Crude Oil Water Research Articles

Modeling of viscosity of unstable crude oil–water mixture by characterization of energy consumption and crude oil physical properties

When oilfield development enters the middle and late stages, the crude oil–water mixture (COWM) produced from oil wells often has a high water cut and cannot form a stable emulsion. The traditional viscosity model of an emulsion is not suitable for this unstable mixture. Mastering the viscosity characteristics of the unstable crude oil–water mixture with high water cut (UCMH) for pipeline transportation of such mixtures is important. The apparent viscosities of UCMH (water cut of mixture ranging from 0.70 to 0.90) for 16 crude oils were determined via the stirring viscometric method. The results showed that the apparent viscosity of UCMH decreased with increasing shear rate, water cut of mixture, and temperature, demonstrating the property of shear thinning. The apparent viscosity of UCMH did not depend on the content of single surfactants such as resins, asphaltenes, waxes, and mechanical impurities but was closely related to the content of the above-mentioned combinatorial surfactants. The parameter exergy loss rate of shear that describes energy consumption was determined to characterize the external shear action on UCMH, which can fully reflect the essence of the mechanical energy consumption in the emulsifying process under different shearing conditions. A new viscosity model for UCMH was established by the quantitative characterization of the energy consumption and crude oil physical properties (i.e., saturate content, aromatic content, surfactant content, acid value, and crude oil viscosity). In light of the statistical results of 336 groups of validation experimental data from four crude oils, the average relative deviation between the apparent viscosity calculated by the new model and the measured apparent viscosity of UCMH was 5.3%, which is considerably better than the traditional emulsion viscosity models, that is, the Einstein, Vand, Taylor, and Richardson models.

Surfactant–polymer binary oil-displacement agents suitable for multiple oilfield blocks

In oil-displacement processes, a compound surfactant system is used to reduce the crude oil–water interfacial tension (IFT) via the synergistic effect of multiple surfactants. To the best of our knowledge, however, since there is no systematic quantitative comparison tool for the intermolecular effects of surfactants, the synergistic mechanisms of surfactant systems have not been analyzed in depth. This paper proposes the use of intermolecular scission energy as a quantitative tool to analyze the synergistic mechanism of surfactants, mitigating the aforementioned issues. As a case study, this paper focuses on the Y-1, K-1, and K-2 blocks of Shengli Oilfield, China. Based on the intermolecular scission energies of the crude oil IFT-reducing agents of each block, along with the fact that they have the same composition, the co-surfactant amide betaine was added to a conventional alkanolamide–hydroxysultaine system to form a common surfactant system suitable for use in all three blocks. This new system achieved ultra-low IFTs—that is, ∼10−3 mN/m—for all three oils at a concentration of only 0.05%. The surfactant system can effectively reduce the oil–water IFT for 125 days under 90 °C formation conditions, with good thermal stability. After flowing in the formation for 30 days, the concentration of the system is still maintained at about 95%, and it is not easily adsorbed. In the visualization of the oil displacement test, the total oil recovery of a surfactant–polymer system (SP system)—composed of a surfactant system and a polymer—was found to be over 62%, an increase of more than 20%.

A systematic review – Chemical EOR using surfactants and polymers

Enhanced Oil Recovery (EOR) techniques can be classified majorly into thermal and non-thermal methods. Thermal methods can be applied to specific field conditions; whereas, non-thermal methods can be applied to a wide range of reservoirs with different conditions. In certain reservoirs where thermal recovery is not possible, Chemical Enhanced Oil Recovery (CEOR) method is applied. The interfacial properties between the reservoir fluids, namely crude oil and formation water, determine the microscopic displacement efficiency of CEOR, specifically for surfactant and/or alkali. The primary benefit from an application of it is to mobilize residual oil saturation by establishing an interfacial tension (IFT) between crude oil and water that is sufficiently low to overcome capillary forces and allow the oil to flow. This paper reviews EOR methods like surfactant and polymer flooding. Subsequently, difference between the uses of the surfactant or polymers according to the favourable reservoir parameters and field conditions. The oil recovery is enriched by either reducing the IFT between the oil–water interfaces using surfactant or by developing a favourable mobility ratio between the displacing water and displaced oil using polymers. Important parameters considered for designing an effective surfactant and polymer formulation design are also studied.

