North Caspian Research Articles

Formation mechanisms of ultradeep sedimentary basins: the North Barents basin. Petroleum potential implications

Consolidated crust in the North Barents basin with sediments 16–18km thick is attenuated approximately by two times. The normal faults in the basin basement ensure only 10-15% stretching, which caused the deposition of 2–3km sediments during the early evolution of the basin. The overlying 16km of sediments have accumulated since the Late Devonian. Judging by the undisturbed reflectors to a depth of 8s, crustal subsidence was not accompanied by any significant stretching throughout that time. Dramatic subsidence under such conditions required considerable contraction of lithospheric rocks. The contraction was mainly due to high-grade metamorphism in mafic rocks in the lower crust. The metamorphism was favored by increasing pressure and temperature in the lower crust with the accumulation of a thick layer of sediments. According to gravity data, the Moho in the basin is underlain by large masses of high-velocity eclogites, which are denser than mantle peridotites. The same is typical of some other ultradeep basins: North Caspian, South Caspian, North Chukchi, and Gulf of Mexico basins. From Late Devonian to Late Jurassic, several episodes of rapid crustal subsidence took place in the North Barents basin, which is typical of large petroleum basins. The subsidence was due to metamorphism in the lower crust, when it was infiltrated by mantle-source fluids in several episodes. The metamorphic contraction in the lower crust gave rise to deep-water basins with sediments with a high content of unoxidized organic matter. Along with numerous structural and nonstructural traps in the cover of the North Barents basin, this is strong evidence that the North Barents basin is a large hydrocarbon basin.

Advancing Oil Spill Response in Arctic Conditions: The Arctic Oil Spill Response Technology - Joint Industry Programme

ABSTRACT The oil and gas industry has made significant advances in being able to detect, contain and clean up spills in arctic environments. To further build on existing research and improve the technologies and methodologies for arctic oil spill response, nine oil and gas companies (BP, Chevron, ConocoPhillips, Eni, ExxonMobil, North Caspian Operating Company, Shell, Statoil, and Total) established the Arctic Oil Spill Response Technology Joint Industry Programme (JIP). The goal of the JIP is to advance arctic oil spill response strategies and equipment as well as to increase understanding of potential impacts of oil on the arctic marine environment. Officially launched in January 2012 at the Arctic Frontiers Conference in Tromsø, Norway, the JIP has six technical working groups (TWG) each focusing on a different key area of oil spill response: dispersants; environmental effects; trajectory modeling; remote sensing; mechanical recovery and in-situ burning (ISB). There is also a field research TWG to pursue opportunities for field releases for validation of response technologies and strategies. Each TWG is led by recognized subject matter experts with years of experience in oil spill response research and operations. This JIP is bringing together the world's foremost experts on oil spill response research, development, and operations from across industry, academia, and independent research centres. Research integrity will be ensured through technical peer review and public dissemination of results. This paper describes the scope and current progress of this Joint Industry Program (JIP).

