A novel approach to oil production optimization considering asphaltene precipitation: a case study on one of the Iranian south oil wells

Abstract

Nowadays, the significance of hydrocarbon reservoirs as the main supply of world energy is being increased more than before. Hence, a safe and continuous production process of oil and gas wells is one of the most important criteria in the oil industry. In this regard, some issues such as deposition of heavy organic materials, especially asphaltene in the tubing, and surface pipelines can cause considerable damages to the production unit. Asphaltene precipitation occurs due to change in thermodynamic conditions, such as the composition of crude oil, temperature and pressure, which can disturb the thermodynamic equilibrium and result in asphaltene deposition. These particles would result in obstruction of the tubing and surface pipelines. In this study, the distribution profile of asphaltene precipitation in a well of one of the Iranian south oil reservoirs has been developed using an integrated thermodynamic modeling. The impacts of hydrodynamic parameters on asphaltene precipitation have also been investigated, and some sensitivity analyses have been made on them in order to optimize well completion and production conditions. Optimization operation can obviate shortcomings associated with the asphaltene deposition, and as a result, it would decrease costs and subsequently lead to more benefit. If there is an optimized integrated model for tubing and surface facilities, it can not only be used for investigating the fluid flow behavior but also it can prolong the lifetime of the entire production unit. In this case study, one of the most important intelligent optimization algorithms (i.e., the particle swarm optimization algorithm) has been used to solve the problem. The results showed that cumulative oil production and thickness of asphaltene deposition under optimum conditions are 5.6 million barrels and 0.33 inches, respectively. According to the outcomes of optimization operation, tubing size and surface choke bean size are 4.25 and 47.9 inches, respectively. In addition, the oil production rate has been determined as 5972 STB/day. At these conditions, well head pressure and temperature should be considered as 1336 psi and 160 °F, respectively.