Legacy and Dispersant Influence Microbial Community Dynamics in Cold Seawater Contaminated by Crude Oil Water Accommodated Fractions

Legacy and Dispersant Influence Microbial Community Dynamics in Cold Seawater Contaminated by Crude Oil Water Accommodated Fractions

Mechanism Responsible in Altering Interfacial Tension and Emulsification of the Crude Oil–Water System with Nano Gemini Surface Active Ionic Liquids, Electrolytes and Ph

Mechanism Responsible in Altering Interfacial Tension and Emulsification of the Crude Oil–Water System with Nano Gemini Surface Active Ionic Liquids, Electrolytes and Ph

Molecular Design and Application of a New Nano Tripodal Surface Active Ionic Liquid for Improving the Crude Oil–Water Behavior

Molecular Design and Application of a New Nano Tripodal Surface Active Ionic Liquid for Improving the Crude Oil–Water Behavior

Behavior of Crude Oil–Water System Under Simultaneous Effects of Nano Gemini Surface Active Ionic Liquids, Electrolytes and Ph

Behavior of Crude Oil–Water System Under Simultaneous Effects of Nano Gemini Surface Active Ionic Liquids, Electrolytes and Ph

Imidazolium-based ionic liquids as demulsifier for water-crude oil emulsion

Most of the crude oils in the world are produced as water-crude oil emulsions. Removal of water from the emulsions is one of the major issues in the industry and the process is completed before transportation and refining. One of the methods to remove water is through demulsification. In the present study, ionic liquids, non-volatile and non-toxic solvents, are used as demulsifiers. Three ionic liquids (ILs), namely 1-ethyl-3-methylimidazolium acetate (EMIM-AC), 1-butyl-3-methylimidazolium chloride (BMIM-Cl) and 1-butyl-3-methylimidazolium hydrogen sulfate (BMIM-HSO4), were evaluated to treat a heterogeneous mixture of crude oil and water. The bottle tests were conducted at 60 °C and salinity of 50,000 ppm. Response surface methodology (RSM) was used to study the effect of IL type, its concentration, and residence time towards demulsification efficiency. The developed correlation gave a high correlation coefficient, R2 of 0.924. Analysis shows that the IL concentration gives the highest influence on the demulsification efficiency, followed by the residence time and the type of ionic liquid. Among the three ILs investigated, 1000 ppm BMIM-HSO4 achieved the highest demulsification efficiency, where complete separation (100% demulsification efficiency) was attained within 30 min. BMIM-Cl achieved 72% efficiency after an hour while the EMIM-AC reached maximum separation after 52 min with 45% efficiency.

Impact of Asphaltene Stabilizers on the Elasticity of a Crude Oil–Water Interface and Its Correlation to Demulsification under Desalting Conditions

Impact of Asphaltene Stabilizers on the Elasticity of a Crude Oil–Water Interface and Its Correlation to Demulsification under Desalting Conditions

Mussel-Inspired Fabrication of PDA@PAN Electrospun Nanofibrous Membrane for Oil-in-Water Emulsion Separation.

Emulsified oily wastewater threatens human health seriously, and traditional technologies are unable to separate emulsion containing small sized oil droplets. Currently, oil–water emulsions are usually separated by special wettability membranes, and researchers are devoted to developing membranes with excellent antifouling performance and high permeability. Herein, a novel, simple and low-cost method has been proposed for the separation of emulsion containing surfactants. Polyacrylonitrile (PAN) nanofibers were prepared via electrospinning and then coated by polydopamine (PDA) by using self-polymerization reactions in aqueous solutions. The morphology, structure and oil-in-water emulsion separation properties of the as-prepared PDA@PAN nanofibrous membrane were tested. The results show that PDA@PAN nanofibrous membrane has superhydrophilicity and almost no adhesion to crude oil in water, which exhibits excellent oil–water separation ability. The permeability and separation efficiency of n-hexane/water emulsion are up to 1570 Lm−2 h−1 bar−1 and 96.1%, respectively. Furthermore, after 10 cycles of separation, the permeability and separation efficiency values do not decrease significantly, indicating its good recycling performance. This research develops a new method for preparing oil–water separation membrane, which can be used for efficient oil-in-water emulsion separation.

