Pricaspian Basin Research Articles

Geological structure and modeling carbonate reservoirs of kt-ii of theKozhasay field(the esatern edge of pricaspian basin

In the present work the major results of integrating data from Kozhasay field for 3D geological modeling had been described (regional geological data, exploration and production drilling results, core and cuttings data, 3D seismic data interpretation results, borehole images). The entire borehole imaging data were revised and used for fracture modeling. The hybrid fracture model was generated (discret and implicit fractures). The Kozhasay field had been under production since 2003 and it has produced 4 % of the STOIIP as for 01.01.2019. Theintegrated geological model of KT-II carbonate reservoirs was used to create hydrodynamic model of the field.

Hydrocarbon potential of the Kobylandy-Tamdy upfold of the northern edge of Pricaspian basin

In the present article geological structure of Kobylandy-Tamdy Paleozoic upfold of the Pricaspian basin is described, the upfold was discovered and delineated based on seismic exploration and drilling results. On the example of Kobylandy area hydrocarbon potential of pre-salt complex of the conjunction of the Northen and Eastern edges of Pricaspian basin was evaluated and resources were estimated. New prospective structures were delineated within the Paleozoic sedimentary cover, which can be ranked as the first priority exploration drilling targets in the region.

The Sierra del Cuera (Pennsylvanian microbial platform margin) in Asturias, north Spain

ABSTRACT Stratal geometry and lithofacies architecture from carbonate outcrops provide critical information for subsurface prediction of rock types, their spatial distribution, and reservoir quality. Such observations guide and support exploration, appraisal, development, and production strategies. The Pennsylvanian Sierra del Cuera (SDC) carbonate platform outcrop of the Cantabrian Mountains in north Spain offers such information through a seismic-scale cross section of a microbial, unrimmed, and high-relief platform to basin transect, deposited during an icehouse period. The SDC outcrops provide alternative platform margin models to those developed from coral–algal-dominated Neogene carbonate systems and serve as direct analogs for supergiant fields such as Tengiz, Kashagan, and Karachaganak in the Pricaspian Basin of Kazakhstan and potentially for other high-relief platforms with microbial margins. Key features of the SDC platform are (1) a flat-topped platform with a rollover into a steep (30°–40°) and high-relief (600–850 m [1960–2790 ft]) depositional slope and (2) the presence of a microbial boundstone factory from the platform break to nearly 300 m (984 ft) paleowater depth on the slope, stabilized by pervasive marine cementation. The SDC represents a nonactualistic type of carbonate platform margin where the microbial carbonate factory on the upper slope controlled the rate of progradation instead of the platform top–sourced sediment input. These features have significant implications for the interpretation of the evolution and controlling factors of carbonate depositional systems in outcrops and in the subsurface.

Excursions along the Lennard Shelf Devonian carbonates, Canning Basin, Western Australia

ABSTRACT The world-class Middle–Upper Devonian carbonate outcrops of the Lennard Shelf, Canning Basin, Western Australia, offer a unique opportunity to examine reefal carbonate shelf-to-basin evolution in response to multiple coeval extrinsic and intrinsic drivers. Variable styles of carbonate stratigraphic architecture and heterogeneity developed as a function of the interplay between long hierarchical accommodation trends, global biological crises, greenhouse-to-transitional climatic changes, and syndepositional tectonics. The linkage of reservoir-scale, shelf-to-basin carbonate expression to regional, seismic-scale architectures made possible by these pristine exposures allows the generation of conceptual models and predictive relationships that are relevant to steep-sided carbonate hydrocarbon reservoirs and plays. Furthermore, exquisite exposure of syndepositional fracture systems and their association with carbonate facies and position along the depositional profile provide templates for characterization of subsurface nonmatrix flow. In particular, the Lennard Shelf outcrops are excellent analogs for the age-equivalent Canadian Alberta Basin and Carboniferous reservoirs of the Pricaspian Basin in Kazakhstan; however, the breadth of insight contained within the Lennard Shelf outcrop belt is applicable to the greater understanding of reefal carbonate systems in general.

