Fault Sealing as the Gateway to Understand Hydrocarbon Column Variability in the Zawtika Field

The objectives of this study are to evaluate the hydrocarbon column height disparity between Fault Block A (higher column) and Block B (lower column) by analyzing reservoir distribution, quality, and structural configuration within the same reservoir unit separated by fault and to perform a comprehensive Fault Seal Analysis through:

• Construction and interpretation of the Fault Displacement Model
• Juxtaposition analysis to assess reservoir connectivity across the fault
• Calculation and interpretation of the Shale Gouge Ratio (SGR) to estimate fault seal capacity.

The study began with Acoustic Impedance vs. Depth analysis across wells with sonic data to assess fluid response and distinguish gas sand, water sand, and shale. This helped evaluate reservoir quality and heterogeneity. Spectral decomposition was then used to map sand distribution, selecting 20 Hz, 25 Hz, and 35 Hz frequencies based on 1–30 m sand thickness. RGB blending revealed subtle variations in shape, size, and lithology. Lastly, fault seal analysis included Fault Displacement, Shale Gouge Ratio (SGR), and Juxtaposition models, all calibrated with well data to assess fault behavior and sealing potential.