Human Paternal Lineages, Languages, and Environment in the Caucasus

Human Paternal Lineages, Languages, and Environment in the Caucasus David Tarkhnishvili, Alexander Gavashelishvili, Marine Murtskhvaladze, Mariam Gabelaia, and Gigi Tevzadze abstract Publications that describe the composition of the human Y-DNA haplogroup in different ethnic or linguistic groups and geographic regions provide no explicit explanation of the distribution of human paternal lineages in relation to specific ecological conditions. Our research attempts to address this topic for the Caucasus, a geographic region that encompasses a relatively small area but harbors high linguistic, ethnic, and Y-DNA haplogroup diversity. We genotyped 224 men that identified themselves as ethnic Georgian for 23 Y-chromosome short tandem-repeat markers and assigned them to their geographic places of origin. The genotyped data were supplemented with published data on haplogroup composition and location of other ethnic groups of the Caucasus. We used multivariate statistical methods to see if linguistics, climate, and landscape accounted for geographical differences in frequencies of the Y-DNA haplogroups G2, R1a, R1b, J1, and J2. The analysis showed significant associations of (1) G2 with well-forested mountains, (2) J2 with warm areas or poorly forested mountains, and (3) J1 with poorly forested mountains. R1b showed no association with environment. Haplogroups J1 and R1a were significantly associated with Daghestanian and Kipchak speakers, respectively, but the other haplogroups showed no such simple associations with languages. Climate and landscape in the context of competition over productive areas among different paternal lineages, arriving in the Caucasus in different times, have played an important role in shaping the present-day spatial distribution of patrilineages in the Caucasus. This spatial pattern had formed before linguistic subdivisions were finally shaped, probably in the Neolithic to Bronze Age. Later historical turmoil had little influence on the patrilineage composition and spatial distribution. Based on our results, the scenario of postglacial expansions of humans and their languages to the Caucasus from the Middle East, western Eurasia, and the East European Plain is plausible. key words Y-DNA Haplogroup, Paternal Lineage, Caucasus, Glacial Refugia, Human Ecology, Landscape Genetics, Ethnogenesis, Language Y-DNA haplogroup diversity is most commonly used to analyze ancestry of individual ethnic groups or linguistic families (Kayser et al. 1997; Brisighelli 2012), because Y-DNA haplogroups generally show more distinct ethnogeographic patterns than does matrilineally inherited mitochondrial DNA (Comas et al. 2000; Nasidze et al. 2003, 2004a), most likely because of higher dispersal rates of women (Seielstad et al. 1998; Oota et al. 2001; Nasidze et al. 2004b), the effects of selective pressures on the mitochondrial genome (Mishmar et al. 2003), and/or sex ratio [End Page 113] in favor of women causing more genetic drift in males (Dupanloup et al. 2003). Moreover, there is a popular nomenclature of the haplogroups linked to a well-established phylogenetic pattern (Underhill et al. 2001; Y Chromosome Consortium 2002; Karafet et al. 2008; Chiaroni et al. 2009). The Caucasus is among the most linguistically and culturally diverse regions of Eurasia (Comrie 2008; Nasidze et al. 2004a; Marchani et al. 2008; Balanovsky et al. 2011; Yunusbayev et al. 2012). Currently, the region hosts dozens of languages that are grouped into three language families (Comrie 2008): Caucasian, Indo-European, and Turkic. The Caucasian language family traditionally includes Adyghean, Vainakh, Daghestanian, and Kartvelian languages (Catford 1977), although the common origin of these languages is disputed (Starostin 1989). A recent study by Pagel et al. (2013) shows that the Kartvelian and Dravidic language families are the most basal in relation to the other Eurasian language families. Diakonoff and Starostin (1988) suggest that Vainakh and Daghestanian (i.e., Northeast Caucasian languages) are related to extinct Hurro-Urartian. Armenian and Ossetian languages belong to the Indo-European language family, and Oghuz and Kipchak subgroups of the Turkic language group are spoken in the Caucasus as well (Catford 1977; Comrie 2008). Linguistic differences, along with the differences in political history, influence (but do not determine) the ethnic identities of the people inhabiting the region. Some ethnic boundaries (e.g., that of Armenians or Ossetians) coincide with the linguistic boundaries, but those of the other ethnic groups do so only partly. Some groups speaking several mutually unintelligible but related languages consider themselves to be part of a single ethnos (e.g., Georgians...

