An additive package for removing oil from solid material recovered from a well bore, e.g., drill cuttings and produced sand, is provided. The additive package includes an aqueous acidic solution containing a polymer substituted with an amino group, a halogenating agent, and optionally one or more surfactants. The polymer substituted with an amino group is preferably chitosan, and the halogenating agent is preferably a sodium hypochlorite solution. A product of the reaction of the polymer and the halogenating agent, in conjunction with the surfactant when present, is capable of causing the separation of at least a portion of the oil from the solid material.