Geology and Geophysics, 2001, V 42, N 11-12, November-December.
Scientific heritage of A. A. Trofimuk
V. S. Vyshemirskii, A. E. Kontorovich, and G. S. Fradkin
THEORETICAL PROBLEMS OF OIL AND GAS GEOLOGY
PETROLEUM RESOURCES AND PRODUCTION
N. A. Krylov
The relationship between oil reserves and annual oil production is
considered. The correlations between the Russian and American resource classes
are discussed in the context of the difference in this relationship in Russia
and USA.
The notions of quality of explored reserves (reserve concentration, well
production rate, and recovery of initial reserves) and inferred resources
(concentration of the initial total resources and degree of their exploration)
are considered. Depauperation of residual resources of various classes during
their development is inferred.
The main results of prediction of petroleum production in Russia in the
21st century are reported. The peak of oil production is expected to be in 2020,
and of gas production, in 2030. A decrease in oil production to 2.0-1.8 <$Ecdot>
108 tons and in gas production to 3.5-1011 m3 is expected by 2100.
Petroleum reserves, explored reserves, production rate, prediction
GEODYNAMIC TYPES OF GLOBAL PETROLEUM-BEARING BELTS AND
THEIR CHARACTERISTICS
V. E. Khain and L. E. Levin
The main petroleum-bearing belts are confined to the passive margins of
continents - recent and ancient. The recent margins form three global belts
which can be considered subtypes differing in time and rifting-spreading stages:
Indooceanic-Atlantic, Circum-Arctic, and Mediterranean-Persian.
Sedimentary basins of the three subtypes are characterized by a high rate
of sedimentation, up to 5-10 cm/ka, but differ in recent thermal regime. One
subtype has an increased thermal regime with a depth of 100 °C isotherm of 2-2.5
km in separate basins. The other two subtypes are characterized by a different
thermal regime, with 100 °C isotherms established at depths of 5-7.5 km.
In the case of ancient passive margins, large fields are connected with
rift massifs. The post-rifting stage of these belts can be finished by thrusting
emerged near orogen and accompanied by formation of molasse foredeeps and
multilayer nappe structures. The second type of petroleum belts is confined to
active margins, mainly to the Circum-Pacific belt and Western Mediterranean
region. Associated with different-age zones of subduction, the basins of the
Caspian-Black Sea region can be distinguished as a specific subtype. Subsidence
at the last stage is accompanied by an avalanche rate of sedimentation, up to 30
cm/ka. The increased thermal regime (except for the basins of the Caspian-Black
Sea subtype) with 100 °C isotherms at depths of 1.5 to 2.5 km contributed to
quick generation of organic matter and the most complete realization of petroleum potential.
The third is intraplatformal type of petroleum-bearing belts associated
with continental platforms. It is subdivided into subtypes - rifting and
epirifting. In the first case, thermal regime is rather high, with the depth of
100 °C isotherm ranging from 1.5 to 0.5 km; in the second case it is low with
the depth of 100 °C isotherm of about 5 km.
The forth type includes basins of intermontane troughs of orogens. The
basins of this type are rather small but with thick sediments and high
sedimentation rate of 3-6 cm/ka at the Cenozoic stage. The thermal regime is
characterized by the depth of 100 °C isotherm of to 5 km in intermontane basins
of young orogens and to 1.5-2.5 km in rejuvenated orogens.
The sedimentary fill of active-margin basins and intraplatformal and
intermontane troughs of young orogens is subject to tangential stress caused by
collision of lithospheric plates and is characterized, especially along the
periphery, by fold-thrust strains, often with stripping of sedimentary units off
the basement or along the plastic horizons in the cover.
To estimate petroleum potential in each type of basins, it is necessary to
take into account some endogenic factors: thermal regime, deep-level fluids,
lateral stress, rate of sedimentation, etc.
