Specification of the Geological Structure of the Inter-Salt Sediments of the Savichskoye Area Based on the Results of Well ?10S2 Drilling and Performing 3D Seismic Surveys in Order to Assess the Prospects for Identifying Hydrocarbons in Low-Permeability Reservoirs

The results of the well 10s2-Savichskaya drilling, laboratory core research are set out. Based on the results of integration the latest methods of wire line survey, laboratory core samples research, seismic facies analysis, typical lithotypes of the Savichsko-Bobrovichi area rocks were identified, reservoir features were predicted, the prospects of inter-salt deposits for identifying accumulations of hydrocarbons in unconventional reservoirs were substantiated. A perspective zone was identified and recommendations for drilling a pilot bore were given.

Robust K-means algorithm with weighted window for seismic facies analysis

Seismic facies analysis can generate a map to describe the spatial distribution characteristics of reservoirs, and therefore plays a critical role in seismic interpretation. To analyse the characteristics of the horizon of interest, it is usually necessary to extract seismic waveforms along the target horizon using a selected time window. The inaccuracy of horizon interpretation often produces some inconsistent phases and leads to inaccurate classification. Therefore, the developed adaptive phase K-means algorithm proposed a sliding time window to extract seismic waveforms. However, setting the maximum offset of the sliding window is difficult in a real data application. A value that is too large may cause the cross-layer problem, whereas a value that is too small reduces the flexibility of the algorithm. To address this disadvantage, this paper proposes a robust K-means (R-K-means) algorithm with a Gaussian-weighted sliding window for seismic waveform classification. The used weights punish those windows distant from the interpretation horizon in the objective function, consequently producing a smaller range of horizon adjustments even when using relatively large maximum offsets and benefitting the generation of stable and reliable seismic facies maps. The application of real seismic data from the F3 block proves the effectiveness of the proposed algorithm.

Seismogeological structure model of the Anabar-Olenek region

The velocity characteristics of the Upper Proterozoic-Phanerozoic sedimentary cover of the Anabar-Olenek region were studied, in particular, the bimodal character of the distribution interval P-wave velocities was established. Taking into account modern ideas about the chronostratigraphy of sediments encountered by the Charchykskaya-1, Burskaya-3410 and Khastakhskaya-930 deep boreholes, stratification of reflecting horizons was carried out and time sections from previous years were reinterpreted. From the perspective of seismic stratigraphic and seismic facies analysis, the Cambrian, Vendian, and Riphean intervals of the section were examined in detail. In the course of the analysis, adjustments to the stratigraphic breakdown of the Burskaya-3410 and Charchykskaya-1 boreholes are proposed. The study shows that the Lapar Formation, which underwent Prepermian erosion, increase in the thickness multiple in an eastward direction. The distribution areas of the Tuessal Formation, the Lower and Middle Cambrian clinoform complex, as well as the areas of the Upper Riphean Formations reaching the Prevendian erosion surface are contoured. An Intrariphean tectonic disagreement between the Kulady Formation and older deposits was established.

The interaction between the Apula plate and the Calabrian Accretionary Wedge in the Northern Ionian Sea: tectonic-stratigraphic evolution and implications for subduction processes.

<p>In the collisional setting of the Northern Ionian Sea, the Calabrian Accretionary Wedge, which represents the Southeastward prolongation of the Southern Apennines, is facing directly the subducting Apula plate, which is mainly made of Mesozoic to Tertiary Carbonate Platform. The aim of this contribution is to illuminate the structures and stratigraphic relationships between the frontal part of the orogenic belt, the foredeep and adjacent Apulian foreland. Because of the lack of exploration wells in these deep offshore basins, a detailed seismic facies analysis of six multichannel seismic profiles has been carried out to define the tectonic-sedimentary evolution of the study area.<br>Seismic interpretation allows to identify four main structural domains. The highly tectonized accretionary wedge is characterized by compressive tectonics. A narrow foredeep basin is filled by a thick (1,5–0,9 s TWT) Pliocene-Holocene subhorizontal succession and lies above buried normal faults. A massive carbonate succession of the Apulian Platform, shows reef and carbonate platform margin facies. A layered carbonate succession of the Apulian Platform is characterized by ‘'intra-platform'’ facies and located in the easternmost portion of the area. Seismic stratigraphic analysis allows to define two main regional unconformities with characteristic relationships with structural trends: i) the Messinian unconformity, related to a regional and significant erosion associated to paleokarst processes on the exposed Mesozoic Apulian Platform, is cut by an array of normal faults affecting the entire Apulian foreland and by reverse faults in the accretionary wedge; ii) the middle Pliocene Unconformity, an angular and erosive unconformity truncating the Lower Pliocene reflectors, is affected by normal faults in the foreland and by compressive tectonics in the Calabrian wedge that is progressively advancing.<br>Seismic data analyses shows that the compressive tectonics is currently active in the Calabrian Accretionary Wedge and concentrated in the innermost domains where thrust faults deform the sea floor. The Mesozoic Apulian Platform is affected by normal faulting driven by flexural bending since Lower Pliocene. The new structural map shows that transpressive and positive inversion tectonics is a common deformational style in the foreland that can be associated with the Dinaric-Hellenic subduction, which is synchronous with respect to Calabrian subduction. According to these observations, the compressive tectonics affecting the Apulia plate can be interpreted as related to both the Calabrian and Dinaric-Hellenic shortening processes. The interference of these two orogenic wedges with the Apulia Plate plays an important role in defining the tectonic evolution of the Northern Ionian Sea.</p>

IMPROVED SPECTRAL CLUSTERING APPROACH – A NEW TOOL FOR UNSUPERVISED SEISMIC FACIES ANALYSIS OF VARIABLE WINDOW LENGTH

Traditional constant time window-based waveform classification method is a robust tool for seismic facies analysis. However, when the interval thickness is seismically variable, the fixed time window is not able to contain the complete geologic information of interest. Therefore, the constant time window-based waveform classification method is inapplicable to conduct seismic facies analysis. To expand the application scope of seismic waveform classification in the strata with varying thickness, we propose a novel scheme for unsupervised seismic facies analysis of variable window length. The input of top and bottom horizons can guarantee the comprehensive geologic information of target interval. Throughout the whole workflow, we utilize DTW (Dynamic Time Warping) distance to measure the similarities between seismic waveforms of different lengths. Firstly, we improve the traditional spectral clustering algorithm by replacing the Euclidean distance with DTW-distance. Therefore, it can be applicable in the interval of variable thickness. Secondly, to solve the problem of large computation when applying the improved spectral clustering approach, we propose the method of seismic data thinning based on the technology of superpixel. Lastly, we combine these two algorithms and perform the integrated workflow of improved spectral clustering. The experiments on synthetic data show that the proposed workflow outperforms the traditional fixed time window-based clustering algorithm in recognizing the boundaries of different lithologies and lithologic associations with varying thickness. The practical application shows great promise for reservoir characterization of interval with varying thickness. The plane map of waveform classification provides convincing reference to delineate reservoir distribution of data set.