Advanced Application of Borehole Images and Acoustic Logs in Building Robust Geomechanical Model for Tapti-Daman Field, Western Offshore India

Abstract

Abstract Tapti-Daman is one of the established prolific gas producing clastic sub-basin in offshore Mumbai, India. Paleo-Miocene shallow sands are the dominant reservoir in this area. Drilling surprises have been observed frequently in this area due to geomechanics-related wellbore instability. We present a case study showcasing detailed analysis and integration of multi-well advanced acoustic and borehole image data set. Considering the uncertainty with the variation in stress regime on well basis as compared to regional geological setting, it becomes critical to identify stress regime in order to optimize mud weight programme to drill high inclined wells where safe mud weight window becomes narrow. The borehole image analysis leads to identification of breakouts and drilling induced fractures which reveal horizontal stress directions whilst sonic anisotropy analysis provides more robust insight on maximum horizontal stress direction based on fast shear azimuth. In addition, radial profiles of fast shear and slow shear were used to invert and determine absolute values of maximum and minimum horizontal stress magnitudes. Integration of the high resolution data set reveals the present day stress regime of the study area is strike slip (σH>σV>σh) regime. Using the quantitative values of horizontal stresses determined at different depth intervals, a post-drill Mechanical Earth Model (MEM) was developed to perform history matching of predicted failure with observed drilling events. This model was then validated with another well in the field which clearly demonstrated the value addition of the sonic answer products and image analysis. Similar workflow can be adopted to address sanding propensity to optimize completion design to mitigate or manage sand production.