GEOLOGY & GEOPHYSICS, 2003, V 44, N 9.
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 depositvv
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 regionv
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 PROVINC
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 Mesozoi
c 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. Mikulenk
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 potentialv
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