Method for estimating formation parameters from imaginary components of measured data

Patent metadata

Field	Value
Publication number	US-11002876-B2
Application number	US-201114114742-A
Country	US
Kind code	B2
Filing date	May 3, 2011
Priority date	May 3, 2011
Publication date	May 11, 2021
Grant date	May 11, 2021

Abstract

A system and method for determining formation parameters is provided. The system includes an induction logging tool having a plurality of transmitter coils. The induction logging tool further includes a plurality of receiver coils, each of the receiver coils being spaced apart from the transmitter coils by a predetermined distance and receiving a response signal from the formation. The system includes circuitry coupled to the induction logging tool, the circuitry determining voltages induced in the plurality of receiver coils by the response signal. The circuitry separates real or in-phase portions of the determined voltages from imaginary of ninety degrees out of phase portions of the determined voltages and determines formation parameters using imaginary portions of the measured voltages.

First claim

What is claimed is:

1. A system for determining formation parameters, comprising:
an induction logging tool, the induction logging tool comprising:
a plurality of transmitter coils, the plurality of transmitter coils transmitting at least one induction signal into the formation;
a plurality of receiver coils, each of the receiver coils being spaced apart from the transmitter coils by a predetermined distance and receiving a response signal from the formation, the response signal being induced by the at least one induction signal; and

circuitry coupled to the induction logging tool, the circuitry determining voltages induced in the plurality of receiver coils by the response signal, wherein the circuitry is further configured to separate real portions of the determined voltages from imaginary portions of the determined voltages and determine formation parameters using only imaginary portions of the measured voltages, wherein the imaginary portions of the determined voltages are ninety degrees out of phase with a current on the transmitter coils, wherein the selected formation parameters include at least one of a horizontal resistivity R h , a vertical resistivity R v , a horizontal conductivity σ h , and a vertical conductivity σ v .

2. The system of claim 1 , wherein:
the determined voltages have the form of V =V ij , wherein V ij is a voltage induced on the j-th receiver coil by the i-th transmitter coil; and, optionally
the plurality of receiver coils include three receiver coils oriented in three linearly independent directions, generally referred to as an x direction, a y direction, and a z direction, and the plurality of transmitter coils include three transmitter coils also oriented in the x, y, and z directions, such that the determined voltages have the form

V
=

=

[

V
xx

V
xy

V
xz

V
yx

V
yy

V
yz

V
zx

V
zy

V
zz

]

;

and, optionally
the x direction, the y direction and the z direction are orthogonal to each other.

3. The system of claim 2 , wherein the x direction, the y direction, and the z direction are not orthogonal to each other and the determined voltages are transformed to an orthogonal orientation.

4. The system of claim 2 , wherein the dip angle α is determined using the equation

α
=

tan

-
1

⁡

[

(

(

Im
⁡

(

V
xy
t

)

Im
⁡

(

V
zx
t

)

)

2

+

(

Im
⁡

(

V
xy
t

)

Im
⁡

(

V
zy
t

)

)

2

)

]

,

wherein Im(V t ij ) is the imaginary component of the voltage induced on the j-th receiver by the i-th transmitter in a coordinate system t of the induction logging tool.

5. The system of claim 1 , where in the strike angle β is determined using at least one of the following equations:

β
=

tan

Assignees

• San Martin Luis Emilio
• Wu Dagang
• Halliburton Energy Services Inc

Inventors

• San Martin Luis Emilio
• Wu Dagang

Classifications

• G01V3/28 Primary

  using induction coils · CPC title

• G01V3/38 Primary

  Processing data, e.g. for analysis, for interpretation, for correction · CPC title