Geodynamic types, thermal regime, rate of sedimentation, petroleum
potential
GIANT DEPOSITS: REGULARITIES IN DISTRIBUTION AND FORECAST POTENTIALITIES
M. D. Belonin and Yu. N. Novikov
The problem of forecast of the largest (giant) oil and gas deposits arises
not from insufficient empirical knowledge (most recoverable HC resources of the
world have been prospected) but from the necessity of its generalization and
theoretical justification. Transition from empirical to theoretical level of
knowledge requires a deeper integration of oil geology as a special study into
the general structure of natural sciences, which requires formalization of a
special knowledge in accordance with general principles and laws of the natural
science. Inductive analysis traditionally used in oil geology in the context of
historical and genetic approach must be complemented with deductive analysis
based on static approach. Particular methodological forms of the latter approach
are techniques of mathematical simulation, based on regularities in distribution
of HC resources of oil and gas basins (OGB) among deposits of various sizing
classes, and techniques of analogous structurization, based on regularities of
distribution of giant deposits in the planetary system of OGB.
HC deposit, giant deposit, oil and gas basin, regularities, distribution,
stock structure, organization levels, self-organization, induction, deduction,
static approach, forecast
THE DEPENDENCE OF GEOLOGICAL AND BIOLOGICAL PROCESSES ON THE
POSITION OF THE SUN IN ITS GALACTIC ORBIT
S. G. Neruchev
Astronomical and geochronological substantiation of galactic years and the
orbital geochronological scale are considered. Climatic seasons of Phanerozoic
galactic years are recognized. The dependence of various geochemical and
biological phenomena and events, as well as formation of mineral deposits, on
the position of the Sun in its galactic orbit and the related galactic climatic
seasons is discussed.
Periodicity, galactic year, climatic seasons, glaciations, transgressions,
vegetations, coal, oil
THEORETICAL FOUNDATIONS OF PREDICTING THE PETROLEUM POTENTIAL OF
SEDIMENTARY BASINS WITH INTENSE MANIFESTATION OF TRAPPEAN MAGMATISM
E. Kontorovich and A. V. Khomenko
The paper considers the criteria of influence of trappean magmatism on the
petroleum potential of sedimentary basins. Particular emphasis is placed on the
thermal effect of intrusive bodies on organic matter and hydrocarbons. The
principles of classification of sedimentary basins are presented based on the
degree of maturity by the time of the most intense stage of trap intrusion. The
foundations of the technique of calculation of the predicted hydrocarbon
resources are given for the basins of different types.
Trappean magmatism, prediction of petroleum potential
ROLE OF PAST EARTHQUAKES IN FORMATION OF OIL AND GAS ACCUMULATION ZONES.
K. I. Mikulenko
Studies of the traces of Riphean and Phanerozoic earthquakes in the
Caucasus, West Siberian Plate, and Siberian Platform, as well as their
comparison with the geological evidence of modern earthquakes, show that they
may have played a role in the formation of oil and gas traps and accumulation
zones. The seismogenic zones of oil and gas accumulation, which are of three
main varieties (autochthonous, allochthonous, or transit), are considered in
terms of their formation mechanisms and prediction. For such zones in the
Caucasian foredeep, West Siberian Plate, and Siberian Platform, probable
stratigraphic levels, locations, and types are outlined and example predictions
are suggested.
Past earthquakes, autochthonous, allochthonous, and transit traps, zones of
oil and gas accumulation
GEOLOGIC AND GEOPHYSICAL PREREQUISITES FOR THE EXISTENCE OF GAS
HYDRATES IN THE TURONIAN DEPOSITS OF THE EAST MESSOYAKHA DEPOSIT
S. E. Agalakov, A. R. Kurchikov, and A. N. Baburin
In many regions of the world, including West Siberia, deposits of
hydrocarbons in hydrate state are considered to be petroliferous formations. As
to methods of search, prospecting, and exploitation of this kind deposits,
however, the state-of-the-art is not satisfactory.
In Russia, the problem of existence of gas hydrate deposits is usually
discussed in the context of hydrate saturation of the Cenomanian gas pool at the
Messoyakha deposit. One more producing horizon has been recognized in the north
of West Siberia, which is related to the Gazsalin Member of the Kuznetsov
Formation of Turonian-Coniacian age, lying above the Cenomanian deposits and
having more favorable PT-conditions for hydrate formation.
Analysis of specific features of geologic structure, temperature regime of
the section, gas composition, mineralization of formation waters, logging data,
seismic prospecting materials, and sampling suggests that gas hydrates can exist
in the Gazsalin Member of the East Messoyakha deposit.
