S Abdolkhalegh Masoumi - Master student of Petroleum Engineering, Sharif University of Technology
Mohsen Mahmoudi - Master student of Reservoir Engineering, Sahand University of Technology

Asphaltene and wax precipitation in production has been a basic issue in most of Iranian oil reservoirs. For scrutiny of asphaltene precipitating behaviour of heavy and light oils, and predicting the best preventing method or treatment of this issue, a research study was done. Asphaltene precipitation in crude oil cause the phenomenon such as decrease of porosity and permeability of hydrocarbon reservoirs, reduce the effectiveness of enhance oil recovery process, well column blocking, blocking or enhance of pressure drop of transmission pipeline of crude oil and extreme reduction of refineries efficiency and petrochemical process. The most expensive and time-consuming problem in production and processing cycle of crude oil from hydrocarbon reservoirs to petrochemical and refinement units, when access to the precipitations it was difficult. So it decreases oil production. By thermodynamic study of precipitating process and path that crude oil traverse at well column, could predict possibility of asphaltene precipitating at well column. In this article with thermodynamic study of crude oil of Ramshir field and analyse of production flow rate diagrams, Temperature and pressure extremely was the problem of asphaltene precipitation. Finally, the result was obtained that only with changing the size of choke could had a safety production and without risk of precipitating at well column. Actually, this method which is type of preventing of precipitating, opposite of conventional method of removal precipitation, is affordable and suitable for he necessities of health safety and environmental (HSE) because of lack of using BETX materials (Benzene, Ethylbenzene, Toluene and Xylene).

Asphaltene precipitation, choke size, heavy debris, deposition diagram (ADE), P-T diagram