Pre-Caspian Depression Research Articles

Geodynamics of Alpine Belt and Caribbean Region: Plate - Tectonics and Plume - Tectonics

The origin and evolution of geological structures reflect lithosphere-asthenosphere interaction in the process of lithospheric plate movement. Mantle diapirs contribute significantly to the sedimentary basins formation in Alpine belt and Caribbean region. Mantle diapirs are the result of density inversion in the asthenosphere–lithosphere system in the periods of tectonomagmatic activations. Increasing heat flow and mantle diapirs on the phone of convergence of Africa and Eurasia in Alpine belt and North and South Americas in Caribbean region produce intercontinental seas in the Cenozoic. The analytical solution of the problem give possibility to find the critical parameters connecting the mantle flow dynamics with surface relief evolution. In Alpine belt, the mantle diapirs form new basins at the final stage of Africa–Eurasia collision in the Cenozoic. In the Caribbean region, great mantle diapir separates the North and South Americas in the Mesozoic, and then the diapir is the source for different smaller diapirs during the convergence of these continents in the Cenozoic. The Gulf of Mexico and Pre-Caspian Depression are connected with mantle diapirs upwelling and have common geological-geophysical features as very rich oil-gas and salt bearing structures. Geodynamics of Alpine belt and the Caribbean region is determined by plume - tectonics on background of plate - tectonics in these regions.

ASSESSMENT OF OIL AND GAS POTENTIAL IN PRIMORSKAYA ZONE OF CARBONATE UPLIFT OF SOUTHERN PRECASPIAN SEDIMENTARY BASIN

The results of lithofacies studies and paleogeographic reconstructions of the Late DevonianEarly Visean stage and stratigraphic evolution of the Primorskaya zone of uplifts in the south of Precaspian Basin are presented. The complex geological structure of the region is mainly due to the influence of tectonic, volcanic and denudation processes on sedimentation. The spatial distribution of carbonate accumulations in the Primorskaya zone of the Precaspian Basin is determined by the different duration of sedimentation stages and the block structure of the basement. The results of the deep wells drilled in the recent years have made it possible to refine the internal geological structure, justification of new exploration objects in the Late Devonian strata and reevaluate the oil and gas potential and petroleum resources in the south of the Precaspian depression. After recent exploration works, the geological model for the onshore prospective structure traps has been improved, additionally prospective exploration objects have been predicted in the shelf of the Caspian Sea. The most of potential petroleum resources of the Primorskaya zone is the resources of the new offshore exploration objects in Caspian Sea. Non-structural traps can accumulate gigantic hydrocarbon volumes. This is a new highly prospective hydrocarbon exploration direction in the Precaspian Basin

Environmental safety issues and challenges and geodynamic monitoring at the Karachaganak oil and gas condensate field

Purpose. Environmental safety evaluation and geodynamic monitoring of the Karachaganak oil and gas condensate field (KOGCF) explored on the north board of the Pre-Caspian depression in order to predict the consequences of long-term operation of this field. Methodology. Synthesis and system analysis of the articles and archival literature on environmental hazards and geodynamic monitoring of the complex methods, repeated levelling process, GPS-measurements, high-precision gravimetry and seismological monitoring. Findings. At a qualitative and quantitative level, the activation of vertical and horizontal movements of rock masses, changes in the field of local gravity anomalies, more frequent earthquakes whose hypocentres are located at depths comparable to the intervals of field development are substantiated. Trends and tendencies in the study on the relationship between the continuously changing geodynamic state of the subsoil and field-geological processes are outlined. All these manifestations in one way or another find manifestations in the environmental risks of the area of the exploited deposit. In the conclusions, it is recommended to carry out a set of measures to reduce environmental risks. Originality. The results of geodynamic monitoring at the KOGCF for the northern board of the Pre-Caspian depression for the first time made it possible to obtain convincing evidence in favour of noticeable seismic-deformation processes in the upper part of the earths crust under the influence of hydrocarbon production processes. Practical value. The conclusions obtained in the work confirm the necessity and binding of geodynamic monitoring in order to study and assess the possibility of different scenarios of geodynamic situations related to the development of hydrocarbon fields, are recommended for levelling factors of potential geodynamic risk at the KOGCF.