One of the possible directions of further study of genesis of natural gas
hydrates and estimation of the effect of gas hydrate processes on the structure
of gas deposits and gas resources is study of the hydrocarbons accumulated in
the Gazsalin Member of the East Messoyakha deposit with sampling of core by a
sealed thermostatically controlled corer.
Gas, gas hydrates, permafrost rocks
BIODEGRADATION OF SATURATED CYCLIC CHEMOFOSSILS
V. A. Kashirtsev, A. E. Kontorovich, R. P. Philp, O. N. Chalaya,
I. N. Zueva, I. K. Ivanova, and N. P. Memetova
The paper deals with the problem of bacterial oxidation (biodegradation) of
crude oil hydrocarbons. The review of the literature on natural biodegraded oils
and laboratory experiments suggest that the normal and branched alkanes are
susceptible to microbiological degradation, as well as polycyclic saturated
biomarker hydrocarbons (steranes, hopanes, and cheilanthanes). The homologous
series of demethylated hopanes are assumed to be of different genesis: 28-
norhopanes have the precursors in membranes of prokaryotes, i. e., they are
"primary" biomarkers, while 25-norhopanes result from bacterial oxidation of
regular hopanes in oil pools. Homohopanes close to "biological" structures (22R)
are the first to be assimilated by bacteria. At the final stages of
biodegradation, demethylation of cheilanthanes occurs at C-10. All this allows
construction of the stage scale of hydrocarbon biodegradation.
Crude oil, natural bitumens, biomarkers, biodegradation, steranes, hopanes,
cheilanthanes
PROBLEMS OF OIL AND GAS GEOLOGY OF THE EAST EUROPEAN
PLATFORM AND ARCTIC SEAS OF RUSSIA
PETROLEUM POTENTIAL OF PRECAMBRIAN AND PALEOZOIC DEPOSITS
OF THE SOUTHERN URALIAN REGION
A. Kamaletdinov, T. T. Kazantseva, Yu. V. Kazantsev, and D. V. Postnikov
The history of investigation into the petroleum potential of deep-seated
horizons of the Uralian region is reviewed. Two major objects for oil and gas
prospecting are considered: 1) Late Precambrian (Riphean and Vendian) deposits
in the platform part of the Bashkir Autonomic Republic and 2) Paleozoic and
Precambrian underthrust series in the fold-nappe zone of the Urals. The
petroleum potential is justified by numerous oil shows on the territory of
Bashkiria and in adjacent areas and by the world data on the presence of
abundant underthrust petroleum deposits in many countries.
Overthrust, thrust, tectonics, structure, Archean, Proterozoic, Riphean,
Vendian, Paleozoic, oil, gas
CATAGENETIC ZONING AND PETROLEUM POTENTIAL OF THE SEDIMENTARY
COVER OF THE BARENTS SEA SHELF
S. Gramberg, N. K. Evdokimova, and O. I. Suprunenko
The maturity of organic matter (OM) has been investigated according to
vitrinite reflectance (R0). This index has been modeled within the sedimentary
cover. The depth dependence of R0 has been studied for the first time in the
region. Model curves of OM maturation have been constructed for prospecting and
test boreholes. This allows prediction of R0 at depths of to 10-12 km. Maps of
OM maturity have been compiled for three OM-rich sequences: Carboniferous-
Permian terrigenous-carbonate, Upper Triassic and Upper Jurassic terrigenous.
The degree of OM conversion varies from protocatagenesis (PC) in the Cretaceous
and Upper Jurassic deposits to apocatagenesis (AC) in the Permian ones.
Structural and catagenetic levels are conformable in depressions, whereas
mismatches of structural and catagenetic surfaces are observed in the
terrigenous-carbonate complex and Lower-Middle Triassic deposits on uplifts,
particularly, on the western flank of the Barents Sea megatrough and, to a
lesser extent, on the Admiralteiskii megarampart.
