Research Progress in Nanofluid-Enhanced Oil Recovery Technology and Mechanism.

Nanofluid-enhanced oil recovery (EOR) technology is an innovative approach to enhancing oil production in oilfields. It entails the dispersion of nanoparticles within a fluid, strategically utilizing the distinctive properties of these nanoparticles (NPs) to engage with reservoir rocks or crude oil, resulting in a significant enhancement of the oil recovery rate. Despite the notable advantages of nanofluid EOR technology over conventional oil recovery methods such as binary and ternary flooding, practical implementations continue to grapple with a range of pressing challenges. These challenges encompass concerns regarding the economic viability, stability, and adaptability of nanomaterials, which pose significant barriers to the widespread adoption of nanofluid EOR technology in the oil field. To tackle these challenges, addressing the current issues may involve selecting simpler and more readily available materials coupled with straightforward material modification techniques. This approach aims to more effectively meet the requirements of large-scale on-site applications. Within this framework, this review systematically explores commonly employed nanofluids in recent years, including inorganic nanofluids, organic nanofluids, and composite nanofluids. It categorizes the research advancements in optimizing modification techniques and provides a comprehensive overview of the mechanisms that underpin nanofluid EOR technology and its practical applications in oilfields. This comprehensive review aims to offer valuable references and serve as a solid foundation for subsequent research endeavors.

Preparation of Surface-Active Hyperbranched-Polymer-Encapsulated Nanometal as a Highly Efficient Cracking Catalyst for In Situ Combustion of Heavy Oil.

In situ combustion of heavy oil is currently the most suitable thermal method that meets energy consumption and carbon dioxide emission requirements for heavy oil recovery. The combustion catalyst needs to perform multiple roles for application; it should be capable of catalyzing heavy oil combustion at high temperatures, as well as be able to migrate in the geological formation for injection. In this work, a hyperbranched polymer composite nanometal fluid was used as the injection vector for a heavy oil in situ combustion catalyst, which enabled the catalyst to rapidly migrate to the surface of the oil phase in porous media and promoted heavy oil cracking deposition at high temperatures. Platinum (Pt) nanoparticles encapsulated with cetyl-hyperbranched poly(amide-amine) (CPAMAM), with high interfacial activity, were synthesized by a facile phase-transfer method; the resulting material is called Pt@CPAMAM. Pt@CPAMAM has good dispersion, and as an aqueous solution, it can reduce the interfacial tension between heavy oil and water. As a catalyst, it can improve the conversion rate during the pyrolysis of heavy oil in a nitrogen atmosphere. The catalyst structure designed in this study is closer to that exhibited in practical geological formation applications, making it a potential method for preparing catalysts for use in heavy oil in situ combustion to resolve the problem of catalyst migration in the geological formation.

Foam stability of temperature-resistant hydrophobic silica particles in porous media.

The world is rich in heavy oil resources, however, the recovery difficulty and cost are both higher than that of conventional crude oil. To date, the most common method of recovering heavy oil is steam flooding. However, once the steam breaks through the geological formation, gas channeling readily occurs, which leads to a rapid decrease of the steam drive efficiency. To improve the swept volume of steam in the geological formation, a series of hydrophobic silica particles for stabilizing foam was synthesized. This kind of particles used hydrophilic nano silica particles as reactant. Hydrophobic groups with cationic long carbon chains were grafted onto the surface of hydrophilic silica particles by synthetic silane quaternary ammonium salt. When the quantity of silane quaternary ammonium salt used in the modification reaction is different, the product had various degrees of wettability. The hydrophobic particles with the contact angle closest to 90° had the best foam stabilization effect on the betaine zwitterionic surfactant LAB. For LAB solution with mass fraction of 0.3%, the half-life of foam was extended into 160% when the mass fraction of particles was 0.5%. The higher the gas-liquid ratio, the better the plugging effect of foam agent with hydrophobic particles presented in porous media. The adsorption test of hydrophobic particles indicated that hydrophobic particles improved the stability of foam liquid membrane by improving the adsorption capacity of surfactant molecules. The thermal stability of hydrophobic silica particles exceeded 200°C, and the good foam stability made it a potential additive for foam oil displacement in high-temperature geological formation.

A Durable Magnetic Superhydrophobic Melamine Sponge: For Solving Complex Marine Oil Spills.

