HPHT cased-hole CCL tool enhancement via DSP techniques for accurate depth control in wire-line well interventions

Down-hole oil and gas operators require a precise depth control method during well interventions. Wire-line technologies using conventional cased-hole casing collar locator (CCL) tools have been proven effective. However, extremely high pressure and high temperature (HPHT) environments make this a challenging task. This work describes a HPHT down-hole tool that use a conventional inductive CCL enhanced by a DSP based electronic module that performs in real-time DSP techniques such as digital filtering and cross-correlation, which permit to store and transmit analog or digital information to a data acquisition system located in the surface. The obtained laboratory tests results of the enhanced CCL down-hole tool, using changes in temperature from 75 °C – 185 °C, provide a firm basis for testing and evaluating the system in the field.