| Popis: |
Tapti-Daman is one of the major hydrocarbon-producing clastic sub basins situated in the northeast region of the Mumbai High structure in Western offshore India. Tapti-Daman sub-basin hosts more than 6 Km of clastic dominated sediments ranging from late Paleocene to Recent, underlained by basement rocks. Drilling failure has been reported in few wells in Tapti-Daman block in the past, which subsequently resulted in well collapse and abandoning the drilled section. The limitation of stress computation in the deviated and horizontal wells further introduced complexity in overcoming the wellbore stability issue. To address this, an innovative methodology was developed to assess the stress regime in this field. An accurate estimation of the stress parameters in the backdrop of geological information led to a more accurate and reliable geomechanical model. Using a multiwell dataset from the C-Structure in the Tapti-Daman block, stress azimuth from vertical and deviated wells was determined with an advanced interpretation module. The module utilizes the borehole microresistivity image-derived azimuths of drilling failure signatures (i.e. breakouts, induced fractures, etc.) to decipher the shape of the stress tensor (Q-factor) and azimuth of minimum horizontal stress. The detailed analysis of the Q-factor and Sh leads to determining stress regime and anisotropy (as a function of well trajectory). The analysis revealed that the present day in situ stress in the study area is compressional in nature, where S3 is vertical (sH>sh>sV) and the minimum horizontal stress azimuth is towards NE-SW. This critical information is represented in 2D stereographic stress plots considering the Sv/Sh or Smax/Smin ratios to ascertain the safe window for various wellbore stability parameters such as sanding, breakout, mudloss, tensional fractures, anisotropy and probability of fracture opening with respect to insitu stresses. The inferences derived provide an edge in optimizing the well trajectories to avoid wellbore stability issues. |
