Modelling of crude oil fouling in heat exchangers has been traditionally limited to a description of the deposit as a thermal resistance. However, consideration of the local change in thickness and the evolution of the properties of the deposit due to ageing or changes in foulant composition is important to capture the thermal and hydraulic impact of fouling. A dynamic, distributed, first-principles model of the deposit is presented that considers it as a multicomponent varying-thickness solid undergoing multiple reactions. For the first time, full cleaning, partial cleaning, and fouling resumption after cleaning can be simulated in any order with a single deposit model. The new model, implemented within a single tube framework, is demonstrated in a case study where various cleaning actions are applied following a period of organic deposition. It is shown that complete mechanical cleaning and chemical cleaning of different extent, according to a condition-based efficacy, can be seamlessly simulated.