Description

Applications Schematic representation of the RAB Coring Tool (RAB-C).

Specifications

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

Logging-While-Coring Resistivity-at-Bit System

♦ Core-log data integration capability♦ Assessment of borehole breakouts for local and

regional stress analyses♦ Detection of formation heterogeneity using

azimuthal resistivity images♦ Lithological characterization

The Logging-While-Coring (LWC) system, developed jointly by the Borehole Research Group, Schlumberger Drilling and Measurements, and Texas A&M University, takes advantage of existing logging, drilling and coring technologies and synthesizes them into a powerful new exploration system. Recent improvements in battery technology have enabled the reformatting of the electronics in an 8-inch Schlumberger Resistivity-at-Bit (RAB) tool. By placing smaller batteries in the drill collar wall and fabricating a new resistivity button sleeve, an existing ODP core barrel can pass through the RAB to carry out coring operations while making azimuthal geophysical measurements. The coring tool technology consists of the Motor Driven Core Barrel (MDCB) system developed by Texas A&M, which needed only minor modifications and the fabrication of crossovers and drilling subs. The assembled system was successfully tested at the Genesis test facility in Sugarland, Texas, then successfully deployed at sea to acquire resistivity images and ocean bottom sediment cores at Hole 1249B on Leg 204.

Assembly of the RAB Coring Tool aboard the JOIDES Resolution.

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Retrievable Motor DrivenCore Barrel (MDCB) InnerCore Tube [O.D. 2 7/8"]

RAB [I.D. 3.45"]

Battery

Azimuthal resistivity electrodes [O.D. 9 5/8"]

Azimuthal gamma ray

Field replaceable stabilizer

Bit resistivity electrode

12/2003

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