The impact of exposure timing on embryo mortality and the partitioning of PAHs when cod eggs are exposed to dispersed and dissolved crude oil

During sub-sea oil spills to the marine environment, oil droplets will rise towards the sea surface at a rate determined by their density and diameter as well as the vertical turbulence in the water. Micro-droplets (< 50 µm) are expected to have prolonged residence times in the water column. If present, pelagic fish eggs may thus be exposed to dispersed oil from subsurface oil spills for days, and the contribution of these micro-droplets to toxicity is not well known. The purpose of this work was to investigate to what extent timing of exposure and the presence of oil micro droplets affects PAH uptake and survival of pelagic Atlantic cod eggs. A single batch of eggs was separated in two groups and exposed to dispersions and corresponding water-soluble fraction at 3–7 days (Early exposure) and 9–13 days (Late exposure) post fertilization. Partitioning of PAHs between crude oil microdroplets, water and eggs was estimated as well as the contribution of oil droplets to PAH body residue and acute and delayed mortality. Timing of oil exposure clearly affects both the mortality rate and the timing of mortality. Even though the body residue of PAHs were lower when embryos were exposed in the later embryonic stage, mortality rate increased relative to the early exposure indicating that critical body residue threshold is stage specific. Although our results suggest that the dissolved fraction is the dominating driver for toxicity in cod embryos exposed to oil dispersions, crude oil micro droplets contribute to increased mortality as well.

A novel and facile preparation of Superhydrophilic/Superoleophobic nanofilter using carbon nitride nanosheet for W/O emulsion separation

In this research, a novel superhydrophilic/ superoleophobic thermoplastic polyurethane@graphitic-carbon nitride@perflourooctanoic acid (TPU@g-C3N4 @PFOA) coated stainless steel mesh was prepared to separate water/oil emulsion. g-C3N4 nanosheets were synthesized with a facile thermal condensation process followed by exfoliation using acid. TPU as a binder is commercially available and provides strong bonding of the nanocomposite coating to the substrate. Wettability characteristics of nanocomposite coated mesh showed the water contact angle of 18.9° and oil contact angle of 151°, which confirmed the special wettability of superhydrophilicity and superoleophobicity. The prepared nanocomposite-coated filter with the surface energy of 92.87 mN/m (dispersive and polar surface energy of 0.199 and 92.68 mN/m) was able to separate water from a 10 wt % water/oil emulsion. Ultimately excellent water–oil separation efficiency of 99% and the filtration flux of 50.5 L.m−2.h−1 were attained under gravity. The particular behavior of the surface is justified with small pore size of mesh, higher roughness and superoleophobic wettability due to the presence of g-C3N4 nanosheets, as well as with the reduction of the surface energy of the synthesized TPU@g-C3N4 by PFOA, as a surfactant with the fluorine tail groups. As-prepared mesh can also separate free crude oil–water mixtures with the separation efficiency and flux of 99.9% and 2157.4 L.M−2.h−1, respectively.The anti-fouling and mechanical stabilities of the as-prepared coated mesh were investigated. This result implied that the as-prepared water-removing filter has great potential for separation of the water-in-oil emulsion, which has long been a problem in industry and is often separated using oil-removing filters in the literature.

