Volume 38: Energy Transitions toward Carbon Neutrality: Part I

A dynamic control technique for improving oil recovery during the in-situ combustion Ziqi Sun, Renbao Zhao, Tiantian Wang, Xin Li, Jintang He

Abstract

In-situ combustion (ISC) has excellent potential in the development of unconventional resources such as heavy oil and tar sand. However, a uniform extension process for the combustion chamber is crucial for maintaining efficient and economical oil recovery during the ISC, which should be given more attention. In this work, a dynamic control technique that is achieved by the regular implementation of production well intermittent shutdown (PWIS) with the aim to improve the uneven extension of combustion chamber is proposed. A 3D combustion model with a volume of 214962 cm3 is utilized in the ISC experiments to study the application effect of dynamic control technique. The variation of effluent gas compositions, spatial distribution of coke zone, swept area of combustion chamber, burning stability, and pressure difference are studied and analyzed. The results show that the PWIS method is able to force the combustion chamber to extend toward the low and medium permeability regions with little influence on the burning state. The volumetric sweep coefficient of combustion chamber in the low and medium permeability zones was improved and the combustion status varied slightly during the PWIS implementation. Final 3D morphology of coke zone is vividly described according to the real size, and its spatial volumes in the low and medium permeability zones enlarge noticeably after the PWIS implementation. Additionally, the cumulative oil production increased from 5586.5 g to 10426 g, and the final oil recovery ratio enhanced from 23.3% to 40.8% after implementing the dynamic control technique. This work provides a practical approach to improving the volumetric sweep coefficient of combustion chamber, which is of great significance in maintaining a higher oil production efficiency during the ISC field application.

Keywords Heavy oil, In-situ combustion, Dynamic control technique, Combustion stability, Coke zone