Figures and related data of a review of the "Global and Russian energy outlook up to 2040"

The Global and Russian Energy Outlook up to 2040, prepared by the Energy Research Institute of the Russian Academy of Sciences and the Analytical Center for the Government of the Russian Federation, analyses the long-term changes in the main energy markets and thereby identifies the threats to the Russian economy and energy sector. Research has shown that shifts in the global energy sector, especially in hydrocarbon markets (primarily the development of technologies for shale oil and gas extraction), will result in a slowdown of Russia's economy by one percentage point each year on average due to a decrease in energy exports comparison with the official projections. Owing to the lack of development of an institutional framework, an outdated tax system, low competition and low investment efficiency, Russia will be the most sensitive to fluctuations in global hydrocarbon markets among all major energy market players within the forecast period.

Gas content, composition of gas hydrate and volumetric gas/water ratios of ODP and DSDP sites

Gas hydrate samples were recovered from four sites (Sites 994, 995, 996, and 997) along the crest of the Blake Ridge during Ocean Drilling Program (ODP) Leg 164. At Site 996, an area of active gas venting, pockmarks, and chemosynthetic communities, vein-like gas hydrate was recovered from less than 1 meter below seafloor (mbsf) and intermittently through the maximum cored depth of 63 mbsf. In contrast, massive gas hydrate, probably fault filling and/or stratigraphically controlled, was recovered from depths of 260 mbsf at Site 994, and from 331 mbsf at Site 997. Downhole-logging data, along with geochemical and core temperature profiles, indicate that gas hydrate at Sites 994, 995, and 997 occurs from about 180 to 450 mbsf and is dispersed in sediment as 5- to 30-m-thick zones of up to about 15% bulk volume gas hydrate. Selected gas hydrate samples were placed in a sealed chamber and allowed to dissociate. Evolved gas to water volumetric ratios measured on seven samples from Site 996 ranged from 20 to 143 mL gas/mL water to 154 mL gas/mL water in one sample from Site 994, and to 139 mL gas/mL water in one sample from Site 997, which can be compared to the theoretical maximum gas to water ratio of 216. These ratios are minimum gas/water ratios for gas hydrate because of partial dissociation during core recovery and potential contamination with pore waters. Nonetheless, the maximum measured volumetric ratio indicates that at least 71% of the cages in this gas hydrate were filled with gas molecules. When corrections for pore-water contamination are made, these volumetric ratios range from 29 to 204, suggesting that cages in some natural gas hydrate are nearly filled. Methane comprises the bulk of the evolved gas from all sites (98.4%-99.9% methane and 0%-1.5% CO2). Site 996 hydrate contained little CO2 (0%-0.56%). Ethane concentrations differed significantly from Site 996, where they ranged from 720 to 1010 parts per million by volume (ppmv), to Sites 994 and 997, which contained much less ethane (up to 86 ppmv). Up to 19 ppmv propane and other higher homologues were noted; however, these gases are likely contaminants derived from sediment in some hydrate samples. CO2 concentrations are less in gas hydrate than in the surrounding sediment, likely an artifact of core depressurization, which released CO2 derived from dissolved organic carbon (DIC) into sediment. The isotopic composition of methane from gas hydrate ranges from d13C of -62.5 per mil to -70.7 per mil and dD of -175 per mil to -200 per mil and is identical to the isotopic composition of methane from surrounding sediment. Methane of this isotopic composition is mainly microbial in origin and likely produced by bacterial reduction of bicarbonate. The hydrocarbon gases here are likely the products of early microbial diagenesis. The isotopic composition of CO2 from gas hydrate ranges from d13C of -5.7 per mil to -6.9 per mil, about 15 per mil lighter than CO2 derived from nearby sediment.

Gas hydrates of the Gulf of Mexico

Gas hydrates were recovered from eight sites on the Louisiana slope of the Gulf of Mexico. The gas hydrate discoveries ranged in water depths from 530 to 2400 m occurring as small to medium sized (0.5-50 mm) nodules, interspersed layers (1-10 mm thick) or as solid masses (> 150 mm thick). The hydrates have gas:fluid ratios as high as 170:1 at STP, C1/(C2 + C3) ratios ranging from 1.9 to > 1000 and d13C ratios from -43 to -71 per mil. Thermogenic gas hydrates are associated with oil-stained cores containing up to 7% extractable oil exhibiting moderate to severe biodegradation. Biogenic gas hydrates are also associated with elevated bitumen levels (10-700 ppm). All gas hydrate associated cores contain high percentages (up to 65%) of authigenic, isotopically light carbonate. The hydrate-containing cores are associated with seismic "wipeout" zones indicative of gassy sediments. Collapsed structures, diapiric crests, or deep faults on the flanks of diapirs appear to be the sites of the shallow hydrates.

