Water content of light n‐alkanes: New measurements and cubic‐plus‐association equation of state modeling

Light hydrocarbon gases such as methane, ethane, propane, and butane or other so called gaseous solvents have been suggested as steam additives to improve bitumen recovery and energy efficiency. The water content of these gases is one of the key requirements in the simulation and design of solvent‐aided thermal heavy oil recovery processes. In this work, we present new experimental data for the water content of these gases at high temperatures (up to 493.15 K) and moderate pressures (P < 6 MPa). The experimental data was regenerated using the cubic‐plus‐association equation of state. The Soave–Redlich–Kwong equation of state is used to treat the physical interactions. The association interactions are captured using Wertheim's first‐order thermodynamic perturbation theory. A set of binary interaction parameters is proposed to calculate the water content of methane, ethane, propane, and n‐butane at the operating conditions of the thermal heavy oil and bitumen recovery processes. © 2016 American Institute of Chemical Engineers AIChE J, 63: 1384–1389, 2017     

Bubble/droplet formation and mass transfer during gas–liquid–liquid segmented flow with soluble gas in a microchannel

Microchannels have great potential in intensification of gas–liquid–liquid reactions involving reacting gases, such as hydrogenation. This work uses CO₂–octane–water system to model the hydrodynamics and mass transfer of such systems in a microchannel with double T‐junctions. Segmented flows are generated with three inlet sequences and the size laws of dispersed phases are obtained. Three generation mechanisms of dispersed gas bubbles/water droplets are identified: squeezing by the oil phase, cutting by the droplet/bubble, cutting by the water–oil/gas–oil interface. Based on the gas dissolution rate, the mass transfer coefficients are calculated. It is found that water droplet can significantly enhance the transfer of CO₂ into the oil phase initially. When bubble‐droplet cluster are formed downstream the microchannel, droplet will retard the mass transfer. Other characteristics such as phase hold‐up, bubble velocity and bubble dissolution rate are also discussed. The information is beneficial for microreactor design when applying three‐phase reactions. © 2016 American Institute of Chemical Engineers AIChE J, 63: 1727–1739, 2017     

Multiphase flow at the edge of a steam chamber

The use of steam‐assisted gravity drainage (SAGD) to recover bitumen from Athabasca deposits in Alberta has been growing. Butler [Butler, J. Can. Pet. Tech. 1985;24:42–51] derived a simple theory to calculate the production rate of oil during SAGD in an ideal reservoir. This simple and useful theory made several assumptions about the properties of the reservoir and operating conditions of the process. The theory also assumed that the highest mobility oil is at the edge of the steam chamber and that the oil phase velocity is highest at the chamber edge and reduces with distance into the oil sand. This research examines flow conditions at the edge of the steam chamber. Specifically, a new theory is derived that takes into account the impact of oil saturation and relative permeability on the oil mobility profile at the edge of a steam chamber. It is shown that the flow behaviour at the edge of a steam chamber is more complex and is not fully represented by Butler's theory. Contrary to Butler's theory, the oil mobility has its maximum some distance away from the edge of the steam chamber. The results reveal that the higher the thermal diffusivity of the oil sand, the deeper the location where the oil phase velocity is maximum. The developed model has been validated against published experimental and field data.     

Steam fingering at the edge of a steam chamber in a heavy oil reservoir

The steam‐assisted gravity drainage (SAGD) process is one of the key in situ recovery processes being used today to recover heavy oil and bitumen. In this process, steam injected through a horizontal well, flows convectively towards the outer edges of a depletion chamber. At the edges of the depletion chamber, the steam releases its latent heat to the cool oil sand and raises its temperature. The heated oil is mobile and flows under the action of gravity to a horizontal production well located several metres below the injection well. It remains unclear what is the exact mechanism of chamber growth. Some have suggested that in addition to heat conduction, it is by convective steam flow in the form of pointed fingers at the edges of the chamber which penetrate the oil sand. In theory published by Butler [Butler, J. Can. Petroleum Technol. 1987;26(3):70–75], it was determined that the fingers can be as long as 6 m for Athabasca bitumen reservoirs. In this research, a new theory is derived and provides predictions of the rise rate which compare better to estimates derived from field thermocouple data and physical model experimental observations than values obtained from Butler's theory. The results suggest that in the absence of mobile water, heat conduction rather than steam fingers at the chamber edge is the dominant heat transfer mechanism.     

