Electromagnetic logging between borehole and surface
First Claim
1. A method to determine a property of an earth formation, comprising:
- providing a transmitter that substantially produces an electric dipole moment moveably disposed in a wellbore penetrating the formation;
providing a plurality of receivers located on or near the earth'"'"'s surface and configured in an array;
transmitting electromagnetic energy from the transmitter into the formation from different locations;
receiving a signal from the formation with the plurality of receivers;
using a background formation model to account for changes associated with transmitting from the different locations, wherein the background formation model includes parameters that vary with the different locations, with the parameters including at least wellbore geometry and solid metallic material in the wellbore; and
using the signal received by the plurality of receivers and the background formation model to determine the property of the formation.
2 Assignments
0 Petitions
Accused Products
Abstract
The present disclosure relates to determining a property, such as resistivity, of an earth formation. A transmitter is disposed in a wellbore penetrating the formation, and a plurality of receivers are distributed on or near the earth'"'"'s surface. The transmitter sends electromagnetic energy into the formation and the resulting signal, after passing through the formation, is detected by the array of receivers. The received signal is used to determine the property of the formation. This is often achieved using an inversion or numerical model of the formation being measured. The inversion takes into account changes in the background formation model due to transmitting from various locations. The measurements made on the formation can be performed while drilling the wellbore or subsequent to the drilling.
22 Citations
14 Claims
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1. A method to determine a property of an earth formation, comprising:
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providing a transmitter that substantially produces an electric dipole moment moveably disposed in a wellbore penetrating the formation; providing a plurality of receivers located on or near the earth'"'"'s surface and configured in an array; transmitting electromagnetic energy from the transmitter into the formation from different locations; receiving a signal from the formation with the plurality of receivers; using a background formation model to account for changes associated with transmitting from the different locations, wherein the background formation model includes parameters that vary with the different locations, with the parameters including at least wellbore geometry and solid metallic material in the wellbore; and using the signal received by the plurality of receivers and the background formation model to determine the property of the formation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method to determine the resistivity of an earth formation while drilling a wellbore, comprising:
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providing a transmitter carried that substantially produces an electric dipole moment on or within a while drilling tool string; providing a plurality of receivers located on or near the earth'"'"'s surface and configured in an array; drilling the wellbore using the while drilling tool string; transmitting electromagnetic energy from the transmitter into the formation while drilling the wellbore; receiving a signal from the formation with the plurality of receivers; using a background formation model to account for changes associated with transmitting from various transmitter locations, wherein the background formation model includes parameters that vary with the transmitter locations, with the parameters including at least wellbore geometry and solid metallic material in the wellbore; and using the signal received by the plurality of receivers and the background formation model to determine the resistivity of the formation. - View Dependent Claims (12, 13, 14)
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Specification