Innovative In Situ Combustion Technique: Moving Air Injection from Toe to Heel in a Single Well for Enhanced Oil Recovery
Creators: Antolinez Jimenez, Juan David
Publisher: name: University of Alberta Library
Year: 2024

<p>Enhanced oil recovery (EOR) methods play a pivotal role in the petroleum industry, enabling the extraction of hydrocarbons that would otherwise remain trapped in reservoirs. Among these methods, thermally induced approaches have garnered significant attention, with two prominent techniques being Steam Assisted Gravity Drainage (SAGD) and In-Situ Combustion (ISC). ISC, in particular, has gained popularity due to its potential environmental benefits and economic advantages.<br>
In the ISC process, an oxidizing agent is injected into heavy bitumen formations. This injection initiates a controlled combustion process within the reservoir, leading to an increase in temperature. The temperature rise reduces the viscosity of the bitumen, making it easier to flow through the reservoir. The continuous air injection ensures the mobilization of less viscous hydrocarbons toward the production well. <br>
Despite the promise of ISC, achieving optimal operational results in the field has proven to be a complex endeavour. Various challenges have led to suboptimal recovery rates, including incomplete combustion, uneven temperature distribution, and difficulties controlling the combustion front. In order to tackle these difficulties and maximize the benefits of ISC, it is crucial to modify and fine-tune the approach to suit the particular conditions of the reservoir.<br>
Numerous analytical and numerical simulation models have been developed and published to understand and optimize ISC processes. However, with the advancement of technology and increasing knowledge, new methods within the ISC framework need to be explored. This thesis investigates different approaches to ISC, primarily concentrating on the &quot;Toe-to-Heel Air Injection&quot; (THAI) method.</p>

<p>The research begins by verifying a pre-existing THAI lab-scale model, followed by kinetic upscaling to ensure accuracy and applicability to real-world reservoir scenarios. It then explores adjustments, including boundary expansion for the field-scale model, to study its implications on oil recovery, fluid dynamics, and combustion front control. Additionally, the study examines the extension of injector wells, the modification of air injection rates, and introduces steam injection as a preheating method.<br>
To achieve the main objective of this research, the study devises an innovative strategy that employs a moving air injection interval within a single well, which simultaneously functions as both producer and injector. This approach is implemented within an expanded boundary field-scale model, aiming to enhance the control and efficiency of ISC processes by selectively injecting air into areas that require oxygen to sustain process stability.<br>
Results indicate that progressively moving the air injection interval every 18 months in a single horizontal well, improved oil recovery by 8% compared to the conventional THAI method. Additionally, the proposed configuration showed earlier economically viable oil production. Parameters such as oil saturation, flue gas composition, temperature, and coke availability were also observed to be more efficient and improved in this proposed method.<br>
Findings indicate that the novel technique has the potential to surpass the current state of the art in both economic performance and environmental sustainability. However, further research and numerical simulations are necessary, as the developed model exhibited issues with coke combustion and the in-situ combustion front&#39;s progression along the horizontal well. Modifying reaction kinetics and incorporating a sensitivity analysis for different time intervals of air injection progression along the well, along with the potential co-injection of water, could enhance the model&#39;s predictability and overall performance.</p>