Human Paternal Lineages, Languages, and Environment in the Caucasus

Human Paternal Lineages, Languages, and Environment in the Caucasus David Tarkhnishvili, Alexander Gavashelishvili, Marine Murtskhvaladze, Mariam Gabelaia, and Gigi Tevzadze abstract Publications that describe the composition of the human Y-DNA haplogroup in different ethnic or linguistic groups and geographic regions provide no explicit explanation of the distribution of human paternal lineages in relation to specific ecological conditions. Our research attempts to address this topic for the Caucasus, a geographic region that encompasses a relatively small area but harbors high linguistic, ethnic, and Y-DNA haplogroup diversity. We genotyped 224 men that identified themselves as ethnic Georgian for 23 Y-chromosome short tandem-repeat markers and assigned them to their geographic places of origin. The genotyped data were supplemented with published data on haplogroup composition and location of other ethnic groups of the Caucasus. We used multivariate statistical methods to see if linguistics, climate, and landscape accounted for geographical differences in frequencies of the Y-DNA haplogroups G2, R1a, R1b, J1, and J2. The analysis showed significant associations of (1) G2 with well-forested mountains, (2) J2 with warm areas or poorly forested mountains, and (3) J1 with poorly forested mountains. R1b showed no association with environment. Haplogroups J1 and R1a were significantly associated with Daghestanian and Kipchak speakers, respectively, but the other haplogroups showed no such simple associations with languages. Climate and landscape in the context of competition over productive areas among different paternal lineages, arriving in the Caucasus in different times, have played an important role in shaping the present-day spatial distribution of patrilineages in the Caucasus. This spatial pattern had formed before linguistic subdivisions were finally shaped, probably in the Neolithic to Bronze Age. Later historical turmoil had little influence on the patrilineage composition and spatial distribution. Based on our results, the scenario of postglacial expansions of humans and their languages to the Caucasus from the Middle East, western Eurasia, and the East European Plain is plausible. key words Y-DNA Haplogroup, Paternal Lineage, Caucasus, Glacial Refugia, Human Ecology, Landscape Genetics, Ethnogenesis, Language Y-DNA haplogroup diversity is most commonly used to analyze ancestry of individual ethnic groups or linguistic families (Kayser et al. 1997; Brisighelli 2012), because Y-DNA haplogroups generally show more distinct ethnogeographic patterns than does matrilineally inherited mitochondrial DNA (Comas et al. 2000; Nasidze et al. 2003, 2004a), most likely because of higher dispersal rates of women (Seielstad et al. 1998; Oota et al. 2001; Nasidze et al. 2004b), the effects of selective pressures on the mitochondrial genome (Mishmar et al. 2003), and/or sex ratio [End Page 113] in favor of women causing more genetic drift in males (Dupanloup et al. 2003). Moreover, there is a popular nomenclature of the haplogroups linked to a well-established phylogenetic pattern (Underhill et al. 2001; Y Chromosome Consortium 2002; Karafet et al. 2008; Chiaroni et al. 2009). The Caucasus is among the most linguistically and culturally diverse regions of Eurasia (Comrie 2008; Nasidze et al. 2004a; Marchani et al. 2008; Balanovsky et al. 2011; Yunusbayev et al. 2012). Currently, the region hosts dozens of languages that are grouped into three language families (Comrie 2008): Caucasian, Indo-European, and Turkic. The Caucasian language family traditionally includes Adyghean, Vainakh, Daghestanian, and Kartvelian languages (Catford 1977), although the common origin of these languages is disputed (Starostin 1989). A recent study by Pagel et al. (2013) shows that the Kartvelian and Dravidic language families are the most basal in relation to the other Eurasian language families. Diakonoff and Starostin (1988) suggest that Vainakh and Daghestanian (i.e., Northeast Caucasian languages) are related to extinct Hurro-Urartian. Armenian and Ossetian languages belong to the Indo-European language family, and Oghuz and Kipchak subgroups of the Turkic language group are spoken in the Caucasus as well (Catford 1977; Comrie 2008). Linguistic differences, along with the differences in political history, influence (but do not determine) the ethnic identities of the people inhabiting the region. Some ethnic boundaries (e.g., that of Armenians or Ossetians) coincide with the linguistic boundaries, but those of the other ethnic groups do so only partly. Some groups speaking several mutually unintelligible but related languages consider themselves to be part of a single ethnos (e.g., Georgians...

