Abstract

Seismic exploration in geologically complex areas and in rugged terrain has been a challenging task before explorationists. The task becomes more challenging when there are limitations of hardware for data acquisition. Earlier seismic investigations have not become successful in delineating the structural configurations in such a geologically complex area primarily on account of poor imaging. However the present case study has been successful in imaging the anticlinal structures using DFS-V instrument and 96 active channels with end on shooting. Repeat shooting in reverse direction was adopted around the unimaged anticlines in order to have higher foldage and thus better imaging. Despite the adverse field conditions like steep hills and deep gorges, dense jungles shot hole drilling problems due to near surface hard formations coupled with insurgency problems, emphasis was laid on quality data acquisition. Optimum shot hole depth was decided using near surface velocity model prepared on the basis of up-hole studies. Charge depth varied from 18- 28 m and a single hole pattern was used. Charge size optimization was carried out on shot to shot basis and optimum charge size of 4 kg was used. Stacked sections of the dip lines clearly delineate the anticlinal structures in the area. This methodology of shooting in the reverse direction used in the limited portion was with a prime objective of improving the subsurface imaging on the expected anticlines and was quite successful. This was done on all the dip lines passing through anticlines. Results indicate the success of the methodology adopted as the imaging of anticlines improved considerably.