Abstract

The area of operations is located in the eastern part of Assam-Arakan Basin close to the foothills of Himalayas in the Belt of Schuppen (Thrust Belt) to the South East facing the upper Assam foreland shelf. The area is filled of boulder bed, decidedly undulating topography, and complex and roofed by intense forest. Seismic data acquisition can provide a better reflection where there is sufficient shot hole depth and not having geologically so complex to get a fruitful reflected energy from the underground. However seismic data acquisition is a great challenging chore for the geoscientists, if the area is geologically complex and logistically difficult in natural world. Apart from this, if there is no energy penetration occurs to the subsurf ace, it is quite difficult to map the sub surface structure. The study area falls in the north eastern part of India, is one of the difficult and geologically complex areas, where seismic data acquisition is a great challenge task till this time. The energ y penetration into the ground surface is very less due to not having sufficient shot hole depth. The area is full of boulders from the top of surface and it is not possible to make shot hole depth even a 3 m after struggling 8 to 10 hours. Due to unavailability of the desired suitable shot hole drilling rigs, in the earlier days, geo-scientists have to make a manual pits for blasting for carrying out 2D seismic data acquisition, where the quality of seismic data is not so encouraging. To map hydrocarbon prospects which are expected in both supra and sub-thrust structures at Girujam, Tipam and Barail levels in this area are situated as deep as 5500m. Thus, imaging both supra and sub-thrust structures in this area is a challenging task due to improper signal. In this paper, an attempt has been made a total overview of acquisition and shot hole drilling strategy and how drilling rigs are improved and could possible to make a drill hole upto a depth of 20 m has been discussed. The quality of seismic data is remarkably improved to map both supra and sub-thrust structures. A comparative study including signal quality and the stacked section prior to better shot hole depth has also been discussed and the results are tinted therefore