Perforating is a common remedial procedure that restores inflow in plugged screens & slotted liners.
The 70% solids viscous oil slurry presented in unconsolidated sand reservoirs is an extreme overload on the filtering capacity of screens & slotted liners causing them to rapidly plug off leaving most of the produceable reserves stranded.
Cavity Completion (known as CHOPS in Western Canada heavy oil wells) is controlled extraction of several hundred cubic meters of near casing or liner sand. Oil inflow is stimulated 4 to 6 times greater than theory predicts. Upticks in rate are 3 to 29 times. Recovery increases more than 3 fold over sand exclusion completions.
Designed perforating plus modern liner sand cleanout equipment and production practice cost effectively manages sand inflow and removal.
Sand inflow rapidly diminishes to less than 1% for the life of the well.
Total sand volume extracted is less than 2% of the volume of reservoir sand in the drained area and is about 4% of the Cumulative oil volume produced.
The entire liner does not need to be perforated. In an uncemented liner in heavy oil unconsolidated sand reservoir the areal size of individual aperatures in the liner are more important than overall Area Open to Flow to maximizing recovery. Perforating a liner is a function of identifying where the liner is in effective pay plus a determination of spacing.