Rapid Salt‐Assisted Microwave Demulsification of Oil‐Rich Emulsion Obtained by Aqueous Enzymatic Extraction of Peanut Seeds

Aqueous enzymatic extraction (AEE) is an environmentally friendly edible‐oil‐extraction process that can also provide edible protein. However, the AEE process may form a stable emulsion in most cases, which seriously limits the large‐scale industry applications for producing vegetable oils. In this study, the salt‐assisted microwave radiation demulsification of the oil‐rich emulsion prepared with AEE from peanuts is investigated. The microwave demulsification method is compared with other conventional demulsification methods, including heating, and freezing–thawing. The salt‐assisted microwave demulsification of the emulsions shows a greater free oil yield than conventional heating demulsification. Moreover, the microwave demulsification shows a similar free oil yield in less time than freezing–thawing method. Under the optimal operating conditions of demulsification, the free oil yield can reach 92.3% with CaCl₂‐assisted microwave demulsification for only 2 min. In addition, the oxidative properties and the fatty acid compositions of the demulsified peanut oil are investigated. No significant difference in the fatty acid composition is observed among salt‐assisted microwave, freezing–thawing, and heating demulsified oil. The oxidative properties of the salt‐assisted microwave demulsified peanut oil is better than the conventional heating demulsified oil. Thus, salt‐assisted microwave demulsification provides a quick and effective demulsification method to obtain vegetable oils with high quality. Practical Applications: Aqueous enzymatic extraction (AEE) is an environmentally friendly edible‐oil‐extraction process. To solve the problem of stable emulsion formed during AEE process, the salt‐assisted microwave demulsification of the oil‐rich emulsion prepared with AEE is developed with high efficiency (demulsification for 2 min). In addition, the oxidative properties of the microwave demulsified oil is better than the conventional heating demulsified oil.     

Heavy oil recovery efficiency using SAGD,SAGD with propane co-injection and STRIP-SAGD

Primary oil recovery methods in heavy oil basins generally extract 5–10% of the available resource, with the vast majority left in the ground and recoverable only through Enhanced Oil Recovery (EOR) methods. Traditional EOR methods, such as SAGD and solvent-assisted SAGD, generate steam in surface facilities and inject it underground to mobilize the oil for production. However, these methods can have considerable energy losses that significantly impact process performance. In contrast, the Solvent Thermal Resource Innovation Process (STRIP) technology, which uses down hole combustion of methane to produce CO₂ and steam, reduces the operating and capital costs of surface facilities, saving more than 50% of the energy typically required for thermal production. In this work, simulations of conventional SAGD, SAGD with a non-condensing solvent (propane), and STRIP-SAGD for a typical bitumen reservoir in the Fort McMurray region in Alberta, Canada were performed using the combined software system ADGPRS/GFLASH. SAGD simulations used steam injection with a quality of 0.8 while STRIP simulations injected a vapor–liquid mixture with a quality of 0.8. Furthermore, both solvent-based EOR methods required longer operation periods than conventional SAGD to recover a similar amount of oil. However, when compared on the basis of cumulative oil produced for the same overall energy input, it is shown that STRIP-SAGD recovered more oil per kJ of energy input to the reservoir than either SAGD or SAGD with propane co-injection.     

Ethyl acetate as a bio-based solvent to reduce energy intensity and CO2 emissions of in situ bitumen recovery

We introduce ethyl acetate (EA), a bio-based chemical, as a potential solvent for bitumen recovery through comprehensive phase behavior and numerical simulation studies. Phase behavior and thermophysical properties of EA/live bitumen are measured at temperatures and pressures up to 190°C and 4 MPa, respectively. Experimental studies suggested that coinjection of EA with steam can reduce the bitumen viscosity by several orders of magnitude. Our numerical simulations show that coinjection of 2–8 mol% EA with steam can significantly reduce the steam-oil-ratio (SOR) by almost 0.9 units while increasing the bitumen production rate. This reduction in SOR can be translated to significant energy saving of ~2.2 GJ, emission reduction of ~120 kg of CO₂, and wastewater reduction of ~120 m³ per ton of the produced bitumen, which are almost 20–25% lower than the steam-assisted gravity drainage (SAGD) process.     

