Bottle Test Method Research Articles

Demulsification efficiency of the leave extract from African blackwood (Delbergia melanoxylon)

The demulsification efficiency of the leave extract from African Blackwood (Delbergia Melanoxylon) was determined using the bottle test method. Methanol, n-heptane and distilled water were used as extraction solvents respectively to extract the active ingredients of the leave. A 200 ml crude oil emulsion obtained from Niger Delta area Nigeria was introduced into six (6) calibrated 500 ml Teflon-stoppered bottles respectively, the leave extract in the solvent was introduced into each of the bottles as a demulsifier at concentrations of 50, 100, 150, 200 and 250 ppm with the sixth bottle left as control (without demulsifier). All the bottles were immersed in a water bath of 60 0C after mixing properly with a mechanical laboratory mixer and left for an hour. After an initial 5 minutes, the percentage of water separated in each bottle was recorded after 10 minutes. Bottle test was also carried out using a synthetic demulsifier (DXO77) on the same crude oil. Results obtained shows that the leave extract using methanol had the highest demulsification efficiency separating 50.5 % water from the crude after 60 minutes with a demulsifier concentration of 250 ppm. A 250 ppm of the synthetic demulsifier (DXO77) separated 51.0% of water from the crude after 60 minutes. The leave extract using n-heptane and distilled water separated 40.5 % and 32.5% water from the crude after 60 minutes at demulsifier concentrations of 250 ppm respectively. There is a consistency in the percentage of water from the crude within the last 15 minutes indicating that the separated water in the crude has reached its threshold, further increase in the demulsifier concentration at this point could lead to emulsification. The demulsification efficiency of plant extracts such as African Blackwood (Delbergia Melanoxylon) are influenced by the characteristics of the extraction solvent such as solvating power and extraction capacity.

Engineering water-shut-off operations: Application of rheological time-temperature superposition approach for organically-crosslinked polymer gel systems

Polymer-based gels have been extensively utilized in reservoirs to prevent excessive water production and improve oil recovery. In this study, a sulfonated-hydrolyzed polyacrylamide polymer (HPAM-S) and low-toxic organic crosslinkers (hydroquinone and hexamethylenetetramine) were mixed in brine at specified concentrations to formulate the polymer-crosslinker fluid system. The quantitative rheological analysis, along with the TTS (Time-Temperature Superposition) approach, was examined for the first time to achieve the water shut-off operations in high-temperature reservoirs (90 °C–150 °C). The TTS approach was defined as modelling of the viscosity vs. time data obtained at various temperatures using an appropriate empirical shift factor (at) such that a single master curve is established for the viscosity evolution of the given fluid system. This approach facilitates the prediction of the gelation behavior of polymer-crosslinker fluid systems as a function of time at varied reservoir temperatures especially over time scales that are not experimentally accessible. The time-dependent rheological evolution of the fluid system was experimentally investigated using batch-wise bottle testing methods as well as viscosity and viscoelastic measurements by employing an advanced rheometer. The TTS approach was applied to the obtained rheological data at varied temperatures. The model was validated for an unknown set of temperature vs. viscosity data. Based on the TTS approach, the term ‘gelation time’ was defined as the time required to reach a pre-specified viscosity to signify a transition from the liquid-like state to the solid-like state. The gelation time decreases with increasing temperatures. After the gelation time, at each temperature, a swift increase in the fluid viscosity was observed, indicating the initiation of the rapid crosslinking in the fluid systems. It was found that beyond the gelation time, the batch-wise bottle testing showed (G-I) gel strength (qualitative). Analogously, the visco-elasticity test demonstrated a rapid rise in elastic modulus (G′) beyond the gelation time. An underlying mechanism based on polymer hydrolysis was utilized to explain the evolution of distinct viscous and viscoelastic properties as a function of temperature. Moreover, the modeling predictions for the fluid systems were examined for in-situ rock plugging with the help of core-flood equipment. The core-flooding tests confirmed a 99% reduction in the rock permeability beyond the gelation time. The gelation time values obtained from both the batch-wise bottle testing method and rheological tests for the polymer-crosslinker fluid systems were found in agreement with each other, with a tolerance of (±5%).