Sedimentology and gas hydrates of IODP Expedition 311 samples

Expedition 311 of the Integrated Ocean Drilling Program (IODP) to northern Cascadia recovered gas-hydrate bearing sediments along a SW-NE transect from the first ridge of the accretionary margin to the eastward limit of gas-hydrate stability. In this study we contrast the gas gas-hydrate distribution from two sites drilled ~ 8 km apart in different tectonic settings. At Site U1325, drilled on a depositional basin with nearly horizontal sedimentary sequences, the gas-hydrate distribution shows a trend of increasing saturation toward the base of gas-hydrate stability, consistent with several model simulations in the literature. Site U1326 was drilled on an uplifted ridge characterized by faulting, which has likely experienced some mass wasting events. Here the gas hydrate does not show a clear depth-distribution trend, the highest gas-hydrate saturation occurs well within the gas-hydrate stability zone at the shallow depth of ~ 49 mbsf. Sediments at both sites are characterized by abundant coarse-grained (sand) layers up to 23 cm in thickness, and are interspaced within fine-grained (clay and silty clay) detrital sediments. The gas-hydrate distribution is punctuated by localized depth intervals of high gas-hydrate saturation, which preferentially occur in the coarse-grained horizons and occupy up to 60% of the pore space at Site U1325 and > 80% at Site U1326. Detailed analyses of contiguous samples of different lithologies show that when enough methane is present, about 90% of the variance in gas-hydrate saturation can be explained by the sand (> 63 µm) content of the sediments. The variability in gas-hydrate occupancy of sandy horizons at Site U1326 reflects an insufficient methane supply to the sediment section between 190 and 245 mbsf.

Chemical and physical oceanography on 131 CTD casts from METEOR cruise M59/2

The oceans absorb and store a significant portion of anthropogenic CO2 emissions, but large uncertainties remain in the quantification of this sink. An improved assessment of the present and future oceanic carbon sink is therefore necessary to provide recommendations for long-term global carbon cycle and climate policies. The formation of North Atlantic Deep Water (NADW) is a unique fast track for transporting anthropogenic CO2 into the ocean's interior, making the deep waters rich in anthropogenic carbon. Thus the Atlantic is presently estimated to hold 38% of the oceanic anthropogenic CO2 inventory, although its volume makes up only 25% of the world ocean. Here we analyze the inventory change of anthropogenic CO2 in the Atlantic between 1997 and 2003 and its relationship to NADW formation. For the whole region between 20°S and 65°N the inventory amounts to 32.5 ± 9.5 Petagram carbon (Pg C) in 1997 and increases up to 36.0 ± 10.5 Pg C in 2003. This result is quite similar to earlier studies. Moreover, the overall increase of anthropogenic carbon is in close agreement with the expected change due to rising atmospheric CO2 levels of 1.69% a?1. On the other hand, when considering the subpolar region only, the results demonstrate that the recent weakening in the formation of Labrador Sea Water, a component of NADW, has already led to a decrease of the anthropogenic carbon inventory in this water mass. As a consequence, the overall inventory for the total water column in the western subpolar North Atlantic increased only by 2% between 1997 and 2003, much less than the 11% that would be expected from the increase in atmospheric CO2 levels.

