English abstract
Rock property analysis are the comer stone of any seismic quantitative interpretation. In the past, in Oman, it is used to be done at a field scale and there are very limited studies that were done regionally and these studies do not cover all the key stratigraphic levels. The present study aims to carry out a detailed geophysical rock property analyses targeting Gharif reservoirs in North Oman and study the geological factors that have an impact on seismic. This study has been done for Gharif Formation because it is one key level of interest that carries some business importance in terms of the near future exploration activities. In general, Gharif Formation in Oman contains significant volumes of oil distributed over a very large area. Well log data from 42 wells from Permian Gharif Formation from different fields in North Oman have been used for the investigating geophysical rock properties as pertaining to understanding rock properties variation and its effects on seismic data attributes. Following the data quality verification and editing, different types of cross-plots have been generated for the purpose of assessing Gharif rock properties. Furthermore, synthetic seismic has been used to study the impact of rock property on seismic. Bringing all the results together, Gharif Formation lithologies have overlapped density and seismic velocity and poisson's ratio is better to distinguish sand from shale. Fluid effect is minor in Gharif Formation. Compaction within Gharif Formation causes a decreased porosity and an increased in Al with depth.
Upper Gharif Member is easier to pick in seismic due to high acoustic contrasts between it and the Khuff Formation. However, lateral changes of acoustic properties within Gharif Formation as well as within its bounding formations add more challenge to seismic quantitative interpretation. Middle Gharif and Lower Gharif members are less distinguishable in seismic due to lateral change in its properties and low acoustic contrast respectively. Amplitude Variation with Offset (AVO) is moderate in the tops of Gharif Formation Members.
