US 2021/0003733 A1 · DECOUPLING TENSOR COMPONENTS WITHOUT MATRIX INVERSION

Abstract

Numerical and/or semi-analytical methods are leveraged to decouple a complete set of nonzero electromagnetic field tensor components (118) from detected signal data (119). Nine nonzero components can serve as inputs for a three-dimensional inversion process to determine formation properties. A resistivity tool (100) containing at least one transmitter (111) and at least one receiver (108, 109) at tilted angles receives an electromagnetic signal throughout a rotation. A difference in the azimuthal positions of the transmitter(s) and receiver(s) during rotation of the resistivity tool can result in an azimuthal offset between resistivity tool subs. The components (118) are decoupled from the detected signal data (119) numerically or semi-analytically according to whether the azimuthal offset angle is known. If the azimuthal offset angle is known, the nine components are determined numerically through curve fitting. If the azimuthal offset angle is unknown, a semi-analytical process is used to solve for the nine components.

Claims20

Dependent claims

A method comprising:

detecting at a first receiver of a set of one or more receivers a formation response to electromagnetic radiation emitted from a first transmitter of a set of one or more transmitters;
determining complex azimuthal electromagnetic field data corresponding to the formation response;
and
decoupling a first plurality of nonzero tensor components from the complex azimuthal electromagnetic field data without matrix inversion, wherein the decoupling comprises numerically decoupling if an azimuthal offset between the first transmitter and the first receiver is known and semi-analytically decoupling if the azimuthal offset between the first transmitter and the first receiver is unknown.

1 more element

One or more non-transitory machine-readable media comprising program code executable by a processor to perform operations comprising:

determining complex azimuthal electromagnetic field data corresponding to a formation response to electromagnetic radiation emitted from at least a first transmitter of a set of one or more transmitters and detected by a set of one or more receivers;
and
decoupling a first plurality of nonzero tensor components from the complex azimuthal electromagnetic field data without matrix inversion, wherein the decoupling comprises numerically decoupling if an azimuthal offset between the first transmitter and the set of one or more receivers is known and semi-analytically decoupling if the azimuthal offset is unknown.

An apparatus comprising:

a multi-sub tool having a transmitter sub with at least one transmitter antenna and a receiver sub with at least one receiver antenna;
a processor;
and
a machine-readable medium having program code executable by the processor to cause the apparatus to,
determine complex azimuthal electromagnetic field data corresponding to a formation response to electromagnetic radiation emitted from at least a first transmitter of a set of one or more transmitters and detected by a set of one or more receivers;
and
decouple a first plurality of nonzero tensor components from the complex azimuthal electromagnetic field data without matrix inversion, wherein the program code to decouple comprises program code to numerically decouple if an azimuthal offset between the first transmitter and the set of one or more receivers is known and program code to semi-analytically decouple if the azimuthal offset is unknown.

4 more elements

Dependencies are inferred from the claim text.

Decoupling tensor components without matrix inversion

Life of this patent

Decoupling tensor components without matrix inversion

Life of this patent

Abstract

Claims20