Facies, geometry and growth phases of the Valdorria carbonate platform (Pennsylvanian, northern Spain)

AbstractThe 14 km wide Valdorria outcrop (Pennsylvanian, northern Spain) is one of the few examples of entirely exposed flat‐topped and high‐relief carbonate platforms reported in the fossil rock record. Laterally and vertically traceable stratal patterns expose three phases of growth. Phase I is a 430 m thick platform to slope succession that prograded over 6 km, and is dated as Early Bashkirian (Akavasian–Askynbashian). Phase II aggraded and prograded, exhibiting 180 m thickness of cyclical platform top deposits, dated as Late Bashkirian (Asatauian). Phase III is a mound‐shape structure that developed over the platform top of Phase II as a new phase of platform nucleation. It is 535 m thick and 2 km wide, and dated as Late Bashkirian (Asatauian–Transition interval). The observed changes of growth styles during platform evolution, from a prograding to an aggrading–prograding system, and a rapid aggradational phase, are inferred to be controlled by flexural subsidence in the active Cantabrian foreland basin, at the Variscan orogenic front. The metre‐scale shallowing‐upward cycles of the platform top are most probably due to glacioeustasy, as evidenced by well‐recorded subaerial exposure surfaces superimposed on subtidal deposits, and by a stratal pattern recurrent in a short interval of about 160 kyr. Observations of outcropping Bashkirian cyclothems in an isolated carbonate system, devoid of siliciclastic input, are relevant for a better understanding of the impact of high‐frequency sea‐level fluctuations on the carbonate factory. Moreover, progradation of the platform margin during Phase I reaches a rate of 2500 m/Myr, and 1810 m/Myr during Phase II; rates that are high when compared to other Pennsylvanian examples. The aggradation rate of 447 m/Myr calculated for the Late Bashkirian–Transition interval (Phases II and III; uncorrected for compaction, missing beats and erosion) is uncommonly high in comparison to coeval Pennsylvanian examples. The platform exhibits a self‐nourishing prograding microbial boundstone‐dominated slope. Thus, the slope‐shedding model applies well to Valdorria. However, Phase II recorded eustatic variations able to inhibit the slope microbial boundstone factory during low sea‐level stands; this is marked by common slope red‐stained breccias synchronous to platform top subaerial exposure phases. Contrarily, periods of relative high sea‐level and rapid subsidence in Phase III registered a greater development of cemented microbial boundstone. These observed, partly opposing relationships of sea‐level stands, shedding modes and slope architecture provide an improvement of the currently used slope‐shedding model. The overall architecture of the Valdorria outcrop compares well with that of other contemporaneous platforms, such as Sierra del Cuera and Bolshoi Karatau. Valdorria shares the high‐relief and flat‐topped, steep slopes, cyclothemic patterns and occurrence of karst features with the Pricaspian Basin platforms (Tengiz, Karachaganak and Kashagan), with minor variations in facies distribution of the internal platform. Furthermore, the continuous seismic‐scale outcrop of Valdorria, together with its isolated setting and asymmetrical growth, makes it a very good candidate for potential subsurface analogues of hydrocarbon‐bearing systems.

Continuous deep microseismic monitoring of the Karachaganak Field, Kazakhstan: integrating reservoir geoscience, drilling and engineering

The Karachaganak Field is an oil and gas condensate supergiant field located in the western Kazakhstan Pricaspian Basin. As part of the challenge to improve reservoir knowledge, KPO has been continuously monitoring the reservoir using a microseismic array deployed downhole since February 2009. Continuous deep recording of microseismic activity is an innovative technique for reservoir monitoring; progressive refinements were made to fine-tune the acquisition and processing techniques. By December 2010, 8074 events had been detected and, from this group, 2556 events have been located. Events within the reservoir were recorded up to 8 km from the array to a depth of 5 km with moment magnitudes (Mw) ranging from −2.4 to +1. Microseismic events are continuously located and their spatial and temporal distribution analysed. This basic analysis is the input to an integrated study that considers the static model for the reservoir, in addition to dynamic and operational aspects such as production and injection rates, pressure baffles, drilling behaviour and casing perforations. The results to date indicate valuable reservoir information concerning the location of lateral and vertical reservoir pressure baffles and delineation of zones of instability at the reservoir–seal interface, important for well integrity issues. This new information is helping to improve dynamic and geomechanical reservoir models and also wellbore stability predictions. This article presents the details of the Karachaganak microseismic array and how microseismic events were located. Discussion follows on the interpretation and the possible impact on reservoir monitoring and drilling. The Karachaganak array is one of the deepest installations of a passive microseismic monitoring system and also represents one of the longer periods of continuous monitoring, with two years of data available.

