Definition - What does Blowback System mean?
A blowback system is installed in rigs to clear sample blockages during the drilling operation and increases oil productivity. During the drilling operation, the percussion cycle is activated by the reverse circulation (RC) hammer into which air from the compressor is blown through the swivel inlet located between the outer and inner tubes.
When the percussion cycle ends, the cuttings are picked up by the same airflow and passed from the bit face through the inner tube to the surface where the RC cyclone collects it. The RC hammer often gets stuck in the hole due to jammed debris. The blowback system helps eliminate this problem.
Trenchlesspedia explains Blowback System
When the RC hammer gets stuck downhole due to debris from cuttings, there can be costly delays and a reduction in the production rate. This is because the entire drill string has to be withdrawn and the debris removed manually.
The blowback system is an excellent way to get rid of the problem without having to withdraw the drill string. The system consists of 3-way valves and an STD valve to reverse the flow. When a jam is detected, the operator slightly raises the drill string and activates the blowback system, This diverts the airflow from the compressor with the help of a valve connected to the air swivel directly into the inner rod of the drill, removing the obstructions, while another valve stops the air flowing into the RC cyclone.
Since the drill string no longer needs to be completely withdrawn for removing the jam, the blowback system can significantly increase production rates by saving time.