Advancing green technology: demulsifier preparation and evaluation for crude oil emulsion treatment using corn oil

Globally, oil production has steadily increased which causes a rise in the coproduction of oil and water emulsions. These emulsions pose significant challenges in transportation and the oil refinery industry, causing high-pressure drops and corrosion problems due to chlorides in the water. Despite advancements in renewable energy, crude oil remains a primary energy source. The crude oil industry faces numerous challenges, including cost emulsion issues. This study developed a corn oil bio-demulsifier (MFK). A unique demulsifier was tested using FTIR, GC-MS, and TGA. Using the bottle test method, the produced demulsifier MFK was tested with Basrah oil and East Baghdad S1 oil. The emulsion-breaking processes have been studied under several factors, such as settling time, dosage, temperature, pH, water content, and mixing time after demulsifier addition. At 2000 ppm Basrah oil, water separation efficiency reached 75%. For East Baghdad S1 oil, the highest separation result was 43.3% at 4000ppm, after 5 h of settling time at 70°C, with a 30/70 water-to-oil ratio. When studying the pH, the best water separation rate was 86.5% at a pH of 10. The best water content was 92% when the water-to-oil ratio was 50/50, and the best demulsifier mixing time with the emulsion was 2 min with a separation rate of 74.5%. When mixing was increased, undesirable results occurred. This study demonstrated that biodemulsifiers may replace conventional biodemulsifiers in early units while reducing environmental and economic impacts with further study and development.

Adsorption behavior of asphaltene aggregates generated by self-association at the oil/water interface

The formation of emulsions is undesirable yet unavoidable in petroleum production. Researchers suggest that asphaltenes adsorb at the oil/water interface, forming a protective film that stabilizes emulsions. This study investigates how asphaltene aggregates, formed through intermolecular interactions, affect emulsion stability and the properties of the oil/water interface. First, the effects of asphaltene concentrations, components, and temperatures on emulsion stability and the association state of asphaltenes were explored using the bottle test method and dynamic light scattering, respectively. The promotion of asphaltene aggregation by higher asphaltene concentrations and liquid paraffin content was confirmed by comparing the average size of aggregates, while higher temperatures were found to inhibit aggregation. Higher temperatures destabilize emulsions containing asphaltenes by increasing water droplet collisions, whereas higher asphaltene concentrations and liquid paraffin content stabilize emulsions. Subsequently, the effects of these conditions on expansion modulus were thoroughly investigated using the pendant drop technology. Pendant drop experiments demonstrate that increasing asphaltene concentration, along with the introduction of liquid paraffin, enhances asphaltene aggregation, thereby reinforcing the structural stability of the interfacial film. Spinning drop experiments were conducted to obtain dynamic interfacial tension (IFT) and analyze the adsorption behavior of aggregates at the oil/water interface. The adsorption process of asphaltenes driven by intermolecular interactions, occurs in three regimes: a short-term diffusion-controlled process, a transition process, and a long-term low-speed descent process, referred to as Regimes I, II, and III. The diffusion coefficient in Regime I increases with temperature, while the equilibrium IFT in Regime III decreases with temperature. In Regime II, adsorbed asphaltene aggregates from Regime I tend to prevent further adsorption, reducing the rate of dynamic IFT decrease. In Regime III, dynamic IFT decreases slowly, primarily due to the continued adsorption of asphaltene aggregates into the sublayer and their subsequent reconfiguration. These findings have significant implications for improving the understanding of oil/water interface properties and emulsion behavior in oil production, transportation, and refining systems.

Performance Assessment of Biomass-derived Urea-Furfuraldehyde Resins as Oilfield Scale Inhibitors

Oilfield-scale formation is a persistent challenge in the oil industry. While numerous scale inhibitors have been in use for decades, there is a significant research gap in discovering renewable, cost-effective, ecologically friendly, and efficient inhibitors. This study sets out to fill this gap by investigating the potential of scale inhibitors (SIs) made from bio-resin derivatives of red onion skin; ROF and ROFU, in reducing CaCO3 and CaSO4 scales. The scale inhibition performance of ROF and ROFU was rigorously evaluated using the NACE standard static bottle test method. The data revealed that increasing scale-inhibitor contact time, concentration, and temperature enhances inhibitor efficacy, with the best inhibition efficiencies found for ROF and ROFU on the CaSO4 scale compared to the CaCO3 scale across all studied parameters. A comparison of the prepared SIs with a commercial scale inhibitor (CSI) showed a high inhibition rate of over 90% at minimal dosage of 60ppm in both scales studied. Despite having a lower inhibition rate (IE) than CSI, ROF and ROFU demonstrate significant potential as green oilfield SIs. This sustainable technique, which transforms agro-waste into a valuable oilfield chemical via a one-pot chemical process, could have profound economic and societal benefits, offering hope for a more sustainable future in the oil industry.

