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1.
The identification of reservoir oil–gas–water layers is a fundamental task in petroleum exploration and exploitation, but is difficult, especially in cases of complex hydrocarbon migration and accumulation. In such cases, hydrocarbon remigration and dysmigration take place very commonly, leading to the presence of residual or paleo-oil accumulations and layers, which cannot be easily identified or misinterpreted as oil layers by conventional logging and geophysical data. In this paper, based on a case study in the Luxi area of the central Junggar Basin, NW China, we seek to characterize such layers in terms of organic geochemistry. We suggest specific indicator parameters of organic geochemistry such as the chloroform bitumen content of reservoir extracts, which is usually >1.0% in oil layers. We explore the application of grains containing oil inclusions (GOI) (the ratio of mineral grains containing oil inclusions to the total number of mineral grains) for the identification of oil–gas–water layers in the Junggar Basin for the first time; this method has been used elsewhere. The maximum GOI values for the oil layers, oil–water layers, water layers and dry layers are >11%, 7%–11%, 6%–7% and <6%, respectively. In addition, gas layers and heavy-oil layers that are difficult to identify by conventional organic geochemical parameters were identified using biomarkers. The typical characteristics of the soluble reservoir bitumen in the gas layers include a much greater abundance of tricyclic terpanes (two times in general) relative to pentacyclic terpanes and a tricyclic terpane distribution of C20 > C21 > C23. In contrast, the typical characteristic of the heavy-oil layers is the presence of 25-norhopanes in reservoir bitumen extracts. These specific indicators can be applied in the Junggar Basin and in similar settings elsewhere. 相似文献
2.
《Ocean Modelling》2011,40(3-4):284-290
The temperature dependency of ocean–atmosphere gas transfer velocities is commonly estimated in terms of Schmidt numbers, i.e. the ratio of kinematic viscosity to diffusivity. In numerical models least square regressions are used to fit the limited number of experimentally derived Schmidt numbers to a function of temperature. For CO2 a well established fit can be found in the literature. This fit constitutes an integral part in standardized carbon cycle simulation projects (e.g. C4MIP, OC4MIP, Friedlingstein et al., 2006). However, the fit is valid only in the range where diffusivity measurements exist, i.e., from 0 to about 30 °C. In many climate warming simulations like e.g. the MPI contribution to the fourth Intergovernmental Panel on Climate Change Assessment Report (IPCC AR 4), sea surface temperatures largely exceed the validated range and approach or even reach the range, where the standard fits leave the physically meaningful range. Thus, this paper underlines the demand for new measurements of seawater diffusivities for CO2 and other trace gases especially for the temperature range >30 °C.In this paper we provide improved fits for the temperature dependence of the Schmidt number. For carbon dioxide our fit is compared to the established fit under identical climate change simulations carried out with the 3D-carbon cycle model HAMOCC. We find that in many tropical and subtropical high temperature regions the established fit leads to unrealistically short adaption times of the surface water pCO2 to altered atmospheric pCO2. In regions where the local oceanic pCO2 is not primarily controlled by the atmospheric boundary pCO2 but by other processes such as biological activity, the atmosphere ocean pCO2 gradient is clearly underestimated when using the established fit. The effect on global oceanic carbon uptake in a greenhouse world is rather small and the potential climate feedback introduced by this bias seems to be negligible. However, the bias will clearly gain in significance the more regions warm up to over 30 °C. On a regional scale, especially in coastal regions at low latitudes, the effect is not negligible and a different steady state is approached. 相似文献
3.
We have performed a simulation of the convectively induced ascent of the gas–dust cloud formed during the atmospheric passage and explosion of the Chelyabinsk meteoroid. The acceleration, velocity, and rise of the gas–dust cloud have been described as functions of time and altitude. The time of dust settling in the atmosphere has been estimated. The results of calculations are in a close agreement with the observational data. 相似文献
4.