Experimental investigation of different simulated formation water salinity in three-phase waxy crude oil-water-gas flow in horizontal pipes

Three-phase oil-water-gas flow experiments have been conducted in a horizontally configured rig made of carbon steel pipe with an ID of 0.041 m and a total length of 24.3 m. The test fluids were Malaysian waxy crude oil from Malay basin and three concentrations of simulated formation water salinity, namely 0 ppm, 15 000 ppm, and 30 000 ppm. The waxy crude oil and simulated formation water are varied at six different superficial liquid velocities ranging from 0.5 to 3.0 m/s while the gas phase is varied at 10 different superficial velocities ranging from 0.01 to 0.61 m/s. Eight flow patterns are observed using observational method; one of which is a newly discovered flow pattern identified as Slug with Oil Film-Oil Continuous (SLOF-OC). Salinity does not give significant effect on oil-gas interface but significantly affects the oil-water interface as lower formation water salinity is dispersed easily in crude oil compared to higher formation water salinity. The highest pressure gradient recorded was 2506.84 Pa/m at the highest superficial gas velocity while the lowest pressure gradient recorded was 89.53 Pa/m at the lowest superficial gas velocity. It is imperative to note that the experimental investigation of Malaysian waxy crude oil with different formation salinity in the three-phase flow study is in an unchartered area, therefore it provides a new platform for furthering more complex research works such as four-phase flow (gas, oil, water, and wax particles) below Wax-Appearing Temperature (WAT).

Interfacial phenomena in petroleum reservoir conditions related to fluid-fluid interactions and rock-fluid interactions: Formulation effects and in porous medium test

Precipitation of asphaltenes in oil fields represents interfacial phenomena of great concern for oil industry. Oil production decreases due to the obstruction of reservoir rock pores by asphaltene blockage. Futhermore, the phenomena of wettability changes and water/oil (W/O) emulsions formation take place in the production processes of crude oil. Herein, the performance and evaluation of a developed product (F2) based on the formulation of an asphaltene inhibitor to overcome these problems is presented. Different systems to assess the product were prepared with crude oil, synthetic formation water and the inhibitor product itself. These components were mixture under certening conditions according to simulated reservoir conditions. Displacement tests using F2 product in three different core samples were carried out. The results of asphaltenes dispersions tests (ADT) indicate that the product has a 100% dispersion effect on the asphaltenes, with a colloidal stability for more than 2 h in the presence of an excess of heptane. The product performance to break up W/O emulsions is evaluated, through the preparation of model systems with synthetic water. Water resolution results indicate that resultant emulsions have low stability. In addition, the interaction (adsorption and adhesion) between crude oil and glass surface was evaluated. Crude oil shows strong adsorption on the glass surface even after water washing. While in the presence of the inhibitor product there is lower adsorption and adherence weakness of crude oil was observed on glass surface. The performance observed within the porous medium after the product been injected at reservoir conditions, shows that the product F2 mitigates formation damages responsible for asphaltene formation and deposition. Observed increments on fluid permeability values after injection of F2 to the crude oil are indication of a greater oil flow in the rock reservoir sample. Based on these findings, it can be concluded that F2 product is a suitable candidate to be evaluated into porous media, as chemical treatment in matrix non-reactive stimulation operations. • Control of asphaltene aggregation is a key to mitigate the problems. • Tuning in the strength of the inhibitor product changing the concentration of the polar additives. • The developed product was shown to be capable of breaking crude oil water emulsions. • Core sample surface shows how the formulation changes the wettability on faster time-lapse.

Breakthrough pressure anisotropy and intra-source migration model of crude oil in shale

With shale oil becoming an increasingly important resource in global oil and gas exploration and development, the breakthrough pressure of crude oil in shale series source rocks has become an important topic for research on hydrocarbon migration. Shale has long been recognized as an effective source and cap rock, with, up to now, the most common method used for breakthrough pressure testing in shale being the gas method. However, this paper sets out a new system for testing the breakthrough pressure of crude oil in siltstone, mudstone, and shale based on differences in electrical resistance between crude oil and formation water. The breakthrough pressure of crude oil with different lithology was tested in different directions using this method. The results show that breakthrough pressure anisotropy can be observed in mudstone, shale, and siltstone, and that the breakthrough pressure parallel to the bedding direction is one fourth or one seventh of the breakthrough pressure perpendicular to the bedding direction. The horizontal breakthrough pressure of shale is one twentieth to one third of that of mudstone and siltstone, and the vertical breakthrough pressure of siltstone is one seventh of that of mudstone and shale. The breakthrough pressure anisotropy of crude oil reveals that the main migration direction in shale series source rocks is in the direction of bedding unless faults or fractures are encountered. The main migration channels in shale series source rocks are in the horizontal direction, and hydrocarbon migration occurs more easily in laminar shale than in mudstone. Horizontal migration is also the principal mode of hydrocarbon expulsion in thick mudstone and shale. The breakthrough pressure experiments on crude oil in this study also reveal the migration directions and modes in intra-source rocks. This improves on the existing oil migration model and has great significance for understanding the migration of oil in shale source rocks.