Synthesis of a low-temperature demulsifier with dual-hydrophobic chains through a simple low-temperature process

The extraction of crude oil generates a significant volume of stable emulsions that can lead to various adverse effects in industrial extraction processes. Therefore, emulsion demulsification is a crucial step. In this paper, PGDA, a low-temperature W/O demulsifier with double hydrophobic chains, was synthesized from poly(ethylene glycol) diacrylate by a simple low-temperature process. The structure of PGDA was analyzed by FTIR and 1H NMR, and the demulsification performance was evaluated by a bottle-testing method. The results demonstrated that PGDA, at a concentration of 500 mg/L, achieved a demulsification efficiency of 100 % under low-temperature conditions (45 °C) over a 5-hour period. Furthermore, it also showed good demulsifying performance in wide pH range (6–10) and high salinity (100,000 mg/L). In addition, the possible mechanism of demulsification of PGDA was investigated by zeta potential, interfacial tension, and three-phase contact angle, etc. PGDA showed strong competitive adsorption ability with asphaltenes at the interface. PGDA has the ability to navigate rapidly to the oil–water boundary and displace the native surfactants there, thus destabilizing the emulsion and thus promoting the separation of oil and water. PGDA by virtue of the simple synthesis process, low demulsification temperature and high efficiency are of practical application.

Demulsification of Water-in-Crude Oil Field Emulsion Using Green Demulsifier Based on Sesamum indicum: Synthesis, Characterization, Performance, and Mechanism

Summary This paper addresses the issues related to poor demulsifier efficiency, low biodegradability, and toxicity of commonly used chemical demulsifiers in the petroleum industry. To overcome these challenges, this study proposes an environmentally friendly demulsifier synthesized from Sesamum indicum (sesame oil). The synthesized demulsifier is characterized using Fourier transform infrared (FTIR), nuclear magnetic resonance (NMR), and thermogravimetric analysis (TGA). The demulsification test was performed for the synthesized demulsifier through the standard bottle test method using water-in-oil field emulsion. The results indicate that the demulsifier has an excellent dehydration rate and can achieve a demulsification efficiency of 85% within 10 minutes at a concentration of 200 ppm and 100% efficiency in 60 minutes at 70°C and performs better than the commercial demulsifier. The paper summarizes the factors affecting the demulsification process, including settling time, temperature, and demulsifier concentration. Furthermore, the demulsification mechanism is explained through interfacial tension (IFT) measurement, competitive adsorption test between asphaltene and demulsifier, and rheology study of emulsion. Moreover, the disuccinimidyl sulfoxide (DSSO) demulsifier is tested for its biodegradability according to Organization for Economic Co-operation and Development procedure, and the results show that it is completely biodegradable. The outcome of this research provides a promising solution for the demulsification of field emulsions through eco-friendly and efficient demulsifier.

One-Pot Synthesis of Amphipathic Esters for Demulsification of Water-in-Crude Oil Emulsions.

The current work aims to synthesize new amphipathic compounds, TGHA and PGHA, and investigate their demulsification performance (DP) in water-in-crude oil emulsions. Their chemical structures, thermal stability, interfacial activity, and micelle formation were investigated by different techniques. The bottle test method was used to investigate the effect of demulsifier concentration, water content, temperature, and demulsification time (DT) on the DP of TGHA and PGHA compared to a commercial demulsifier (CD). The results indicated that these parameters have a noticeable impact on the DP of TGHA and PGHA. The results also showed that TGHA exhibited higher DP than PGHA at all investigated parameters, which could be explained by increasing its hydrophobicity due to lower oxyethylene units in its structure than PGHA. An increase in these units means increased hydrophilicity, which led to obstruction of PGHA molecule diffusion in crude oil as a continuous phase. Moreover, TGHA gave a comparable DP with CD, as it gave a higher DP and shorter DT than CD at a higher water content (50%), while the latter achieved the highest DP and the shortest DT at a low water content (10%).

