Bitumen Extraction by Expanding Solvent-Steam Assisted Gravity Drainage (ES-SAGD) with Asphaltene Solvents and Non-Solvents

Abstract

Steam Assisted Gravity Drainage (SAGD) is a proven enhanced oil recovery technique for oil sand extraction. However, the environmental and economic challenges associated with steam generation limit the application of this technology. To address these issues, we investigated the effectiveness of Expanding Solvent SAGD (ES-SAGD) over base SAGD on a bitumen sample (8.8 °API). Experimental studies are conducted with a two-dimensional physical model. Different strategies for solvent injection are tested (co-injection and cyclic injection) to examine the deposition of polar fractions of the bitumen on porous media or producing polar fractions with non-polar ones. To investigate the level of oil upgrading while toluene is used as asphaltene soluble solvent, n-hexane was selected as asphaltene insoluble. Steam chamber development is monitored with temperature profiles from 47 separate positions. Steam oil ratios, solvent oil ratios, and the level of oil upgrading in terms of viscosity reduction and API gravity improvement are evaluated together. Environmental footprints of SAGD with ES-SAGD are discussed in terms of solvent toxicity, total produced greenhouse gases, and asphaltene precipitation with FTIR analysis on postmortem samples. Furthermore, the energy intensity of the processes is assessed by considering steam generation and solvent costs. This study reveals that co-injection of hydrocarbon solvents with steam enhances the steam chamber development with higher oil production rate. Moreover, ES-SAGD results in recovery of more upgraded oil and has less environment impact. We observe that the selection of the solvent type and injection strategy are the most crucial parameters for the design of hybrid SAGD process and solvent cost can be minimized by using the recycled solvent for continuous injection of solvents. High energy consumption for steam generation during SAGD process can be reduced by co-injection with steam proper solvent type at proper injection strategy. This experimental study reveals that ES-SAGD process has environmental and economic benefits over base SAGD. However, some solvents can cause undesirable effects due to the asphaltene destabilization and precipitation in production or transportation lines. Results of this work can be used to better address solvent interaction with polar components during SAGD.

The Role of Resins, Asphaltenes, and Water in Water–Oil Emulsion Breaking with Microwave Heating

“…23 Sand and clay mixture was used to prepare the reservoir rock. The clay has 90 weight % kaolinite and 10 weight % illite with 2.3 µm particle size.…”

“…Thus, the detailed description of the experimental procedure for SAGD and ES-SAGD can be found in the previously published technical papers. 23,33 Emulsion characterization: The produced oil samples originated from SAGD and ES-SAGD experiments were visualized with the Meiji Techno Japan-Microscope (100X magnification) and 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 7 ProgRes CT5-Camera. Then, the amounts of water, clays, and SARA (saturates, aromatics, resins, and asphaltenes) fractions in the produced oil samples were determined.…”

“…Several trial experimental studies for troubleshooting technical issues with the setup has been conducted before starting the main experiments 23. …”

The role of condensing and non-condensing solvents in SA-SAGD

“…In this regard, the use of light solvents to reduce the viscosity of bitumen through dilution, known as vapor extraction (VAPEX), has been proposed [7][8][9][10]. Furthermore, a hybrid method of co-injecting a minor volume of solvents (5-15 vol%) with steam has been implemented showing promising results in increasing bitumen recovery and reducing energy costs [11][12][13][14][15][16][17][18]. This process is known as solvent-aided steam assisted gravity drainage (SA-SAGD), or expanding solvent steam assisted gravity drainage (ES-SAGD), its name derived from the expansion characteristic of solvents over the steam.…”

The Role of Asphaltenes in Emulsion Formation for Steam Assisted Gravity Drainage (SAGD) and Expanding Solvent - SAGD (ES-SAGD)

“…Even though, SAGD presents promising oil recovery results from bitumen reservoirs, the environmental and economic drawbacks of steam generation make the alternatives of SAGD more attractive. Expanding Solvent-SAGD is one of the most pronounced alternative SAGD technologies which reduces steam generation cost, greenhouse gas (GHG) emissions due to steam generation, and increase the oil recovery (Nasr, et al, 1991). However, the adverse effects of ES-SAGD have not been studied fully in terms of produced water treatment and oil processing.…”