《Marine and Petroleum Geology》2003,20(3-4):385-397
Various settings took place during the Late Mesozoic: divergent, convergent, collisional, and transform. After mid-Jurassic collision of the Siberian and Chinese cratons, a latitudinal system of post-collision troughs developed along the Mongol-Okhotsk suture (the Uda, Torom basins and others), filled with terrigenous coal-bearing molasse.The dispersion of Pangea, creation of oceans during the Late Jurassic are correlated to the emergence of the East Asian submeridional rift system with volcano-terrigenous coal-bearing deposits (the Amur-Zeya basin). At that time, to the east there existed an Andean-type continental margin. Foreland (Upper Bureya, Partizansk, and Razdolny) and flexural (Sangjiang-Middle Amur) basins were formed along the margin of the rigid massifs during the Late Jurassic to Berriasian.During the Valanginian-mid-Albian an oblique subduction of the Izanagi plate beneath the Asian continent occurred, producing a transform margin type, considerable sinistral strike slip displacements, and formation of pull-apart basins filled with turbidites (the Sangjiang-Middle Amur basin).The Aptian is characterized by plate reorganization and formation of epioceanic island arcs, fore-arc and back-arc basins in Sakhalin and the Sikhote-Alin (the Alchan and Sangjiang-Middle Amur basins), filled with volcanoclastics.During the mid-Albian a series of terranes accreted to the Asian continental margin. By the end of the Albian, the East Asian marginal volcanic belt began to form due to the subduction of the Kula plate beneath the Asian continent. During the Cenomanian–Coniacian shallow marine coarse clastics accumulated in the fore-arc basins, which were followed by continental deposits in the Santonian–Campanian. From the Coniacian to the Maastrichtian, a thermal subsidence started in rift basins, and continental oil-bearing clastics accumulated (the Amur-Zeya basin).Widespread elevation and denudation were dominant during the Maastrichtian. This is evidenced by thick sediments accumulated in the Western Sakhalin fore-arc basin.During the Cenozoic, an extensive rift belt rmade up of a system of grabens, which were filled with lacustrine–alluvial coal–and oil-bearing deposits, developed along the East Asian margin. 相似文献
5.
During the India National Gas Hydrate Program (NGHP) Expedition 01 in 2006 significant sand and gas hydrate were recovered at Site NGHP-01-15 within the Krishna–Godavari Basin, East Coast off India. At the drill site NGHP-01-15, a 5–8 m thick interval was found that is characterized by higher sand content than anywhere else at the site and within the KG Basin. Gas hydrate concentrations were determined to be 20–40% of the pore volume using wire-line electrical resistivity data as well as core-derived pore-fluid freshening trends. The gas hydrate-bearing interval was linked to a prominent seismic reflection observed in the 3D seismic data. This reflection event, mapped for about 1 km2 south of the drill site, is bound by a fault at its northern limit that may act as migration conduit for free gas to enter the gas hydrate stability zone (GHSZ) and subsequently charge the sand-rich layer. On 3D and additional regional 2D seismic data a prominent channel system was imaged mainly by using the seismic instantaneous amplitude attribute. The channel can be clearly identified by changes in the seismic character of the channel fill (sand-rich) and pronounced levees (less sand content than in the fill, but higher than in surrounding mud-dominated sediments). The entire channel sequence (channel fill and levees) has been subsequently covered and back-filled with a more mud-prone sediment sequence. Where the levees intersect the base of the GHSZ, their reflection strengths are significantly increased to 5- to 6-times the surrounding reflection amplitudes. Using the 3D seismic data these high-amplitude reflection edges where linked to the gas hydrate-bearing layer at Site NGHP-01-15. Further south along the channel the same reflection elements representing the levees do not show similarly large reflection amplitudes. However, the channel system is still characterized by several high-amplitude reflection events (a few hundred meters wide and up to ~ 1 km in extent) interpreted as gas hydrate-bearing sand intervals along the length of the channel. 相似文献
6.
