2D VISUALIZATION OF THE NAGA THRUST TRIANGLE ZONE, NORTH EAST INDIA, USING STRUCTURAL MODELING OF 2D SEISMIC DATA
The Naga Thrust and Fold Belt (NTFB) located at the foothills of the Himalayas in Northeast India is a structurally complex conjugate zone. 2D seismic data was acquired in the central part of the NTFB approximately 20 kilometers southwest of the Digboi oil field. Previous seismic imaging has presented promising structural characteristics of this study area however this case study attempts to present a mechanically feasible and rigorous model for the development of the Naga Thrust Triangle zone with associated structures.
The initial 2D seismic data was imaged with a combination of traveltime inversion and prestack depth migration (PSDM). An improved image was acquired from a combination of multiscale waveform inversion and PSDM. The latter image provided more detailed structural features related to the Naga thrust fault. The perturbations from the final waveform inversion model were overlain on the seismic depth image, resulting in a good correlation with the formation tops from an exploration well. Interpretation of this image illustrates that the Naga Thrust is associated with both a triangle zone structure and an additional series of conjugate faults.
Structural interpretation in this study area provides insight into the geologic history, continued structural deformation and future hydrocarbon exploration of this region. Further study of migration and maturation may prove the potential of petroleum systems in sub-thrust features of the Naga thrust triangle zone. Sub-thrust traps beneath the Naga thrust sheet are possible as shown in this restored cross section. This study provides insight into the use of traditional and non-traditional geological processing methods in combination with traditional structural methods, which can provide transformative insight for interpretation of previously studied data.