A low-temperature ionic liquid demulsifier derived from recycled PET waste plastics

The petroleum industry produces a large volume of water-in-oil (W/O) emulsion annually, which has detrimental consequences for both the industry and the environment. Therefore, effective demulsification of these emulsions is crucial. In current work, a low-temperature demulsifier (EBTA) for W/O emulsions was synthesized using PET waste plastic as starting materials through a simple method. Chemical structure of EBTA was characterized by FT-IR and 1H NMR. The demulsification performance was assessed using bottle-test method, and a comprehensive examination was conducted on the influence of EBTA concentration, settling time, temperature, pH value, and salinity on the demulsifying efficiency (DE). At a low temperature of 40 ℃ and a concentration of 250 mg/L, EBTA achieved a DE of 95.36% in an Emul30 emulsion, while a DE of 100% could be obtained in an Emul70 emulsion. Furthermore, EBTA demonstrated excellent tolerance for salts, acids and alkalis. In addition, the demulsification mechanism of EBTA was investigated using various techniques, such as interfacial tension (IFT), zeta potential, three-phase contact angle and coalescence time of droplets. The results revealed that EBTA had a lower IFT and was easily adsorbed on the oil–water interface. This led to the damage of the interface film and facilitated the oil–water separation. Due to the simple and safe synthesis process and remarkable demulsification performance, EBTA is a promising demulsifier for separating W/O emulsions.

Demulsification efficiency and mechanism of hydrophobic carbon chains modified hyperbranched polyethylenimide on oil-in-water emulsion

A series of amphiphilic hyperbranched polyethylenimine (HPEI-Cn) with different length hydrophobic carbon chains were synthesized by amidation modification of hyperbranched polyethylenimine (HPEI), which can be used for separation of oil-in-water emulsion. The demulsification effect of HPEI-Cn under different demulsifier concentration, temperature, settling time and pH value were evaluated by bottle test method. The results indicated that the demulsification efficiency (DE) of HPEI-Cn increased with the increase of graft length of carbon chain. Encouragingly, the HPEI-C16 had the characteristics of small amount (50 mg/L), short settling time (30 min) and wide temperature adaptation range (20–60 °C). Through three-phase contact angle tests (CA), dynamic interfacial tension tests (IFT), elastic modulus analysis, Zeta potential and microscope observation, the demulsification mechanism of HPEI-Cn was systematically revealed. The excellent DE of HPEI-C16 was attributed to the high interfacial activity and appropriate length of hydrophobic groups. On the one hand, the high interfacial activity drives hyperbranched macromolecules to rapidly diffuse and adsorb to the oil-water interface. On the other hand, it contains appropriate hydrophobic carbon chains C16 to flocculate and coalesce oil droplets, thus achieving efficient demulsification.

Efficient Demulsification Performance of Emulsified Condensate Oil by Hyperbranched Low-Temperature Demulsifiers.

Focusing on the problem of poor demulsification performance of light crude oil emulsions in low-permeability oilfields at low temperatures, the composition of the emulsion samples, clay particle size distribution, and the viscosity-temperature relationship curve of samples were analyzed. Based on the results of emulsion composition analysis and characteristics, the bottle test method was used to analyze the demulsifying effect of different commercial types of demulsifiers, revealing the demulsification mechanism. The field tests confirm the demulsification capabilities of Polyoxyethylene polyoxypropylene quaternized polyoxyolefins surfactants (PR demulsifiers). The results reveal that PR demulsifiers combine the features of decreasing the interfacial tension between oil and water and adsorbing SiO2, allowing for quick demulsification and flocculation at low temperatures. This research serves as a theoretical and practical foundation for the study and advancement of low-temperature demulsification technology in oilfields.