Gas hydrate structures and C1-C5 hydrocarbons at individual sites in the Gulf of Mexico

Gas hydrate samples from various locations in the Gulf of Mexico (GOM) differ considerably in their microstructure. Distinct microstructure characteristics coincide with discrete crystallographic structures, gas compositions and calculated thermodynamic stabilities. The crystallographic structures were established by X-ray diffraction, using both conventional X-ray sources and high-energy synchrotron radiation. The microstructures were examined by cryo-stage Field-Emission Scanning Electron Microscopy (FE-SEM). Good sample preservation was warranted by the low ice fractions shown from quantitative phase analyses. Gas hydrate structure II samples from the Green Canyon in the northern GOM had methane concentrations of 70-80% and up to 30% of C2-C5 of measured hydrocarbons. Hydrocarbons in the crystallographic structure I hydrate from the Chapopote asphalt volcano in the southern GOM was comprised of more than 98% methane. Fairly different microstructures were identified for those different hydrates: Pores measuring 200-400 nm in diameter were present in structure I gas hydrate samples; no such pores but dense crystal surfaces instead were discovered in structure II gas hydrate. The stability of the hydrate samples is discussed regarding gas composition, crystallographic structure and microstructure. Electron microscopic observations showed evidence of gas hydrate and liquid oil co-occurrence on a micrometer scale. That demonstrates that oil has direct contact to gas hydrates when it diffuses through a hydrate matrix.

Carbon dioxide assimilation rate, gas and ion composition in samples, and bacterial production of organic matter within and above the Broken Spur and TAG hydrothermal fields, Mid-Atlantic Ridge

Rate of CO2 assimilation was determined above the Broken Spur and TAG active hydrothermal fields for three main ecosystems: (1) hydrothermal vents; (2) 300 m near-bottom layer of plume water; and (3) bottom sediments. In water samples from warm (40-45°C) vents assimilation rates were maximal and reached 2.82-3.76 µg C/l/day. In plume waters CO2 assimilation rates ranged from 0.38 to 0.65 µg C/l/day. In bottom sediments CO2 assimilation rates varied from 0.8 to 28.0 µg C/l/day, rising up to 56 mg C/kg/day near shrimp swarms. In the most active plume zone of the long-living TAG field bacterial production of organic matter (OM) from carbonic is up to 170 mg C/m**2/day); production of autotrophic process of bacterial chemosynthesis reaches about 90% (156 mg C/m**2/day). Thus, chemosynthetic production of OM in September-October is almost equal to that of photosynthetic production in the oceanic region. Bacterial production of OM above the Broken Spur hydrothermal field is one order lower and reaches only 20 mg C/m**2/day.

Gas hydrates of nonpressurized (GC) and pressurized (DAPC) sediment cores from the Hakon Mosby Mud Volcano, SW Barents Sea

The occurrence of gas hydrates at submarine mud volcanoes (MVs) located within the gas hydrate stability zone (GHSZ) is controlled by upward fluid and heat flux associated with MV activity. Determining the spatial distribution of gas hydrates at MVs is crucial to evaluate their sensitivity to known episodic changes in volcanic activity. We determined the hydrocarbon inventory and spatial distribution of hydrates at an individual MV structure. The Håkon Mosby Mud Volcano (HMMV), located at 1,250 m water depth on the Barents Sea slope, was investigated by combined pressure core sampling, heat flow measurements, and pore water chemical analysis. Quantitative pressure core degassing revealed gas-sediment ratios between 3.1 and 25.7, corresponding to hydrate concentrations of up to 21.3% of the pore volume. Hydrocarbon compositions and physicochemical conditions imply that gas hydrates incipiently crystallize as structure I hydrate, with a dissociation temperature of around 13.8°C at this water depth. Based on numerous in situ measurements of the geothermal gradient in the seabed, pore water sulfate profiles and microbathymetric data, we show that the thickness of the GHSZ increases from less than 1 m at the warm center to around 47 m in the outer parts of the HMMV. We estimate the total mass of hydrate-bound methane stored at the HMMV to be about 102.5 kt, of which 2.8 kt are located within the morphological Unit I around the center and thus are likely to be dissociated in the course of a large eruption.

Pore-water concentration of chloride in sediment cores and equilibrium temperatures and gas bubble analysis at ROV stations from the Vodyanitskii mud volcano