A growing number of studies on shallow marine gas/fluid systems from across the globe indicate their abundance throughout geological epochs. However, these episodic events have not been fully integrated into the fundamental concepts of continental margin development, which are thought to be dictated by three elements: tectonics, sedimentation and eustasy. The current study focuses on the passive sector of the Levant Basin on the eastern Mediterranean continental margin where these elements are well constrained, in order to isolate the contribution of gas/fluid systems. Single-channel, multichannel and 3D seismic reflection data are interpreted in terms of variance, chaos, envelope and sweetness attributes. Correlation with the Romi-1 borehole and sequence boundaries constrains interpretation of seismic stratigraphy. Results show a variety of fluid- or gas-related features such as seafloor and subsurface pockmarks, volumes of acoustic blanking, bright spots, conic pinnacle mounds, gas chimneys and high sweetness zones that represent possible secondary reservoirs. It is suggested that gas/fluid migrate upwards along lithological conduits such as falling-stage systems tracts and sequence boundaries during both highstands and lowstands. In all, 13 mid-late Pleistocene sequence boundaries are accompanied by independent evidence of 13 eustatic sea-level drops. Whether this connection is coincidental or not requires further research. These findings fill gaps between previously reported sporadic appearances throughout the Levant Basin and margin and throughout geological time from the Messinian until the present day, and create a unified framework for understanding the system as a whole. Repetitive appearance of these features suggests that their role in the morphodynamics of continental margins is more important than previously thought and thus may constitute one of the key elements of continental margin development. 相似文献
7.
Eocene–Oligocene dolomite concretions and beds from the Grybów and Dukla units of the Polish Outer Carpathians were studied. These rocks occur in the organic carbon-rich, marine and fine-grained deposits of hemipelagic or turbiditic origin. Mineralogic, elemental and stable C and O isotopic composition of the dolomites was determined. Results indicate that the rocks were formed by precipitation of predominantly Fe-rich dolomite cement close to the sediment-water interface prior to significant compaction. The main source of bicarbonate for dolomite formation was bacterial methanogenesis as evidenced by the high δ13C values up to 16.6‰. The main source of alkalinity was probably weathering of silicate minerals which might have also liberated Ca and Mg ions for the dolomites to form. The distribution of these dolomites indicates that microbial methane production was widespread in the Silesian basin. Moreover, formation of some dolomites in the Eastern part of the Dukla unit was probably associated with gas hydrates as suggested by the elemental and oxygen isotopic composition of dolomitic matrix. Therefore, the dolomites may serve as a proxy of areas where biogenic methane was produced, where the rocks had high hydrocarbon potential, and where hydrates could have existed.Detailed mineralogic and petrographic analyses allowed for the reconstruction of the diagenetic sequence and the evolution of pore fluids. Textural relationships between successive cement generations indicate that the central parts of the composite dolomite crystals experienced corrosion and that the latest ankerite cement filled the secondary intragranular cavities within those crystals. This observation shows that reconstructions of pore fluid evolution based on core-to-rim analyses of such composite crystals may lead to wrong interpretations. Septarian cracks developed in the dolomites are often filled with multistage cements. The earliest generations are ferroan dolomite and ankerite cements which precipitated within the cracks simultaneously to the ferroan dolomite and ankerite cements from the matrix of the dolomitic rocks which shows that septarian cracking occurred very early, during the final stages of concretionary formation. These cements were followed by the late-diagenetic precipitates, mainly quartz, kaolinite and blocky calcite. This calcite is commonly associated with bitumen which shows that it precipitated during or after oil migration in the decarboxylation zone. 相似文献
8.
