Nanotechnology Application in Chemical Enhanced Oil Recovery: Current Opinion and Recent Advances

Chemical enhanced oil recovery (EOR) has been adjudged as an efficient oil recovery technique to recover bypassed oil and residual oil trapped in the reservoir. This EOR method relies on the injection of chemicals to boost oil recovery. Recently, due to the limitations of the application of chemical EOR methods to reservoirs having elevated temperatures and high salinity and hardness concentrations, nanotechnology have been applied to enhance its efficiency and improve oil productivity. The synergistic combination of nanoparticles and conventional EOR chemicals has opened new routes for the synthesis and application of novel materials with sterling and fascinating properties. In this chapter, an up-to-date synopsis of nanotechnology applications in chemical EOR is discussed. A detailed explanation of the mechanism and applications of these novel methods for oil recovery are appraised and analyzed. Finally, experimental and laboratory results were outlined. This overview presents extensive information about new frontiers in chemical EOR applications for sustainable energy production

Laboratory experiment based permeability reduction estimation for enhanced oil recovery

Formation damage is an unwanted operational problem-taking place through several phases of oil reservoir life. The permeability reduction is a key indicator for the formation damage. Suitable assessment of permeability reduction is critical for hydrocarbon recovery. As oil production reach tertiary recovery stage in many fields, formation damage critical evaluation is needed to avoid additional operational cost and technical feasibility concern. The interaction between reservoir minerals and chemical injection practices is not fully understood. Also, clay mineral presence is highly sensitive to the chemicals, while adsorption phenomena can also occur. The degree of permeability reduction cannot be generalized for core/field scales; therefore investigating the permeability reduction in core scale is important before field-scale assessment. Therefore, this study investigates the permeability reduction after chemicals injection under low flow rate in sand-quartz cores and in the presence of kaolinite. Artificial sandpacks were used to control the sand-kaolinite mixture percentage. The permeability was measured before and after each flood by pressure drop calculation. The study showed that the seawater flood has the highest reduction in permeability followed by polymer and surfactants. Also, the results showed a strong effect of surfactant nature and molecular weight on the adsorption process and consequently the permeability reduction. The study provides an insight for the effect of chemicals on cores physical properties

Extraction, characterization and evaluation of saponin-based natural surfactant for enhanced oil recovery

To minimize environmental impact and costs, natural surfactants are suggested as an ecologically sustainable replacement for synthetic surfactants. The aim of this work is to evaluate the efficiency of low-cost saponin-based natural surfactant (SBNS) from Vernonia amygdalina (VA) leaves for enhanced oil recovery (EOR). Furthermore, the study investigated the IFT behaviour of SBNS at oil-water interface and the emulsion behaviour and oil displacement efficiency of SBNS. The SBNS was obtained via ultrasonic extraction of dried VA leaves in a water bath, centrifuging the obtained liquid mixture and freeze drying to evaporate to dryness. Thereafter, Fourier-transform infrared spectroscopy (FTIR) and high-performance liquid chromatography were used to characterize the extracted SBNS. Moreover, tensiometer (Easy-Dyne KRUSS) was used to study the interfacial tension (IFT) behaviour of the SBNS at oil-water interface. Also, the SBNS ability to form stable emulsion in the presence of crude oil was determined. Finally, oil displacement by SBNS solution was investigated under simulated reservoir conditions (3000 psi and 100 °C) with high-pressure high-temperature (Fars EOR) core flooding equipment. The performance of SBNS was compared to commercial non-ionic surfactant 4-octylphenol polyethoxylated (TX-100). Experimental result indicated that the SBNS reduced the IFT at oil-water interface. The natural surfactant lowered the IFT of the oil-water interface from 18.0 to 0.97 mN/m. Moreover, emulsions formed with SBNS showed good stability characterized by a decrease in the median drop diameter with an increase in SBNS concentration. Finally, oil displacement test shows that oil recovery of TX-100 and SBNS increased by 9% and 15% original-oil-in-place (OOIP), respectively. Hence, SBNS is recommended as an appropriate substitute for conventional surfactant due to its inexpensive raw material, lower toxicity, and higher efficiency

An Overview of Natural Surfactant Application for Enhanced Oil Recovery

Surfactant flooding is an enhanced oil recovery (EOR) method that recovers residual and capillary trapped oil by improving pore scale displacement efficiency. Due to toxicity and high cost of conventional surfactant, recent trend involves the use of natural surfactant for EOR. Natural surfactants are benign and biodegradable as they are derived from plant leaves and oil extracts. Herein, a synopsis of recent trend in the incorporation of newly devised natural surfactant for EOR was reviewed. Experimental results show that the surfactants exhibited sterling properties desired for EOR such as lower adsorption, interfacial tension (IFT) reduction, stable emulsion, and wettability alteration of sandstone and carbonate rocks. Overall, natural surfactants are suitable replacement for conventional surfactant. Nonetheless, an accurate modeling and pilot scale studies of natural surfactants remain obscure in literature

