The Enhanced Digital Telemetry Cartridge (EDTC-B*) is a downhole tool that combines two commonly run sensors with a high-speed telemetry downhole modem that can be used in high-pressure and high-temperature environments. The primary function is to provide high-speed (over 1 Mbps) communications between the wireline tools downhole and the acquisition system at surface. Additionally, it includes a scintillation gamma ray detector that provides a simple total GR count in API units that is used for correlation between logging runs. Therefore, the use of the EDTC eliminates the need for the spectral gamma ray tool (HNGS), thus reducing the length of the string. The gamma ray curve Finally, the EDTC includes a single-axis accelerometer to provide the “z-axis” (i.e., along the longitudinal axis of the tool string) acceleration. This measurement can be used to observe downhole tool motion and apply speed corrections during the post-logging data processing, if desired. If a wireline heave compensator is used, the vertical (z-axis) acceleration data can be used to evaluate the heave compensator performance. The auxiliary measurements (GR and Az) provided by the EDTC cannot be used unless the EDTC is the downhole modem (telemetry module) for the entire string, so it cannot be run strictly for those measurements in combination with a different telemetry tool. On the other hand, if the EDTC is deployed as the telemetry cartridge, it is still quite possible to use alternate sensors such as the HNGS and GPIT to provide the GR and Az measurements without any conflict. By combining telemetry, basic gamma ray, and a vertical accelerometer, the EDTC provides the greatest telemetry bandwidth currently available in a shorter package than would otherwise be necessary to acquire the same basic measurements.
|ECGR:||Environmentally Corrected Gamma Ray|
|EHGR:||High Resolution Corrected Gamma Ray|
|HGR:||High Resolution Gamma Ray|
The EDTC-B is typically run at the top of the tool string. In most cases, the more accurate HNGS (spectral gamma ray tool) is run as well.
* ®trademark of Schlumberger