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Results
Abstract Despite the plethora amount of research have been conducted on the Low Salinity Water Injection (LSWI) and the pertinent mechanisms, this Enhanced Oil Recovery (EOR) method still seems not to be well understood. Although the rock/fluid interactions are used to be highlighted as the main elements of chemical mechanism of LSWI, fluid/fluid interactions have been brought into attentions much more than anytime before. Formation of microdispersion within the crude oil phase leading to wettability alteration has been proposed repeatedly as the underlying mechanism of LSWI without clarifying the functional compounds of crude oil toward this EOR method. Discovering the responsible compounds of crude oils towards Low Salinity Water (LSW) and formation of microdispersion is demanding to achieve a reliable screening tool of oil reservoir toward LSWI. For this purpose, the crude oils and brines were contacted for an extended period of time until the oil/water interface reached an equilibrium state right before taking crude oil samples from the interface. The Karl Fischer titration (KFT) analyses were carried out to quantify the amount of microdispersion within the crude oil phase. The crude oil sample with the strongest propensity toward microdispersion formation was further investigated through Fourier Transform Infrared (FT-IR) spectroscopy and Negative Electrospray Ionisation (NESI) mode of Fourier Transform Ion Cyclotron Resonance mass spectroscopy (FT-ICR) to evaluate the chemical compositional changes taking place at the interface due to salinity effect. FT-IR analyses revealed the conjugated acidic compounds or the acidic asphaltenes within the crude oil to be the most functional compounds toward microdispersion formation. Consistently, the NESI mode of FT-ICR MS suggested the carboxylic acids (with C=O functional groups) promoting the formation of microdispersion when the crude oil is swept by LSW. Also highlighted was the structure of functional carboxylic acids during LSWI that appeared to be those compounds with DBE of 1, 2, and 3 and carbon number of C15-C20. The results of this study represent an important step toward understanding the mechanism responsible for the LSE. The knowledge will help the oil and gas industry in the task of evaluating and ranking oil reservoirs for EOR by LSWI.
- North America > United States (0.93)
- Europe > United Kingdom (0.68)
- Geology > Geological Subdiscipline (0.69)
- Geology > Mineral (0.68)
- Energy > Oil & Gas > Upstream (1.00)
- Materials > Chemicals > Commodity Chemicals > Petrochemicals (0.94)
- Water & Waste Management > Water Management > Lifecycle > Disposal/Injection (0.62)
Fundamental Investigation of Auto-Emulsification of Water in Crude Oil: An Interfacial Phenomenon and its Pertinence for Low Salinity EOR
Jennifer, Duboué (Total SA) | Maurice, Bourrel (Total SA) | Théo, Dusautoir (Total SA) | Enric, Santanach Carreras (Total SA) | Alexandra, Klimenko (Total SA) | Nicolas, Agenet (Total SA) | Nicolas, Passade-Boupat (Total SA) | François, Lequeux (ESPCI Paris)
Abstract The phenomenon of auto-emulsification occurring when crude oil is gently contacted with water was investigated using various techniques. This spontaneous emulsification which creates a micro-droplet layer at the oil/brine interface is believed to be linked to the improved oil recovery during low salinity Enhanced Oil Recovery (EOR). Crude oils and a model system (asphaltenes solubilized in toluene) have been studied. Observations were facilitated when using the model system, this allowed to have a better insight into the underlying mechanism of micro-droplet formation. It was established that the water micro-droplets appear in the oil phase due to an osmotic phenomenon: molecular water diffuses from the bulk water which provokes the water micro-droplets swelling. The kinetics of the micro-droplet formation is directly linked to the brine salinity in contact with the crude oil: salt addition slows down the emulsification process. This was further confirmed by the evaluation of the water chemical activity in the oil phase from calorimetry measurements. Micromodel experiments showed a higher oil recovery when water micro-droplets are present in the system, irrespective of the initial wettability imposed to the micromodel material. Dilatational rheology measurement did not show significant visco-elasticity arising from the water micro-droplet presence; hence, the visco-elasticity difference cannot completely explain the higher recovery. Manipulation of crude oil droplet during dilatational rheology experiments highlighted the impact of micro-droplets on the shape of the macroscopic oil droplet. The nucleation of micro-droplets at oil/brine or solid/oil interface suggests an explanation for the EOR effect. We have observed that micro-droplets organize at the oil/water interface, while others nucleate at the oil/solid interface or sediment on the solid surface. The interaction of asphaltenes with water molecules dissolved in the oil phase may promote wettability alteration. The micro-droplet formation indicates the magnitude of this interaction for a given asphaltenes/brine system.
