Figure 1 - uploaded by Camelia Cristina Knapp
Content may be subject to copyright.
Geographic setting of the Caspian Sea within Central Eurasia (inset); (2) Location map of the Absheron multichannel seismic reflection profiles, showing the Absheron exploration block in relation to the Shah Deniz and Oguz structures as well as interpreted continental slope failure and slides and slumps (from Abdullayev, 2000). Absheron 1 and 2 regional profiles discussed here are shown in pink across the Absheron seafloor bathymetry from the 3D seismic volume. Available well log within the study area (ABX-Well) to be correlated with the seismic data in order to provide stratigraphic constraints is displayed as black star. Blue stars represent earthquake epicenters from the ISC Catalog. Red dots and triangles are mud volcanoes. Bathymetric contours are in meters.
Source publication
A large (640 km*2), industry-quality, 3-D multichannel seismic
reflection dataset (3 s) and well-logs from the South Caspian basin,
offshore Azerbaijan, were interpreted and analyzed in order to clarify
the origin, age, and areal extent of a large-scale (2,500 km*2)
late-Pleistocene zone of seafloor deformation and submarine slumping,
the Absheron...
Contexts in source publication
Context 1
... South Caspian Sea (Fig. 1), the largest inland sea in the world, is situated within the Alpine-Himalayan collisional zone, and separates the locus of Neogene continental collision in 8 the Caucasus to the west from large-scale strike-slip faulting in the Kopeh-Dagh system of Turkmenistan to the east ( Zonenshain and Le Pichon, 1986). Although the basin is ...
Context 2
... conditions required for gas hydrate formation. It has deep water (1,100 m), low seafloor temperature (5.8-6.2°C), natural gas, and very low geothermal gradients (11-17°C/km) (Bagirov and Lerche, 1997). The only gas hydrates harvested from the South Caspian Sea floor were collected from two mud volcano sites, Elm and Buzdag (red triangles in Fig. 1; Ginsburg et al., 1992;Soloviev, 1994, 1998). The hydrocarbon gases released from these gas hydrates showed a high (4-40%) concentration in methane homologues, especially ethane, indicating primarily a thermogenic rather than biogenic origin. Sample of water released from the Caspian hydrates indicated salinity of 13.7-23.2 g/l and ...
Context 3
... Absheron 1 and 2 profiles ( Figs. 1 and 2), collected in the deep water of the SCB, ...
Context 4
... of these profiles was focused on noise reduction and preservation of true amplitudes, necessary for the accurate evaluation of the elastic properties, including possible "blanking" (reduced acoustic impedance) effects, identification of Bottom Simulating Reflectors (BSRs), and amplitude vs. offset (AVO) effects for examination of free gas accumulations beneath the gas hydrate layer ( Diaconescu et al., 2001). The water depth in this region varies between 200 and 715 m ( Figs. 1 and 2). As observed in other gas hydrate localities worldwide (e.g. ...
Context 5
... the Absheron 2D seismic data suggest that the continental slope of the South Caspian Sea in the study area is in structural failure, and may be controlled at the base and toe by the presence of gas hydrates in the subsurface (Fig. 5). Seafloor bathymetry shows evidence for active(?) and recent massive slope failure on the continental shelf ( Figs. 1 and 2). Comparison of the gas hydrate distribution on the two seismic profiles with the seafloor bathymetry generated from the 3D survey in the region suggests a close spatial relationship with the nearby Absheron mud volcano and its associated moat. ...
Context 6
... of the gas hydrate distribution on the two seismic profiles with the seafloor bathymetry generated from the 3D survey in the region suggests a close spatial relationship with the nearby Absheron mud volcano and its associated moat. Based on constraints from the Absheron 1 and 2 regional lines, the structurally complex and actively deforming sea floor, including massive slope failure, extends for more than 2,500 km 2 (50 x 52 km) south of the Absheron Ridge (Figs. 1 and 5). Due to the complexity of disruption, the relatively sharp boundaries to the zone of deformation, the discontinuity of stratigraphy across these boundaries, and the shallow level of detachment, this confined zone appears to be allochthonous in origin (the "Absheron Allochthon"). ...
Context 7
... interpretation of the Absheron 1 and 2 lines shown in Figure 5 relies on stratigraphic control derived from the Shah Deniz well ( Fowler et al., 2000) located a few tens of km further to the west ( Fig. 1) and from the Oguz structure further to the north-east ( Davies and Stewart, 2005. From these stratigraphic correlations, the Absheron Allochthon appears to have originated in late Pleistocene (~15 ky). Note that, the strata underlying the interpreted Absheron Allochthon appear continuous on both seismic lines, with no obvious evidence ...
Context 8
... structural features from Abdulayev (2000, Fig. 1), it could be as large as ~10,000 km ...
