Experimental Evaluation of Dimethyl Ether as a Performance Enhancing Additive for Bitumen Recovery with Steam Assisted Gravity Drainage (SAGD), Using a Three-Dimensional Semi-Scaled Model

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Abstract Canada has the second largest heavy oil and bitumen resource in the world which is mostly located in Alberta and Saskatchewan. Different approaches have been implemented to access heavy oil and bitumen resources. The main goal of such methods is to find an economically acceptable solution to decrease bitumen viscosity and increase its mobility. Steam assisted gravity drainage (SAGD) and cyclic steam stimulation (CSS) have been the two commercially viable thermal recovery methods. Both methods’ large water consumption and high energy demand encouraged the researchers to find more efficient recovery processes with less GHG emission. To achieve this goal, solvent assisted, and solvent-based heavy oil recovery processes have been investigated in both laboratory experiments and field tests. Up until recently, all proposed solvents were non-polar single or multi-component hydrocarbons. Recently, a limited amount of research proposed DME as a potential solvent to be used in EOR methods. These studies are focused on numerical studies or PVT analysis. Only a very few studies focused on linear or two-dimensional physical experiments. DME can be synthesized by direct and indirect methods and is relatively inexpensive and accessible in comparison to most studied single component solvents. DME has not been conventionally used for enhanced oil recovery (EOR) in the past but due to its polarity and unique ability to mix and partition in both aqueous and oleic phase, DME can be an alternative to the conventional non-polar solvent used and investigated in SA-SAGD operations. To the best of our knowledge this study is the only experimental study of its kind on the DME assisted SAGD operation using a large semi-scaled three-dimensional physical model. The result of the study provided unique insight on DME’s effect on oil recovery and vapor chamber development. The goal of this research is to investigate oil recovery, and steam oil ratio (SOR) improvement using dimethyl ether (DME), as a potential additive to steam in SA-SAGD methods by means of experimental and numerical investigation using a large semi scaled three-dimensional physical sand-pack. For the experimental part of the work, an improved three-dimensional semi-scaled physical model was designed and built to evaluate DME-steam performance in SA-SAGD process and accurately measure pressure, temperature and fluid flow rates. For the purpose of this study, a series of seven SAGD and SA-SAGD experiments were conducted at operating conditions similar to the Long Lake SAGD project, with actual reservoir and bitumen properties. Upon completion of each experiment, extensive emulsion and sand analysis were conducted to evaluate the performance of each SA-SAGD in comparison to SAGD. The results from these analyses demonstrate that DME-steam co-injection significantly increases the oil recovery factor, decreases SOR and reduces the overall production time. To optimize the experiment, a series of three tests were conducted to study the DME concentration effect on the recovery performance. In the next stage, the best performance of DME-steam co-injection concentration’s study was compared with same concentration of similar non-polar hydrocarbons (propane and butane). The result proved that DME has the best performance in comparison to steam and steam-propane-butane co-injection. In the last chapter of this research the results obtained from physical experiment were adopted to a simulation model. The numerical model was tuned by history matching to obtain a reliable, experimental based model that can be used to study the effect of other parameters that can’t be investigated in the lab studies.
Dimethyl ether, Heavy oil recovery, Bitumen recovery, SA-SAGD, Solvent assisted SAGD, Experimental Study, Physical Model
Amini, Z. (2023). Experimental evaluation of dimethyl ether as a performance enhancing additive for bitumen recovery with steam assisted gravity drainage (SAGD), using a three-dimensional semi-scaled model (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.