Screened boot basket/filter

摘要

A downhole debris filtering apparatus is disclosed. In a preferred embodiment, the flow diverter is retracted as the tool is run in to provide easy passage for debris. Settling velocity is the rate at which debris will fall through the fluid. Settling velocity is dependent on the density of the fluid and the debris density. If the fluid velocity exceeds the settling velocity, the debris will rise. The restricted annular area outside the screens raises the fluid velocity. Above the cup sleeve, the annular area increases significantly and the fluid velocity is reduce to below the settling velocity to allow debris to settle to the bottom of the tool. On run in, the fluid merely bypasses on the outside of the filter. Large debris will settle into the tool as described. When pulled out of the hole the swab cup/flow diverter is actuated into casing or liner wall contact and a large passage is opened to allow flow though the filter. Small debris that has risen above the tool will be captured as the fluid is filtered through the screen. Another embodiment with a non-retractable cup uses a sliding sleeve valve with a large open area which promotes free flow and minimizes fouling from deposited debris.