Prediction of Lithological Section of the Shatsky Ridge (Shelf of the Black Sea) Based on Analysis of Seismic Velocities

摘要

North-Black Sea structure, which is located in the northwestern part of the Shatsky ridge is the largest oil and gas object of the Black Sea. In the absence of wells the most important sources of information for lithology prediction are the data on interval velocity changes. These data were obtained using depth- velocity tomography based on 3D-seismic survey. Reservoir prediction is based on comparison of interval velocities of various parts of the North-Black Sea structure with vertical seismic profiling and sonic logging of reference wells in reference Pre-Caucasian areas. The evaluation was conducted both, throughout the whole of sedimentary section, and separately for each target stratigraphic interval. The pattern of velocity changes with depth throughout the whole section, firstly, predetermines the presence or absence of abnormally high pore pressure areas. Velocity comparison by stratigraphic intervals gives indication on lithological peculiarities. The seismic velocity analysis can reduce the risks and increase reliability of lithological prediction for oil and gas deposits.As a result of conducted work the proposed general geological assumptions regarding the character of potential production reservoirs within Shatsky ridge were confirmed. The results of the survey were used for exploration planning and predicting geological conditions of the planned wells.