CT cleanouts are used to remove debris and particulates from boreholes. Water- or oil-based fluids can be used and mixed with nitrogen if required. Most cleanouts are done with a simple BHA comprising a connector, a double check valve, and a wash nozzle. Wash nozzles are offered in different configurations, depending on the particular job and preference.
Other options for cleanout tools include
- mandrel bypass tools when gas lift mandrels are included in the well completion
- packer jumpers when encountering difficulties while passing through restrictions
- positive displacement motors and bits.
In large casings with a restriction in the wellbore above, CT can be used for reverse circulation. A special surface rig-up is used switch the direction of flow simply by operating a few valves, and a safety pop-off valve is included to control the annulus pressure.