Definition - What does Gas-Oil Contact mean?
Gas-Oil Contact is the bounding surface present in a reservoir below which oil occurs predominantly and above which gas occurs predominantly. As oil and gas are miscible, the contact between them is transitional and it forms a zone containing a blend of oil and gas. Defining Gas-Oil Contacts in reservoirs is essential for the volumetric and detailed petrophysical calculations. A detailed analysis of gas identifies the Gas-Oil Contact from the increasing ratios of heavier components or hydrocarbon compared with methane when the depth increases.
Petropedia explains Gas-Oil Contact
The Gas-Oil Contact acts as the interface between oil and gas phases of reservoir formation. During well production, the Gas-Oil Contact may move and result in undesirable conditions of production like a high proportion of gas which may be too much for the facilities of surface processing. Monitoring the oil-water and Gas-Oil Contacts is one of the key elements of the good reservoir management practices. The direct observations of brown or yellow ultraviolet fluorescence and oil staining on drill cuttings can identify oil. While the drill cuttings are crumpled in solvents, the mobile oil transfers the solvent. Gas condensates have bright white fluorescence. These characteristics help in the identification of gas and oil reservoirs, Gas-Oil Contact, the top and the base to reservoirs.