Halliburton Energy Services, Inc.

Myrick L Monroe

Luis Emilio San Martin

Carl Dodge

William Joseph Schaecher

Wallace R Gardner

Marian Morys

Raj Pai

Geoff Nightingale

Bruce S Huckaba

Humberto E Rosa

Oil-based mud imaging systems and methods that measure formation permittivity. In some embodiments, disclosed logging systems include a logging tool in communication with surface computing facilities. The logging tool is provided with a sensor array having at least two voltage electrodes positioned between at least two current electrodes that create an electric field in a borehole wall, and is further provided with electronics coupled to the voltage electrodes to determine a differential voltage magnitude and phase. From the magnitude and phase, formation resistivity and permittivity measurements can be determined and used to construct a borehole wall image.

Permittivity measurements with oil-based mud imaging tool

Oil-based mud imaging systems and methods having standoff compensation. In some embodiments, disclosed logging systems include a logging tool in communication with surface computing facilities. The logging tool is provided with a sensor array having at least two voltage electrodes positioned between two current electrodes energized by an excitation source to create an oscillatory electric field in a borehole wall. The two current electrodes are each shielded with conductive shields to prevent current leakage into the logging tool body. A common mode voltage is measured, and the phase and amplitude of the excitation source is controlled to reduce the difference between the common mode voltage and reference voltage of a voltage detector. The logging tool is further provided with electronics coupled to the voltage detector and the current electrodes to determine a differential voltage between the voltage electrodes and two current flows from separate ones of the current electrodes. From the differential voltage and multiple current flows, the computing facilities determine borehole wall resistivity, and may display the resistivity as a borehole wall image.

Standoff compensation for imaging in oil-based muds

A downhole telemetry system having discrete multi-tone modulation and dynamic bandwidth allocation is disclosed herein. In one embodiment, the downhole telemetry system comprises a surface transceiver, a cable, and a downhole transceiver coupled to the surface transceiver via the cable. The downhole transceiver communicates to the surface transceiver using discrete multi-tone (DMT) modulation to transmit telemetry information over a set of frequency subchannels allocated for uplink communications. The surface transceiver may likewise communicate to the downhole transceiver using DMT modulation to transmit information over a set of frequency subchannels allocated for downlink communications. The number of uplink and downlink communications subchannels is preferably variable and preferably can be changed depending on the operating mode of the system. This allows additional subchannels to be allocated for downlink communications during programming and configuration of the downhole equipment, and additional subchannels to be allocated for uplink communications during normal logging operations. The set of uplink communications subchannels may be disjoint from the set of downlink communications subchannels, and the sets may be spaced apart in frequency or interleaved in frequency. The cable may be a single conductor or multi-conductor logging cable. In the case of the multi-conductor logging cable, one of several possible orthogonal transmission modes may be used to convey the information signals.

Downhole telemetry system having discrete multi-tone modulation and dynamic bandwidth allocation

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Katy, TX, United States of America

Myrick L Monroe