Dropping an activation ball is a common method used in various downhole tool activations. Here’s a breakdown of how the activation ball is used for tools like:
- Liner Hanger (Hydraulic Set)
-Purpose: To set the liner hanger in place.
-Ball Drop Use:
-Ball is dropped from surface and pumped down.
-It lands on a ball seat inside the liner running tool.
-Pressure is applied, and once a predetermined pressure is reached, the liner hanger sets against the casing wall.
-The ball is often designed to pass or dissolve later. - PBL Sub (Pump-Bypass Sub)
-Purpose: Allows circulation through the tool when regular paths are restricted or for activating jetting/bypass functions.
-Ball Drop Use:
-Ball is dropped and lands on an internal seat.
-Once pressure is applied, the internal sleeve shifts, opening the bypass ports.
-Multiple balls of different sizes can be used for multi-stage activation.
-After use, the ports may be closed by reverse pumping or using another activation ball. - Underreamer
-Purpose: To open expandable cutting arms for underreaming the hole below casing or liner.
-Ball Drop Use:
-Ball is pumped down to seat in the underreamer activation chamber.
-Pressure builds up and activates a hydraulic mechanism, causing the cutting arms to deploy.
-After deployment, the underreamer stays open as long as flow is maintained. - ETC (Expandable Tools, Cementing Tools, etc.):
Depending on the exact tool, activation by ball drop is commonly used for:
-Stage Cementing Collars: Ball activates the opening of ports.
-Toe Sleeves / Open Hole Packers: Ball lands, pressure activates the tool.
-Hydraulically Activated Valves: Same concept.
General Considerations
-Ball Material: Aluminum, dissolvable, or composite.
-Size: Critical to match internal seat; multiple tools can be activated in sequence using balls of increasing diameter.
-Pressure Monitoring: Surface pressure signature confirms tool activation.
-Compatibility: Ensure tools are compatible with ball-drop methods.