Rectisol wash for purification of partial oxidation gases

The Rectisol wash unit with methanol as solvent is a very economical and well-proven process for the removal of acid components from raw gases produced by partial oxidation of oil or coal. The design can be adapted to the specific process requirements such as desired acid gas purity of the treated gas or the recovery of by-products like CO₂. Using Rectisol it is easy to produce a variety of product gases (simultaneously), such as, ammonia synthesis gas, methanol synthesis gas, hydrogen or fuel gas. For example, for a complex producing fuel gas for combined-cycle plus syngas for an ammonia plant, Rectisol is the most favourable wash system.     

A novel conceptual design by integrating NGL recovery and LNG regasification processes for maximum energy savings

Natural gas liquids (NGL) recovery from shale gas needs large amounts of cold energy for cooling, while liquefied natural gas (LNG) regasification requires tremendous hot energy for heating. Thus, recycling the cold energy from LNG regasification process at a receiving terminal to assist the NGL recovery process has great economic benefits on both energy saving and high‐value product recovery. A novel conceptual design by integrating NGL recovery from shale gas and LNG regasification at receiving terminals has been developed. It first generates a process superstructure. Then, a simulation‐assisted mixed‐integer linear programming (MILP) model is developed and solved for the optimal process synthesis. Next, heat exchange network (HEN) design and analysis are performed to accomplish the maximum energy‐saving target. Finally, rigorous plant‐wide simulations are conducted to validate the feasibility and capability of the entire conceptual design coupling of separation and heat integration. © 2013 American Institute of Chemical Engineers AIChE J, 59: 4673–4685, 2013     

Optimization strategies and impact of low oil price on long term SAGD projects

Steam assisted gravity drainage (SAGD) has been known as a commercially proven high ultimate recovery process for bitumen and heavy crudes. It is an energy intensive process, which is economical when oil price is above certain value. When the oil price goes below the economic threshold of project, steam injection can be decreased or completely stopped for a certain period of time, and can resume thereafter when the condition alters. The objective of this study is to provide comprehensive information about the effect of steam injection interruptions on thermal project performance. An optimization strategy for the SAGD process, in cases where steam injection interruption occurs, is discussed using actual reservoir models of different geological formations. An economical model is used to evaluate operating strategy effect on the net present value (NPV) of the project. The parameters, like shut-in period, initial steam injection period, etc, are optimized for Athabasca type oil sand reservoirs. The results show several key mechanisms exist in the life cycle of the SAGD process that must be included to reflect the field scale behaviour; otherwise, the mechanistic simplicity of the models could lead to directional and semi-quantitative conclusions. Among the mechanisms, temperature effect on basic petrophysical properties of reservoir rocks was found to have an important role in the oil recovery, and considerably impacts the results of optimization. When the steam injection is interrupted, an optimum shut-in period can be determined to maximize the oil recovery. The optimum length of steam injection interruption depends on the initial steam injection period.     

Impact of Microwave Assisted Infusion on the Quality and Volatile Composition of Olive Oil Aromatized with Rosemary Leaves

Olive oil with rosemary leaves by microwave assisted infusion (MAI) as an alternative to conventional infusion (CI) was evaluated. Microwave heating was applied to the mixture in order to accelerate diffusion of the rosemary volatile compounds into the olive oil. The volatile components of the aromatized oils were quantified by HS‐SPME/GC–MS, as well as several quality indexes such as free fatty acids (FFA), peroxide value (PV), specific coefficients of extinction, chlorophyll and carotenoid content, and color assessment. Fatty acid profiles of the oils aromatized by MAI were compared to those produced by CI. Results showed that the infusion time is reduced from 12 h to 10 min when utilizing MAI in place of CI. MAI treatment caused a slight increase in FFA levels, and specific extinction coefficient indices (K₂₃₂ and K₂₇₀). PV during MAI remained unchanged for the first 3 min, after which there was an observable increase. All physico‐chemical values were found to be well below the maximum permitted limits. The MAI treatment reduced chlorophyll and carotenoid levels during the final step of aromatization, thus affecting final color. The MAI aromatized oil was characterized by its clear green color (L*, a*, b* parameters). Fatty acid analysis showed that MAI slightly changed the fatty acid composition of the olive oil. This study indicates that MAI appears to be a viable and rapid method to flavor olive oil with rosemary leaves.     