The catagenetic model suggests a large-scale hydrocarbon generation in the
sedimentary deposits of the deep-seated Barents Sea megatrough from Early
Paleozoic to Late Mesozoic. During the last 250 Ma, the greatest petroleum
catchment area has occurred in the zone of uplifts on the western flank of the
Barents Sea megatrough. The potential of this area is comparable with that of
the structures of the Shtokman-Lunin megasaddle, proven by exploration drilling.
Catagenetic zoning, modeling, prediction, vitrinite, reflectance, Barents
Sea megatrough, petroleum potential
FORMATION AND DISTRIBUTION OF LITHOLOGICAL OIL AND GAS TRAPS
IN THE DEVONIAN FILL OF THE PRIPYAT' PALEORIFT
S. M. Obrovets, A. M. Sinichka, and R. E. Aizberg
The Famennian intersalt and uppersalt petroliferous deposits in the
Pripyat' basin (Byelorussia) formed during the main rifting stage of its
evolution. The related lithologically and facially diverse sections, cut by
synsedimentary and postsedimentary faults, contain a broad variety of oil and
gas traps and pools, including lithologically confined ones. All lithologically
confined traps in the Pripyat' paleorift are grouped into zones; eleven zones
have been discovered to date, and economic oil pools were found in four of them.
Pripyat' basin, Devonian, intersalt and uppersalt deposits, petroleum
potential, lithological traps, hydrocarbon pools and deposits
PROBLEMS OF OIL AND GAS GEOLOGY OF THE WEST SIBERIAN PROVINCE
TECTONIC STRUCTURE AND HISTORY OF EVOLUTION OF THE WEST
SIBERIAN GEOSYNECLISE IN THE MESOZOIC AND CENOZOIC
V. A. Kontorovich, S. Yu. Belyaev, A. E. Kontorovich,
V. O. Krasavchikov, A. A. Kontorovich, and O. I. Suprunenko
The results of generalized regional studies of the West Siberian
geosyneclise are presented. The structural maps for the bottom of the plate
complex and top of the Jurassic and Cenomanian complexes were compiled at the
modern informative and technological level. The refined classification of the
tectonic elements allowed comilation of tectonic maps for these levels, in which
the tectonic elements and faults differentiated by the time of their formation
and depth of occurrence are shown.
The structural and tectonic maps for the top of the Jurassic structural
stage are presented and briefly.
Analysis of the structural and tectonic maps, isopach maps, and seismic
profiles enabled description of the tectonic history of the West Siberian
geosyneclise during the Cretaceous and Cenozoic in relation to its petroleum
potential.
West Siberian geosyneclise, seals, structural maps, classification of
tectonic elements, tectonic maps, tectonic history, faults, petroleum potential
STRUCTURAL ANALYSIS OF THE PRIPYAT' PALEORIFT AND RIFTS IN
WEST SIBERIA IN TERMS OF PETROLEUM POTENTIAL
R. E. Aizberg, R. G. Garetskii, N. P. Zapivalov, and V. A. Kashtanov
Paleorifts of the Pripyat' and West Siberian petroleum basins have been
compared in terms of their tectonic evolution as fault-bounded intracratonal
rift basins (aulacogens). The paleorifts existed within old cratons at different
stages of their tectonic activity. It was concluded that the young West Siberian
Plate was an old platform over the greatest portion of its territory, which may
be fundamental as a background of the high petroleum potential of Paleozoic and
Upper Proterozoic deposits in West Siberia and makes a basis for revealing
various types of untraditional oil and gas traps.
Tectonics, resources, aulacogens, petroleum potential, untraditional oil
and gas traps, Pripyat' basin, West Siberia
THE GEOTHERMAL REGIME OF HYDROCARBON POOLS IN WEST SIBERIA
A. R. Kurchikov
A map of deep heat flow of West Siberia has been compiled on the basis of
over 6000 heat flow determinations, and the present temperature field has been
analyzed in terms of the role of various factors forming the geothermal regime.
Analysis of local temperature fields in the vicinity of 340 hydrocarbon
pools shows that almost 80% of them are associated with considerable heat flow
variations, of which some are positive anomalies.
