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US 9,435,909 B2Granted
Imaging using directional resistivity measurements
AssigneeSchlumberger Technology Corporation
InventorsGerald Minerbo, Sofia Davydycheva, Jian Yang
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AssigneeSchlumberger Technology Corporation
InventorsGerald Minerbo, Sofia Davydycheva, Jian Yang
Estimating the term…
The present disclosure relates to a method to produce an image of a subsurface formation using directional measurements. A downhole logging tool having one or more transmitters and one or more receivers, and being capable of making directional measurement, is used to measure the voltage in a particular receiver due to a particular transmitter for one or more transmitter/receiver pairs, at least one of those voltage measurements being a directional measurement. The complex (phasor) voltage recorded on a receiver coil is divided by the complex voltage recorded at another reference receiver coil. Alternatively, we can use the ratio of a receiver voltage at a particular rotation angle of the tool divided by the voltage on the same receiver when the tool has rotated by an angle of 180 degrees. The information in those ratios is combined to produce images of the resistivity of the subsurface formation surrounding the tool.
A method to produce a differential image of a subsurface formation using directional measurements, comprising:
The method claim of 1, further comprising preserving a symmetric spatial response.
The method claim of 2, wherein preserving the symmetric spatial response comprises using a fraction that follows the Born approximation at low frequency or low conductivity.
The method claim of 1, further comprising showing changes in conductivity on the differential image.
A method for generating a differential image of a subsurface formation using directional measurements, the method comprising:
Dependencies are inferred from the claim text.