TITLE:
Modeling and Simulation of Two-Staged Separation Process for an Onshore Early Production Facility
AUTHORS:
Ojo Ademola, J. G. Akpa, K. K. Dagde
KEYWORDS:
Modeling and Simulation, 2-Phase Process Vessel, 3-Phase Process Vessel, Effective Length, Seam-Seam Length, Slenderness Ratio
JOURNAL NAME:
Advances in Chemical Engineering and Science,
Vol.9 No.2,
February
1,
2019
ABSTRACT: Early Production Facilities are makeshift process deployment that ensures that marginal oilfield operators make revenues from their new discoveries with little cash outlay and limited investment risks. Authors have in past simulated a gas process facility using Hysys without particularly developing mathematical models for the key equipment. There also has been modeling of phase separation dynamics and process simulation but still without models for equipment. We
basically developed models for the critical process equipment for early production, sized the equipment with data from a marginal field in the Niger delta region
of Nigeria and then ran a dynamic simulation with the sized equipment. The important elements of the deployment are two-phase process vessel, 3-phase process vessel; knock-out drum, produced water treatment unit. Mathematical models were developed and adapted with Mathlab for the equipment sizing whilst ASPEN
PLUS was used for simulating the process. Process data retrieved from a marginal field in Nigeria was used as input to quantify the equipment models.
Sized equipment was deployed in Hysys V8.8 for a steady and dynamic state. The system simulation was comprised of a two-phase process vessel followed by a 3-phase process vessel [1]. The unwanted gas was sent to knock out drum for removal of entrained
liquid droplets before flaring (this was because the volume of gas processed is deemed uneconomical) and produced water to treatment unit for removing droplets of oil before disposal. Gas, oil and water were fed into the first stage separator (2-phase) at 132918.34 Ibmole/hr, 7622.95 Ibmole/hr and 1082.74 Ibmole/hr respectively. The operating pressures of the first and second
vessels were at 850 psi and 150 psi respectively. The 2-phase vessel flashed off 96.7% of the gas and increased the liquid recovery by 3.3%. At the end of the second stage separation, oil yield increased by 270 Ibmole/hr, the gas increased by 110.15 Ibmole/hr whilst water reduced by 379 Ibmole/hr. This result confirmed that the vessels were sized to optimize recovery of hydrocarbons entrained in the various phases into the most required oil phase.