- North America > United States (0.46)
- Europe > Norway > Norwegian Sea (0.24)
- Energy > Oil & Gas > Upstream (1.00)
- Materials > Chemicals > Commodity Chemicals > Petrochemicals (0.54)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery > Waterflooding (1.00)
- Production and Well Operations > Production Chemistry, Metallurgy and Biology > Inhibition and remediation of hydrates, scale, paraffin / wax and asphaltene (1.00)
- Facilities Design, Construction and Operation > Flow Assurance > Precipitates (paraffin, asphaltenes, etc.) (1.00)
- Production and Well Operations > Production Chemistry, Metallurgy and Biology > Downhole chemical treatments and fluid compatibility (0.68)
Abstract The potential application of surface modified silica nanomaterials to boost the stability of oil in water emulsions created by alkali-polymer flooding has been investigated. Long-term phase behavior experiments and interfacial tension measurements are performed. We evaluate the effects of particle size and surface modification, as well the influence of the alkali type and concentration on the emulsion stability. The workflow helps understanding the fluid-fluid interactions and facilitates the selection of materials for further core-flood evaluations. Three types of nanomaterials allowed investigating the effect of particle size (60 and 100 nm) and two different surface modifications, which differ slightly in hydrophilicity and zeta-potential. Phase-experiments were performed at 1:1 water/oil ratio using a high TAN crude-oil. Emulsion volume was recorded over 100 days and aqueous-phase composition was varied to study the effect of alkali concentration (1000−15000 ppm), particle type/concentration (0.05−5 wt.%), alkali (Na2CO3 versus K2CO3), and polymer (0 and 2000 ppm). Overall, ∼100 different combinations with triplicates were tested. IFT experiments were performed using a spinning-drop tensiometer, and results were compared at 300 min of observation. Phase experiments revealed that surface modified nanomaterials have the ability to stabilize oil-in-water emulsions that were formed due to reaction of alkaline brine with crude-oil, supported by a low IFT in the alkali/particle system. Combination of 0.1 wt% silica particles and 3000ppm alkali produces very-long lived emulsions and outperforms the control experiments by a factor of four in terms of emulsion volume (at 100 days). The type of surface modification of the nanomaterial had a negligible effect on the volume of the stabilized emulsion. However, density and viscosity of the emulsion were influenced, which will affect fluid flow in the reservoir. A synergistic effect of smaller size (higher effective concentration of particles) and more neutral surface charge of the modified particles resulted in emulsification of crude-oil with silica particles alone, which did not occur for the samples with larger particle size and lower zeta potential. Too high concentrations of alkali and particles resulted in destabilization of the emulsions, which may be due to charge reversal of particles and exceedance of the critical coagulation concentration. Since the viscosity of an emulsion is larger than that of the continuous phase, polymer could be required to flood the emulsion out of the reservoir. In our experiments, the addition of polymer reduced emulsion stability in the alkali-only experiments, but adding nanomaterial boosted the emulsion stability. Nano-EOR is an embryonic technology and to the best knowledge of the authors, literature data is scarce on how nanomaterials emulsify crude-oil, since most studies have been done with simple hydrocarbons such as decane. The majority of the existing literature addresses the stabilizing effect of nanoparticles on emulsions created due to the mixing of surfactants with hydrocarbons, whereas in this study we use alkali as an economically more attractive saponifying agent.
- Europe > Austria (0.68)
- North America (0.68)
- Europe > Austria > Vienna > Vienna Basin (0.99)
- Europe > Austria > Vienna Basin > Matzen Field (0.99)
- Europe > Austria > Lower Austria > Vienna Basin (0.99)