The Astrakhan Arch of the Pricaspian basin: Geothermal analysis and modelling

The Astrakhan Arch (ASAR) region contains one of the largest sub-salt carbonate structures of the Pricaspian salt basin (located to the northwest of the Caspian Sea), where prospects for hydrocarbon generation and accumulation in the Devonian to Carboniferous deposits are considered to be high. We evaluate the regional vertical temperature gradient within stratigraphic units based on the analysis of 34 boreholes drilled in the region. To show that the thermal gradient is altered in the vicinity of salt diapirs, we study measured temperatures in six deep boreholes. We develop a three-dimensional geothermal model of the ASAR region constrained by temperature measurements, seismic stratigraphic and lithological data. The temperatures of the sub-salt sediments predicted by the geothermal model range from about 100 °C to 200 °C and are consistent with the temperatures obtained from the analysis of vitrinite reflectivity and from previous two-dimensional geothermal models. Temperature anomalies are positive in the uppermost portions of salt diapirs as well as within the salt-withdrawal basins at the depth of 3.5 km depth and are negative beneath the diapirs. Two areas of positive temperature anomalies in the sub-salt sediments are likely to be associated with the deep withdrawal basins above and with the general uplift of salt/sub-salt interface in the southern part of the study region. This implies an enhancement of thermal maturity of any organically rich source rocks within these areas. The surface heat flux in the model varies laterally from about 40 to 55 mW m−2. These variations in the heat flux are likely to be associated with structural heterogeneities of the sedimentary rocks and with the presence of salt diapirs. The results of our modelling support the hypothesis of oil and gas condensate generation in the Upper Carboniferous to Middle Devonian sediments of the ASAR region.

Geothermal evolution of the Astrakhan Arch region of the Pricaspian basin

The Astrakhan Arch region contains one of the largest sub-salt structures of the Pricaspian basin, where perspectives for hydrocarbon generation and accumulation in the Devonian to Carboniferous deposits are considered to be high. The paper addresses the problem of structural and geothermal evolution of the region deformed by salt movements. Initially, we developed a model of the regional structural evolution along a geological profile using the volume-balancing and back-stripping methods and geo- logical constraints on the sedimentation, erosion, and paleo-water depths. Then we developed geothermal models (along the study profile) associated with the regional structural evolution. The models were constrained by the temperatures measured in four deep boreholes along the profile. We show that the present temperatures and heat flux are influenced by the presence of salt diapirs. Since the Early Carboniferous and till Middle Permian times, the temperatures predicted by the models vary significantly due to the regional transgression and the presence of sea- water. The temperature of Devonian-Carboniferous carbonates increases since the Late Permian (time of post- salt deposition) and attains its maximum values in the SW- part of the profile. If the model assumptions concerning the constant vertical and zero lateral heat fluxes are valid, we can conclude that hydrocarbons are most likely to be generated in the SW-part of the region for the post-Early Permian time.

Detailed velocity structure of salt domes in Pricaspian basin from refraction data

Detailed velocity structure of salt domes in Pricaspian basin from refraction data

Three-dimensional forward and backward modelling of diapirism: numerical approach and its applicability to the evolution of salt structures in the Pricaspian basin

Numerical studies of ductile deformations induced by salt movements have, until now, been restricted to two-dimensional (2D) modelling of diapirism. This paper suggests a numerical approach to model the evolution of three-dimensional (3D) salt structures toward increasing maturity. This approach is also used here to restore the evolution of salt structures through successive earlier stages. The numerical methodology is applied to study several model examples. We analyse a model of salt diapirs that develop from an initial random perturbation of the interface between salt and its overburden and restore the evolved salt diapirs to their initial stages. We show that the average restoration errors are less than 1%. An evolutionary model of a 2D salt wall loaded by a 2D pile of sediments predicts a decomposition of the salt wall into 3D diapiric structures when the overburden of salt is supplied by 3D synkinematic wedge of sediments. We model salt extrusion feeding a gravity current over the depositional surface and estimate an average rate of extrusion and horizontal velocity of salt spreading. Faulting of the overburden to salt overhangs initiates new secondary diapirs, and we analyse the growth of these secondary diapirs. We also study how lateral flow effects the evolution of salt diapirs. The shape of a salt diapir can be very different if the rate of horizontal flow is much greater than the initial rate of diapiric growth solely due to gravity. We discuss the applicability of the results of the models to the evolution of Late Permian salt structures in the Pricaspian basin (Russia and Kazakhstan). These structures are distinguishable into a variety of styles representing different stages of growth: salt pillows, diapirs, giant salt massifs, 2D diapiric walls and 3D stocks complicated by large overhangs. The different sizes, shapes and maturities of salt structures in different parts of the Pricaspian basin reflect areal differences in salt thickness and loading history. Our results suggest that the numerical methodology can be employed to analyse the evolution of all salt structures that have upbuilt through younger ductile overburdens.

