Numerical Simulation Studies on Development of an Offshore Heavy Oil Field by Early-Stage Chemical Flooding

Abstract Heavy oil resources, as a non-renewable energy resource, often requires extra enhanced oil recovery techniques such as solvent-based processes. Many kinds of solvents including pure and mixed solvent have been tested in the solvent-based applications. Compared with pure solvent, the solvent mixture has an advantage of relatively higher dew point pressure while maintaining desirable solubility in heavy oil. The characterization of foamy oil behavior in pure solvent system is different from the solvent mixture system despite their similarities. Thus, an additional numerical simulation study is necessary for solvent mixture system. This work conducted simulation studies to investigate foamy oil behavior in a heavy oil-mixture solvent (C1+C3) system from pressure depletion tests. A better understanding of foamy oil characterization and mechanism in a heavy oil-mixture solvent system is obtained. A reliable non-equilibrium model is developed to perform simulation studies. Since previous experiments suggest the behavior of foamy oil in the solvent mixture system share similarities with the heavy oil-methane system, this investigation first conducted simulation study with consideration of two reactions in the model and achieved good agreements between the simulated calculation results and experimentally measurement. Then four reactions are considered in the model for simulation study and obtained better history match results. The simulation results suggest methane has more impact on the foamy oil behaviors than propane in the heavy oil-mixture solvent system. This work also discussed effect of model parameters involved in the history matching process and conducted sensitivity analysis.

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The Supercritical Multithermal Fluid Flooding Investigation: Experiments and Numerical Simulation for Deep Offshore Heavy Oil Reservoirs

Geofluids ◽

10.1155/2021/5589543 ◽

2021 ◽

Vol 2021 ◽

pp. 1-17

Author(s):

Xianhong Tan ◽

Wei Zheng ◽

Taichao Wang ◽

Guojin Zhu ◽

Xiaofei Sun ◽

...

Keyword(s):

Numerical Simulation ◽

Numerical Model ◽

Oil Recovery ◽

Heavy Oil ◽

Oil Production ◽

Oil Field ◽

Oil Reservoirs ◽

Oil Viscosity ◽

Steam Flooding ◽

Heavy Oil Reservoirs

The supercritical multithermal fluids (SCMTF) were developed for deep offshore heavy oil reservoirs. However, its EOR mechanisms are still unclear, and its numerical simulation method is deficient. In this study, a series of sandpack flooding experiments were first performed to investigate the viability of SCMTF flooding. Then, a novel numerical model for SCMTF flooding was developed based on the experimental results to characterize the flooding processes and to study the effects of injection parameters on oil recovery on a lab scale. Finally, the performance of SCMTF flooding in a practical deep offshore oil field was evaluated through simulation. The experiment results show that the SCMTF flooding gave the highest oil recovery of 80.89%, which was 29.60% higher than that of the steam flooding and 11.09% higher than that of SCW flooding. The history matching process illustrated that the average errors of 3.24% in oil recovery and of 4.33% in pressure difference confirm that the developed numerical model can precisely simulate the dynamic of SCMTF flooding. Increases in temperature, pressure, and the mole ratio of scN2 and scCO2 mixture to SCW benefit the heavy oil production. However, too much increase in temperature resulted in formation damage. In addition, an excess of scN2 and scCO2 contributed to an early SCMTF breakthrough. The field-scale simulation indicated that compared to steam flooding, the SCMTF flooding increased cumulative oil production by 27122 m3 due to higher reservoir temperature, expanded heating area, and lower oil viscosity, suggesting that the SCMTF flooding is feasible in enhancing offshore heavy oil recovery.

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