Variations in formation resistivity and geometric tortuosity factors for consolidated niger delta formations

Formation resistivity evaluation is an essential part of electrical properties measurement of porous media. Such deduced properties are often considered in modeling of associated rock properties for better hydrocarbon exploitation. Cognizance of these properties trend are necessary to ensure acceptable magnitudes for regional-based analyses. The aim of this research study was to establish a trend in formation resistivity factor and geometric tortuosity factor for Niger delta formations in Nigeria. These electrical properties were evaluated via core analysis using direct and alternating current sources. Consolidated core samples were procured from different terrains of producing oilfields in Nigeria. Characterized samples in terms of porosities and permeabilities conformed to existing trends. However, clay minerals embedded in acquired samples resulted in lower values of formation resistivity factor. Deduced formation resistivity factors show acceptable values in the range of 3.55–10.26. Geometric tortuosity factor was adopted to evaluate the tortuous nature of Niger delta porous media due to electrical conductivity. Results obtained for geometric tortuosity factors were all < 1. This was used to infer the highly tortuous and sinuous nature of consolidated Niger delta formations. Furthermore, experimental data were subjected to multivariate regression analysis model of second order. All deduced mathematical formulations were comparatively analyzed with existing geometric tortuosity factor models. Mathematical models show reasonable forecast ability for prescribed porosity range with corrected Akaike’s Information Criteria difference of 0.98 and 1.59

LABORATORY EXPERIMENT BASED PERMEABILITY REDUCTION ESTIMATION FOR ENHANCED OIL RECOVERY

Formation damage is an unwanted operational problem-taking place through several phases of oil reservoir life. The permeability reduction is a key indicator for the formation damage. Suitable assessment of permeability reduction is critical for hydrocarbon recovery. As oil production reach tertiary recovery stage in many fields, formation damage critical evaluation is needed to avoid additional operational cost and technical feasibility concern. The interaction between reservoir minerals and chemical injection practices is not fully understood. Also, clay mineral presence is highly sensitive to the chemicals, while adsorption phenomena can also occur. The degree of permeability reduction cannot be generalized for core/field scales; therefore investigating the permeability reduction in core scale is important before field-scale assessment. Therefore, this study investigates the permeability reduction after chemicals injection under low flow rate in sand-quartz cores and in the presence of kaolinite. Artificial sandpacks were used to control the sand-kaolinite mixture percentage. The permeability was measured before and after each flood by pressure drop calculation. The study showed that the seawater flood has the highest reduction in permeability followed by polymer and surfactants. Also, the results showed a strong effect of surfactant nature and molecular weight on the adsorption process and consequently the permeability reduction. The study provides an insight for the effect of chemicals on cores physical properties

Comparative numerical study for polymer alternating gas (PAG) flooding in high permeability condition

Polymers have been used in water alternative gas, to viscosify the water and improve the overall sweep efficiency. The use of polymer alternative gas was successful in increasing the oil production in high permeability zones. However, few practical factors affecting the field applicability have been overlooked. Therefore, this study is aimed at bridging the gap between the possibility of using several EOR such as water flooding, CO2 flooding, water alternative gas, polymer flooding and polymer alternative gas. The research based on progressive comparison considering constant constraint. The numerical simulation STARS-CMG was used to predict the characteristics and behaviour of the fluid in the reservoir. The designed flooding pattern chosen was a single producer-single injection (P-I) scheme in homogeneous high permeable reservoir. The results of oil incremental recovery showed the following order compared to Water flooding < (3%) CO2 flooding < (6.8%) < Water alternative gas (11.6%) Polymer flooding < (15%) Polymer alternative gas. The impact of polymer on enhancing the water alternative gas was mostly noticeable in the reduction of water cut% (83%). The controlled conformance by polymer aided in improving the sweep efficiency as indicated by the uninform U-shape. Moreover, the delayed gas breakthrough was significant and resulted in the lowest gas oil ratio of 5.17E + 04 ft3/bbl. The low gas oil ratio observation is indication of potential capturing of CO2 in the reservoir and thus, good evidence to further implementation of CO2 as green utilization

Performance evaluation of nanosilica derived from agro-waste as lost circulation agent in water-based mud

