Abstract: Methods, apparatus, and systems are provided for collecting data from a plurality of downhole sensors located in a wellbore utilizing an asynchronous direct-sequence code division multiple access (DS-CDMA)-based communication scheme. One example method includes receiving a superposed signal comprising asynchronous signals from the downhole sensors, wherein a spreading sequence has been applied to data generated by each of the downhole sensors to form each of the asynchronous signals; sampling the received superposed signal; and processing the sampled superposed signal using decorrelation to determine the data from at least one of the downhole sensors before the spreading sequence was applied.

Abstract: A telemetry system and method configured to communicate a wellbore parameter such as fluid composition, temperature, and pressure. In one embodiment, a plurality of tracers is stored downhole, and each of the tracers represents a different value of the wellbore parameter. After measuring the wellbore parameter, the measured value is correlated to one or more of the plurality of tracers that is equivalent to the measured value of the downhole parameter. The one or more tracers representing the measured value are then released from their respective containers to travel upstream. A sensor located upstream may detect the one or more tracers, which are then correlated back to obtain the measured value of the wellbore parameter. In another embodiment, ratiometric amounts of the tracers may be used to represent additional values of the wellbore parameter.

Abstract: Methods, apparatus, and systems are provided for collecting data from a plurality of downhole sensors located in a wellbore utilizing an asynchronous direct-sequence code division multiple access (DS-CDMA)-based communication scheme. One example method includes receiving a superposed signal comprising asynchronous signals from the downhole sensors, wherein a spreading sequence has been applied to data generated by each of the downhole sensors to form each of the asynchronous signals; sampling the received superposed signal; and processing the sampled superposed signal using decorrelation to determine the data from at least one of the downhole sensors before the spreading sequence was applied.