Фитопланктон Северного Каспия в ледовых условиях

Фитопланктон Северного Каспия в ледовых условиях

A Canonical Approach to the Argument/Adjunct Distinction

This paper provides an account of the argument/adjunct distinction implementing the 'canonical approach'. I identify five criteria (obligatoriness, latency, co-occurrence restrictions, grammatical relations, and iterability) and seven diagnostic tendencies that can be used to distinguish canonical arguments from canonical adjuncts. I then apply the criteria and tendencies to data from the Nakh-Daghestanian language Hinuq. Hinuq makes extensive use of spatial cases for marking adjunct-like and argument-like NPs. By means of the criteria and tendencies it is possible to distinguish spatial NPs that come close to canonical arguments from those that are canonical adjuncts, and to place the remaining NPs bearing spatial cases within the argument-adjunct continuum.

Teleconnections, midlatitude cyclones and Aegean Sea turbulent heat flux variability on daily through decadal time scales

We analyze daily wintertime cyclone variability in the central and eastern Mediterranean during 1958-2001, and identify four distinct cyclone states, corresponding to the presence or absence of cyclones in each basin. Each cyclone state is associated with wind flows that induce characteristic patterns of cooling via turbulent (sensible and latent) heat fluxes in the eastern Mediterranean basin and Aegean Sea. The relative frequency of occurrence of each state determines the heat loss from the Aegean Sea during that winter, with largest heat losses occurring when there is a storm in the eastern but not central Mediterranean (eNOTc), and the smallest occurring when there is a storm in the central but not eastern Mediterranean (cNOTe). Time series of daily cyclone states for each winter allow us to infer Aegean Sea cooling for winters prior to 1985, the earliest year for which we have daily heat flux observations. We show that cyclone states conducive to Aegean Sea convection occurred in 1991/1992 and 1992/1993, the winters during which deep water formation was observed in the Aegean Sea, and also during the mid-1970s and the winters of 1963/1964 and 1968/1969. We find that the eNOTc cyclone state is anticorrelated with the North Atlantic Oscillation (NAO) prior to 1977/1978. After 1977/1978, the cNOTe state is anticorrelated with both the NAO and the North Caspian Pattern (NCP), showing that the area of influence of large scale atmospheric teleconnections on regional cyclone activity shifted from the eastern to the central Mediterranean during the late 1970s. A trend toward more frequent occurrence of the positive phase of the NAO produced less frequent cNOTe states since the late 1970s, increasing the number of days with strong cooling of the Aegean Sea surface waters.

Y-chromosome diversity in the Kalmyks at the ethnical and tribal levels

The Mongolic-speaking Kalmyks currently inhabiting the steppes of the Volga region have Central Asian ancestry and are organized into the tribal groups. The genetic relationships among these tribes and their origin have remained obscure. We analyzed 17 short tandem repeat and 44 binary polymorphisms of Y-chromosome in 426 individuals mainly from three major tribes of the Kalmyks (the Torguuds, Dörwöds and Khoshuuds). Among these tribes, the Dörwöds and Torguuds, as well as the Kalmyks collectively as an ethnic group, showed relatively close genetic affinities to each other and to the Mongols and Altaian Kazakhs, whereas the Khoshuuds were clearly separated from all of them, gathering with the Manchu, Tibetans or Evenks (depending on the algorithm used to calculate genetic distances). The genetic results also indicate that paternal gene flow from East Europeans to the Kalmyks is very little, despite their cohabitation in the North Caspian Steppe during the last 380 years. The occurrence of unique cluster of N1c-Tat haplotypes in the Khoshuuds, which dates to about 340 years and is likely to have East European ancestry, is considered as a result of interethnic contacts occurred soon after the appearance of the Kalmyk tribes in the Volga-Ural region.

Spatial functional organization of ecotones on shores of intermittent lake Bulukhta (North Caspian lowland)

The spatial organization of nature systems on shores of lake Bulukhta with variable water level (North Precaspian lowland) was examined by field investigations. The regularities of the composition and spatial structure of the soil-vegetation cover and the peculiarities of the seasonal dynamics and mineralization of the water table were determined. The possibility of applying the ecotone concept as a methodological approach when studying the spatial and functional organization of the soil-vegetation cover and the dynamics of shores of lakes with variable water levels under arid climate conditions has been presented.

