Comparing WAG injection with continuous injection of gas and water in separate wells with numerical simulation of a carbonate reservoir

Author(s)

Josias Pereira de Oliveira Junior

• Document type: Master's Dissertation
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Engenharia Mecânica
• Defense date: 2024-03-14

Examining board members

Denis José Schiozer; João Carlos von Hohendorff Filho; William Godoy de Azevedo Lopes da Silva

• Advisor: Denis José Schiozer

Abstract

Gas alternating water (WAG) injection is an enhanced oil recovery (EOR) method that can be applied in some Brazilian offshore fields, particularly in the pre-salt region, to prevent gas venting due to high concentration of gas (rich in CO2) dissolved in the oil produced. This method offers effective technical-environmental policies by providing ecologically safe disposal of the gas and flexible gas management strategies, and results in increased residual oil recovery due to the combination of optimal gas displacement and water sweeping efficiencies. However, WAG injection operations are complex and expensive, and some studies suggest that longer cycles may yield better results than shorter ones; there are also those who highlight the possibility of gravitational segregation, which reduces the efficiency of the method. As an alternative development plan, continuous injection of gas and water (CIWG) in separate wells is also environmentally friendly, less complex and less expensive. The purpose of this study is to compare WAG injection and continuous injection of gas and water in separate wells by developing and managing a light-oil carbonate reservoir subject to full gas recycling through computational tools, economic and risk analysis, and application in the UNISIM-II model. The results show that the development plan by continuous injection of gas and water in separate wells is competitive when compared to WAG injection, since it achieves similar indicators, especially when analyzed in the reference model. On the other hand, WAG injection presents a little more flexibility in terms of the need to pre-define the recovery method before the design variables. This conclusion allows greater certainty in the decision regarding the simplest development plan for the case study and possibly for the Brazilian pre-salt fields (AU)

• FAPESP's process: 20/13938-0 - Comparison of WAG-CO2 injection with other injection alternatives for a light-oil fractured carbonate reservoir
• Grantee: Josias Pereira de Oliveira Junior
• Support Opportunities: Scholarships in Brazil - Master