Context 9
... South Caspian Sea is the locus of highly active tectonic processes, frequent 1) Seismicity There is a larger abundance of earthquake epicenters north and west of the study area (blue stars in Fig. 1), yet, there is no such obvious evidence for seafloor deformation and slumping in these regions. Moreover, there is a good reason to believe that the South Caspian Sea has been seismically active for a long time prior to the late Pleistocene (at least since the relative convergent movement of the Arabian ...
Similar publications
A vast accumulation of high‐saturation gas hydrates has been hypothesized to be present in the central Gulf of Mexico; the interpretation was based on seismic travel time deficits underlying high velocity Pleistocene coarse‐grained turbidites. While these deposits could represent one of the largest‐known gas hydrate reservoirs, some workers have co...
Empirical methods often fail to accurately depict in-situ gas hydrate saturation distributions, despite their relationships with petrophysical and elastic properties remaining partially unclear. We proposed a data-driven approach to estimate gas hydrate saturation employing several machine learning techniques, including radial basis function neural...
The occurrence of gas hydrate in shallow marine sediments causes an increase of seismic velocity compared to that of water saturated host sediments. This increase of velocity depends on the spatial distribution of hydrates in pore spaces of sediments. Velocities derived from seismic data are low frequency effective values, which cannot be uniquely...
To develop gas hydrates as a potential energy source, geophysical surveys and geological studies of gas hydrates in the Ulleung Basin, East Sea off the east coast of Korea have been carried out since 1997. Bottom-simulating reflector (BSR), initially used indicator for the potential presence of gas hydrates was first identified on seismic data acqu...
Gas hydrate saturation is an important index for evaluating gas hydrate reservoirs, and well logs are an effective method for estimating gas hydrate saturation. To use well logs better to estimate gas hydrate saturation, and to establish the deep internal connections and laws of the data, we propose a method of using deep learning technology to est...
Citations
... These characteristics include thermo-baric conditions, favorable features of deposits, thick clayey deposits and high concentrations of organic matter (Muradov 2004). In addition, several geophysical surveys and modeling studies in the Caspian Sea have reported the existence of both gas hydrate and shallow free gas with related seabed features (Diaconescu and Knapp 2000;Diaconescu, Kieckhefer, and Knapp 2001;Knapp and Knapp 2002;Gerivani and Gerivani 2017). ...
Physicochemical conditions are proper to form gas hydrate and free gas in the Caspian Sea which are considered both for geohazard assessment and future possible source of energy. Gas migration, hydrate formation and decomposition cause different types of features to form in the seabed and sediments which can be affected by geological and physical conditions of sea. In this study, high-resolution marine seismoacoustic profiles were interpreted to investigate features formed by gas hydrate and free gas and assess their characteristics in the continental slope and abyssal plain of the middle Caspian Sea. A mud volcano, gas chimneys, pockmarks, gas pipes, sediment disturbances, a crater, a giant landslide and a big gentle diapir were investigated and reported in the present study. The geological and physical conditions including bathymetry, tectonic activity, sediments supply and water depth are different in the continental slope and abyssal plain, thereby the features of these two environments were compared to understand the effect of different conditions.
... One of them is located in Absheron (Azerbaijan) and other one in Turkmenistan offshore (Figure 7). In Absheron, two geophysical profiles were surveyed by Knapp and Knapp (2002) which is presented in Figure 8. They interpreted high seismic velocity anomalies as gas hydrate accumulation. ...
... Anomalous high velocities were interpreted as gas hydrate occurrences. TAH, top Absheron hydrate; BAH, base Absheron hydrate; SF, shallow faulting(Knapp and Knapp 2002). ...
Preliminary studies of Caspian Sea have shown the possibility of gas hydrate accumulations, because of suitable physicochemical conditions, existence of clayey deposits and high concentrations of organic matter. Studies have indicated that gas hydrates are mainly composed of Methane. Therefore, based on physicochemical equations for methane hydrate stability in different pressure, temperature and salinity, this study was designed to calculate the potential of gas hydrate formation in Caspian Sea basin. For this, data of more than 600 locations were analyzed and in each location, upper and lower limits of methane hydrate formation zone were calculated. Then, the zoning maps of upper and lower limits were prepared which can be useful for exploring the gas hydrate as an energy source or predicting gas hydrate hazards. According to the calculations and maps, methane hydrate formation in Caspian Sea, theoretically, can take place from near the seabed to 4000 and 2500 m beneath the sea surface when low and high geothermal gradient are supposed, respectively. By comparing the results with gas hydrate zones revealed in geophysical profiles, it has been shown that, in Caspian Sea, gas hydrates probably accumulate near to lower limit when high geothermal gradient are supposed.
