A modified scaling equation based on properties of bottom hole live oil for asphaltene precipitation estimation under pressure depletion and gas injection conditions

• Developing a modified scaling equation for asphaltene precipitation estimation.
• Application of the proposed model under pressure depletion and gas injection conditions.
• Application of PC-SAFT EOS for asphaltene precipitation estimation of bottom hole live oil.
• Testing and validation of the proposed model for several bottom hole live oil samples.

The process of asphaltene precipitation has a substantial effect on oil flow during primary oil production and enhanced oil recovery processes in the petroleum industry. In this work, a modified scaling model based on the PVT properties of bottom hole live oil including resin to asphaltene ratio, onset pressure, bubble point pressure, reservoir temperature, asphaltene content of bottom hole live oil and gas to oil ratio has been proposed to account for asphaltene precipitation under pressure depletion/gas injection conditions and the proposed model was verified using experimental data obtained in this work and also with those reported in the literature. In the proposed scaling model the resin to asphaltene ratio in bottom hole live oil was included as an additional parameter. In order to compare the performance of the proposed scaling model, the asphaltene precipitation experimental data at different pressure were correlated using PC-SAFT, Solid, Flory–Huggins and the proposed models. The results show that the proposed model correlates more accurately the asphaltene precipitation experimental data of bottom hole live oil in comparison to other above mentioned models. Sensitivity analysis shows that the modified scaling model is highly sensitive to the new term of resin to asphaltene ratio and also the gas–oil ratio of bottom hole live oil. Also, a series of experiments was carried to determine the asphaltene precipitation of bottom hole live oil during pressure depletion with Iranian bottom hole live oil samples which is close to reservoir conditions using high pressure–high temperature equilibrium cell.