Single-well through casing induction logging tool
AssigneeSchlumberger Technology Corporation
InventorsLuis Eduard DePavia, Hong Zhang
Life of this patent
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Abstract
Methods and related systems are described for making electromagnetic measurements of a subterranean rock formation through a conductive casing of a borehole. A number of transmitters/receivers are deployed into single well having a conductive casing. A magnetic field is induced through the conductive casing and into a surrounding subterranean rock formation, and the magnetic field is detected by the receivers. The receivers have main windings, feedback winding and bucking windings. One of the receiver coils in the tool string is excited at a time, and induced voltages at all of the other receiver coils, either in straight mode, or in feedback mode, are measured.
Claims36
A downhole tool system for making electromagnetic measurements in a borehole comprising:
- a first downhole transceiver adapted to be deployed in a borehole having a conductive casing and induce a magnetic field through the conductive casing and into a surrounding subterranean rock formation;
- and
- a second downhole transceiver adapted to be deployed in the borehole at the same time as the first downhole transceiver, and to inductively detect the magnetic field in the rock formation through the conductive casing.
A method for making electromagnetic measurements in a borehole comprising:
- deploying a first transceiver and a second transceiver into a borehole having a conductive casing;
- inducing with the first transceiver, a magnetic field through the conductive casing and into a surrounding subterranean rock formation;
- and
- detecting inductively with the second transceiver, the magnetic field in the rock formation through the conductive casing.
Dependencies are inferred from the claim text.