Geothermal regime, deep heat flow, temperature, hydrocarbon pool
METHODOLOGY AND EXPERIENCE OF MAIN PETROLIFEROUS OBJECTS IN NORTHERN
WEST SIBERIA AT THE PRESENT STAGE OF PETROLEUM FIELD EXPLORATION
A. M. Brekhuntsov, V. S. Bochkarev, V. N. Borodkin, and N. P. Deshchenya
Integral methodology of geological survey, exploration, and production for
Russia as a whole is in progress. Criteria for recognition of petroliferous
megacomplexes and their basic elements are described. It is demonstrated that
oil pools of Jurassic and older deposits are confined to large "hot" fields
(regions), whereas gas accumulations exist under more moderate bed temperatures.
This regularity is used for predicting oil and gas deposits.
West Siberian geosyneclise, basin, Paleozoic cover, ranking of tectonic
structures, petroleum potential
PETROLEUM-BEARING COMPLEXES IN THE LOWER-MIDDLE JURASSIC AND
LOWER CRETACEOUS CLINOFORMS OF THE WEST SIBERIAN BASIN
V. S. Surkov, L. V. Smirnov, F. G. Gurari, A. M. Kazakov, V. P. Devyatov,
A. E. Ekhanin, and O. V. Serebrennikova
The West Siberian basin formed as a result of the Early Triassic rifting
and downwarping of the Earth's crust during the Mesozoic and Cenozoic. Three
stages are recognized in this process: early (postrift, Middle Triassic-Middle
Jurassic), middle (platform, late Middle Jurassic-Eocene), and late
(neotectonic, late Eocene-Quaternary). In this paper, the regularities and
conditions of sedimentation are described concisely, and the potential of Lower-
Middle Jurassic petroleum-bearing complexes (Zimnii, Sharapov, Nadoyakh, Vym',
and Malyshev) and Neocomian cllinoforms is estimated. The conclusion is made
that the further increase in reserves of hydrocarbons in the West Siberian
petroliferous province in a sufficient volume is possible at the cost of these
two petroleum-bearing stories. A program of their further study on a regional
scale is proposed. This program will be a base for a more complete estimation of
resources of the complexes under study, for determination of areas for detailed
seismic prospecting and parametric drilling, and for their geological and
economical estimation aimed at a necessary licence.
Petroleum potential, Lower-Middle Jurassic complxes, West Siberia
CATAGENESIS OF ORGANIC MATTER AND PETROLEUM POTENTIAL OF THE
JURASSIC, TRIASSIC, AND PALEOZOIC DEPOSITS IN THE NORTHERN AREAS
OF THE WEST SIBERIAN MEGABASIN
A. N. Fomin, A. E. Kontorovich, and V. O. Krasavchikov
Based on generalization of 1500 measurements of vitrinite reflectance, deep
zoning of organic-matter (OM) catagenesis in Mesozoic deposits has been
established, and schemes of catagenesis were constructed for the top and bottom
of the Jurassic deposits. The OM catagenesis is within the range of grades PC3
to MC32 in the Upper Jurassic deposits and PC3-AC3 in the basal Jurassic
horizons. Throughout most of the West Siberian megabasin, OM reached the end of
mesocatagenesis and apocatagenesis. Regionally, the degree of OM catagenesis of
the Jurassic deposits increases from the margins to the central and northern,
most buried, areas of the West Siberian megabasin. The level of OM maturity
ubiquitously increases with depth, but the rate of these changes varies
throughout the area. The highest deep gradient of variations in OM catagenesis
was identified in the Yamal and Gydan regions. Depth ranges of the main zone of
oil generation (oil window) were determined from vitrinite reflectance values in
different petroliferous regions. In the Nadym-Pur region, the main zone of oil
generation is identified in the depth range 2.9-3.8 km, in the Pur-Taz region,
at 2.8-3.6 km, in the Gydan region, at 2.4-3.3 km, and in the Yamal region, at
2.0-2.8 km. The Jurassic deposits to depths of about 4.0 km have not passed out
of the oil window yet and can be of interest for oil and gas exploration. Down
the section, the sequences are in the zone of intense gas generation, and,
therefore, preservation of only dry and fat gas accumulations is possible at
great depths. The same is true for the Triassic and Paleozoic sediments, in
which the organic matter underwent significant thermobaric changes (grades MC32
- AC3).