Technology Focus: EOR Operations (November 2021)

As the discovery rate of new hydrocarbon resources decreases, the need for more-efficient enhanced-oil-recovery (EOR) processes increases. Unlike in the past, however, when the efficiency was defined in terms of maximizing the recovery factor (RF), the new interpretation of efficiency is based on optimizing the balance between RF and the reduction of carbon footprint. This is done through an integrated approach in which both surface and subsurface elements of the oil-production systems are used to determine energy efficiency and carbon footprint of a unit volume of oil produced by EOR methods. When choosing traditional EOR methods, new innovations may be needed to arrive at new injectant composition to reduce emissions or make the process more efficient. Adding chemicals to the injectant gas to improve the mobility ratio and increase the sweep efficiency is desirable. One example is the use of hydrogels. These are hydrophilic structures that swell when hydrated. Hydrogels are of interest in EOR because of their ability to respond to stimuli such as pH, temperature, light, and ionic strength. EOR methods that involve use of fresh water are also switching to alternative methods that reduce or remove its usage as part of water sustainability. The produced water could be treated properly to make it suitable for injection. Alternatively, polymers that are effective under high salinity or temperature could be used to deal with injecting saline water. For unconventional reservoirs, waterless fracturing techniques are progressing. Paper SPE 201609 discusses the application of a reversible hydrogel that can be added to the injected carbon dioxide (CO2) stream in order to make it a more-efficient injectant for EOR and, hence, create more opportunity for CO2 storage. Paper SPE 202809 deals with utility of new polymers that are suitable for injection into carbonate reservoirs under high-temperature and ultrahigh-salinity conditions. Finally, paper OTC 30437 discusses ways of mitigating safety risks associated with CO2 waterless fracturing in unconventional reservoirs as part of water sustainability as well as prevention of environmental pollution. Recommended additional reading at OnePetro: www.onepetro.org. SPE 200357 - Fundamental Investigation of Auto-Emulsification of Water in Crude Oil: An Interfacial Phenomenon and Its Pertinence for Low-Salinity EOR by Duboué Jennifer, TotalEnergies, et al. SPE 205118 - Experimental Design and Evaluation of Surfactant Polymer for a Heavy-Oil Field in South of Sultanate of Oman by Ali Reham Al-Jabri, Petroleum Development of Oman, et al. SPE 200256 - Chemical Enhanced Oil Recovery and the Dilemma of More and Cleaner Energy by Rouhi Farajzadeh, Delft University of Technology, et al.

Efficacy of Curcumin-based amphiphilic ionic liquids towards the demulsification of water-in-heavy crude oil emulsions

Over the past few decades, the use natural products and their derivatives as green chemicals in different applications has been increasing, due to these products’ green character, wide availability, and renewability. Curcumin is a widely available and utilized natural compound, and in this work it was converted to potassium curcuminate, which was made to react with ethoxylated hexadecyl ammonium chloride (EHC) or ethoxylated octadecyl ammonium chloride (EOC) to produce the amphiphilic ionic liquids (AILs) ethoxylated hexadecylammonium curcuminate (EHC-IL) and ethoxylated octadecylammonium curcuminate (EOC-IL), respectively. The chemical structure, surface activity, relative solubility number, thermal stability, and dynamic light scattering of EHC-IL and EOC-IL were determined with different techniques. In addition, their efficiencies in the demulsification of emulsions of water in heavy crude oil were evaluated. Moreover, the factors affecting on the demulsification efficiency, including the effect of AIL concentration, water content, temperature, and salinity were also evaluated. Both compounds displayed high efficiency as demulsifiers with efficiency increasing with the demulsifier concentration, water content, and demulsification temperature. Furthermore, EHC-IL displayed higher efficiency and produced cleaner demulsified water than EOC-IL.

