Schlumberger Technology Corporation

Robert C Smith

Dean M Homan

Gerald N Minerbo

Gary A Hazen

David T Oliver

Jan Smits

Kuo Chiang Chen

Reza Taherian

Richard A Rosthal

Thomas D Barber

Jean P Seydoux

Emmanuel Legendre

Stephen D Bonner

Kuo-Chiang Chen

Charles G Kibbe

Sergiy Kryukov

Eunmi Choi

A method to obtain gain-corrected measurements. A measurement tool having one or more arrays is provided, wherein the arrays include two co-located triaxial transmitters and two co-located triaxial receivers. Measurements are obtained using the transmitters and the receivers. Impedance matrices are formed from the obtained measurements and the impedance matrices are combined to provide gain-corrected measurements. The apparatus may alternatively be a while-drilling logging tool having one or more arrays, wherein each array comprises a transmitter, a receiver, and a buck, and wherein the signal received by the receiver is subtracted from the signal received by the buck or vice versa. A slotted shield may be incorporated into either embodiment of the tool. The slots may form one or more island elements. A material is disposed in the slots. The islands and shield body have complementary tapered sides that confine the islands within the shield body.

Gain-corrected measurements

A downhole logging tool includes a tool body having a co-located set of antennas located on the tool body and first and second antennas formed from respective first and second pairs of coil windings having a closed-loop pattern. Both the first and second pair of coil windings are arranged on diametrically opposed antenna sections. A cylindrical shield is disposed over the co-located set of antennas and has a first set of vertical slots arranged interposed between each of the underlying antenna sections, a second set of vertical slots arranged over each of the underlying antenna sections, with each of the second set of vertical slots being perpendicular to a portion of the coil winding in the underlying antenna section, and a set of non-vertical slots arranged over each the underlying antenna sections. Each of non-vertical slots is perpendicular to a portion of the coil winding in the underlying antenna section.

Shielded antenna for a downhole logging tool

This disclosure relates to a downhole logging tool for acquiring data in an earth formation. In one embodiment, the downhole logging tool has a tool body with a longitudinal axis, a set of antennas located on the tool body and including coil windings forming a closed-loop pattern, and a shield disposed over the antennas and having an arrangement of slots with each slot being substantially perpendicular to a proximate portion of at least one of the underlying coil windings, wherein the path length around each slot is more than twice the length of the distance between the slot and a directly adjacent slot along an arc of the coil windings. The downhole logging tool may be a wireline or while-drilling tool, and it may be an induction or propagation tool.

The present invention relates to a downhole logging tool having on its tool body a set of co-located antennas, one or more additional antennas spaced longitudinally apart from the set of co-located antennas, an electromagnetically transparent shield circumferentially surrounding the set of co-located antennas, and an electromagnetically transparent shield circumferentially surrounding each of the one or more additional antennas. The downhole logging tool may be a wireline or while-drilling tool, and it may be an induction or propagation tool. The shields may have slots that are locally perpendicular to the windings of underlying coil antennas.

Logging tool having shielded triaxial antennas

A well logging tool and method are disclosed comprising a conductive mandrel, an antenna array disposed around the conductive mandrel, wherein the antenna array comprises a plurality of antennas disposed on insulating supports and at least one contact spacer, the at least one contact spacer having at least one conductor channel having a contact assembly disposed therein, a sleeve disposed over the antenna array, wherein the sleeve includes at least one electrode assembly, the at least one electrode and the contact assembly adapted to provide a radially conductive path from an exterior of the well logging tool to the conductive mandrel and wherein the electrode assembly comprises a first conductor exposed to the exterior of the well logging tool and at least one second conductor conductively connected to the first conductor and exposed to an inner surface of the sleeve, wherein at least one of the first conductor or the second conductor being in sealed contact with the sleeve to prevent the passage of fluid through the sleeve.

Insulated sleeve with conductive electrodes to reduce borehole effects for an induction tool

A well logging tool includes a conductive mandrel; an antenna array disposed around the conductive mandrel, wherein the antenna array comprises a plurality of antennas disposed on insulating supports and at least one contact spacer, the at least one contact spacer having at least one conductor channel having a contact assembly disposed therein; and a sleeve disposed over the antenna array, wherein the sleeve includes at least one electrode, the at least one electrode and the contact assembly adapted to provide a radially conductive path from an exterior of the well logging tool to the conductive mandrel.

Growing community of inventors

Houston, TX, United States of America

Robert C Smith