FORMULA FOR THE DURABILITY OF OIL AND GAS FIELDS

The article is concerned with the issues of the status and results of long-term development of oil and gas fields, with consideration and justification of the factors that influence the extension of their further cost-effective development. To evaluate the potential factors of “plant life extension” of hydrocarbon reservoirs, the Munaily field in above-salt deposits of the southeastern part of the PreCaspian Depression has been designated as a pilot option. Pursuant thereto, the sequence of the major stages in the study and development, as well as the specific features of this field are provided. The forecast made by the authors for the longevity of field production is based on the factor of natural replenishment of reserves, which can be achieved through the establishment of certain restrictive measures and observance of the optimum operation mode appropriate for the conditions of each particular field. This refers to the setting of optimal oil withdrawals, the average daily flow rate of the well, etc. Determination of this pattern and its use in practical terms has favorable historical prerequisites, which is confirmed by the example of numerous objects under development in Russia and Kazakhstan. When substantiating this forecast, the main features of the geological structure of the Munaily field have also been taken into account, among which considerable importance in evaluating the mode of occurrence and productivity of above-salt deposits in the Pre-Caspian Depression is given to the presence and impact of underlying complexes of sediments. This concerns the salt-bearing section of the Kungurian age, the subsalt Paleozoic strata, and the influence of fault tectonics, which contributes to the development in the field section of certain oil and gas feed channels due to disturbances of various order, zones of decompaction, and fracture porosity of the rock formations. Following the results of the analysis, the necessity of compliance with the rehabilitation cycle of 10-15 years has been substantiated, which allows restoring the internal indicators of the energy state and the volume of hydrocarbons in line with the existing model of the reservoir (trap) of the field to the level at which the continuation of further cost-effective development is possible.

Lithological and facial features of organogenic structures of the second carbonate stratum of the eastern flang of the Pre-Caspian depression on Zharkamys uplift

The Pre-Caspian Basin is the major oil and gas basin in Kazakhstan. It contains huge hydrocarbon reserves within pre-salt carbonate deposits. There had been numerous discoveries of oil and gas-condensate fields associated with pre-salt carbonate complexes in the Eastern part of the Caspian Basin.
 The object of this study is the second carbonate stratum (CS-II) of the Late Visean Early Moskovian age of the Eastern part of the Pre-Caspian Basin. The formation of the Eastern part of the Pre-Caspian Basin took place in the zone of the junction of the East European craton and folded structures of the Urals. These conditions predetermined the complexity of sedimentation processes, variety of lithological types of rocks and diagenesis processes with the formation of reservoir heterogeneity.
 CS-II will retain the leading role as the main reservoir of hydrocarbons and it has further potential for oil exploration in the region for two to three decades. It has been proven by the discovery of large oil and gas-condensate fields in the CS-II, such as Zhanazhol, Urikhtau, Kozhasai, Alibekmola, etc.

Современные проблемы геологии и нефтегазоносности недр Прикаспийской впадины

The deep structure and formation of the North Caspian (Precaspian) depression have not been fully understood due to the scarcity of depth studies at 18–22 km. The existing concepts and hypotheses are clearly insufficient to interpret the unexplained facts. New approaches and research efforts are necessary to solve the old problems. The current state of the depression deep structure problems is reviewed, and the existing explanation flaws are demonstrated. The depression consolidated crust has oceanic and riftogenic origin as it has been suggested by the author before. This explanation is supported by the Astrakhan deposit D-2 deep well core data. The Astrakhan-Aktobe zone arched uplift genesis, formation and role in the carbonate platforms emergence are discussed. Deep geothermy and fluid dynamics problems, as well as recent geophysical data are considered in view of the North Caspian depression hydrocarbon prospects.

Features of the Structure and Development of the Southeastern Part of the East European Platform and the Caspian Basin in the Late Precambrian‒Early Paleozoic

The geological and sedimentological interpretation of several time and deep seismic profiles within junction zone of the Volga‒Ural area of the East European Platform, Pre-Caspian Depression, Ural Foredeep, Bashkir Anticlinorium, and northern margin of the Scythian Platform allowed us to identify a number of previously unknown structural features of Later Precambrian and Early Paleozoic formation. On this basis, structural-facies maps were compiled for the Riphean and Vendian stages of development. It was shown that as a result of the collision of the southeastern passive margin of the continent Baltica with Scythia in the Early Vendian and with the Timanides of the Urals in the Later Vendian, a complex tectonic structure of the Orenburg tectonic node was formed, which forms the foundation of the Caspian oil and gas province. The results obtained substantially clarify the structure of the sedimentary cover of the East European Platform and the Pre-Caspian Basin, the stages of the formation and evolution of their structure, and the degree of influence on the sedimentation of structural changes in the adjacent territories of the folded Urals and the Scythian Platform.

