Abstract

Geothermal wells play a key role in the development, understanding and utilization of geothermal resources. Understanding the thermodynamic processes that occur within geothermal wells assists with their design, the interpretation of downhole measurements, and the optimization of reservoir management. However, the behavior of geothermal wells can be difficult or impossible to measure directly. Numerical simulation provides low-cost insight into the transient behavior of geothermal wells.

In this seminar, we will discuss the development of a transient geothermal wellbore simulator that can model complex flows of multi-phase fluid. We present example simulations that demonstrate rapid transient processes (e.g., opening and closing geothermal wells), interzonal flow, counter-flow processes, discharge stimulation methods such as air compression and gas lifts, and wells with water levels below the wellhead. Recent investigations of methods for coupling this wellbore simulator with a geothermal reservoir simulator will also be discussed.

Coupled simulation of production from a liquid-dominated geothermal reservoir (250 °C at 100 bara) with 1% CO₂. A loose-lagged (explicit) coupling scheme
was used. The wellbore conditions are shown in black and green (dashed), and reservoir conditions at varying distances from the well are shown in color (full).

Bio

Ryan Tonkin (he/him) is a research fellow in the Department of Engineering Science and Biomedical Engineering at the University of Auckland. His role includes researching geothermal engineering, lecturing for the Faculty of Engineering, international capacity building, and geothermal consulting. Ryan has a PhD in Engineering Science, specializing in geothermal engineering, and a BE (Hon) in Engineering Science. 

Ryan’s overarching research goal is to improve the numerical modelling tools and methodologies used in the geothermal industry. Through his research, he has developed a transient wellbore simulator capable of modelling complex flows of geothermal fluids. Ryan’s current research interests include coupled wellbore-reservoir simulation, modelling super-critical flow, and CO₂ sequestration in geothermal reservoirs.

Research and Related Papers

[1] Tonkin, R., O’Sullivan, M., & O’Sullivan, J. (2021). A review of mathematical models for geothermal wellbore simulation. Geothermics, 97. https://doi.org/10.1016/j.geothermics.2021.102255

[2] Tonkin, R., O’Sullivan, J., Gravatt, M., & O’Sullivan, M. (2023). A transient geothermal wellbore simulator. Geothermics, 110. https://doi.org/10.1016/j.geothermics.2023.102653

[3] Tonkin, R., O’Sullivan, J., Gravatt, M., & O’Sullivan, M. (2023). Simulation of complex transient flows in geothermal wells. Geothermics, 108. https://doi.org/10.1016/j.geothermics.2022.102631

[4] Tonkin, R., Nugraha, R., Renaud, T., Gravatt, M., O’Sullivan, J., & O’Sullivan, M. (2024). A Loose-Lagged Coupling Procedure for Reservoir-Wellbore Simulation with Non-Condensable Gases. Proceedings 10th African Rift Geothermal Conference, 23–25.