Mechanical Well Cleaning Tool (MWCT)

The Mechanical Well Cleaning Tool (HWCT) is designed for cleaning oil, gas, and geological exploration wells with low formation pressure from clay-based mud, sludge, sand, scale, and small debris. It is also used to clean wellbores obstructed by proppant plugs following hydraulic fracturing without requiring circulation or washing. The mechanical well cleaning device operates on the principle of a piston pump. Design features and operating principle Bottomhole normalization and cleaning are achieved by running a depression chamber into the well on a tubing string. The depression chamber consists of a cylinder and a piston, both equipped with integrated check valves. Below the depression chamber is a receiving chamber, formed by the tubing string itself. There are a check valve and a cleaning crown (scraper) below the receiving chamber. The drain valve is installed above the depression chamber. During bottomhole cleaning, the tool assembly is run to the bottom (e.g., onto a plug) and allowed to fill with wellbore fluid. Reciprocating movements are then applied, causing the crown to loosen the upper layer of the plug. On the upstroke, the piston extends out of the cylinder over its working stroke. The check valve mounted on the piston closes under the combined effect of gravity and the hydrostatic pressure of the fluid column above it. This creates a depression (reduced pressure) inside the chamber, which opens the check valve located below the piston, allowing wellbore fluid to enter the receiving chamber. Simultaneously, the check valve above the crown opens, drawing in fluid from the bottomhole area along with debris from the milled plug. On the downstroke, the piston re-enters the cylinder. The fluid in the depression chamber is compressed, causing the lower check valve (below the piston) to close. The piston-mounted check valve then opens, allowing fluid to flow upward through the tubing string. At the same time, the check valve above the crown closes, preventing plug fragments, sand, or sludge from escaping the receiving chamber. This cycle is repeated until the bottomhole area is fully cleaned. The length of the receiving chamber is selected during assembly based on the expected size of the plug. Excess fluid is discharged back into the wellbore through the drain valve during operation. If torque transmission is required, special spline slots between the cover and the sub.