Simulation of chemical enhanced oil recovery using huff-and-puff technique

Abstract

Exploiting unconventional petroleum is needed in this era and thus more enhancement has been introduced including chemical additives to manipulate the fluid flow characteristics, although most of the examinations were at laboratory scale the scaling-up to reservoir applicability is in question and needs further studies. The current study examined laboratory-derived relative permeability (k_r) and capillary pressure (p_c) at various wettability and the oil-water interfacial tension on reservoir-scale numerical simulation, utilizing a huff-n-puff technique, aiming to emphasize suitability and limitations of those k_r toward field implementation of tight reservoir. Simulations of primary oil production agreed with those of experiment, confirming the model validity. Following secondary of 6-cycle huff-n-puff process also yielded the same trend of oil production performances – dictated by the k_r as primary fluid flow characteristics. Four influencing factors of reservoir properties and producing design were further investigated for their sensitivity to the oil production performances. At various k_r investigated in the current study, porosity factor was distinctively found a limited suitability to low values if high oil production is anticipated, owing to the nature of tight reservoir pe se. On the contrary, reservoir permeability likely not has much influence since more oil was produced with higher value of permeability, albeit no sensitivity at much higher values. The shut-in period for the huff-n-puff process was not sensitive to the oil production of all fluids. Interestingly, the critical water saturation where water phase starts to flow (k_rw> 0) has a strong influence on the oil production in two approaches, either demoting the oil production or having no contribution, depending on the k_rw-S_w character. The results of the study offer guidelines for utilizing the data in designing field applications. Although the data were obtained from laboratory testing, it is essential to consider relative permeability in the design of improved oil recovery methods for field-scale applications. This consideration is crucial because each relative permeability has specific suitability and limitations that must be accounted for to ensure effective implementation in the field.