АНОМАЛЬНАЯ ЛИТОСФЕРА И ПЕРСПЕКТИВЫ НЕФТЕГАЗОНОСНОСТИ НЕДР ПРИКАСПИЙСКОЙ ВПАДИНЫ

АНОМАЛЬНАЯ ЛИТОСФЕРА И ПЕРСПЕКТИВЫ НЕФТЕГАЗОНОСНОСТИ НЕДР ПРИКАСПИЙСКОЙ ВПАДИНЫ

НОВЫЕ ДАННЫЕ О МАГНИТНЫХ СВОЙСТВАХ ВЕРХНЕПАЛЕОЗОЙСКИХ ОТЛОЖЕНИЙ ЮЖНОЙ ЧАСТИ ПРИКАСПИЙСКОЙ ВПАДИНЫ

НОВЫЕ ДАННЫЕ О МАГНИТНЫХ СВОЙСТВАХ ВЕРХНЕПАЛЕОЗОЙСКИХ ОТЛОЖЕНИЙ ЮЖНОЙ ЧАСТИ ПРИКАСПИЙСКОЙ ВПАДИНЫ

INDICATIVE ROLE OF VEGETATION IN THE RECLAMATION OF PRECASPIAN ARID LANDSCAPES (THE REPUBLIC OF KALMYKIA)

Aim. The paper studies the influence of water reclamation on vegetation in the central part of the Caspian depression. Findings are necessary for the monitoring studies of natural ecosystems in their modern usage. Methods. The use of key site method and eco-dynamic profiling makes it possible to trace changes in the horizontal structure of vegetation in the coastal and canal areas of the salt lakes. Results. The findings of field research allowed identifying the environmental levels: low, medium, high. Xerophilous species fall out of the phytocenosis composition, while the typical salt-loving plants become widespread, forming endogenous succession of progressive type in a Precaspian desert zone. It aims to desalinize the upper layers of the soil, lower the groundwater and salinity levels. Conclusions. Fluctuation and succession processes can be observed in the central part of the Precaspian depression, the indicator of which is vegetation, its species composition.

Раннекаменноугольный вулканизм на юго-востоке Прикаспийской впадины

Раннекаменноугольный вулканизм на юго-востоке Прикаспийской впадины

О возможных источниках магнитных аномалий юга Прикаспийской впадины

О возможных источниках магнитных аномалий юга Прикаспийской впадины

Водоросли Tasmanites Newton, 1875 нижнепермских отложений западной части Прикаспийской впадины и их значение для стратиграфии и нефтяной геологии

Водоросли Tasmanites Newton, 1875 нижнепермских отложений западной части Прикаспийской впадины и их значение для стратиграфии и нефтяной геологии

Геотермический режим, тепловой и флюидный потоки Прикаспийской впадины

Геотермический режим, тепловой и флюидный потоки Прикаспийской впадины

Magnetotelluric studies in salt-dome tectonic settings in the Pre-Caspian depression

Abstract E.D. Aleksanova, D.A. Alekseev, A.K. Suleimanov and A.G. Yakovlev present findings from the use of magnetotellurics as an efficient tool for subsalt imaging in the Pre-Caspian depression.

Thiols and disulphides of gaseous condensates of the Pre-Caspian depression

Thiols and disulphides of gaseous condensates of the Pre-Caspian depression

Middle and Late Permian stratigraphic correlations on the Russian Platform: significance of ostracodes

During the International Peri-Tethys Program, the realization of the maps required efficient correlation tools. During the Late Paleozoic and particularly during the Wordian (Middle Permian), the Russian Platform was under continental and/or marginal paleoenvironmental conditions. This paper draws up the synthesis of the ostracode species recognized in the Middle-Late Permian in this area, from the Barents Sea up to the Precaspian Depression, and shows their importance as a stratigraphic tool for the correlations of continental series. Au cours du Programme international « Peri-Tethys », l’établissement des cartes paléogéographiques a nécessité des outils de corrélations précis et efficaces. Au Paléozoïque supérieur et plus particulièrement au Permien moyen et supérieur, la sédimentation sur la plate-forme russe est continentale et/ou margino-littorale. Cet article dresse une synthèse des espèces d’ostracodes reconnues dans le Permien moyen et supérieur de cette région, de la Mer de Barents jusqu’à la Dépression Pré-Caspienne, et montre l’importance de ce groupe comme marqueur stratigraphique dans les séries continentales.

