Do not perforate slotted liners to effect sand inflow in these two situations:
1. A zone with a gas cap or the potential for formation of a secondary gas cap. Foamy heavy oil, although compressible, is not problematic. The gas micro-bubbles do not coalesce remaining intact until exposed to atmospheric pressure plus temperatures above reservoir temperature.
2. A zone with active bottom or down-dip water. Water breakthrough occurs in three to twelve months in wells with slotted liners. Successful cavity completion (CHOPS) operates at maximum drawdown. Maximum drawdown accelerates breakthrough in these reservoirs leaving a substantial portion of reserves unrecoverable.