The Dniepr-Donets Basin (DDB) hosts a multi-source petroleum system with more than 200 oil and gas fields, mainly in Carboniferous clastic rocks. Main aim of the present study was to correlate accumulated hydrocarbons with the most important source rocks and to verify their potential to generate oil and gas. Therefore, molecular and isotopic composition as well as biomarker data obtained from 12 oil and condensate samples and 48 source rock extracts was used together with USGS data for a geological interpretation of hydrocarbon charging history.Within the central DDB, results point to a significant contribution from (Upper) Visean black shales, highly oil-prone as well as mixed oil- and gas-prone Serpukhovian rocks and minor contribution from an additional Tournaisian source. Devonian rocks, an important hydrocarbon source within the Pripyat Trough, have not been identified as a major source within the central DDB. Additional input from Bashkirian to Moscovian (?) (Shebelinka Field) as well as Tournaisian to Lower Visean rocks (e.g. Dovgal Field) with higher contents of terrestrial organic matter is indicated in the SE and NW part, respectively.Whereas oil–source correlation contradicts major hydrocarbon migration in many cases for Tournaisian to Middle Carboniferous reservoir horizons, accumulations within Upper Carboniferous to Permian reservoirs require vertical migration up to 4000 m along faults related to Devonian salt domes.1-D thermal models indicate hydrocarbon generation during Permo-Carboniferous time. However, generation in coal-bearing Middle Carboniferous horizons in the SE part of the basin may have occurred during the Mesozoic. 相似文献
9.
Thomas Whelan III J. M. Coleman J. N. Suhayda H. H. Roberts 《Marine Georesources & Geotechnology》2013,31(1-4):147-159
Abstract Methane concentrations and sediment shear strengths were measured in three foundation borings taken from areas of variable acoustical penetration in the Mississippi river delta front. Acoustically impenetrable or “turbid”; zones were associated with sedimentary methane concentrations above about 30 ml/liter, measured at atmospheric pressure. Sediments in the high‐gas, acoustically turbid zones demonstrated a smaller percentage increase in shear strength with depth than in zones of low gas concentration. The results indicate that a 3.5‐kHz system used for sub‐bottom profiles is unable to determine the thickness of gas‐charged sediments. 相似文献
10.
It is a conventional method for petroleum prospecting to generally use paraffin hydrocarbon as basic indexes of oil and gas. This conventional geochemical technology, however, shows some limits in the prospecting as paraffin is vulnerable to influences from human and biologic activities. Consequently, BTEX (short for benzene, toluene, ethyl benzene and xylem, which are direct biomarkers) among aromatic hydrocarbon series has been taken into account for the oil and gas prediction. Domestic and foreign study results demonstrate that BTEX is hardly disturbed and can well indicate oil and gas reservoirs. Based on measured data from a South China Sea area, the present authors have used self-developed visual assessment software for petroleum prospecting has been used to process data, strip background anomalies, and outline significant BTEX anomalies. By comparison with stratigraphic profiles of the target area, it is confirmed that BTEX is a good indication of marine oil and gas during the petroleum prospecting. 相似文献
11.
S. J. Wheeler 《Marine Georesources & Geotechnology》2013,31(2):113-129
Abstract Where undissolved gas occurs within fine‐grained marine sediments it usually takes the form of discrete bubbles that are much larger than the normal void spaces. The possibility of buoyancy‐induced movement of these relatively large bubbles must be included when considering the transport of gas through marine sediments. A theoretical analysis shows that, under static loading conditions, bubbles larger than a critical size should have sufficient buoyancy to move upward through a fine‐grained sediment stratum, whereas bubbles smaller than the critical size should remain fixed in position. The critical radius is directly proportional to sediment shear strength, and bubbles of a realistic size should move upward only in extremely weak sediments. Further theoretical analysis shows that the critical bubble size is reduced under cyclic loading conditions, but movement of typical‐sized bubbles should still be restricted to sediments of low shear strength. A simple laboratory experiment provides support for the conclusions of the theoretical analysis. The results indicate that buoyancy‐induced movement of relatively large gas bubbles in fine‐grained sediments is most likely to occur under storm loading conditions and is unlikely to occur at depths greater than a few meters below the seabed. 相似文献
12.
