INTERPRETATION OF A SEISMIC REFLECTION PROFILE IN EASTERN UPPER INDUS BASIN

Abstract

Approximately 16 kilometres long 2d seismic line, acquired by OGDC, has been analysed from an academic point of view. From published geological literature about the surface and subsurface structural trends and major stratigraphic unconformities, observed in the area, it is depicted that along the NNW-SSE orientation of the 2d seismic line, the structural interpretation can be more meaningful than the stratigraphic interpretation. The 2d seismic section has been displayed on such horizontal and vertical scales, that the image has an apparent, laterally varying, vertical exaggeration. Three major distinct seismic reflection character sequences have been identified and correlated with major depositional environments in the area. Velocity contour sections of Dix average, RMS and Interval velocity have been plotted and it is depicted that the lateral variation of velocity follows structural trends. Depth conversion by a model which takes lateral velocity variation into account, seems more reasonable above the decollement but demands smoothing of structural depth section by using valid geological constraints. The understanding of the structure of the deeper parts of the depth section between salt decollement and the basement demands fine-scale study of the natural seismicity, gravity and magnetic data as well as reprocessing / reacquisition of the 2d seismic line, with special controlling parameters, for enhancing deeper objectives.