High-Temperature Solvent Injection for Heavy-Oil Recovery From Oil Sands: Determination of Optimal Application Conditions Through Genetic Algorithm

Abstract

Summary Our recent experimental studies on superheated solvent injection for heavy-oil recovery showed that when a solvent is injected into the reservoir, the process is highly sensitive to pressure and temperature. The effects of these parameters on the recovery factor (RF) are accentuated when the operating conditions are closer to the saturation curve of the solvent injected. This paper investigates this process and formulates the optimal field-scale application conditions that yield the maximum profit, as a continuation of previous work. To achieve this, a hypothetical field-scale numerical model was constructed, and the key parameters identified through the aforementioned sensitivity analysis were incorporated. Then, the injection process was simulated for a two-horizontal injection/production pattern. An optimization study was performed to identify the relative contributions of the effective parameters (pressure, temperature, and injection rate) and to propose an optimal application scheme with a genetic algorithm (GA). The critical pressure and temperature yielding maximum production and highest profit considering solvent retrieval were defined for different injection rates and application scenarios. Our results indicate that, at the end of the hot solvent-injection process, an important volume of solvent is left in the reservoir, and its volume depends on the injection–production scheme selected. Nevertheless, if the project is performed under appropriately selected operational parameters (obtained through the optimization processes) and followed by the proper process to retrieve the solvent from the reservoir (low-temperature steam or hot-water applications), it can make the hot solvent-injection process profitable.

Solvent temperature: An injection condition to bring multiple changes in the heavy oil exploitation process based on the cyclic solvent injection (CSI) recovery method

“…Besides, the less energy requirement of the hot solvent‐based method means a relatively lower cost of surface construction compared with the SAGD method . Hot solvent‐based recovery methods can be profitable if operational parameters of the project are optimized and the solvent retrieval process is appropriate according to a numerical study based on a field‐scale reservoir model …”

“…17 Hot solvent-based recovery methods can be profitable if operational parameters of the project are optimized and the solvent retrieval process is appropriate according to a numerical study based on a field-scale reservoir model. 18 The key driving mechanism of the hot solvent-based method is to maintain the solvent temperature higher than the reservoir temperature so that sensible heat is transferred onto the solvent-oil interface. The solvent condenses and spreads at the interface and transfers latent heat into the vapor chamber where diluted oil is warmed and then deasphaltened.…”

Hot Solvent-Assisted Gravity Drainage in Naturally Fractured Heavy Oil Reservoirs: A New Model and Approach to Determine Optimal Solvent Injection Temperature

“…Recently, thermal solvent methods such as solvent-assisted SAGD (SA-SAGD) have been applied to real reservoirs and showed promising results. , Semianalytical models have also been developed to model this process . Leyva-Gomez and Babadagli in 2017 numerically modeled heavy oil recovery from oil sands with a high-temperature solvent, and they showed that the process is highly sensitive to temperature and pressure . Their numerical studies also showed that a considerable amount of oil and solvent are left in the reservoir and that other production processes should be considered to recover the residual hydrocarbons to increase efficiency and profit.…”