1. n. [Geology]

A bounding surface in a reservoir above which predominantly gas occurs and below which predominantly oil occurs. Gas and oil are miscible, so the contact between gas and oil is transitional, forming a zone containing a mix of gas and oil.

Alternate Form: GOC

See related terms: downdip,  fluid contact,  gas-water contact,  immiscible,  oil-water contact,  updip

2. n. [Well Completions]

The interface between the gas and oil phases present in a reservoir formation. During the production of a well, the GOC may move, resulting in undesirable production conditions such as a high proportion of gas that may be too much for surface processing facilities. Monitoring the gas-oil and oil-water contacts is a key element of good reservoir management practices.

Alternate Form: GOC

See related terms: gas-water contact