Seismic Facies Analysis of Lower Productive Series of Gurgan-Deniz Field in South Caspian Basin with the Aid of Seismic Attributes

2021 ◽  
Author(s):  
Ulvi Zamanbayov

Abstract Drilled for the first time in 1946 and one of the oldest fields in the South Caspian Basin located in the western part of Apsheron sill, Gurgan-Deniz has been subject to redevelopment. A 3D seismic survey, conducted over the area for the first time, has been interpreted, analysing the lower Productive Series with regard to seismic facies and prospectivity. The facies analysis allows for better understanding of eustatic levels in the region and depositional environments of lower Productive Series in the area. A composite seismic attribute Sweetness and an RGB blend of Spectral Decomposition have been applied to the 3D volume, as well as to the interpreted stratigraphic surfaces. With the aid of the attributes and petrophysical well description, direct and indirect facies interpretation have been carried out. First, considering reflection parameters such as parallelism, continuity and hummockiness, as well as sedimentary features. Subsequently, reaching conclusions on depositional processes, environments, and geological evolution. Finally, analysing field prospectivity and migration pathways. Eight seismic facies have been identified by analysing stratigraphic horizons representing the tops of Kalin Suite (KaS), Pre-Kirmaky Sand Suite (PK) and Kirmaky Suite (KS). Facies have been interpreted as mass-flow deposits, amalgamated channel systems, channel and bar systems, sheetflow and floodplain deposits in a varying lacustrine-fluvial environment. KaS has been deposited following a sea- level drop and increased sediment inflow from Palaeo-Volga. The origin of the mass-flow facies is thought to be related to the increase of sedimentation speed, as well as tectonics decreasing the terrace stability. PK shows evidence of further sea-level drop and shows mainly fluvial depositional environment. Starting from KS, sea level has started to rise, once again showing mixed depositional environment. Attribute anomalies have been explored in the lower wing of the anticline structure in PK and KaS. A 3-way trap and possible migration pathways generate considerable risks.

2010 ◽  
Vol 89 (3-4) ◽  
pp. 203-237 ◽  
Author(s):  
J.M. Jeremiah ◽  
S. Duxbury ◽  
P. Rawson

AbstractFacies belts exhibit a back-stepping trend towards the London Brabant/ Rhenish Massif through the Early Cretaceous. The overall eustatic sea-level rise was punctuated by short-term tectonic events identified either as localised or North Sea wide in extent. The biostratigraphically constrained sequences have, for the first time, allowed a detailed calibration of tectonic and eustatic events on a North Sea scale. The most extensive database available to any North Sea Cretaceous study was available to the authors together with a comprehensive suite of new high-resolution biostratigraphy and sedimentology. This has allowed unique insights into provenance, depositional environment, extent of sequence stratigraphical events and the degree to which unconformities have been tectonically accentuated.


2012 ◽  
Vol 16 (7) ◽  
pp. 1845-1862 ◽  
Author(s):  
F. Jørgensen ◽  
W. Scheer ◽  
S. Thomsen ◽  
T. O. Sonnenborg ◽  
K. Hinsby ◽  
...  

Abstract. Geophysical techniques are increasingly being used as tools for characterising the subsurface, and they are generally required to develop subsurface models that properly delineate the distribution of aquifers and aquitards, salt/freshwater interfaces, and geological structures that affect groundwater flow. In a study area covering 730 km2 across the border between Germany and Denmark, a combination of an airborne electromagnetic survey (performed with the SkyTEM system), a high-resolution seismic survey and borehole logging has been used in an integrated mapping of important geological, physical and chemical features of the subsurface. The spacing between flight lines is 200–250 m which gives a total of about 3200 line km. About 38 km of seismic lines have been collected. Faults bordering a graben structure, buried tunnel valleys, glaciotectonic thrust complexes, marine clay units, and sand aquifers are all examples of geological structures mapped by the geophysical data that control groundwater flow and to some extent hydrochemistry. Additionally, the data provide an excellent picture of the salinity distribution in the area and thus provide important information on the salt/freshwater boundary and the chemical status of groundwater. Although the westernmost part of the study area along the North Sea coast is saturated with saline water and the TEM data therefore are strongly influenced by the increased electrical conductivity there, buried valleys and other geological elements are still revealed. The mapped salinity distribution indicates preferential flow paths through and along specific geological structures within the area. The effects of a future sea level rise on the groundwater system and groundwater chemistry are discussed with special emphasis on the importance of knowing the existence, distribution and geometry of the mapped geological elements, and their control on the groundwater salinity distribution is assessed.


2019 ◽  
Vol 56 (12) ◽  
pp. 1347-1365 ◽  
Author(s):  
Vahid Teknik ◽  
Abdolreza Ghods ◽  
Hans Thybo ◽  
Irina M. Artemieva

We present a new 2D crustal-scale model of the northwestern Iranian plateau based on gravity–magnetic modeling along the 500 km long China–Iran Geological and Geophysical Survey in the Iranian plateau (CIGSIP) seismic profile across major tectonic provinces of Iran from the Arabian plate into the South Caspian Basin (SCB). The seismic P-wave receiver function (RF) model along the profile is used to constrain major crustal boundaries in the density model. Our 2D crustal model shows significant variation in the sedimentary thickness, Moho depth, and the depth and extent of intra-crustal interfaces. The Main Recent Fault (MRF) between the Arabian crust and the overriding central Iran crust dips at approximately 13° towards the northeast to a depth of about 40 km. The geometry of the MRF suggests about 150 km of underthrusting of the Arabian plate beneath central Iran. Our results indicate the presence of a high-density lower crustal layer beneath Zagros. We identify a new crustal-scale suture beneath the Tarom valley between the South Caspian Basin crust and Central Iran and the Alborz. This suture is associated with sharp variation in Moho depth, topography, and magnetic anomalies, and is underlain by a 20 km thick high-density crustal root at 35–55 km depth. The high-density lower crust in Alborz and Zagros may be related to partial eclogitization of crustal roots below about 40 km depth. The gravity and magnetic models indicate a highly extended continental crust for the SCB crust along the profile. Low observed magnetic susceptibility of the Kermanshah ophiolites likely indicates that the ophiolite rocks only form a thin layer that has been thrust over the sedimentary cover.


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