Paraffinic Crude Oil Research Articles

A novel green nanocomposite for EOR: Experimental Investigation of IFT Reduction, wettability Shift, and nanofluid stability

A stable nanofluid (NF) is crucial for success of nano-enhanced oil recovery (nEOR) processes. However, this represents a significant challenge as nanoparticles (NPs) tend to agglomerate under high salinity and NP concentration adversely affecting the oil recovery. New nanomaterials including functionalized nanoparticles also known as nanocomposites (NC) can help to overcome these issues. In this paper, first, we reported synthesis, characterization, and performance evaluation of a novel hydrophobic CuO-SiO2-Montmorillonite-K+-Thiazine NC for the first time. The NC was characterized using Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Analysis (EDAX), X-Ray Diffraction (XRD), Thermogravimetry Analysis (TGA), and Fourier Transform Infrared Spectroscopy (FTIR). SEM analysis showed that the NC is composed of uniformly distributed NPs. EDAX results confirmed presence of Cu, SiO2, O2, and Cl in the NC. XRD analysis indicated that SiO2 is the dominant phase in the crystal lattice and responsible for adsorption capacity of the NC. TGA analysis showed that the NC will be thermally stable in typical reservoir temperatures (∼80°C). FTIR results confirmed presence of Si-O, Cu-O, Si-O-Si, Al-O-Si, Al-OH, and OH bonds in the NC. In the second phase of this research work, the novel NC was used to investigate recovery of a Kazakhstani paraffinic heavy crude oil from Berea sandstone with focus on IFT reduction, oil recovery, wettability alteration, and stability analysis of the NFs. NFs were prepared with NC concentrations of 250, 500, and 1,000 ppm using moderate salinity (MS), low salinity (LS), and distilled water (DW). The results showed that the optimal NF (250 ppm LS) exhibited a high zeta potential value (−65.5 mV) indicating a high stability which is superior to all of the previously reported NCs. This high stability is attributed to use of thaizine as a source of natural surfactant. The optimum NF also altered the wettability of the sandstone by 77.6% and the contact angle (CA) was reduced from 117.9° to 26.4° making the system strongly water wet. The nanoclay has significantly facilitated the wettability alteration. The optimum NF also reduced the IFT by 92.3% from 27.42 mN/m to 2.11 mN/m. An incremental oil recovery of 20% was also achieved in the tertiary or EOR stage of oil. A comparison with the NCs reported in the literature confirmed the excellent performance of this novel NC in terms of NF stability, IFT reduction, and wettability alteration. The novel NC has a great potential for nEOR and other oilfield and environmental applications.

Role of acrylate terpolymers in flow assurance studies of crude oil

Paraffinic crude oil causes deposition in the pipeline at low temperatures which hinders the flow during pipeline transportation. The primary technique for mitigation of paraffin deposition is chemical treatment. Polymeric chemical additives have gained considerable attention as flow improvers for waxy crude oil. Terpolymer application for flow assurance is a novel approach since terpolymers are seldom used as chemical additives for crude oil. Current research aims to synthesize four acrylate terpolymers with different alkyl pendant chains and study their effect on the rheological behavior of crude oil. The structure of additives was validated and their depression effect was investigated. The results of the investigation revealed that the additives showed significant decrease in pour point (ΔPP = 21 °C for CO-1 and 15 °C for CO-2) at a dose of 1000 ppm for CO-1 and 2000 ppm for CO-2. These results were also supported by rheological data which exhibited a significant reduction in viscosity (>75%) of both the crude oils which showed the efficiency of additives as flow improvers. Moreover, the cold finger test displayed excellent paraffin inhibition efficiency of synthesized additives (66 and 52% for CO-1 and CO-2, respectively). The investigation demonstrated a promising role of terpolymers as flow improvers for waxy crude oil.