Gas seeps in the North Caspian water area

Seismoacoustic profiling and sonar survey of the North Caspian water area revealed in some areas signs of intense release of methane from the sedimentary sequence. This fact was also supported by submarine videorecording data. Such sites are characterized by hummocky and ridgy morphologies, which accommodate local cone-shaped bodies (up to 1.3–1.5 m high) overgrown with algae, Balanus, and shelly material. Based on dredging data, these rises are composed of hard sandstones and shells. They can cover the seafloor or make up separate interlayers in the bottom sediments down to a depth of 2.7 m. Mineralogical studies demonstrated that the coarse-grained sediments are cemented with Mg-calcite, with δ13C reaching −32.6‰. They also include microcrystalline barite and globular iron sulfides. The results of investigation suggest that the local activation of authigenic mineral formation is related to gas discharge sources.

Elisional processes and salt tectonics: Communication 1. Catagenetic transformations in saliferous sequences

The work is dedicated to catagenetic transformations in sedimentary rocks with consideration of defluidization in clayey and evaporite sediments and analysis of salt tectonics and hydrogeology in the North Caspian depression.

Issues in Khinalug Syntax: Building on Corpus Evidence

The paper treats several issues in the syntax of Khinalug, an East Caucasian language of Northern Azerbaijan, presenting some results of the author’s ongoing research of Khinalug syntax. The analysis is based on corpus data and covers three issues that can not be adequately accounted for by mere elicitation: the locus of expression of shared participants in a polypredicative construction; the non-coordinative uses of the additive particle; and some properties of the constructions involving the quotative particle.

Technology Focus: Multilateral/Extended Reach (May 2013)

Technology Focus The producing assets of unconventional shale-gas and shale-oil plays in North America are among the strategic alternatives for future growth of exploration-and-production companies. Although the economics of the unconventional plays was quite marginal at the beginning, further advancements in planning and operations have made feasible the exploitation of such assets with a reasonable return on investment. The use of horizontal drilling in conjunction with hydraulic fracturing has expanded the ability of operators to recover natural gas and oil from low-permeability geologic plays in a profitable way. However, there is still room for improvement in efficiency. The exploitation of the unconventional areas with the current number of wells per acre and the amount of water used for the fracturing jobs is counterproductive. The current reality imposes fewer wells per acre, a reduction in drilling pads, and a minimum use of water in fracturing jobs. The implementation of multilateral, extended-reach, or fishbone wells is playing an essential role in the reduction of the wells, meanwhile maintaining or improving the production and recovery per acre. Thanks to the development of a new generation of fluids that improve hydraulics and wellbore stability, those wells can now reach targets farther from drilling centers, with a substantial increase in recovery and productivity per well. The selected papers give a perspective on the challenges faced on these well profiles and the technologies used to overcome them. On the other hand, the fracturing treatment has reached a considerable number of stages because of the long extension of the wells, resulting in a required water volume that has jeopardized the economics of the project and created problems with the local communities. The environmental effect of the wastewater from the fracturing jobs has brought concerns, urging the development of techniques that reduce the amount of such water. The volume of water in fracturing jobs is directly proportional to the fluid-loss-coefficient property, so decreasing that will result in more-effective fracture propagation with less water. Some research projects with the new generation of fracturing fluids—some including the use of nanotechnology—are aiming for this objective of improving fracturing jobs with a substantial reduction in water volume. The implementation of this new generation of fracturing fluids with multilateral/horizontal/extended-reach wells has the potential to enable the exploitation of unconventional reserves around the world with minimum visual and environmental effect, diminishing substantially the criticism about current unconventional shale operations. Recommended additional reading at OnePetro: www.onepetro.org. SPE 162099 Drilling World-Class ERD Wells in the North Caspian Sea by Sergey Bogdanov, Lukoil, et al. SPE 161532 Drilling Multilateral Infill Wells for Incremental Oil Production: A Case Study From a Mature Field by E. Zuckmeyer, Total, et al. SPE/IADC 163463 Extended-Reach Drilling—New Solution With a Unique Potential by O. Vestavik, Reelwell, et al.