Seepage or loss of the mix-water from the drilling muds into the porous and permeable formations is a common problem during drilling operation. The drilling mud design requires a good knowledge of sealing integrity and all the factors influencing the mud to bridge through fractures or pore throat of exposed rocks. Loss circulation materials (LCMs) are commonly introduced into the drilling mud to prevent or minimize filtrate loss. This study investigates silica nanoparticle (SNP) derived from rice husk (RH) termed RH-SNP using the wet-milling method as an LCM in water-based mud (WBM). The impact of the RH-SNP in the enhancement of rheology and filtrate loss control properties of WBM was studied. Subsequently, the sealing integrity of the RH-SNP in a 1 mm and 2 mm simulated fracture for 7 min was determined using a stainless-steel slotted filter disk. The performance of the developed RH-SNP was compared with the widely applied nutshell. The synthesized RH-SNP at amount of 2.0 wt% significantly enhanced the yield point and plastic viscosity of the WBM by 75% and 386%, respectively, and minimized the fluid loss of the WBM by 47% at 80 °F. The enhancement is due to the particles ability to spread and interact efficiently with the WBM. With the use of 1 mm and 2 mm simulated fracture for 7 min, the mud loss volume of the base mud reduced by 50%, 66.7%, 86%, and 90% (for 1 mm) and 40%, 65.7%, 77.1%, and 80% (for 2 mm) with the inclusion of 0.5 wt%, 1.0 wt%, 1.5 wt%, and 2.0 wt% of RH-SNP, respectively. Overall, the results showed that RH-SNP enhanced the seal integrity of the drilling mud and was more resistant to deformation compared to the nutshell. The findings of this study can help for better understanding of the application of RH-SNP as a loss circulation agent owing to its superior ability to seal fractured formation compared with the often used nutshell

Simulation study of polymer flooding performance : Effect of salinity, polymer concentration in the Malay Basin

The major problem of the water flooding development process is the flood process's high mobility and viscous fingering. Previous studies have shown that polymer flooding is viable and can recover bypassed oil. However, the mechanism of the polymer flooding process is still tenuous in literature. Therefore, in this study, a two-dimensional model was used to simulate polymer flooding and forecast the mechanism of the polymer flood in the presence of electrolytes. Likewise, the effect of pH, pressure, and temperature on the polymer flooding process was investigated. Thereafter, the model was validated with an independent set of experimental data from the literature. The results show that the polymer flooding mobility ratio (M) was 0.36 indicating a favorable mobility control, thereby improving oil recovery by 60% of original oil in place (OOIP). In comparison, to water flooding mobility ratio of 3.6, which was greater than 1, thus resulted in viscous fingering, early water breakthrough, and oil recovery of 36% OOIP. Besides, at high salinity concentrations, the polymer adsorption was 3.3 mg/g compared to 2.2 mg/g from the experimental results. This indicates that the simulation results were consistent with the experimental results at the same concentration. Likewise, the simulation and experimental studies suggest high oil recovery was obtained at a higher injected pore volume. Finally, it can be concluded from this study that mechanical trapping and adsorption of the polymer on the pores of the porous media were the dominant mechanisms during the polymer flooding

Giant mud crab shell biochar: A promising adsorbent for methyl violet removal in wastewater treatment

Giant mud crab (Scylla serrata sp.) shell prepared through pyrolysis at various temperatures without any modification were characterized for physicochemical properties and methyl violet (MV) removal potential. Hence, this paper investigated the performance and mechanism of biochar derived from giant mud crab shell as adsorbent in the removal of methyl violet as well as the potential for regenerating adsorbents via hot water regeneration. The results show that CSB500 (produced through pyrolysis at 500 °C) exhibits a surface area of 59.73 m2/g and mesopore size of 31.3 nm, favorable for methyl violet removal at 3139 mg/g. The equilibrium adsorption data agreed well with Langmuir and Redlich-Peterson isotherm models, indicating a monolayer adsorption of MV. The kinetics data fitted better with both pseudo-first-order and pseudo-second-order models. The intraparticle diffusion and Boyd's models revealed that both film and pore diffusion may be involved in the adsorption process. In hot water regeneration studies, CSB500 shown superior regeneration performance when using water with temperature of 70 °C rather than 30 °C for 9th regeneration cycles, with retained to achieve >90 % MV removal for 6th regeneration cycles. Biochar derived from giant mud crab shell has shown significant promise as a low-cost, effective, and ecologically friendly with reasonably good adsorption capacity and reusability for dye removal, and it can be considered as an environmental sustainability strategy in wastewater treatment