Integrating PVT Data of Complex Fluid Systems with the Regional Geology of the Northern Oman Fahud and Ghaba Salt Basins: Examples from the Haima Supergroup of Oman

Abstract An integrated analysis of fluid property data of deep tight gas-condensate stacked reservoirs was coupled with regional petroleum system analysis across North-Central Oman to investigate variations observed in PVT data. The study, focused on the lower Haima reservoirs of the Haima Supergroup, aims to identify the broad links between the petroleum system and the PVT properties in order to delineate areas of varying properties within the basin and develop a common Equation of State (EoS) fluid model for modelling purposes. The approach is based on investigating fluid property variation observed from PVT lab reports across multiple fields and reservoirs. Data trends were plotted against a range of key subsurface parameters for multiple fluid samples. A comparison of the fluid property data from PVT with the maturity and temperature history of the basin was carried out to understand property variation and link it with the regional geology. The process links PVT trends to Geochemistry by investigating HC maturity and mixing of Hydrocarbon sources. It also dives into the reservoirs’ temperature and maturity history within the basin. The study focused on ensuring that the developed approach can help in understanding fluid property variation within the subsurface by integrating PVT Lab data with the charge history. While it was anticipated that reservoir stratigraphy and depth would have a direct relationship with fluid density and composition, the findings revealed that the complexity of charge history, hydrocarbon mixing, and temperature history significantly influence the observed variability. However, coming to this understanding can aid in identifying areas with potential for development, such as delineating uncertainty range of the fluid properties & CGR across the basins. Despite these insights, the common EoS model was found to be reasonably effective across the area of interest. This workflow has provided good insights into the fluid history of the basin by linking PVT data trends and variation with observations from charge history understanding. It has also assisted in understanding the limitations of PVT modelling across complex reservoir fluid systems.