Salt structures and hydrocarbons in the Pricaspian basin

Pricaspian basin geology is reviewed in the light of 500,000 km of seismic profiles and several thousand wells. We focus on how hydrocarbons from three sources accumulated in relation to the 1800 salt structures in a basin that changed little in planform from the Devonian to the Paleogene. Riphean to Carboniferous shelf sedimentary strata are still flat lying between a poorly known crystalline basement and a base of salt now 10 km deep. Slow and almost continuous sedimentation in the basin center downbuilt huge massifs in Permian salt initially 4.5 km thick. Basin sediments are flat lying or backtilted between down-to-basin growth faults along northern and western margins starved of sediments. By contrast, progradation of Permian sediments from the Urals, Triassic sediments from the South Emba shear zone, and Jurassic sediments from the Dombass-Tuarkyr fold belt downbuilt successive waves of salt structures basinward from margins in the east, southeast and then the south. A zone of salt overhangs records extrusion that starved basin-marginal salt structures, particularly during a basinwide hiatus in the Early Jurassic. Salt diapirs along polygonal normal faults rooting to the crests of still-potent salt structures through Cretaceous–Paleogene strata indicate that salt upbuilt back to the surface and resumed downbuilding. Coarse clastic fans infill deep canyons incised across the basin by rivers draining to the Caspian in Pliocene times.

Abstract: Exploration in the Temir Block, Pricaspian Basin, Kazakhstan: Integration of Surface and Subsurface Data in a Salt Basin 

Abstract: Exploration in the Temir Block, Pricaspian Basin, Kazakhstan: Integration of Surface and Subsurface Data in a Salt Basin 

Predicting hydrocarbon accumulations below deep Permian salt in the Pricaspian Basin; the use of shallow geochemical indicators

The Pricaspian Basin in the southeast of the Russian Platform contains a sedimentary column up to 20 km thick comprising Palaeozoic subsalt formations, Permian salt and suprasalt Mesozoic and Cenozoic terrigenous formations. The huge oil and gas reserves of the Basin are concentrated in subsalt Upper Palaeozoic carbonate reservoirs. Geologists generally agree that the hydrocarbons in the numerous, generally small fields discovered in Mesozoic reservoirs migrated from deeper, subsalt strata. This suggests that traces of fluids at shallow stratigraphic levels may indicate the deep, subsalt sources of the hydrocarbons and associated components. Subsalt reservoirs at depths of more than 6000 m are targets for future exploration. The location of hydrocarbon pools in such reservoirs may be indicated by geochemical investigations of the salt and of the terrigenous rocks above the salt. The distribution of geochemical indicators in the post-salt section may aid the prediction of undiscovered hydrocarbon pools in deep Palaeozoic carbonate formations.

Comparison of Lower to Middle Carboniferous Platform Carbonate Reservoir Development along the Northern, Easter and Southwestern Margins of the Pricaspian Basin, Republic of Kazakhstan: ABSTRACTS

Comparison of Lower to Middle Carboniferous Platform Carbonate Reservoir Development along the Northern, Easter and Southwestern Margins of the Pricaspian Basin, Republic of Kazakhstan: ABSTRACTS

Abstract :Outcrops of Intact Lower Carboniferous Carbonate Platforms in Asturias (Northern Spain) as Analogues of Coeval Reservoirs in the Subsurface of the Pricaspian Basin (Kazakstan, Russia)

