Water-Oil Emulsions with Fines in Smart Water Enhanced Oil Recovery

Abstract

Smart water flooding is an advanced method for enhanced oil recovery (EOR) in which the composition of injected brine is altered by varying the concentration of selected ions that can increase the oil recovery from various carbonate reservoirs. Besides wettability alteration mechanism, the formation of water-soluble oil emulsions has been reported as a possible reason to explain the observed increase in oil recovery using smart water. The formation of water-soluble oil emulsions takes place on the interaction of insoluble salts (fines) with oils. However, the interaction of these fines with the crude oil is not very well studied for carbonate reservoirs. This work presents emulsion formation in water-oil systems in the presence of water-insoluble fines. The effect of amount of fines on emulsion formation is also examined. Synthetic seawater (SSW) and deionized water (DIW) were used as water phase, two model oils (decane (D) and 1:1 vol. ratio of hexane-hexadecane (HH) mixture) and North Sea crude oil (NSCO) were used as oil phase, and fines of CaCO3 (≤ 30 µm) and CaSO4 (≈ 44 µm) were used as solid phase. Branson Sonifier® SFX250 was used for emulsion formation (based on the principle of ultrasonic processing). All the experiments were performed for the same conditions of 5 minutes of ultrasonic processing at an output power of 30 W by using 6.5 mm tapered microtip (sonication probe). Emulsion characterization was done by using an optical microscope (Axio Scaope.A1). Several combinations of water-oil-fines were tested. The tests consisted of control experiments (in which only water-oil without any fines were tested) and water-oil-fines experiments. In the control experiments (without fines), SSW did not show any tendency to emulsify neither with the model oils nor with NSCO. However, DIW showed clear tendency to emulsify with model oils and NSCO. Amongst model oils, DIW emulsified with HH better compared to decane. Similar results were observed in the water-oil-fines experiments. SSW did not form any emulsion with the model oils in the presence of fines of CaCO3 and CaSO4. However, significant amounts of emulsion formation were observed when DIW was sonicated with model oils and fines. HH formed more emulsions compared to decane. For NSCO case, both SSW and DIW formed a significant amount of emulsions with both types of fines (CaCO3 and CaSO4). An increase in amount of fines showed an increase in emulsion formation and a better emulsion stabilization. Sonication is a quick and reliable technique to screen out emulsion formation in different combinations of water-oil-fines. This work will further develop our understanding of emulsion formation in the water-oil-fines systems.

Mechanisms of smart waterflooding in carbonate oil reservoirs - A review

“…The sonification method was applied to create emulsions. Increase in emulsion formation and better emulsion stability was observed with increasing the amount of fines (Arshad et al, 2017). This study confirmed the results of Chakravarty et al (2015aChakravarty et al ( , 2015bChakravarty et al ( , 2015c) that the distilled water emulsifies better than the seawater when synthetic oils are involved.…”

“…Formation of such fines promotes in situ emulsification. Arshad et al (2017) investigated the effect of CaCO 3 and CaSO 4 fines on emulsification with model (decane and hexane-hexadecane) and North Sea crude oils with deionized water, seawater and formation water. The sonification method was applied to create emulsions.…”

Synergistic System of Alkyl Polyglucoside and Amine Oxide for Enhanced Oil Recovery

“…Multitudinous laboratory investigations and field applications have proved that the emulsification enabled by a surfactant is an important mechanism to enhance oil recovery. ,− On the one hand, an emulsion can improve microscopic displacement efficiency by stripping oil. − On the other hand, due to emulsification with entrapment and the Jamin effect, the emulsion droplets can block the pore throat of the formation, leading to the permeability reduction and regulating the water injection profile. , Consequently, an emulsion can be used as a mobility control agent, reducing the water production and enhancing macroscopic oil sweep efficiency. − Feng et al established a kind of fine emulsion (FE) and found that the oil recovery efficiency can reach 16.8% after water flooding by FE system emulsification. They have discovered the emulsification mechanisms including emulsification with entrainment and the performance control of the emulsion through a microscopic oil displacement experiment.…”