Oil Deposits in Highly Paraffinic Crude Oils and in Model System

Oil Deposits in Highly Paraffinic Crude Oils and in Model System

EXPERIMENTAL STUDY OF NON-EQUILIBRIUM RHEOLOGICAL EFFECTS DURING THE FLOW OF PARAFFINIC OILS OF TIMAN-PECHORA BASIN. THIXOTROPY, SUPER ANOMALOUS VISCOSITY, OSCILLATIONS OF SHEAR STRESS

Laboratory experiments were carried out to study the non-stationary and non-equilibrium flow regimes of some paraffinic and high paraffinic crude oils of the Timan-Pechora Basin in a rotational viscometer. The presence of thixotropic properties (shear thinnig and hy steresis loops on the flow curves) is shown. The threshold character of the dependence of the area of the hysteresis loop on the oil tempera ture is demonstrated. Experiments have shown that under certain conditions on the flow curves of the studied oils, there are areas of a decrease in shear stress with an increase in shear rate, similar to areas of a «super anomalous» viscosity (SAV) in plastic lubricants. The shape and size of these areas, i.e. the intensity of the «superanomality» manifestation strongly depends on the experiment conditions and are poorly reproducible from experiment to experiment. In experiments, the SAV phenomenon at temperatures below the gelation temperature was always observed when the sample of paraffinic oil was at rest for a sufficiently long time before deformation. If, however, it was in the gap between the viscometer cylinders after the end of the next measurement cycle for a short time (no more than a few minutes), then at the next cycle of recording the flow curve, the SAV phenomenon can be practically imperceptible, although the hysteresis remains. Experiments show that if a sample of high paraffinic oil is deformed at a constant low shear rate, i.e. constant angular velocity of rotation of the device cylinder, and a temperature below the temperature of gelation, then on the falling curve of the dependence of shear stress on time («shear thinning»), oscillations in shear stress with a period equal to the period of rotation of the viscometer cylinder can be observed.

The effect of lipophilicity of corrosion bacteria on the stability of crude oil Pickering emulsions in produced water

A major environmental challenge often encountered during the production of crude oil is the formation of extremely stable oil-in-water emulsions in the effluent. The stability of these emulsions is so high that it reduces the efficiency of treatment methods. Among different parameters, the absorption of corrosion bacteria (CB) on the surfaces of crude oil droplets even more increases the emulsions stability. Therefore, in this study the lipophilicity and surface charge of three types of CBs (SRB, APB and IRB) with respect to three types of crude oil samples (paraffinic, aromatic and naphthenic) were investigated experimentally. The results revealed that based on the Langmuir adsorption isotherm a portion of CBs are adsorbed on the surface of crude oil droplets as monolayer, while another portion adheres to this monolayer leading to form a multilayer CBs. On the other hand, it was showed that the nature and chemical characteristics of droplet's organic phase affects the reversibility of the adsorbed layer of CBs. The CBs adsorption on the surface of paraffinic crude oil droplets was determined to be completely irreversible, while those of aromatic and naphthenic oil droplets were semi-reversible and reversible, respectively. The lipophilicity of SRB cells was decreased in acidic and alkaline media while it was maximum at pH = 5 corresponding to the critical zeta potential (ζC ≈ −15 mV).

Effect of polyaniline doped with dodecylbenzene sulfonic acid on pour point depressant of waxy crude oil

The production, transportation, and storage of the crude oil below or near its pour point require a deep realizing the physical, chemical properties, and operating conditions of crude oil. Out of all the methods available for pumping waxy crude oil, the use of pour point depressant (PPD) is preferred economically. Chemical oxidative polymerization of polyaniline (PANI) doped with dodecylbenzene sulfonic acid (DBSA) was prepared and applied as a PPD for paraffinic crude oil. The prepared polymer was characterized using Fourier transform infrared, UV–Visible spectroscopy, photomicrographic analysis, and scanning electron microscope (SEM). It was found that the pour point of paraffinic crude oil reduced from +42 °C to −6 °C by treating this oil with 2500 ppm of PANI-DBSA dissolved in the heavy naphtha (PONA). This result was attributed to the innovative solvent (PONA) and represents a new achievement. In addition, the value of the crystallinity index of the paraffinic crude oil decreased from 80% to 74.7% after the addition of the PANI-DBSA. The conclusion is that the pour point of paraffinic crude oil decreases with decreasing the crystallinity index. This was mainly attributed to the effect of the polar groups of the prepared pour point depressant.

