Abstract

The paper aims to provide a comparative study of different methods of saturation modelling (BVW or Bulk Volume of Water method proposed by Cuddy et al. (1993, 2017), which postulates that the product of porosity and saturation can be a function of height alone and Geo-statistical method using collocated co-krigging) in the absence of SCAL data and their applicability based on the depositional history, entrapment, and hydrocarbon distribution in the reservoir taking examples of fields of Upper Assam North basin. Although well data gives the highest possible resolution of pore fluid distribution vertically, however the areal extent is limited and as a result populating properties such as saturation becomes uncertain. As a result uncertainty creeps into populated saturation volumes owing to nonreliance of saturation with seismic attributes. This has profound effect on the estimated hydrocarbon volumes and in turn the field development schemes. In this paper both the methods were applied in tandem in the reservoirs of deltaic and fluvial origin from Upper Assam Shelf region. Pros and cons of the both the methods were analysed in details. The effects of structural disposition, stratigraphic framework etc. have been catalogued for both the methods. It is observed that BVW method works best in case of structural entrapment while in case of strati-structural entrapment Geo-statistical method provides better results.