US Patent 8627902 Estimating drill cutting origination depth using marking agents

A method for estimating a depth from which cuttings have been recovered from a well may include varying a parameter of one or more marking agents added into a drilling fluid circulated into the well and recovering the cuttings from the well. The depth may be estimated by estimating a value associated with the marking agent that marks the cuttings. A system for estimating a depth from which cuttings have been recovered from a well includes at least one marking agent configured to mark the cuttings and a marking agent dispensing device configured to add the at least one marking agent into a drilling fluid circulated into the well. The marking agent dispensing device may be further configured to vary a parameter of the at least one marking agent.