Geochemical characteristics of organic matter in the profiles of Dukla, Silesian, Sub-Silesian and Skole units of the Polish Outer Carpathians and of the Palaeozoic–Mesozoic basement in the Dębica-Rzeszów-Leżajsk-Sanok area were established based on Rock-Eval, vitrinite reflectance, isotopic and biomarker analyses of 485 rock samples. The Oligocene Menilite beds have the best hydrocarbon potential of all investigated formations within the Dukla, Silesian, and Skole units. The Ordovician, Silurian, Lower Devonian and locally Middle Jurassic strata of the Palaeozoic–Mesozoic basement are potential source rocks for oil and gas accumulated in Palaeozoic and Mesozoic reservoirs. Thirty one natural gas samples from sandstone reservoirs of the Lower Cretaceous-Lower Miocene strata within the Outer Carpathian sequence and eight from sandstone and carbonate reservoirs of the Palaeozoic–Mesozoic basement were analysed for molecular and isotopic compositions to determine their origin. Natural gases accumulated both in the Outer Carpathian and the Palaeozoic–Mesozoic basement reservoirs are genetically related to thermogenic and microbial processes. Thermogenic gaseous hydrocarbons that accumulated in the Dukla and Silesian units were generated from the Menilite beds. Thermogenic gaseous hydrocarbons that accumulated in the Sub-Silesian Unit most probably migrated from the Silesian Unit. Initial, and probably also secondary microbial methane component has been generated during microbial carbon dioxide reduction within the Oligocene Menilite beds in the Dukla Unit and Oligocene-Lower Miocene Krosno beds in the Silesian Unit. Natural gases that accumulated in traps within the Middle Devonian, Mississippian, Upper Jurassic, and Upper Cretaceous reservoirs of the Palaeozoic–Mesozoic basement were mainly generated during thermogenic processes and only sporadically from initial microbial processes. The thermogenic gases were generated from kerogen of the Ordovician-Silurian and Middle Jurassic strata. The microbial methane component occurs in a few fields of the Dukla and Silesian units and in the two accumulations in the Middle Devonian reservoirs of the Palaeozoic–Mesozoic basement. 相似文献
13.
《Marine Policy》2016
Offshore exploration and production in the U.S. Gulf of Mexico is supported by a large number of service vessels characterized by complex logistical patterns and demand points distributed across an expansive geographic area. No quantitative data on the spatial and temporal distributions of service vessel activity in the region is available due to the size, complexity and dynamics of the network. The purpose of this paper is to apply Automatic Identification System position data to quantify service vessel activity in the U.S. Gulf of Mexico from 2009 to 2010. A total of 1.1 million vessel arrivals and departures were recorded in 2009–2010, and in 2010, the number of vessel events increased by 40% due in part to the Macondo oil spill and cleanup response. Port-to-port movements comprise the majority of events and about 30% of activity relates to movements offshore. Port Fourchon, Venice, New Orleans, Sabine-Neches, and Lake Charles were the most active ports during the period. A detailed breakdown of vessel counts and the limitations of the analysis are outlined. 相似文献
14.
The results of acoustic investigations of over 250 gas “flares” (GFs) located in the depth range of 160–1400 m in the vicinity
of the northeastern slope of Sakhalin Island are presented. Pronounced features in the GFs distribution by the seabed’s depth
have been identified, which allowed dividing them into four groups corresponding to four depth intervals. The number of GFs
per seabed unit area decreases, and the power of the individual GFs increases with depth. The average methane flux per seabed
unit of area has been estimated for each depth interval. It has been demonstrated that the total quantity of methane emitted
from the seabed in the form of bubbles in the studied area is ∼0.1 million tons per year. 相似文献
15.
《Marine Policy》2002,26(5):337-343
This paper chronicles and analyzes the political dispute that resulted when Russia gave South Korea permission to fish for saury in the Kurile area disputed by Russia and Japan. The dispute became a three-sided diplomatic wrangle and threatened to disrupt relations between the countries involved. In the resolution of the dispute, each side gained and lost both politically and economically. Given the difficult political relations in Northeast Asia, fisheries policy makers should consider the international political ramifications of their decisions. 相似文献
16.
