Complexation of Surfactant/β‐Cyclodextrin to Inhibit Surfactant Adsorption onto Sand, Kaolin, and Shale for Applications in Enhanced Oil Recovery Processes. Part III: Oil Displacement Evaluation

Abstract

This proof of concept research evaluates the performance of a surfactant/b-cyclodextrin (b-CD) inclusion complex during chemical flooding for enhanced oil recovery. It was hypothesized that the encapsulated surfactant propagates well through the porous media. Sodium dodecyl sulfate (SDS) was used to study the surfactant/b-CD complexations. Phase behavior analysis was carried out to prepare the most favorable chemical slug formulation. A series of core flooding tests were conducted to determine the efficiency of the SDS/b-CD inclusion complex in displacing residual oil. Surfactant flooding was conducted as tertiary oil recovery mode (after mature water flooding) by injecting 0.3 pore volume (PV) of the optimum surfactant slug that was chased by 0.3 PV of a polymer slug; followed by continuous water flooding until oil production stopped. The experimental results indicate that the encapsulated surfactant propagates well through the sandpack system and consistently produces higher incremental oil recoveries that range from 40 to 82 % over the incremental oil recovery achieved by conventional surfactant flooding. KeywordsSurfactant delivery system Á Surfactant carrier system Á Surfactant/b-cyclodextrin complexation Á Surfactant/b-cyclodextrin inclusion complexes Á Surfactant adsorption Á Surfactant adsorption inhibition Á Surfactant flooding Á Enhanced oil recovery Á Surfactant encapsulation in b-cyclodextrin List of symbols k Permeability in md (millidarcy) S or Residual oil saturation in fraction t Time uFlux in cm/h V sm Surfactant volume in the microemulsion phase V wm Water volume in the microemulsion phase V om Oil volume in the microemulsion phase r mw Interfacial tension (IFT) between the microemulsion/water phases r mo Interfacial tension (IFT) between the microemulsion/oil phases / Porosity

Sulfonated Polystyrene Nanoparticles as Oleic Acid Diethanolamide Surfactant Nanocarriers for Enhanced Oil Recovery Processes

“…Therefore, the 12sulf20 SPSNP is the best surfactant delivery system developed in this work. In the same way, other studies in the literature observed that complex (dextrin-SDS) carrier systems were more efficient, achieving a similar incremental oil recovery in relation to the SDS flooding recovery in a sand porous media [32,34].…”

“…The water flooding process produced a recovery in the range of 40–46% of the original oil in place in the same way as reported by other studies using sandstone as a porous medium [11,32,34]. In order to better discuss the system′s performance, Figure 17 displays the incremental oil recovery results from the chemical flooding stage, i.e., considering only the pore volumes injected after the secondary oil recovery.…”

“…Surprisingly, the use of greater amounts of OADA in the polymerization process did not result in an increase on the retained surfactant amount ( Q e ) as could be expected when comparing with the results of the adsorption process as described in the literature [17,32,34]. Since OADA presents a double role in the nanoparticles′ formation, its consumption may occur during the formation of a greater number of micelles and nuclei, producing smaller nanoparticles, as observed in Figure 9, and consequently resting less OADA molecules available to be immobilized or encapsulated in the nanocarriers.…”

“…Effluents were collected in 10 mL graduated cylinders and, based on the oil volume measured from every effluent collected, materials balance calculations were carried out to evaluate the oil recovery as a function of fluid injected [11,14,34].…”

A Nanocomposite of Halloysite/Surfactant/Wax to Inhibit Surfactant Adsorption onto Reservoir Rock Surfaces for Improved Oil Recovery

“…A remarkable way of protecting surfactants is the use of cyclodextrins, which sequester surfactant tails in their hydrophobic cores, thus minimizing contact with oil-free surfaces. Kittisrisawai and Romero-Zerón showed that complexation between the hydrophobic tail of surfactants and β-cyclodextrin could inhibit the adsorption of surfactants onto shale cores for enhanced oil recovery. − Other developments include the use of carbon nanotubes as surfactant carriers, where the carbon nanotube surface hydrophobicity allows surfactant adsorption through hydrophobic interactions . Surfactants have also been sequestered in cross-linked polystyrene nanoparticles that swell on contact with the oil–water interface, releasing the amphiphiles .…”