Methods and systems for detecting relative positions of downhole elements in downhole operations

摘要

Methods and systems to initiate downhole operations in a borehole include deploying a first structure at least partially in the borehole, moving a second structure at least partially along the first structure, wherein at least one of the first structure and the second structure is equipped with a sensor and the other of the first and second structure is equipped with a marker detectable by the sensor, detecting a critical event that is related to an interaction of the sensor and the marker, measuring a time-since-critical event, determining a time delay based on the time-since-critical event, transmitting, with a telemetry system, data from the earth's subsurface to the earth's surface indicating that the critical event has been detected, and initiating a downhole operation by using the determined time delay.