| 摘要 |
An adjustable hole cleaning device is provided for cleaning a hole in a subterranean formation. A drillstring containing the device is rotated to drill a hole through the subterranean formation. While rotating the drillstring, drilling fluid is circulated through the drillstring and the device into the hole. In response to an increase in a hydrostatic pressure of the fluid in the drillstring, cleaning elements are extended from the device to clean accumulated cuttings from the drilled hole. The cleaning elements may clean the accumulated cuttings by agitating the circulating fluid in the hole. In response to a decrease in a hydrostatic pressure of the fluid in the drillstring, the cleaning elements may be retracted back into the device. The device may also include a set of ports which hydraulically open in response to the increase of hydrostatic pressure in the drillstring to disperse drilling fluid into the hole for cleaning accumulated cuttings. The device may be deactivated by dropping an object, such as a ball, into the device to prevent the extension of the cleaning elements and the opening of the ports.
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