Gas Research Institute

Farhad Esfahani

James Lynn Davis

Robert L Toellner

The system of the subject invention includes an antenna system, a surface apparatus and a battery-powered remote apparatus useful for applications such as well bore telemetry. In well bore telemetry, the surface apparatus is located uphole on the earth's surface and the remote apparatus is positioned at a remote location downhole in a well bore. The remote apparatus includes a sensor/transmitter unit for sensing physical characteristics such as pressure and/or temperature. The remote apparatus conserves power stored in its battery by transmitting change-in-pressure and/or change-in-temperature data that requires less power for transmission than absolute pressure and/or temperature data. The remote apparatus also conserves power by transmitting absolute pressure data in a single data frame and transmitting absolute temperature data in portions in a series of data frames. The remote apparatus can transition between initial time delay, fixed transmit sequence, sleep, operation, and test states based on its control program and/or based upon the transmission of control data from the surface apparatus. The surface apparatus receives a main signal from the remote apparatus and a reference signal from the antenna system and uses the reference signal to remove noise components from the main signal.

Apparatuses and systems for reducing power consumption in remote sensing

The methods of this invention reduce the amount of power consumed by a remotely positioned (i.e. downhole) sensor/transmitter used in applications such as well bore telemetry. The method involves the sensing of physical characteristics such as pressure and/or temperature to generate a first absolute value than is transmitted to a surface receiver located at the earth's surface. At a later time (or period) the physical characteristic is again sensed to generate a second absolute value that is subtracted from the first absolute value to generate a difference. If the difference is significant (i.e., greater than a predetermined value), the difference will be transmitted to the surface receiver. Because the difference will generally have fewer bits of data than the absolute data, less data can be transmitted so that battery power is conserved in the remote sensor/transmitter. In the event that the difference is not significant, even fewer bits need to be transmitted by the remote sensor/transmitter. Another method uses the fact that temperature is a more slowly changing phenomenon than pressure, and transmits data in frame formats constructed so that the transmission bit rate of sensed pressure data is higher than the transmission rate of sensed temperature data. In another method of this invention, the remote sensor/transmitter is programmed into a sleep state in which the remote sensor/transmitter consumes no appreciable battery power, for example, while being run down a well bore. The remote sensor/transmitter then transitions from the sleep state to the operation state after the expiration of a predetermined time period or by transmission of a control signal thereto.

Methods for reducing power consumption in remote sensing applications

The present invention comprises an apparatus and method for substantially canceling impulsive noise from data. Such substantial cancellation is achieved by converting the time-domain data into its corresponding frequency spectrum, such that the impulsive noise threshold can be determined. Once such threshold is determined, all frequency components less than this threshold are canceled with the resulting spectrum being converted back to the time-domain. This substantially impulse free signal can then be substituted into the original signal where the impulsive noise occurs, thus, resulting in a signal having minimally distorted data that is substantially devoid of any impulsive noise. This signal may be further processed by an adaptive filter stage to substantially remove any remaining noise from the signal.

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Dallas, TX, United States of America

Farhad Esfahani