Experimental investigation of wax inhibition tendency of Jatropha oil in Niger Delta waxy crude-oil

Wax formation from paraffinic crude oil and deposition in reservoir pores; production and transportation lines are a foremost severe challenge to flow assurance. Chemical wax control has received huge acceptance and is mostly used in the petroleum industry. This work experimentally examined the Paraffin Inhibition tendencies of Jatropha oil (JTO), Jatropha oil-based Polyaminoamine (JPA), JTO dissolved in xylene (JTOX), and JPA dissolved in xylene (JPAX) in Niger Delta waxy crude-oils. Four performance indicators; Pour Point (PP), Weight of Wax Deposited (WWD), Wax Appearance Temperature (WAT), and Wax Crystal Morphology (WCM) were used to test the wax inhibition tendency of three crude oils. All experiments were performed on the blank and additives-treated crude-oils. The results obtained confirm that JTOX and JPAX act as PP depressants. Also, WWD decreases with increasing cold finger temperature correlating to the higher Wax Inhibition Efficiency (PIE) of the chemical additive. Below the WAT, the viscosity increased at a higher rate and the least wax amount was deposited, hence, the highest PIE (Crude-oil A:71%; Crude-oil B:72%; Crude-oil C:70%) was observed and close to the industrial control paraffin inhibitor (Crude-oil A:67%; Crude-oil B:65%; Crude-oil C:75%). JPAX has a significantly improved performance as a PP depressant than JTO alone.

Designing of a washing composition model to conduct the hot flushing wells producing paraffin crude oil

The article discusses the problems of asphaltene, resin and paraffin deposition and paraffin control methods in an oil production well. This is a critical issue in the oil and gas industry, especially in the oilfields of the Ural-Volga region (Russia). This work aimed at the development of a basic model of a detergent for hot flushing in oil wells. Traditionally in oilfield practice, well cleanouts are followed by discharge of used flush fluid into production fluid gathering and transportation system. This is a counterproductive and unsustainable practice involving costly chemical agents that retain all their useful properties after use. The authors have developed a water-based detergent model for hot flushing at a target facility. Its process efficiency was evaluated against the use of hydrocarbon solvents. Proposed is the developed solvent technology that will allow to increase its effective use and to reduce costs due to its re-use. The technology's novelty consists in the waste reduction during well cleanout and the increase of process efficiency of measures based on several flushing operations. The theoretical studies have highlighted the possibility of repeated use of the developed detergent, which will considerably reduce the subsoil users' costs.

Short-Term Biodegradation of Crude Petroleum Oil in Water by Photostimulated Janibacter terrae Strain S1N1.

Biodegradation is a sustainable green strategy that gives the opportunity for remediation of water contaminated with petroleum products. In this study, 12 bacterial isolates were recovered from River Nile, Egypt and screened for their potential to degrade a mixture of paraffinic petroleum crude oil. The most promising isolate was identified according to 16S rRNA sequencing as Janibacter terrae strain S1N1 (GenBank accession No. KX570955.1). In order to boost the biodegradation efficiency, the bacterial suspension was photostimulated by exposure to different irradiation doses using a low-power helium–neon (He–Ne) laser (λ = 632.8 nm). Maximum biodegradation was achieved after 4 min of exposure (134.07 J cm–2) at optimized pH value (6) and temperature (35 °C). The gas chromatography–mass spectrometry (GC-MS) analysis revealed the biodegradation of 96.5% of the substrate after only 48 h of incubation. The n-C17/Pr and n-C18/Ph ratios indicated a preferential biodegradation of iso-paraffines over normal ones. Meanwhile, pristane/phytane (Pr/Ph) ratios were indicative of selective biodegradation for pristane. The carbon preference index (CPI) was nearly around unity indicating the ability of Janibacter terrae to attack the odd and even n-alkanes simultaneously. These results support the superiority of irradiated bacteria in optimizing the biodegradation efficiency and shortening the time of treatment, thus proposing an eco-friendly technique in water bioremediation programs.