Recovery and Recycling of CO2/N2‐Switchable Anionic Surfactants in Emulsions

To develop a mild, effective, and clean strategy for recovery and recycling of anionic surfactants in CO₂/N₂‐switchable emulsions, a CO₂/N₂‐switchable anionic surfactant, which is a combination of dodecyl seleninic acid (DSA) and N,N,N′,N′‐tetramethyl‐1,2‐ethylenediamine (TMEDA), here referred to as DSA–TMEDA, was used to stabilize an oil‐in‐water (O/W) emulsion. Upon stimulation with CO₂, DSA–TMEDA was switched off to form insoluble DSA and the water‐soluble TMEDA bicarbonate. Upon N₂ bubbling and heating, the OFF state of DSA–TMEDA was restored to the surfactant of DSA–TMEDA. In this manner, O/W emulsions stabilized by DSA–TMEDA can be switched reversibly between demulsification (phase separation) and re‐emulsification (recovered emulsion) by triggering with CO₂/N₂ over ten times. After breakage of the emulsion, nearly all of the OFF state surfactant could be separated conveniently away from the oil phase, thus facilitating recovery and recycling of the surfactant afterward in emulsifying oil. No obvious adverse changes in the dispersed oil particles size and the relative stability of the regenerated emulsions were observed over five cycles, and the surfactant loss can be neglected during the recycling.     

Gas evolution from the aquathermolysis of heavy oils

Aquathermolysis experiments were performed on core samples taken from three large bitumen and heavy oil deposits found in Alberta, to investigate gas evolution over the temperature range 360 to 420°C. Experiments conducted on Athabasca included runs with an initially pre-oxidized oil sample and runs with a change in core mineralogy. Pre-oxidizing the oil was found to substantially increase the amount of carbon monoxide and molecular hydrogen generated. Core mineralogy played an important role in the generation of carbon dioxide, and the amount of hydrogen sulphide produced was dependent on oil composition, mineralogy and time. Although substantial amounts of gaseous products are produced by simple thermolysis reactions (i.e., without water present), the main thermal recovery methods, steam injection and in-situ combustion, bring the oil phase and its host rock into direct contact with water. As water has been shown to take part in thermal cracking reactions, these experiments provide usful data for the estimation of produced gas composition during thermal recovery projects.     

Effects of coating solvent and thermal treatment on transport and morphological characteristics of PDMS/Torlon composite hollow fiber membrane

A new approach for formation of the polydimethylsiloxane (PDMS) layer on Torlon polyamide‐imide hollow fiber (PAI‐HF) support has been developed by directly after fiber spinning without the need to undergo the final conventional solvent exchange and drying step, thereby saving postspinning processing steps. The produced PDMS/PAI‐HF composite membranes were found to have high CO₂ permeance (i.e., 1100 GPU) and exhibited good CO₂/N₂ selectivities of 8–10 which is close to 90% of that of a PDMS dense film. The effects of coating solution, rewetting and crosslinking temperature on the PAI‐HF morphological features, that is, gas transport, skin thickness, skin integrity, and substructure resistance are investigated. The rewetting and thermal treatment of the PAI‐HF caused the densification of the skin layer and reduced the pore sizes on the top layer. In addition, the potential use of the PAI‐HF support with polymers that are insoluble in hexane is also considered. Effects of water, methanol, and hexane exposure of PAI‐HF to these solvents are considered. This evaluation calls attention to issues that must be addressed in any eventual use of the PAI‐HF with water‐soluble or methanol‐soluble selective layer polymers, rather than simple hexane‐soluble polymers such as PDMS. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45418.     

Characterizations of surfactant synthesized from Jatropha oil and its application in enhanced oil recovery

Surfactants are frequently used in chemical enhanced oil recovery (EOR) as it reduces the interfacial tension (IFT) to an ultra‐low value and also alter the wettability of oil‐wet rock, which are important mechanisms for EOR. However, most of the commercial surfactants used in chemical EOR are very expensive. In view of that an attempt has been made to synthesis an anionic surfactant from non‐edible Jatropha oil for its application in EOR. Synthesized surfactant was characterized by FTIR, NMR, dynamic light scattering, thermogravimeter analyser, FESEM, and EDX analysis. Thermal degradability study of the surfactant shows no significant loss till the conventional reservoir temperature. The ability of the surfactant for its use in chemical EOR has been tested by measuring its physicochemical properties, viz., reduction of surface tension, IFT and wettability alteration. The surfactant solution shows a surface tension value of 31.6 mN/m at its critical micelle concentration (CMC). An ultra‐low IFT of 0.0917 mN/m is obtained at CMC of surfactant solution, which is further reduced to 0.00108 mN/m at optimum salinity. The synthesized surfactant alters the oil‐wet quartz surface to water‐wet which favors enhanced recovery of oil. Flooding experiments were conducted with surfactant slugs with different concentrations. Encouraging results with additional recovery more than 25% of original oil in place above the conventional water flooding have been observed. © 2017 American Institute of Chemical Engineers AIChE J, 63: 2731–2741, 2017     

