PASSIVE RANGING TO A TARGET WELL USING A FIBER OPTIC RANGING ASSEMBLY

A well system includes a target wellbore that penetrates a subterranean formation and a relief wellbore drilled toward the target wellbore and a target intercept location where a fluid flows into the target wellbore from the subterranean formation. A bottom hole assembly is coupled to a drill string extended into the relief wellbore and includes a fiber optic ranging assembly having one or more fiber optic sensors positioned on a tubular member. The fiber optic sensors measure at least one of acoustic energy and thermal energy emitted by the fluid as it flows into the target wellbore. A computer system is communicably coupled to the one or more fiber optic sensors to process measurements of the fluid obtained by the one or more fiber optic sensors.