1. n. [Well Workover and Intervention]

The gas present in the fluids of a wellbore circulatory system. Many well-intervention operations are conducted with the well live or held on balance. Fluids circulated within the wellbore under these conditions are likely to pick up reservoir fluid and gas. The entrained gas and fluid require special handling and processing before the base fluid can be safely recirculated in the wellbore or prepared for disposal.

See: circulation system