Composites containing a hydrocarbon-soluble well treatment agent may be supplied to a well using a porous particulate. Such well treatment agents may for example inhibit the formation of paraffins, salts, gas hydrates, asphaltenes and/or other deleterious processes such as emulsification (both water-in-oil and oil-in-water). Further, other well treatment agents include foaming agents, oxygen scavengers, biocides and surfactants as well as other agents wherein slow release into the production well is desired.