High frequency dielectric measurement tool

摘要

Disclosed dielectric logging tools and methods employ three or more receive horn antennas positioned between at least two transmit antennas, which can also be horn antennas. The logging tools can operate in the range between 100 MHz and 10 GHz to provide logs of formation permittivity, formation conductivity, standoff distance, and electrical properties of material in the standoff gap. Logs of water-saturated porosity and/or oil movability can be readily derived. The presence of additional receive antennas offers a significantly extended operating range, additional depths of investigation, increased measurement accuracy, and further offers compensation for tool standoff and mudcake effects. In both wireline and logging while drilling embodiments, at least some disclosed dielectric logging tools employ a set of three axially-spaced receive antennas positioned between pairs of axially-spaced transmit antennas. At least some disclosed methods employ absolute amplitude and phase measurements in response to alternate firings of the transmit antennas.

主权项

1. A dielectric logging tool that comprises:
a first transmitter antenna; a second transmitter antenna spaced axially from the first transmitter antenna; three axially spaced receiver antennas positioned between the first and second transmitter antennas; and a processing system, wherein each of the transmitter and receiver antennas are horn antennas providing a usable frequency range between about 100 Mhz and 10 GHz; and wherein the processing system determines a standoff distance between the tool and a borehole wall based on measurements provided by each of the receiver antennas.