Delineation of oil-water contact within Tipam reservoir: A study from Upper Assam Basin, North-East India

Fluid contacts within a reservoir can vary either because of compartmentalization by faults, lithological variations, hydrocarbon fill history or changes in the hydrodynamic activity of fluids. Their detailed interpretation is significant for estimating potential reserves and developing an explored hydrocarbon field. This study uses high-quality three-dimensional (3D) seismic reflection data to decipher the fluid contact zones and their types from the well-known Tipam reservoir in the petroliferous Upper Assam foreland basin. Different seismic attributes are used to understand the seismic response of fluids and associated structures that structurally control the reservoir geometry. Fluid contact analysis is performed by amalgamating these responses within the target interval. The analysis indicates that the south-west part of the reservoir is a promising hydrocarbon-bearing zone and consists of oil-water contacts. These contacts possess a dominant trend of NE-SW within the reservoir. Further, a decreasing trend in the density, velocity and an increasing trend in the resistivity and porosity logs of the wellbore SC-2 calibrates these inferences and confirms the presence of oil-bearing zones underlain by water in the SW part of the Tipam reservoir. Thus, the Upper Assam foreland basin is a promising area for hydrocarbon exploration, in which Mid-Miocene sequences are the potential leads that can be unlocked. The analysis presented through this research could be efficiently and similarly carried out in onshore basins worldwide.