Performance of Plastic Waste-Based Polyionic Liquid toward the Dehydration of Crude Oil Emulsions

Polyethylene terephthalate (PET) is one of the most widely used plastics in the world. Due to the large production and use of this plastic, its waste represents one of the most critical environmental problems. The purpose of this study is to convert PET waste into a valuable material. The consumed PET was transformed into a precursor to synthesize a polyionic liquid (PIL) that was used for dehydrating crude oil emulsions. To do so, the consumed PET was converted to bis(2-hydroxyethyl) terephthalate (BHET). First, BHET and tetraethylene glycol were reacted separately with thionyl chloride, obtaining the corresponding alkyl halides, bis(2-chloroethyl) terephthalate, BCET, and TEC, respectively. Next, the obtained alkyl halides, BCET and TEC, were reacted with 1,5-pentanediamine, yielding a polymer (BTP). Finally, BTP was reacted with acetic acid to produce the corresponding PIL (BTP–PIL). The structure and thermal stability of BTP–PIL were characterized using nuclear magnetic resonance spectroscopy and thermal gravimetric analysis. The dehydration performance of PIL and the original polymer was investigated using the bottle test method, including several factors such as demulsifier dose, brine content, temperature, and settling time. Results indicated that PIL achieved high performance in dehydrating crude oil emulsions.

Synthesis of Green Polyethylene Glycol-Lauric Acid Demulsifier from a Natural Source and Its Application in Demulsification of Field Emulsion: Experimental and Modeling Approach

Summary Green demulsifier was synthesized through an esterification technique by using polyethylene glycol (PEG) and fatty acid (lauric acid). The synthesized demulsifier was characterized through several tests to analyze the functional groups and determined the molecular structure, thermal stability, and biodegradability of the demulsifier molecule. The performance of the synthesized demulsifier was investigated using the standard static bottle test method to break the water-in-oil (W/O) tight emulsion. Optical microscopic and viscosity studies of emulsions were also performed to understand the demulsification process and mechanism. Based on the response surface method (RSM), central composite design (CCD) was used to develop the statistical model of demulsification efficiency by considering the four most influencing factors—demulsifier concentration, water content, settling time, and temperature—and to examine the optimal condition for maximum water separation from the emulsion. The statistical model’s accuracy and significance were evaluated using analysis of variance (ANOVA) and diagnostic plots. The effect of each factor was analyzed through 3D graphs and contour maps. The result indicates that all the factors significantly influenced the demulsification efficiency with a p-value of <0.0001, among which the presence of water is the dominating variable. At the optimal condition, the lauric acid-PEG-demulsifier (LPED) achieves a maximum demulsification efficiency of 95% in 30.9 minutes. Furthermore, the percent absolute deviation was computed after comparing the experimental findings to those predicted by the model and it was observed that the model’s prediction accuracy was >97%. Finally, the biodegradability test results showed that the developed demulsifier is completely biodegradable in 21 days. Because the synthesized demulsifier is eco-friendly and has an excellent dehydration rate, it may be used in the petroleum industry for breaking field-tight emulsions as an alternative to chemical demulsifiers.

Ultimate and primary biodegradation of a range of non-polymeric and polymeric surfactants in seawater.

Surfactants are a major class of chemicals commonly used in a wide range of domestic and industrial products. In this study, ultimate biodegradation of 18 surfactants representing different classes (including several polymeric alcohol ethoxylates), was determined in seawater (SW) at 20°C by the OECD306 Closed Bottle test method. After 28 days of incubation, 12 surfactants reached 60% biodegradation and were considered to be readily biodegradable in SW. The results for the 6 additional surfactants indicated that the 60% threshold level may be reached by extended incubation time, or that reduced biodegradation could be associated with toxicity of the chemicals. All these 6 surfactants were biodegraded >20% after 28 days, indicative of primary biodegradation in SW. Polymeric ethoxylates with high numbers of ethylene oxide (EO) groups (40-50 EO groups) were more slowly biodegraded than polyethoxylates with 4 to 23 EO groups. A primary biodegradation experiments of the alcohol ethoxylate (AE) C12-EO9 (3 to 18 EO groups) in a carousel system at 20°C with natural SW and a surfactant concentration of 500 µg/L, showed rapid primary biodegradation by targeted analyses of the AE, with >99% primary biodegradation after 2 days of incubation. The surfactant depletion coincided with temporary formation of polyethylene glycols, suggesting that central fission is an important degradation step in SW. A primary biodegradation experiment in the carousel system with C12-EO9 was conducted in the presence of suspended particulate materials (SPMs; marine phytoplankton and clay particles), showing that the presence of SPMs did not hamper the primary biodegradation of the surfactant. Separation of fractions in 20 µm steel filters indicated some particle association of the surfactant. This article is protected by copyright. All rights reserved. Environ Toxicol Chem 2023;00:0-0. © 2023 SETAC.