Study on the influence of poly (m-aminophenol) as pour point depressant of paraffinic crude oil

Paraffin wax in crude oil can cause significant problems such as a block of pipelines because of the deposition of wax components during the production, transportation and storage of the crude oil. This work aims to inhibit the deposition of paraffin wax at low temperatures. Poly (m-aminophenol) (PmAP) was prepared by oxidative polymerization technique to act as a pour point depressant (PPDs) for paraffinic crude oil. PmAP was characterized by Fourier Transform Infrared (FTIR) and Scanning Electron Microscope (SEM). The thermal stability of the polymer was investigated by thermal gravimetric analysis (TGA). The effect of the PmAP on the wax crystal modification was studied using photomicrographic analysis. The pour point of paraffinic crude oil was reduced from +42ºC to +6ºC when treated with 2500 ppm of PmAP dissolved in a solvent-based on paraffinic compounds (PONA). The photomicrographs showed that the PmAP has reduced the large size of the spherical wax crystals of the North Silah-1X crude oil this was mainly attributed to the effect of the polar groups of the prepared pour point depressant.

Development of wax molecular diffusivity correlation suitable for crude oil in wax deposition: Experiments with a cold-finger apparatus

Wax deposition is a hot and difficult topic in waxy crude oil transportation. Wax molecular diffusion is recognized to play a crucial role in wax deposition. Empirical correlations of Hayduk-Minhas and Wilke-Chang are widely used to calculate the wax molecular diffusivity. However, they are developed based on binary solutions and underestimate the diffusion coefficient of wax components. To address this issue, wax deposition experiments with different crude oils were conducted in cold-finger apparatus. The temperature distribution was obtained by computational fluid dynamics software of Fluent and the characteristics of wax deposit were investigated. In addition, the wax molecular diffusion process under saturated and partial saturated conditions were theoretically elucidated. It was found that the bulk temperature, deposition duration and carbon number distribution of wax molecules can significantly influence the total wax content and wax precipitation properties of wax deposits. Moreover, the wax molecular diffusivity experimentally calculated based on the Fick's first law were found larger than that obtained by correlations of Hayduk-Minhas and Wilke-Chang. A new correlation calculating the wax diffusion in crude oil was developed and verified with experiments. Good agreement between predicted and experimental values was observed with maximum relative deviation being 12.52% and mean absolute error being 8.90%. This new correlation is suitable in wax molecular diffusivity calculation for crude oils. • Highly paraffinic crude oils under saturated and partial saturated conditions were used in the wax deposition experiments. • Wax precipitation characteristics and morphologies of the wax deposits were compared and analyzed. • The wax molecular diffusion process was theoretically elucidated and the wax molecular diffusivity was calculated. • A new correlation for predicting wax molecular diffusivity in crude oil was developed and verified with experiments.

Glycerol-modified cashew nut shell liquid as eco-friendly flow improvers for waxy crude oil

Use of pour point depressants/flow improvers is an effective strategy for alleviation of flow problems associated with wax formation in paraffinic crude oil. Biobased oilfield chemicals derived from renewables are appealing as low-cost, eco-friendly alternatives to conventional pour point depressants. Cashew nut shell liquid (CNSL) extracted from Anacardium occidentale shells was modified by esterification with glycerol. The CNSL derivatives were evaluated as pour point depressants and low-temperature flow improver for waxy crude oil. Pour point and viscosity of doped crude oil were reduced by a maximum of 15 °C and 86%, respectively. Cross-polarized micrographs of doped oil were analyzed with Image J software and showed decrease in wax crystal aspect ratio and boundary fractal dimension indicating modifications to wax morphology and microstructure.

