Formation evaluation and geological interpretation from the resistivity-at-the-bit tool

Conference · Sun Dec 31 04:00:00 EST 1995

OSTI ID:207259

Rosthal, R A; Lovell, J R; Arceneaux, Jr, C L ^[1]

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1. and others

The RAB (Resistivity-at-the-Bit) tool is a logging-while-drilling device designed to accurately measure resistivity in salty muds and high resistivity formations such as carbonates. Included among the RAB`s measurements are three azimuthally oriented buttons that provide focused resistivity images with shallow, medium and deep depths of investigation. Combinations of these measurements with a focused ring electrode can be used to determine Rt in the presence of invasion. RAB data can also be combined with other LWD measurements to obtain high quality formation evaluation. The RAB tool is unique among LWD tools in its ability to acquire fullbore formation images. Such images not only provide quantitative resistivity, but also give information on the structural geology and depositional environment. Bedding dips computed from the RAB tool compare well with those from wireline image logs. Large scale structural features (bedding, faults, etc.) are readily interpreted from RAB images and dips. As with dip interpretation from other image logs, best results are obtained when images are used to evaluate structural interpretation from batch-processed RAB dips. To help operators more fully utilize RAB data in time-critical drilling situations, a technique is proposed to compute high-angle apparent dips in real-time. Such a capability will be particularly useful for geosteering near-horizontal wells.

• OSTI ID: 207259
• Report Number(s): CONF-951002--
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
ELECTRICAL EQUIPMENT
MWD SYSTEMS
OIL FIELDS
OIL WELLS
RESISTIVITY LOGGING
RESOURCE MANAGEMENT
WELL DRILLING