when a depth of 121 m was
reached. This event, in 1885, heralded oil production
in Indonesia and is also the origin of the Shell com-
pany (Gerritson, 1939).
A proper analysis of the find came after a govern- .e,, e,,. ...~ _,, q .
ment mining engineer, R. Fennema, was put in tech-
nical charge in 1886. Fennema was not only a com-
petent engineer but also an accomplished geologist.
He carried out geological surveys and showed the
anticlinical nature of the oil accumulation at Talaga
Toenggal, the site of the discovery well. In one of his
letters from 1888 one can read the following:
At one boring near Telaga Toenggal really magnificent
Fig. .4 Sketch of a section across the Telaga-Toenggal anticline
results were obtained. Here the proper petroleum-
drawn by the mining engineer .R Fennema (1886). This section
reservoir had been reached; geological investigations clearly shows the stratigraphy, structure and fissures which control
related with the results of the wells has shown us that the hydrocarbon distribution (from A Century of ,noitarolpxE 1885-
this petroleum-reservoir a( thick sand layer soaked with ,5891 Shell Internationale Petroleum Maatschappij B.V., The Hague).
A historical overview of hydrocarbon trapping features 5
Beri~l ~ ~ ........ "%
Z.W. ~t2 -"" z az,, u s
(cid:12)9 " ....... N.O.
" ' - I _ I,_ ___v ""
..-- " r-r-" .t. l" '
. .--" .... d=a,,,., , . . r, , , , ,
(cid:12)9 mndT ~" u, (cid:12)9 "-
2our ~-~ter
, -. -- -- -- . . . . . ~, , ,'~ , x x "--; _.._
Dr Z. B/u~
Fig. .5 Section of the famous Telaga Said oil field which was the major oil producer in Sumatra at the end of the 19th century. The surface expres-
sions of the structure of this overturned anticline are indicated showing that geological field work had been executed (from Gerritson, 1939).
fault had been understood (Fig. 7). Correlations be- Migration can thus be upwards, downwards or
-
tween wells were carried out with the help of logs laterally.
made by glueing cuttings to narrow wooden planks. - Sometimes the more volatile oils will escape
Because the regular bailing out of the holes in cable where the strata have been eroded, unless asphal-
tool drilling gives a quite accurate depth control on tic or paraffinic deposits coat the faces of the
the sampling, this method results in excellent well strata, and act as seals.
records. The above gives a good overview of the state-of-
From Hager's book, it is worthwhile to paraphrase the-art in 1915. By that time the USA produced 65%
some of the keys statements: of the world's oil, Russia was second with 16%, fol-
- All oil and gas deposits, so far as known, are lowed by Mexico with 6%. Rumania and Indonesia
capped or covered by practically impervious beds produced 3% each, Burma and East Galicia with 2%
of shale, sandstone or limestone; also such beds and finally Japan and Iran with 1% close the list of
are underlaid by impervious beds. prominent oil producing countries in the fateful year
- No beds are actually impervious but are impervi- 1914.
ous only in a relative sense.
- Where faults or unconformities occur, water will Years of development, 1915-1935
force oil to enter the upper strata by driving it
from the lower sands. This is a period in which technical development
- Since water has about 50% higher surface tension was rapid. Rotary drilling led to much deeper drilling
than oil, it tends to be drawn into the finest capil- compared with the now outdated cable tool drilling.
laries with half again as much force as that draw- Surface mapping was insufficient to reveal the traps
ing oil into the fine openings. Thus the tendency is at greater depth, and a search was made for other
for water to occupy the shale and oil and gas to fill methods. In 1915, the first field use was made of the
the pores of the coarser strata. torsion balance in gravimetric surveys in Czechoslo-
1
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Fig. .6 Fault trap from the early book on petroleum geology by Hager (1915).