Biodemulsification combined with fixed-bed biosorption for the recovery of crude oil from produced water

Produced water can be used as a source of potable water and valuable chemical components (pure elements, minerals). The recovery and beneficial use of emulsified and dissolved hydrocarbons from these brines are not a priority. Oil removal methods focus on water decontamination without further management of recovered oil. In this work, biosorption combined with “green” demulsification is applied to recover paraffinic crude oil from artificial brine. Soapwort extract at a concentration of 0.5 g/L destabilized oil/water emulsion allowed 85–95 % oil recovery. Adsorption beds made of sunflower pith were applied to remove dissolved hydrocarbons. To enhance sorption capacity, the plant material was impregnated with polydimethylsiloxane (PDMS) and hydrophobic nanosilica. The oil removal kinetics on the modified pith followed a pseudo-second order model. The adsorption isotherm at 20 °C was well described by the Temkin model, while the Toth model provided the best fit to experimental data at 40 °C. The maximum sorption capacities in a two-phase oil-water system were 3.544 g/g and 4.187 g/g for the hydrophobized and raw pith, respectively. The pith filter performed well. A maximum oil reduction of 73 % in effluent was achieved at 10 cm bed height and 15 mL/min flow rate. Sorbent regeneration studies show that residual oil from spent material can be easily drained, and the recovery ratio is up to 68 %. Both bioprocesses, biodemulsification and biosorption, are effective technologies that can be used to separate oil from oily water.

Effects of 4-vinylbenzyl trioctylphosphonium- bentonite containing poly(octadecylacrylate-co-1-vinyldodecanoate) pour point depressants on the cold flow characteristics of waxy crude oil

Wax crystals networks of paraffinic crude oil are a result of cooling processes that greatly affect the macroscopic properties of wax oil, which in turn affect the rheological behavior of waxy crude oil. Therefore, it is very important to study the effect of the formation of these crystals on the rheological properties of wax oil by considering the inhibition of the formation of these crystals. This research paper aims to study the impact of polymer nanocomposite on the pour point of paraffinic crude oil and to determine the rhetorical properties of paraffin oil treated with a polymer containing nano-layered bentonite material. Firstly, the bentonite clay (BT) was treated with a 4-vinylbenzyl trioctylphosphonium chloride monomer (VTOP) to turn the clay surface from hydrophilic to lipophilic clay (VTOP-BT) and consequently facilitate its incorporation into the octadecylacrylate-co-vinyldodecanoate copolymer.A series of the poly(octadecylacrylate-co-1-vinyldodecanoate-co-VTOP-BT) nanocomposites with different ratios of VTOP-BT (0.5–3%) was prepared using radical solution polymerization and described using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction, high-resolution transmission microscopy, and proton nuclear magnetic resonance (1H NMR). The collected results from the effect of the additives on crude oil have demonstrated that polymers nanocomposites have a significant impact in reducing the viscosity of wax crude oil compared to poly(octadecylacrylate-co-vinyldodecanoate). By using a dose of 1500 ppm of poly(octadecylacrylate-co-vinyldodecanoate-co-VTOP-BT) nanocomposite that contains 1% VTOP-BT, the pour point decreased from 27 to −3 °C (i.e., 30 °C). By the same token, the long-term stability measurement, the polymer nanocomposite slowed excellent behavior compared to virgin polymer.