Vodyanitskii mud volcano is located at a depth of about 2070 m in the Sorokin Trough, Black sea. It is a 500-m wide and 20-m high cone surrounded by a depression, which is typical of many mud volcanoes in the Black Sea. 75 kHz sidescan sonar show different generations of mud flows that include mud breccia, authigenic carbonates, and gas hydrates that were sampled by gravity coring. The fluids that flow through or erupt with the mud are enriched in chloride (up to 650 mmol L**-1 at 150-cm sediment depth) suggesting a deep source, which is similar to the fluids of the close-by Dvurechenskii mud volcano. Direct observation with the remotely operated vehicle Quest revealed gas bubbles emanating at two distinct sites at the crest of the mud volcano, which confirms earlier observations of bubble-induced hydroacoustic anomalies in echosounder records. The sediments at the main bubble emission site show a thermal anomaly with temperatures at 60 cm sediment depth that were 0.9 °C warmer than the bottom water. Chemical and isotopic analyses of the emanated gas revealed that it consisted primarily of methane (99.8%) and was of microbial origin (dD-CH4 = -170.8 per mil (SMOW), d13C-CH4 = -61.0 per mil (V-PDB), d13C-C2H6 = -44.0 per mil (V-PDB)). The gas flux was estimated using the video observations of the ROV. Assuming that the flux is constant with time, about 0.9 ± 0.5 x 10**6 mol of methane is released every year. This value is of the same order-of-magnitude as reported fluxes of dissolved methane released with pore water at other mud volcanoes. This suggests that bubble emanation is a significant pathway transporting methane from the sediments into the water column.

Table 4. Trace gas concentrations from samples taken at Ginninderra

We assess the performance of an inverse Lagrangian dispersion technique for its suitability to quantify leakages from geological storage of CO2. We find the technique is accurate ((QbLS/Q)=0.99, sigma=0.29) when strict meteorological filtering is applied to ensure that Monin-Obukhov Similarity Theory is valid for the periods analysed and when downwind enrichments in tracer gas concentration are 1% or more above background concentration. Because of their respective baseline atmospheric concentrations, this enrichment criterion is less onerous for CH4 than for CO2. Therefore for geologically sequestered gas reservoirs with a significant CH4 component, monitoring CH4 as a surrogate for CO2 leakage could be as much as 10 times more sensitive than monitoring CO2 alone. Additional recommendations for designing a robust atmospheric monitoring strategy for geosequestration include: continuous concentration data; exact inter-calibration of up- and downwind concentration measurements; use of an array of point concentration sensors to maximise the use of spatial information about the leakage plume; and precise isotope ratio measurement to confirm the source of any concentration elevations detected.

Gas hydrate investigation at the Amsterdam mud volcano

We investigated gas hydrate in situ inventories as well as the composition and principal transport mechanisms of fluids expelled at the Amsterdam mud volcano (AMV; 2,025 m water depth) in the Eastern Mediterranean Sea. Pressure coring (the only technique preventing hydrates from decomposition during recovery) was used for the quantification of light hydrocarbons in near-surface deposits. The cores (up to 2.5 m in length) were retrieved with an autoclave piston corer, and served for analyses of gas quantities and compositions, and pore-water chemistry. For comparison, gravity cores from sites at the summit and beyond the AMV were analyzed. A prevalence of thermogenic light hydrocarbons was inferred from average C1/C2+ ratios <35 and d13C-CH4 values of -50.6 per mil. Gas venting from the seafloor indicated methane oversaturation, and volumetric gas-sediment ratios of up to 17.0 in pressure cores taken from the center demonstrated hydrate presence at the time of sampling. Relative enrichments in ethane, propane, and iso-butane in gas released from pressure cores, and from an intact hydrate piece compared to venting gas suggest incipient crystallization of hydrate structure II (sII). Nonetheless, the co-existence of sI hydrate can not be excluded from our dataset. Hydrates fill up to 16.7% of pore volume within the sediment interval between the base of the sulfate zone and the maximum sampling depth at the summit. The concave-down shapes of pore-water concentration profiles recorded in the center indicate the influence of upward-directed advection of low-salinity fluids/fluidized mud. Furthermore, the SO42- and Ba2+ pore-water profiles in the central part of the AMV demonstrate that sulfate reduction driven by the anaerobic oxidation of methane is complete at depths between 30 cm and 70 cm below seafloor. Our results indicate that methane oversaturation, high hydrostatic pressure, and elevated pore-water activity caused by low salinity promote fixing of considerable proportions of light hydrocarbons in shallow hydrates even at the summit of the AMV, and possibly also of other MVs in the region. Depending on their crystallographic structure, however, hydrates will already decompose and release hydrocarbon masses if sediment temperatures exceed ca. 19.3°C and 21.0°C, respectively. Based on observations from other mud volcanoes, the common occurrence of such temperatures induced by heat flux from below into the immediate subsurface appears likely for the AMV.