Petroleum potential, vitrinite reflectance, catagenesis grades, Jurassic,
Triassic, and Paleozoic deposits, West Siberia
UPPER JURASSIC DELTAS OF WEST SIBERIA (BY THE EXAMPLE OF THE VAKH
OIL DEPOSIT)
V. B. Belozerov, I. A. Ivanov, and G. I. Rezyapov
The paper discusses the structure of the Upper Jurassic delta system within the
Vakh zone of oil and gas accumulation on the basis of analysis of geological and
geophysical information on 2500 wells of prospecting and exploitation drilling.
Differences in the structure of deltas of various ages of a single delta
complex, peculiarities of formation of oil deposits in the reservoirs of deltas
of various types, and differences in the parameters of development of sandstones
of different facies have been shown.
Delta, facies, bed, deposit, permeability
LITHOLOGY OF CALLOVIAN-OXFORDIAN DEPOSITS IN VARIOUS FACIES
DISTRICTS OF THE WEST SIBERIAN PLATE
P. A. Yan, L. G. Vakulenko, O. V. Burleva, T. P. Aksenova, and I. K. Mikulenko
The structure, composition, and formation settings of the Callovian-
Oxfordian deposits of the Pur-Irtysh, Taz-Kheta, and Silgin facies districts of
West Siberia are considered. In the first of them the Callovian-Oxfordian
deposits include the Vasyugan and Abalak Formations; in the second, the Tochino
and Sigovsk Formations; and in the third, the Naunak Formation. The variability
of the Vasyugan Formation in the southeastern areas of the West Siberian Plate,
in the latitudinal Ob' region, and in the Nadym-Taz interfluve has been shown by
lithological and mineralogy-petrographical studies invoking production
geophysics and geochemical and paleontological evidence. This allows recognition
of three facies subdistricts: Ob'-Tara, Ob'-Agan, and Nadym-Pur. In addition,
the Yamal-Nadym facies subdistrict, where the Abalak Formation occurs, has been
recognized.
Lithology, sedimentation settings, lithofacies zonation, Jurassic, West
Siberia
SEDIMENTATION IN THE EARLY CRETACEOUS BASIN OF WEST SIBERIA AND
ITS INFLUENCE ON OIL AND GAS POTENTIAL
S. V. Ershov, K. V. Zverev, V. A. Kazanenkov, and Yu. N. Karogodin
The opinions about the structure of the Neocomian deposits in West Siberia
are discussed. We defend the viewpoint of its clinoform structure. According to
studies performed, clinoforms are bodies of transgressive-regressive
sedimentation cycles (cyclites) formed during avalanche sedimentation. Their
structure involves two types of sand-siltstone reservoirs related to shallow-
water shelf and distal fairly deep-water sediments, each containing a wide range
of traps. Clinoforms are stratigraphic and petroliferous subdivisions calling
for independent complex studies.
West Siberia, Neocomian, avalanche sedimentation, clinoform
PROBLEMS OF OIL AND GAS GEOLOGY OF THE SIBERIAN PLATFORM
COMPARATIVE ANALYSIS OF PROSPECTS FOR FORMATION OF LARGE
HYDROCARBON ACCUMULATIONS IN THE NORTH OF THE TUNGUSKA SYNECLISE
V. S. Starosel'tsev and T. A. Divina
The prospects for oil and gas potential of the northern Tunguska syneclise
are estimated with regard to quantitative oil-geologic characteristics of
Riphean-Paleozoic deposits overlapped by Permian-Triassic basalts. These
characteristics have been for the first time obtained for the inner regions of
this syneclise. On the basis of spatial combination of the deepest (to 10 km and
more) large negative structures of platform cover and adjacent uplifts -
potential zones of gas and oil accumulation, - the areas of the most probable
formation of large accumulations of hydrocarbons were supposed. Two of them,
Upper Khugdyakit and Khantai, have been recommended for top-priority studies by
parametric drilling to a depth of up to 3.5 km.