An experimental evaluation of low salinity water mechanisms in a typical Brazilian sandstone and light crude oil with low acid/basic number

Low salinity water injection (LSWI) is a current and cost-effective method to enhance oil recovery by changing the salinity and composition of the injected water. However, the synergistic effect of chemical composition, concentration and in particular the pH of the brine in oil recovery during LSWI remains not well understood. In addition, there is a lack of low salinity studies in Brazilian sandstone rocks and light paraffinic crude oils of low acid/basic number to date. This paper investigates oil recovery mechanisms and the pH effect in high and low salinity brine solutions using samples from a clastic reservoir in Recôncavo basin, northeastern Brazil. Zeta potential and interfacial tension measurements, oil adsorption analysis using a quartz crystal microbalance with dissipation monitoring, and core flooding experiments were performed using different concentrations and pH values of synthetic formation water (SFW), NaCl and CaCl2 brine solutions. The results indicate that when the reservoir pH changes towards the alkaline conditions driven by ionic exchanges during LSWI, it may approximate the isoelectric point (IEP) of pH-dependent surface charges in oil and rock minerals, weakening the electrostatic attraction between their surfaces, and consequently contributing to increased oil recovery. The findings of this study can help understand oil recovery mechanisms during LSWI according to the type and content of pH-dependent surface charges in sandstone rocks and crude oils. This study also shows how to pre-select potential field candidates in the Recôncavo basin and similar formations for stand-alone and hybrid LSWI applications.

Oil Recovery Efficiency and Mechanism of Low Salinity-Enhanced Oil Recovery for Light Crude Oil with a Low Acid Number.

Low salinity waterflooding (low salinity-EOR) has attracted great interest from many giant oil producers and is currently under trial in some of the oil fields of the United States, Middle Eastern countries, and North Sea reservoirs. Most of the reported studies on this process were carried out for medium to relatively heavy oil with significant polar contents. In this work, we have investigated low salinity waterflooding performance for light paraffinic crude oil with a low acid number. This study has been performed using crude oil from an Indian offshore oilfield and Indian offshore seawater. Oil recovery efficiencies of seawater and its diluted versions (low salinity seawater) were evaluated through core-flooding experiments performed on a silica sand pack containing small amounts (2 wt %) of bentonite clay saturated with crude oil. Interfacial tension and wettability studies were performed to understand the associated low salinity effects on the crude oil/brine/rock properties. Effluent brine produced during the flooding experiments was also analyzed to obtain a clearer insight into the low salinity-enhanced oil recovery (EOR) mechanism. The results showed that injection of low salinity seawater can significantly increase the waterflood recovery in comparison with high salinity seawater injection. Interfacial tension and contact angle studies revealed that there is an optimum dilution level at which the interfacial tension and wettability are the most favorable for enhanced oil recovery even in the case of light paraffinic crude. These results are in line with the results obtained from the core-flooding experiments. The possible reason behind recovery improvement based on the interfacial tension and wettability studies in conjugation with the effluent brine analysis has been discussed in detail. In this study, we have observed that the enhanced oil recovery efficiency could be achieved by applying low salinity seawater flooding even in the case of light paraffinic oil with a low acid number.

Influence of Heavy Organics Composition on Wax Properties and Flow Behavior of Waxy Crude Oils

Paraffinic crude oils are desirable because of their high content of saturated hydrocarbons but may present handling challenges due to crystallization of high molecular weight paraffin at low temperatures. The prediction of wax properties and behavior of waxy crude oil is important in order to adopt appropriate mitigative measures to forestall flow assurance problems associated with wax crystallization and deposition. Accurate predictive models are limited mainly by the sheer complexity of crude oil composition. Result of analysis of saturates, aromatics, resins and asphaltene content of crude oils (SARA) has been used as a simple tool to predict and interpret crude oil properties and behavior but has been found inadequate in predicting wax instability. In this paper, we report on the use of SARA analysis and paraffin distribution data to interpret the wax properties and flow behavior of Niger-Delta crude oils. The crude oil properties determined include wax content, asphaltene and resin content by gravimetry, pour point, wax appearance temperature by cross-polarized microscopy and paraffin carbon number distribution of whole oil and wax precipitate by GC-FID. Asphaltene and resin content were found to influence the oil pour point, while saturates content, paraffin carbon number of crystallizing waxes and wax content control its low-temperature flow properties.

