The combination clean-out and drilling tool, often called "Hy-Tech Tool", is a unique concept in downhole remedial and completion work.
It is particularly suitable for wells that cannot support a high column of fluid or are susceptible to permeability damage. When used along with other tools, it can provide several services like drilling, washing sand and perforations, drilling out cement, packers and plugs, and washing on stuck liners and tubings.
The pump assembly, the tailpipe and the check valves make it a high performance tool. The pump with an hexagonal kelly provides torque to perform heavy-duty drilling and milling jobs when used with a rotary table or a power swivel.
By reciprocating the tubing at surface, the pump performs as a "syringe" pulling sand and loose material up into the tailpipe, where it is held by the two ball-and-seat valves.
The fluid can be pumped to surface or recirculated into the annulus through discharge and drainage valves.
When the tailpipe is full, the string is pulled out to remove the fill. Normally, many meters can be cleaned out in a single run. The same pump design is maintained for all applications. This is a compact 54" long tool that permits full circulation in wells unable to support a full column of fluid for conventional circulations.
Fluid loss to the formation is kept to the minimum because the tool performs under almost any hydrostatic pressure. The tool uses the fluid existing in the well to do its work. This eliminates the need for water and the associated hauling charges, as well as the pumping units and earthen pits used for disposal of the produced fluid. Also rig time costs for circulating materials to surface are saved.
Additionally, the CCDT may be used without a rig pump to remove perforation ball sealers and drillable bridge plugs on a single trip. The CCDT provides a practically fail-safe operation and is safer to run than wireline tools or other cleanout tools.
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The string is continually reciprocated keeping the casing walls clean and preventing the tailpipe from tunneling into sand and the tool from getting buried or stuck.
The rig weight indicator and the position of the tool stroke keep the operator informed of downhole conditions at all times. At tight spots, the operator pulls up and works through again.
The kelly coupled with the long stroke of the pump makes it possible for the tool to jerk up and down (imparting a powerful jarring action) to release plugs or for fishing operations.
If for any reason the tool is left in the well, it can be perfectly fished in 4 1/2" casing or larger.
The tool helps save time and money and solves fishing and cleaning problems without a pump or back up unit, with little or no fluid loss to formation.
Environmental advantages
Swabbing with wire rope and cup assembly unavoidably contaminates the wellsite and the rig due to the fluid that is pulled from the wellbore. This makes tasks highly unsafe and increases the likelihood of injuries and fires from the sparks generated by the wire friction at the sheaves. On the other hand, swabbing with the Sand Pump assembly poses no risks because the fluid is moved inside the tubing string up to a surface line.
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