Pre-Mesozoic geodynamics of the Precaspian Basin (Kazakhstan)

This paper concentrates on the Pre-Mesozoic history of the Precaspian Basin representing more than half of the 20 km of its sedimentary thickness. We present the evolution of sediments deposited in the basin through time by several regional sections of the basin. These image, from the Devonian, the creation and evolution of a deep intercontinental basin which existed from Carboniferous to Permian. Palinspastic reconstructions show also the evolution of the basin's margins, their relations with the southern pre-Uralian foredeep in the east and carbonate build-ups in the southeast. We present a reconstruction for the early history of the Precaspian Basin, which became an individual basin only at the end of the Permian as a result of the Uralian orogeny. The basement of the Central Precaspian depression is characterised by a thin crust where a low-velocity layer is absent. A layer of abnormally high velocities exists below the crust, which on the basis of structural and gravitational field data is interpreted as eclogite. We put forward a scenario for the age and emplacement of eclogite lenses at the base of the crust. They are possibly implemented in the hangingwall, from a westward subduction zone existing during the Vendian, before the collision giving birth to the Proto-Urals. Most of the basin subsidence is due to the thinning (mainly during Devonian) and increase of the average density of the crust. Present crustal density has characteristics of intermediate to lower crust interpreted by some authors as oceanic. We propose that the loading effect of the eclogites emplacement may explain also a part of the Precaspian Basin subsidence.

Structure and genetic mechanisms of the Precambrian rifts of the East-European Platform in Russia by integrated study of seismic, gravity, and magnetic data

Integrated models of the deep structure and origin of rifts located within the Russian portion of the East-European Platform have been developed from recent DSS results, new gravity and magnetic modelling, and geological and older geophysical data acquired over the last 50 years. The Mezen rift province, the Middle-Russian rift, the Valday rift, the Pachelma rift, and the rifts within the Pre-Caspian depression were studied. All of these rifts were affected by extension and filled with syn-rift sediments at different times through the Riphean (1650–650 Ma). Post-rift sedimentary basins developed from the end of the Neoproterozoic until the Cenozoic. The models indicate that the crustal structure and genesis of the individual rifts are different. The Mezen rift province was formed under a condition of limited extension of the continental crust. The McKenzie pure strain mechanism is acceptable for lithosphere extension in the Middle-Russian rift. The Wernicke model best expresses the Valday and Pachelma rifts. The rift process in the Pre-Caspian area is explained in terms of large-scale sliding apart of lithospheric plates, and approached the stage of development of oceanic crust.

Carbonate platform drowning in a foreland setting; the Mid-Carboniferous platform in western Urals (Russia)

ABSTRACT The stratigraphic evolution through time of the mid-Carboniferous Russian Platform deposited on the distal margin of the West Uralian prograding foredeep basin can be observed in the approximately 3000-m-thick sedimentary cover that constitutes the upper Paleozoic foreland (mid-Carboniferous-Permian) of the Uralian fold belt. It is composed of wave-dominated, low-angle carbonate ramps of late Visean to early Moscovian age and carbonate platforms bordered by slope reef mounds from the Kasimovian to the late Artinskian-early Kungurian. Eastward, in the foredeep, the carbonate platforms pass into terrigenous deposits. A complete transgressive-progradational section at the transition between carbonate ramp and terrigenous deposits exhibits, from base to top, (1) deepening-upward carbonate ramp deposits, (2) a shaly condensed section with volcaniclastics, glauconite, and phosphorites of late Moscovian to early Asselian age (the transgressive part), and (3) a shallowing-upward section of turbidites ending in coarse-grained fan deltas, evaporites, and meandering-river redbeds by the earliest Triassic (the progradational section). This paper focuses on the uppermost part of the carbonate ramp deposits (Serpukhovian to early Moscovian). These ramp facies comprise peritidal channels and mud flats, wave- to storm-dominated shoals, and patch reefs that are overlain by channel-attached sand lobes of turbidites, black shales, and radiolarites of the condensed section. This large-scale deepening-upward trend from inner-ramp to outer-ramp environments reflects a change in the depositional profile, from a tide- and wave-dominated flat ramp to a wave- and storm-dominated, steepened ramp margin and then to foreslope turbidites. Correlation of sections, dated by fusulinid faunas in southern Urals, shows that the ramp evolved from emergent in the north (Perm-Solikamsk area), as evidenced by karstification, and deepened to the south (Belaya area) with emplacement of carbonaceous foreslope debris flows and turbidites, capped by deep-marine black shales and radiolarites. The time gap increases northward and reaches a span including the Siuransky pro parte, the Akavassky, the Askynbashky, and the Asatausky pro parte biohorizons. The mapping of these facies belts across all the Urals shows that carbonate ramps wedge out in the middle Urals and give rise to widely distributed, diversified, and deeper marine facies belts not only to the South, towards the Precaspian depression, but also to the North, towards the polar Urals. The drowning of these carbonate ramps and the cutoff in carbonate production on the Russian Platform during the mid-Carboniferous is explained by a succession of low-frequency flexure-relaxation cycles in the foreland associated with dilution by siliciclastics, outpouring of volcaniclastics, and changes in the nature and direction of the sediment input and high-frequency cycles mainly controlled by eustasy.