Basalt covers, petroleum potential of Paleozoic deposits, tectonic
prerequisites
PREDICTION OF THE PETROLEUM POTENTIAL OF THE VENDIAN AND LOWER
CAMBRIAN DEPOSITS IN THE CENTER OF THE SIBERIAN PLATFORM
G. G. Shemin
Criteria for predicting the petroleum potential of ancient deposits of
complicated structure with a long evolution history of hydrocarbon pools are
considered. They rest on combined stratigraphic, tectonic, lithofacies,
geochemical, and hydrogeological data. Detailed prediction of petroleum
potential has been made for the Vendian-Lower Cambrian subsalt terrigenous and
carbonate deposits of the Vilyuchan, Lower Nepa, Upper Nepa, Tira, Lower
Danilovo, Upper Danilovo, and Usol'e reservoirs. Fields different in potential,
petroliferous zones, and first-order prospecting objects have been recognized in
the areas of their occurrence. Predominant types of traps, pool volumes, and
phase compositions of hydrocarbons are predicted. The results will add to the
efficiency of search for petroleum.
Horizon, formation, bed, correlation, oil, gas, petroliferous zone, first-
order object, pool, trap, hydrocarbon migration
EVAPORITE SCREENS OF OIL AND GAS RESERVOIRS IN THE SIBERIAN AND
TARIM PLATFORMS
G. S. Fradkin, Jin Zhijun, A. K. Basharin, and S. Yu. Belyaev
Vendian-Cambrian and Devonian evaporite and salt sequences have been
reliably distinguished in the sedimentary cover of the Siberian Platform, the
lower part of which controls the economic petroleum potential of Precambrian
reservoirs, and the upper one shows good prospects for productivity of subsalt
and intersalt beds. In this context it is suggested that evaporite sequences in
the Tarim Platform, which occur in Cambrian, Carboniferous, and Paleogene
sections, make a subject of a special study in terms of their screening role in
order to refine the prospecting guidelines for hydrocarbon pools in the subsalt
reservoirs of the Tarim petroleum province.
Evaporites, screen, reservoir, Siberian Platform, Tarim Platform
PRODUCING HORIZONS OF THE CHAYANDINSKOE FIELD (YAKUTIA):
STRUCTURE AND GENESIS
A. F. Safronov, A. V. Bubnov, I. A. Gerasimov, and V. Yu. Mironenko
This paper deals with the structure and genesis of the Talakh, Khamakin,
and Botuobiyan Horizons of the Chayandinskoe oil and gas condensate field,
located on the northeastern slope of the Nepa-Peledui dome of the Nepa-
Botuobiyan anteclise. It is shown that the models for these horizons are dip-
lenticular rather than plane-parallel. The producing horizons are characterized
by significant lateral and vertical inhomogeneity related to the sedimentation
conditions. The deposits formed in the setting of sea coast, which evolved from
rock-type coast with the strongly dissected relief of the sea bottom (Talakh
Horizon), gradually acquiring geomorphologic elements typical of open sea coast.
This evolution provided a set of facies making up the producing horizons: The
Talakh Horizon is dominated by the turbidite facies; the Khamakin Horizon, by
the facies of the cis-frontal zone of the beach; and the Botuobiya Horizon, by
the facies of the beach and its cis-frontal zone. The lateral and vertical
inhomogeneity intensifies in the horizon sequence: Botuobiyan-Khamakin-Talakh.
Horizon, facies, reservoir rocks, logging, porosity, permeability,
sedimentation conditions, model, inhomogeneity
THE REGULARITIES OF FORMATION OF THE POROSITY OF VENDIAN-CAMBRIAN
TERRIGENOUS DEPOSITS IN THE SOUTHERN SIBERIAN PLATFORM
(FROM DATA OF COMPLEX PETROPHYSICAL RESEARCH)
M. M. Mandel'baum and K. S. Turitsyn
We have studied the main factors that effect consolidation of terrigenous
rocks. The porosity of mudstones of the Nepa Formation (Siberian Platform) is
shown to reflect the maximum pressures under which the rocks existed throughout
their geologic history. It can be used for regional paleotectonic analysis. The
porosity of sandstones depends on much more factors operating both on
sedimentogenesis and on subsequent catagenesis of the rocks; the major of them
are the depths of the maximum burial of sediments, the size of mineral grains,
and the intensity and time of secondary cementation of rocks.
Porosity, consolidation of rocks, diagenesis, regeneration of quartz