Application of a novel surface-active green demulsifier for demulsification of field crude oil emulsion

ABSTRACT In the petroleum industry, generally surface-active chemicals are used to break the crude oil emulsion. But these chemicals are toxic and less biodegradable, which can cause environmental pollution. Therefore, in this paper, eco-friendly demulsifiers (LA1 and LA2) were synthesized by esterification based on fatty acid having low cost and biodegradability. It was characterized by FTIR, NMR, DLS analysis, and TGA. The synthesized demulsifiers were comprehensively characterized by evaluating the micellization parameters such as CMC, Amin, etc. The demulsification performance of synthesized demulsifiers was studied through the static bottle test method. The effect of temperature, demulsifier concentration, pH, settling time, and water content on the demulsification efficiency was thoroughly examined. The result shows that both demulsifiers have excellent surface-active properties. The demulsification mechanism of demulsifiers was elucidated by measuring dynamic interfacial tension and rheological behavior. The bottle test results indicated that the LA1 demulsifier gave 100% separation efficiency at 70°C in 90 min, which performed better than the commercial demulsifier. The present study will give a new route for the eco-friendly and cost-effective treatment of asphaltene-based crude oil emulsion.

Gelation of an Organically Crosslinked PHPA Polymer Gel System: An Experimental Study

Excessive water production in the oil field is the major difficulty in production for the petroleum industry. Remedial techniques need to be applied to control this excess water production considering the health, safety, and environmental issues and improve the reservoir's economic and productive life. In this study polymer gel system comprising the polymer partially hydrolyzed polyacrylamide (PHPA) and organic cross-linkers (Hydroquinone and Hexamethylene tetramine) were prepared as a water shut-off system to control the excessive production of water in the oil field. The effect of various parameters such as temperature, pH, cross-linker concentration, degree of hydrolysis, and divalent cations on gelation time was investigated using the bottle testing method. The importance of retarders at high temperatures was also evaluated. The gelation temperature was varied from 90 °C to 120 °C to study the effect of different parameters on the gelation time and gel behavior. This study suggests that Partially Hydrolyzed Polyacrylamide (PHPA) with organic cross-linkers can be an effective polymer gel system for water shut-off operations, and with the addition of retarders at high temperature to control gelation time, the performance of the gel can be improved.

Evaluation of novel organically crosslinked polymer gel for water shut-off purposes

One common issue faced in the lifespan of oil or gas wells is water-cut, which leads to economic challenges due to water handling and operational costs, as well as reduced oil productivity. In this study, an organically cross-linked system consisting of HQ/HMTA is used for experimental work, as a substitute for the phenol/formaldehyde system with lower toxicity levels. The present study focuses on bulk gelation studies using the bottle testing method with polymer gelant prepared from PAM and HQ/HMTA. Determining the gelation time at different temperatures is important to understand the depth up to which the gel can be placed in the formation at reservoir temperature. The study revealed that gelation time can be controlled by adjusting gel composition and environmental conditions, ranging from a few hours to several days; higher polymer and crosslinker concentration in the gelant solution results in decreased gelation time, but excessive cross-linking leads to syneresis beyond a certain range; Gelation occurs more rapidly in the presence of low concentration salt compared to distilled water, but when brine concentration is increased, the gelation time increases due to the screening effect and reduced availability of cross-linking agents; Divalent ions tend to promote faster gelation compared to monovalent ions, likely due to their higher charge density. Overall, presented gel system is highly efficient in shutting off water in reservoirs. Keywords: water shut-off; organically crosslinked gel; gelation time; resistance factor; residual resistance factor; divalent ions.

