Vorrichtung und Verfahren zum Bohren von Erdformationen

摘要

A core sampling assembly is provided with borehole data instrumentation which can measure downhole parameters concurrently with the cutting of a core. A core barrel 10 has an inner tube 40 for coring and, alternately, a centre plug assembly 80 (not shown) for closing the throat 30 of the core bit 24 at the bottom of the assembly for drilling in lieu of coring. The inner tube assembly 40 and plug assembly 80 are disposable and retrievable through the drill string on a wireline using an overshot. The core bit 24 is of a stabilized, preferably anti-whirl, design and may be a low-invasion core bit used in cooperation with a low-invasion coring shoe. A logging tool and data transmission assembly may be incorporated in the plug assembly 80 for logging while drilling. Alternatively, sensors for logging borehole parameters and a data transmission assembly may be incorporated in the inner tube assembly 40, in the wall of the core barrel 10, above the core barrel 10, or in a combination of such locations. A significant feature of the apparatus and its operation is the ability to concurrently sense one or more characteristics of the formation surrounding the core barrel 10 in combination with the sensing of one or more such parameters of the core being cut as it proceeds into the inner tube assembly 40.