Investigation of Crude Palm Oil as an Alternative Processing Oils in Natural Rubber : Effect of the Unsaturated Fatty Acid

Petroleum based processing oils is the hydrocarbon oils derived from petroleum refining process and commonly used as extender or processing oils to improve the rubber processability. Hydrocarbon oils can be classified as paraffins, aromatics, naphthene and olefins oil based on their molecular structure. The studies on replacement of hydrocarbon oils with natural processing oils had been studied by vast number of researchers due to finite resources and the toxicity of the hydrocarbon oils which enhanced awareness in using natural based oils. These natural processing oils are from vegetable or animal. The vegetable oils contain mainly unsaturated fatty acids. Studies showed that the unsaturated fatty acids affect the cure characteristics and the mechanical properties of the filled vulcanizates as these fatty acids took part during the vulcanization and promote the filler-rubber interaction. In this study, natural rubber (NR) of grade Standard Malaysian Rubber 20 (SMR 20) with the loadings of paraffin oil (PO) and crude palm oil (CPO) between 1 to 5 phr was investigated. Within the loadings of PO and CPO studied, the unsaturated fatty acid in CPOs were reported to results in plasticizing effect which results in lower minimum and maximum torques. Though that the unsaturated fatty acid which took part during the vulcanization prolonged the cure time, it resulted in higher CB-SMR 20 interaction. The tensile properties, tear strength, hardness and abrasion resistance of the CPO recipes were affected by combination of plasticizing effect and better CB-SMR 20 interaction.

A novel method for the separation of high-molecular-weight saturates from paraffinic petroleum based samples

The precise chromatographic isolation of saturates is a common problem of the characterization of highly paraffinic petroleum based samples. Incomplete elution of high-molecular-weight saturates (HMWS) or contamination of saturates by aromatics can occur when alumina or silica gel are used to separate highly paraffinic samples. Here, we present a precise, fast and simple method for the quantitative isolation of HMWS from samples of highly paraffinic crude oils, crude oil deposits, high-boiling petroleum distillates, distillation residues and waxes. The method is based on a direct chromatographic elution of HMWS with n-heptane at 80 °C on a column packed with silica gel modified with silver nitrate. The pre-separation of asphaltenes from samples is not necessary. This allowed for a quantitative elution of all present HMWS (up to C100) with no contamination by aromatics. As an example of a practical application to benefit from this efficient hydrocarbon fractionation procedure, is the analysis of crude oils and deposits. A detailed knowledge of the content of high-molecular-weight n-alkanes in these samples can help to prevent problems during crude oil transport and storage.

Application of novel hydrophobically modified polybetaines based on alkylaminocrotonates and methacrylic acid as pour point depressants and ASP flooding agent

A series of hydrophobically modified polymeric betaines (HMPB) were synthesized from alkylaminocrotonates and methacrylic acid, analyzed by methods of GPC, potentiometric titration and DSC and applied as pour point depressants (PPD) to high paraffinic crude oils of Western Kazakhstan. The efficiency of paraffin inhibition with the help of HMPB was evaluated in static and dynamic conditions. The physicochemical properties of the Mangyshlak oil and the Buzachi–Mangyshlak oil mixture (67:33 vol%) were determined. Paraffins were found to form gelled networks in the Mangyshlak oil and Buzachi–Mangyshlak oil mixture within the fractions of hydrocarbons with lengths of C12–C17 and C13–C16. The results of testing the HMPB as PPD in the model tank and oil pipeline showed that, at a concentration of polymeric additives of 500 ppm and at an injection temperature of 60 °C, the quantity of precipitated asphaltene–resin–paraffin depositions was significantly reduced. The efficiency of HMPB bearing C16H33 groups was tested as a prototype alkaline–surfactant–polymer flooding agent on the heavy oil of the Karazhanbas oilfield.