8/3/2019 LWD-RAB

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Description

Applications

Schematic illustration of the Resistivity-at-Bit tool (LWD-RAB).

Specifcations

ODP Logging Services, Lamont-Doherty Earth Observatory, Rt. 9W, Palisades, NY 10964

Logging-While-DrillingResistivity-at-Bit Tool

Detection of resistivity heterogeneity viaazimuthal resistivity images

Lithology estimation

Instantaneous detection of casing and coringpoints

Accurate resistivity when mud is salty orformation resistivity is high

Detection of early invasion of borehole uidsinto the formation

The Schlumberger Resistivity-at-Bit tool (LWD-RAB)makes azimuthal resistivity and gamma ray measurements while drilling. Using an azimuthal positioning system,measurements are acquired around the borehole to create ahigh resolution, 360-degree resistivity image of the drilledhole. The RAB tool may be connected directly behind thebit or further back in the bottom hole assembly. It may berun with other LWD tools such as the ADN, ISONIC orNMR. Typically, the RAB data are stored in memory withinthe tool and retrieved at the end of the bit run. As an option,the data may be transmitted to a surface acquisition system

if a Measurement-While-Drilling (MWD) power pulse toolis run in conjunction with the RAB.

Assembly of the RAB tool aboardtheJOIDES Resolution .

Optionalupholeconnector

Batteries

Upper sensor

Middle sensor,containingfocused ringelectrode

Azimuthal gamma ray

Field-replaceablestabilizer

Lower sensor

Float valve boreRbitelectrode

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