Hinuq verb forms and finiteness

This paper offers a comprehensive account of the verbal morphology in the Nakh-Daghestanian (or Northeast Caucasian) language Hinuq. As typical of the languages of that part of the world, Hinuq has a rich inventory of verbal inflectional suffixes, giving rise to verb forms with only verbal properties, and other verb forms lacking some verbal properties and having adjectival, adverbial or nominal properties instead. I argue that all Hinuq verb forms can be divided into two groups along the lines of their usage as heads of independent or dependent clauses. Furthermore, I demonstrate that some verb forms, which at first glance seem to violate this classification, synchronically represent different verb forms that can clearly be distinguished functionally and partially also on formal grounds. The paper also contributes to the actual discussion of the notion ‘finiteness’ and its applicability to Nakh-Daghestanian languages.

Historische und areale Aspekte der Bodenschatz-Terminologie in den ostkaukasischen Sprachen

The present paper discusses the historical background of selected terms in the world of East Caucasian languages that are related to the domain of metallurgy (copper, iron, tin, plumb, gold, and silver) augmented by terms for ‘coal’ and ‘salt’. A closer inspection of these terms shows that none of them can be reconstructed for Proto-East Caucasian. Rather, we have to deal either with terms that have been coined in the intermediate protolanguages (Nakh, Avar-Andian, Tsezian, Lezgian, Lak, Dargwa, and Khinalug) or with more or less recent loans stemming mainly from the Iranian and Turkic languages. The absence of reconstructable terms for the items under review suggests that the speakers of the East Caucasian proto-language had not been involved expressively in metallurgic traditions (as opposed to farming traditions). Tentatively, these speakers can thus be associated with the early farming culture within the complex of the Kuro-Araxes Culture. Only after the protolanguage disintegrated due to the migration of most of its speakers in the Dagestan and the regions of Chechnya, some societies related to these intermediate proto-languages must have been involved more expressively in metallurgic traditions. The more recent loans, e.g. for copper, gold, and silver, stemming from Iranian (Persian) and Turkic (Kumyk and Azeri) illustrate a shift in conceptualising these objects: They were now interpreted as artifacts (rather than as natural resources) that were associated with the cultures of the dominant ‘Oriental’ societies. The paper can be seen as a preliminary study concerning the areal distribution of lexical patterns in the Eastern Caucasus from a historical perspective.

The problem of the neolithisation process chronology in Povolzhye

The Lower and Middle Volga basin regions border the Caucasus and Central Asia in the South. These regions are important in the study of the neolithisation process in Europe and the chronology of Neolithic cultures is of great significance in this respect. New 14C dates of different organic materials from archaeological sites in these regions have been obtained in the last five years. According to these data, the beginning of neolithisation in North Caspian region can be dated to the beginning of the 5th millennium BC; but in the Povolzhye it happened at least a millennium earlier.

New insights into hydrocarbon plays in the Caspian Sea, Kazakhstan

New exploration opportunities and improved imaging of already known prospects in the Caspian Sea, Kazakhstan, are presented, based on the acquisition, processing and interpretation of long-offset 2D seismic data acquired by CGGVeritas from 2006–2009. We have identified further examples of three already successful plays in the Caspian Sea and onshore, within open blocks in the North Caspian and North Ustyurt basins and a fourth, relatively unknown play, in the North Ustyurt basin. The already known plays include Devono-Carboniferous carbonate reefs and clastics, Triassic–Tertiary post-salt clastics and carbonates in the North Caspian basin and Jurassic–Cretaceous post-thrust clastics and carbonates in the North Ustyurt basin. The fourth play that we have identified comprises thrust faults, anticlinal structures with Late Palaeozoic–Early Mesozoic clastic and carbonate reservoirs in the North Ustyurt basin which, to our knowledge, has not been tested elsewhere in the region.

Magnetic properties of greigite in the Late Pleistocene sediments of the North Caspian

The results of magnetic and X-ray studies of the magnetic extracts separated from highly magnetically susceptible horizons of the Late Pleistocene sediments from the North Caspian Basin are presented. Greigite is shown to be the major carrier of magnetic properties in these horizons. Its coercive parameters are characteristic of the predominantly single-domain state of magnetic grains. It is found that the Curie point of greigite is at least 460°C, while the specific magnetization of pure greigite is half the saturation magnetization of magnetite.