The viscosifying behavior of W/O emulsion and its underlying mechanisms: Considering the interfacial adsorption of heavy components

Formation of water-in-oil (W/O) emulsion seriously limits heavy oil production, and the interfacial adsorption of heavy components of oil is the key to clarify the emulsification of crude oil and formation water. In this study, the viscosifying behavior of W/O emulsion was correlated with the interfacial adsorption of heavy components using two typical heavy oil samples, i.e., high-resins oil and high-asphaltenes oil. Results showed that the resins, instead of the asphaltenes, contributed to the pseudoplastic behavior of W/O emulsion. The interfacial adsorption of resins presented the lower interfacial tension (IFT), the higher interfacial viscosity and the stronger film stability. However, when more asphaltenes was adsorbed on the interface, the film of oil-water interface changed from viscous to brittle and breakable. According to the composition analysis, the interfacial activity of resins was much stronger than asphaltenes. Besides, the W/O emulsion formed using model oil with resins performed the better stability compared with that formed using model oil with asphaltenes. This study provided that the interfacial adsorption of resins enhanced the emulsifying ability of crude oil and the film stability of W/O emulsion, which heavily aggravated the viscosifying behavior.

Novel Bio-Based Amphiphilic Ionic Liquids for the Efficient Demulsification of Heavy Crude Oil Emulsions.

In the last few decades, there has been an increasing trend for the usage of natural products and their derivatives as green and renewable oil-filed chemicals. Use of these compounds or their derivatives contributes to reducing the use of traditional chemicals, and enhances green chemistry principles. Curcumin (CRC) is one of the most popular natural products and is widely available. The green character, antioxidant action, and low cost of CRC prompt its use in several applications. In the present study, Curcumin was used to synthesize two new amphiphilic ionic liquids (AILs) by reacting with 1,3-propanesultone or bromoacetic acid to produce corresponding sulfonic and carboxylic acids, CRC-PS and CRC-BA, respectively. Following this, the formed CRC-PS and CRC-BA were allowed to react with 12-(2-hydroxyethyl)-15-(4-nonylphenoxy)-3,6,9-trioxa-12-azapentadecane-1,14-diol (HNTA) to form corresponding AILs, GCP-IL and GRB-IL, respectively. The chemical structures, surface tension, interfacial tension, and relative solubility number (RSN) of the synthesized AILs were investigated. The efficiency of GCP-IL and GRB-IL to demulsify water in heavy crude oil (W/O) emulsions was also investigated, where we observed that both GCP-IL and GRB-IL served as high-efficiency demulsifiers and the efficiency increased with a decreased ratio of water in W/O emulsion. Moreover, the data showed an increased efficiency of these AILs with an increased concentration. Among the two AILs, under testing conditions, GCP-IL exhibited a higher efficiency, shorter demulsification time, and cleaner demulsified water.

INVESTIGATION OF EFFECT OF NEW REAGENT COMPOSITIONS ON VARIOUS CRUDE OIL EMULSIONS OF AZERBAIJAN

The article is devoted to the decomposition of strong water-crude oil emulsions formed during the preparation of crude oil for transportation. In the petroleum industry, there is a great need to develop new chemicals to improve the degradation efficiency of stable water- crude oil emulsions. Decomposition of strong water-oil emulsions is considered a key part of crude oil preparation for transportation. Therefore, the development of new demulsifying compositions to improve the degradation efficiency of stable crue oil emulsions remains relevant. This paper presents the results of studies of dehydration processes of Azerbaijani oils and emulsions depending on the degree of watering. The composition is based on Disulfan 4411, Disulfan 13280, Sarola 412, Difron 9426, ND-12 and Gossipol, they were also used to prepare Azerbaijani oil for transportation during laboratory tests of demulsification efficiency (except Difron 9426). During laboratory tests, it was determined that the best results on the degree of residual dehydration of petroleum phases were achieved using a composition called KAV-22. Keywords: Muradhanly, Bulla, Balakhany, Neft dashlari, Dehydration, Surahany, KAV-22.