Imaging using directional resistivity measurements

摘要

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.

主权项

1. A method to produce a differential image of a subsurface formation using directional measurements, comprising:
providing a downhole logging tool having one or more transmitters and one or more receivers, and being capable of making directional measurement; using the downhole logging tool to make the voltage in a particular tilted receiver due to a particular transmitter for two or more transmitter/receiver pairs; for each of two equally spaced transmitter/receiver pairs, forming a ratio between the voltage at a particular rotation angle and the voltage at a rotation angle 180 degrees from the particular rotation angle; forming a product of the two ratios; and using the product as a basis from which to produce the differential image of the subsurface formation.