Abstract

Rugged topography and fluctuating terrains, such as mountainous areas and foothills, exhibit complexities in terms of large elevation changes, complex near surface & lateral velocity variations. Acquiring 3D seismic data in thrust and fold belt (TFB) provinces is neither feasible nor techno-economically viable. So, 2D seismic data remains the only practical tool for subsurface exploration in such terrains. However, seismic imaging in these structurally complex regions is generally hindered by poor illumination of thrustal and sub-thrustal features, primarily due to inadequate energy penetration and complex wave propagation paths. Moreover, the 2D seismic data inherently suffer from mismatch issues at line intersections due to inconsistent datuming, variable near-surface modelling and inconsistent velocity analysis across vintages. This can significantly mislead interpretation, especially for complex geological settings. This paper presents implementation of a structured workflow for the processing of multiple 2D lines across vintages from one of the most complex thrust & fold belts settings, i.e., Himalayan foothills encompassing robust nearsurface velocity estimation, modulated time series analysis on seismic data, and an interpretative velocity analysis ingraining the structural constraints. The study also outlines specific measures that effectively minimized misties across lines, leading to seamless, geologically consistent horizons and helping to avoid interpretation pitfalls.