Development of re-crosslinkable dispersed particle gels for conformance improvement in extremely high-temperature reservoirs

Micro-scale and nano-scale dispersed gel particles (DPG) are capable of deep migration in oil reservoirs due to their deformability, viscoelasticity, and suitable particle size. Therefore, it has been widely studied and applied in reservoir conformance control in recent years. However, for highly permeable channels, their plugging performance is still limited. In addition, conventional in situ cross-linked polymer gels (ISCPGs) have fast gelation time under extremely high-temperature conditions, which often causes problems such as difficulty in pumping. Therefore, a re-crosslinkable dispersed particle gel (RDPG) system applied for conformance control in highly permeable channels of extremely high-temperature petroleum reservoirs was investigated. The particle size distribution, gelation time, gel strength, injection performance, and performance strength in porous media were investigated using a laser particle size meter, the Sydansk bottle test method, rheometer, and core displacement experiments, respectively. Results show that the RDPG suspension can be stable for more than 6 months at room temperature with storage modulus G ′ much lower than 10 Pa. It can pass through the pore throat by elastic deformation effect and does not cause strong blockage. Moreover, it can undergo re-crosslinking reaction at 150 °C to form a strong bulk gel. The gel strength G ′ of re-crosslinked RDPG can be as high as 69.3 Pa, which meets the strength requirement of conformance control. The RDPG suspension has the properties of easy injection, and it also has strong plugging, and high-temperature resistance after re-crosslinked in the core, which can be a very promising material for conformance improvement in extremely high-temperature reservoirs.

Comprehensive evaluation of a novel re-crosslinkable preformed particle gel for the water management of reservoir with concentrated divalent ions

As one of the most widely used technology to ameliorate the reservoir's heterogeneity, polymer gels have been applied for more than 60 years. However, how to plug fractured reservoirs with significant abnormal features, high temperature and high salinity, especially the divalent cations, is still a challenging target. This work systematically evaluated a novel salt-resistant re-crosslinkable preformed particle gel (SR-RPPG) designed for fractured reservoirs with excellent salt resistance (up to 5 % CaCl2). We evaluated the swelling kinetics, thermal stability and plugging efficiency of this SR-RPPG. We assessed the swelling kinetic and re-crosslinking behavior of the SR-RPPG through the bottle test method. High temperature-resistant glass tubes with thermally stable O-rings were employed to evaluate the long-term thermal stability of the SR-RPPG product, and the testing lasted for over 200 days. A fractured model was used to assess the plugging efficiency of the SR-RPPG product. Results showed that the SR-RPPG could swell more than 30 times its original volume in 5 % CaCl2 and a middle east formation water. Besides, the SR-RPPG gel slurry can re-crosslink to form a rubber-like elastic bulk gel at 80–100 °C, and the elastic modulus of the re-crosslinked bulk gel can reach up to 1350 Pa with a swelling ratio of 10. The SR-RPPG prepared in 1 % NaCl, 2 % KCl, middle east formation water and 5 % CaCl2 with a swelling ratio of 10 have been stable for over 200 days at 100 °C. The core flooding test demonstrated that the SR-RPPG could efficiently block the open fractures, and the water breakthrough pressure gradient reached 927.30 psi/ft (20.98 MPa/m).

Effect of Magnetic Graphene Oxide on Heavy Oil Demulsification

Chemical demulsification is the most efficient demulsification approach that can attain the desired separation efficiency and meet the environmental regulation standards whilst impose minimal economic burden on the petroleum industry. However, current demulsification methods using chemical demulsifiers suffer from significant secondary pollution, particularly after the demulsification process. Therefore, in this work, magnetic graphene oxide (MGO) was synthesized by a one-step co-precipitation method from graphene oxide (GO). The properties of MGO were then characterized by X-ray diffraction and Fourier transform infrared. MGO was successfully synthesized and used as the demulsifier for diluted heavy oil emulsions. Different MGO concentrations (40, 80, 120, 160, and 200 ppm) were used at different water cuts (20:80, 30:70, 40:60, 50:50, and 60:40 v/v%). Demulsification tests using the bottle test method indicated that MGO could separate the emulsions up to 99.98% efficiency due to the high surface area-to-volume ratio of nanoparticles and magnetic features, which enhanced the adsorptive capacity for separating water from the oil. The residual oil content in the separated water was then analyzed by an ultraviolet-visible spectrophotometer. The oil concentration in the separated water reduced to 398.8 mg/ml, corresponding to a demulsification efficiency of 99.98% observed at 40 ppm MGO concentration. The interfacial tension of the emulsions during demulsification was also analyzed, where the interfacial tension decreased with increasing MGO concentration.