Rapid and large‐scale separation of magnetic nanoparticles by low‐field permanent magnet with gas assistance

Bubbles can be used to greatly improve the speed of magnetic separation (MS) and overcome the limitation of magnetic force on the capture distance, making low‐field MS highly efficient and easily scalable. This novel method leads to the development of a medium‐free continuous gas‐assisted magnetic separator on small pilot scale using low‐field permanent magnet. This separator is demonstrated highly efficient for recovery of proteins‐loaded magnetic nanoparticles from large volume biosuspension. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3101–3106, 2014     

Upgrading of low rank coal with solvent

In this study, thermal upgrading of low-rank coal with solvent at 380–440 °C under an initial nitrogen pressure of 2 MPa was studied as a possible method for producing clean solid fuel with a high heating value and less spontaneous ignition behavior. Upgrading of Buckskin coal (USA, subbituminous coal) in the presence of t-decalin (non hydrogen-donor solvent) at 440 °C gave 11.4 wt.% of gas, 5.3 wt.% of oil and 74.1 wt.% of upgraded solid product with a small amount of water. The gaseous product consisted mainly of carbon dioxide (67 wt.%), methane, carbon monoxide, hydrogen and a trace of C₂ and C₃ hydrocarbon gases. The oil product from coal contained BTX, phenol, and their alkyl-derivatives. The heating value of the upgraded solid product from the Buckskin coal increased to 31.0 MJ/kg in dry base as compared to the heating value of wet base of the untreated raw coal, which was 19.3 MJ/kg. Spontaneous ignition behavior was greatly reduced by the upgrading. The effect of catalyst and additives on the upgrading was investigated in terms of product distribution and the quality of the solid product. Taiheiyo (Japan, subbituminous) and Yallourn (Australia, brown) coals were also studied.     

Design,construction and operation of lab scale cylindrical steam assisted gravity drainage model for heavy oil recovery

Based on a theoretical background [1,2], a lab scale cylindrical SAGD (steam assisted gravity drainage) model was designed, constructed and operated. There are six different parts in the apparatus: (1) water supplier, (2) steam generator, (3) SAGD cylindrical model, (4) cooling system, (5) constant pressure maintaining system and (6) production system. Temperature, pressure and steam injection rate were controlled by computer, and product (mixture of oil and water) was collected/separated manually. Extra heavy oil (<10 cp at 200 °C) and glass bead (diameter 1.5 mm) were mixed homogeneously for making porosity of 0.3 and applied for simulating oil sand. For obtaining optimum operation conditions of SAGD apparatus, several attempts were made. When the steam at high temperature (160–180 °C), high pressure (8–9 atm) was injected with 20–25 cc/min, cSOR (cumulative steam to oil ratio) of about 5 was obtained with oil recovery of 78.8%.     

A water droplet size distribution dependent modeling of hydrate formation in water/oil emulsion

Experimental data on chord length distributions and growth rate during methane hydrate formation in water‐in‐oil emulsions were obtained in a high pressure stirring reactor using focused beam reflectance measurement and particle video microscope. The experiments were carried out at 274.2 K for 10–30% water cuts and agitation rates ranging from 200 to 500 rpm initially at 7.72 MPa. Rapid growth was accompanied by gradually decrease in rate. Free water was observed to become depleted during rapid growth while some water remained encapsulated inside hydrate layers constituting a mass transfer barrier. The apparent kinetic constants of methane hydrate formation and free‐water fractions were determined using a newly developed kinetic model independent of the dissolution rate at the gas–oil interface. It was illustrated that continued growth depends on distribution and transfer of water in oil‐dominated systems. This perception accords with observations of hydrate film growth on suspended water droplet in oil and clarifies transfer limits in kinetics. © 2016 American Institute of Chemical Engineers AIChE J, 63: 1010–1023, 2017