Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
Analysis of water alternating gas (WAG) in an immiscible reservoir
Submission Author:
Vinicius Rafael de Freitas , DF , Brazil
Co-Authors:
Vinicius Rafael de Freitas, Eugenio Fortaleza, José Oniram de Aquino Limaverde Filho, Fernando Munerato
Presenter: Vinicius Rafael de Freitas
doi://10.26678/ABCM.COBEM2021.COB2021-2104
Abstract
Understand the flow dynamics in the reservoir is extremely important to maximize the net present value (NPV) of oil exploration in any reservoir. Water or gas breakthroughs are the main issue in reservoirs because, after this moment, water or gas production increases progressively reducing the oil production and, therefore, the NPV of the exploration. To mitigate these issues, the water alternating gas injection (WAG) schedule emerged as an interesting solution as it provides the total oil production eventually higher than in the other injection schedule. However, the WAG NPV can be lower when compared to early oil production since the oil production is spaced in time. This study aims to analyze the influence of alternating WAG in an immiscible reservoir, which is, where there is no miscibility of the gas in the oil. In this way, only the interaction due to the differences of viscosity and density between the three fluids (oil, water, and gas) are analyzed under this hypothesis. The findings of this study propose a semi-analytical technique for determining the optimum amount of gas using the SPE5 as the reference scenario with the necessary modifications for gas immiscibility. Numerical simulations were carried out using Open Porous Media Flow (OPM Flow) open-source software to compare the proposed waterflooding followed by gas injection (WFG) with continuous waterflooding (CW) and different WAG ratios. The WFG case, proposed in this paper, shows a slightly higher NPV than WAG and CW in the studied cases, representing the best injection scenario. This is because the initial water injection shows better sweeping efficiency and rapid oil production and, close to the end of the production time, the gas injection helps to maintain the pressure in the reservoir as well as to balance the density of the injected fluids at a considerably lower cost, then increasing the NPV.
Keywords
Water Alternating Gas (WAG), Enhanced Oil Recovery (EOR), Water injection, gas injection, OPM Flow, NPV, oil production
