Content of PetroWiki is intended for personal use only and to supplement, not replace, engineering judgment. SPE disclaims any and all liability for your use of such content. More information
Oil smearing in a petroleum reservoir occurs when oil migrates to the gas-cap, and is trapped and lost in it.
It usually occurs during gas well production or gas-cap blowdown, when the pressure drawdown is higher than gravitational force, and the oil is sucked into the gas-cap.
It can also occur if an oil field is depleted by a nearby field via its gas cap, causing the oil rim to be sucked into the gas-cap.
Because it leads to oil production and reserves losses, gas-cap blowdown projects are delayed until after commercial oil recovery is completed.