Abstract :Outcrops of Intact Lower Carboniferous Carbonate Platforms in Asturias (Northern Spain) as Analogues of Coeval Reservoirs in the Subsurface of the Pricaspian Basin (Kazakstan, Russia)

Seismic Expression of the Pre-Kungurian Carbonate Platform and Domes in the Pricaspian Basin, Kazakhstan

Seismic Expression of the Pre-Kungurian Carbonate Platform and Domes in the Pricaspian Basin, Kazakhstan

Diapiric Structures in the Pricaspian Basin, Kazakhstan

Diapiric Structures in the Pricaspian Basin, Kazakhstan

The Tengis Oil Field, Pri-Caspian Basin, USSR--A Super Giant of the 1980s: ABSTRACT

The Tengis Oil Field, Pri-Caspian Basin, USSR--A Super Giant of the 1980s: ABSTRACT

The Tengiz Oil Field, Pri-Caspian Basin, USSR, A Super Giant of the '80s: ABSTRACT

The Tengiz Oil Field, Pri-Caspian Basin, USSR, A Super Giant of the '80s: ABSTRACT

Future Petroleum-Productive Regions of USSR and Mongolia: ABSTRACT

The potential for major discoveries of oil and gas is high in the USSR, but remote in Mongolia. Development of the USSR's potential is plagued by six factors: (1) remoteness of prospective basins from commercial markets, (2) lack of adequate infrastructure within prospective basins, (3) inadequate drilling technology for economic development below depths of 3,200-3,800 m (10,500-12,500 ft), (4) poor-quality indigenous equipment, (5) absence of offshore capabilities, not only in the warm Caspian and Black Seas, but also in the ice-plagued Arctic and Pacific Oceans, and (6) a chronic manpower shortage. Imports of foreign technology are alleviating the problems gradually, but they are far from solved. European USSR: The most important objectives of the future are: (1) Jurassic through Devonian in the Greater Barents basin and Svalbard platform, offshore Barents Sea, (2) deep Carboniferous-Ordovician of Timian-Pechora basin, (3) subthrust plays of western Urals, (4) pre-Kungurian salt section of the Pricaspian basin, (5) Devonian of the Dnepr-Donets graben, (6) Jurassic through Paleogene of the Black Sea shelf, (7) pre-Tertiary formations of the North Caucasus trough, and (8) deep Tertiary objectives near Baku in the central and southern Caspian Sea. Asiatic USSR: The most important targets are: (1) deep Mesozoic and Paleozoic (Carboniferous, Devonian, Silurian) carbonates of the Nyurol'ka, Frolovo, and other depressions in and below the West Siberian basin, including the Kara Sea, (2) late Paleozoic-Mesozoic of the Aral' Sea, the Ustyurt depression, the Chu-Sarysu basin, and the Turgay and Syrdar'ya syneclises, most of them unexplored, (3) the pre-Upper Jurassic of the central Asian basins, (4) the deep Tertiary of the Cheleken district, (5) the subthrust and pre-Tithonian salt section of the South Tadzhik basin, (6) the Proterozoic-Silurian marine sequences of the Tunguska, Lena, and Sukhana basins, and of the Nepa-Botuoba arch, (7) the Carboniferous-Lower Jurassic of the Vilyuy, Lena-Anabar, Khatanga, and Yenisey basins, with the associated sub hrust plays of the Taymyr and Verkhoyansk ranges, and (8) the numerous late Paleozoic-Mesozoic offshore basins of the Arctic shelf plus the Tertiary basins of the Pacific, especially the Severny basin. Mongolia: Principal objectives are Jurassic and Cretaceous fluviatile and lacustrine sandstones in southeastern Mongolia, especially in the East Gobi basin and in the Hailar basin, which is shared with China. Similar basins in China have giant fields, such as Karamay in the Junggar basin and Daqing in the Songliao basin. Resources: Through 1983, the USSR had produced about 75 billion bbl of oil and condensate and 217 tcf of gas. Estimated proved plus probable liquids was 35-36 billion bbl and, of gas, about 800 tcf. Resource potential, above and beyond proved plus probable, is estimated at about 90 billion bbl and 1,000 tcf (these numbers will increase as offshore icepack technology is improved). In contrast, Mongolia's produced and proved oil is less than 2 million bbl, but the resource potential could be large. End_of_Article - Last_Page 1205------------