Using Boussinesq scaling for water waves while imposing no constraints on rotationality, we derive and test model equations for nonlinear water wave transformation over varying depth. These use polynomial basis functions to create velocity profiles which are inserted into the basic equations of motion keeping terms up to the desired Boussinesq scaling order, and solved in a weighted residual sense. The models show rapid convergence to exact solutions for linear dispersion, shoaling, and orbital velocities; however, properties may be substantially improved for a given order of approximation using asymptotic rearrangements. This improvement is accomplished using the large numbers of degrees of freedom inherent in the definitions of the polynomial basis functions either to match additional terms in a Taylor series, or to minimize errors over a range. Explicit coefficients are given at O(μ2) and O(μ4), while more generalized basis functions are given at higher order. Nonlinear performance is somewhat more limited as, for reasons of complexity, we only provide explicitly lower order nonlinear terms. Still, second order harmonics may remain good to kh ≈ 10 for O(μ4) equations. Numerical tests for wave transformation over a shoal show good agreement with experiments. Future work will harness the full rotational performance of these systems by incorporating turbulent and viscous stresses into the equations, making them into surf zone models. 相似文献
17.
The continuous research and improvement of ocean modelling helps to provide a more sustainable development of coastal and offshore regions. This paper focuses on ocean modelling at the NW Mediterranean using the POLCOMS–WAM model with new developments. The Stokes’ drift effect on currents has been included and the distribution of surface stress between waves and currents has also been considered. The system is evaluated in the NW Mediterranean and an evaluation of different forcing terms is performed. The temperature and salinity distributions control the main patterns of the Mediterranean circulation. Currents are typically small and therefore the modification of waves due to the effect of currents is minimal. However, the wave induced currents, mainly caused by a modified wind drag due to waves, produce changes that become an important source of mass transport. POLCOMS was able to reproduce the main Mediterranean features, its coupling with WAM can be a very useful tool for ocean and wave modelling in the Mediterranean and other shelf seas. 相似文献
18.
SUN Peiyan BAO Mutai GAO Zhenhui LI Mei ZHAO Yuhui WANG Xinping ZHOU Qing WANG Xiulin 《海洋学报(英文版)》2006,25(5):55-62
1 IntroductionWith the development of industry, more andmore petroleum energy sources are needed. The ex-ploitation of, especially benthal, develops quickly.The spilled oil accidents occur inevitably during oilexploitation and transportation. For example, in theBohai Sea, there are more than 1 000 oil wells andthe spilled oil accidents occur almost every year. Allkinds of dissension arose since the accidents couldnot be dealt with effectively in time. The key stepwhich affects the accidents … 相似文献
19.
This paper deals with the hydrodynamic analysis of an array of Oscillating Water Column (OWC) devices, made up of coaxial cylinders, which are floating either independently or as a unit forming a floating platform. The platform is considered either free – floating or as TLP configuration connected to the sea bottom. Numerical results concerning the three boundary value problems, namely, the diffraction, the motion – and the pressure – dependent radiation ones are given. They have been obtained through an analytical solution method using matched axisymmetric eigenfunction expansion formulations. In all cases the interaction phenomena with neighbouring bodies have been taken properly into account using the physical idea of multiple scattering. Numerical results for the first – and the mean second – order wave forces, the hydrodynamic interaction coefficients along with pressure hydrodynamic parameters, inner air pressure and free–surface oscillation amplitude inside and outside of each device are parametrically evaluated and supplemented by experimental data. 相似文献
20.
Several multistacked gas fields, located in very different parts of Hungary, display a large variation in their gas composition. The shallow position of the mantle beneath the basement of the PBS is responsible for the high heat flux. It facilitates that the CO2 – intensely released from the ascending upper-mantle derived melts – could reach the basin system. In this work the results of a geochemical study of the main components and noble gases of the multistacked Répcelak (CO2–HC–N2) and Mihályi (CO2) fields are presented and discussed. The vertical variations of gas composition in the Répcelak and Mihályi fields fit well with in-reservoir mixing of two end-members, a mantle-related magmatic CO2 fluid and a N2-rich HC-gas fluid of crustal origin. However, it is very likely that other processes modified to some extent the gas composition of the two fields. Carbon isotopic composition of the CO2 of the samples studied agrees with both the carbonate decomposition and mantle degassing origins. It is very likely that the marked difference in helium isotopic composition between the neighbouring Répcelak and Mihályi fields also reflects this heterogeneity. 相似文献