Stratification and seasonal dynamics of weevil (Coleoptera, Curculionoidea) assemblages in the North Caspian semi-desert

In 2003–2004, 102 species of five weevil families were found in the steppe and desert associations of the Caspian semi-desert (Dzhanybek Station). Representatives of Curculionidae predominated (87 species). The majority of the commonest weevil species (20) were most abundant in the steppe associations, only 6 species being found in the desert ones. The composition of the weevil community changed abruptly from spring to summer. The greatest species richness (86 species) was observed in spring; only in this period weevils living mostly on the soil surface had high densities. In the herbage, both in the steppe and desert communities, detritophagous steppe species Archaeophloeus inermis and Trachyphloeus amplithorax were abundant; the habitats of the solonetz complex (on microelevations and in the depressions), the desert-steppe and steppe species (Humeromima nitida, Mesagroicus poriventris, Temnorhinus strabus) associated with saline substrates were also present. The spring hortobiont assemblage was dominated by the polyphagous steppe weevils, Euidosomus acuminatus, Phyllobius brevis and Omias spp. In summer, 53 species of weevils were recorded; their numbers on the soil surface sharply dropped, the core of the herbage assemblage consisted of the weevils feeding on alfalfa (Stenopterapion tenue, Sitona spp., Tychius spp.) in the steppe associations, with the maximum abundance in the more humid depressions. The summer assemblage of the desert herbage was poor and consisted of the species associated with wormwoods and chenopods (Ptochus porcellus, Phacephorus argyrostomus, Metadonus anceps). The autumn groupings with only 24 species were poor and had low population densities.

Advanced Upscaling for Kashagan Reservoir Modeling

Summary The Kashagan field is a huge carbonate formation located 4.5 km below the bottom of the North Caspian sea. The reservoir is saturated by overpressured light oil, and the development is based on first-contact-miscible gas injection. The reservoir is highly stratified, with a fine sequence of depositional cycles and long-range lateral correlations. Three porosity systems (matrix, karst, and fractures) can be organized in two main environments: a massive, low-permeability, matrix-like inner platform and a highly fractured/karstified rim. The reservoir geology is modeled by means of detailed geological grids consisting of tens of millions of cells, with vertical spacing of 1 m or even less to account for high-order depositional cycles. Geological grid cannot be used to run compositional simulations, and much-coarser grids, in which hundreds of geological layers are lumped in few tens of dynamic layers, are used by reservoir engineers. To minimize coarse-scale errors, an average lateral spacing of 250×250 m is used for both simulation and geological grid; nonetheless, upscaling remains a challenge. Traditional permeability (k*) upscaling methods, including flow-based methods, overestimate Kashagan field/wells production and injection potentials. We implemented a method in which the outcome of the upscaling is effective transmissibility (T*) instead of k*. T* upscaling has been proposed in the past as an alternative to k* upscaling, but it is neither part of commercial workflows nor widely accepted in the reservoir-modeling community. In our T* upscaling, the solution of local flow problems around coarse-cell interfaces is used to compute coarse transmissibility. T* and k* upscaling were compared by simulating both single-phase and gas-injection problems, including platform and rim, using the results of fine-scale simulation as a reference. We considered (1) single-porosity simulations with geological grid populated by only matrix (first medium) and karst+fracture (second medium) properties and (2) dual-porosity/ dual-permeability simulations encompassing both media. Contrary to k* upscaling, T*-based coarse simulations perfectly replicate fine-scale field and well injection/production potentials. Using T* upscaling as a cornerstone for company activities on Kashagan, we can run coarse-scale full-field simulations in a few hours without loss of consistency with the results provided by weeks-long, often unpractical, fine-scale simulations. On the contrary, the inaccuracy of k* upscaling would have required much finer and more computationally-expensive simulation grids together with the implementation of ad hoc multiphase upscaling.