The problem of offshore oil leakage has wreaked havoc on the environment and people's health. A simple and environmentally friendly impregnation method combined with marine mussel bionics was used to address this issue. Using the viscosity of polydopamine (PDA), nano- Fe3O4 and WS2 adhered to the framework of the melamine sponge (MS), and then the magnetic sponge was modified with n-octadecanethiol (OTD), and finally the superhydrophobic magnetic melamine sponge (mMS) was prepared. The modified sponge has superhydrophobicity (WCA, 156.8° ± 1.18°), high adsorbability (40~100 g°g−1), recyclability (oil adsorbability remains essentially unchanged after 25 cycles), efficient oil−water separation performance (>98%), and can quickly separate oil on the water's surface and underwater. Furthermore, the modified sponge exhibits excellent stability and durability under harsh operating conditions such as strong sunlight, strong acid, strong alkali, and high salt, and can control the direction of the sponge's movement by loading a magnetic field. To summarize, mMS has many potential applications as a new magnetic adsorption material for dealing with complex offshore oil spill events.

Magnetic Hyperbranched Molecular Materials for Treatment of Oily Sewage Containing Polymer in Oilfield Compound Flooding.

With the continuous improvement in oilfield development and the application of tertiary oil recovery technology, the water content of oilfield-produced fluids has gradually increased, and a large number of oilfield sewage with complex components has also been produced after oil-water separation, and effective treatment is urgently needed. ASP flooding sewage contains alkali, various surfactants, polymers, microemulsion oil droplets, and solid impurities, which are difficult to be effectively treated by traditional water treatment agents and methods. In this study, aminopropyl triethoxysilane (APTES) was used to modify the nano-Fe3O4 coated with tetraethyl silicate (TEOS). The product was used as the ferromagnetic nano-core for the iterative reaction of Michael addition and ester amidation to synthesize a magnetic hyperbranched polyamide amine, and its performance in the treatment of ASP flooding wastewater was evaluated experimentally. For the preparation of APTES-modified Fe3O4@SiO2 (FOSN) product, TEOS was coated over Fe3O4 in an ethanol aqueous solution environment and then APTES was added dropwise. The first-generation branched product (1-FSMN) was obtained by the reaction of FOSN and methyl acrylate graft product (FOSN-M) with ethylenediamine, and the highest yield was 93.7%. The highest yield of the second-generation branched product (2-FSMN) was 91.6%. In this study, a composite flooding wastewater sample from a block in the Bohai oilfield was taken. The suspended solids content was 143 mg/L, the oil content was 921.09 mg/L, the turbidity was 135 NTU, and the zeta potential was -47 mV. The third-generation hyperbranched polymer (3-FSMN) and its quaternary ammonium salt (3-FSMN-Q) performed best in the appropriate dosage range, with the highest oil removal rate of 97%, suspended solid removal rate of 90.3%, turbidity reduction rate of 86.6% and zeta potential reduction rate of 88%. For 3-FSMN and its quaternary ammonium salt, the gravity/magnetic PAC compound treatment experiment was carried out. In the settlement time of only 5 min, 3-FSMN/PAC and 3-FSMN-Q/PAC can achieve the maximum oil removal rate of 87.1% and suspended solids removal rate of 87.3% for polymer containing wastewater from ASP flooding, and 86.3 and 86.0% for 120 mg/L. Its treatment capacity was much better than that of common treatment agent combination (CPAM/PAC).

Synthesis of a Superhydrophobic Fluorinated Nano-Emulsion and Its Modification on the Wettability of Tight Sandstone.

The water-blocking effect is a serious problem when developing tight sandstone gas reservoirs, which can cause a sharp reduction in gas production. Wettability alteration of near-wellbore sand rock surface from superhydrophilicity to superhydrophobicity is an effective method to decrease capillary pressure. In this study, a superhydrophobic fluorinated nano-emulsion was synthesized via a soap-free emulsion polymerization process using methacryloxyethyl trimethyl ammonium chloride, trifluoctyl methacrylate, and styrene as monomers. The effect of the fluorinated monomer concentration on wettability alteration was evaluated by measuring the contact angle of the formation water droplet on the modified glass slides using nano-emulsions with different fluorinated monomer concentrations. The results showed that the nano-emulsion had a good dispersibility and homogeneous particle size of around 90 nm, and with the increase in fluorinated monomer concentration, the contact angle increased. The contact angle was the largest when the fluorinated monomer mass rate concentration reached 50%. The adsorption of nanoparticles could alter the rock wettability from a super hydrophilic state (θ = 7°) to a superhydrophobic state (θ = 150°). The spontaneous imbibition experiments showed that the formation water adsorption quality of the core decreased by 49.7% after being modified by the nano-emulsion. The nano-emulsion showed a good superhydrophobicity and had the potential to be used to reduce the water-blocking damage in the tight gas reservoirs.

Preparation and Application of Superhydrophobic Copper Mesh by Chemical Etching and In-situ Growth.

Oily sewage and floating oil in the ocean post a huge threat to the ecological environment, therefore, developing an efficient separation for oil/water mixtures is an urgent need. Currently, superhydrophobic materials exhibit excellent oil/water separation ability. In this study, a superhydrophobic copper mesh prepared by the chemical etching method and the in-situ growth method and the performance evaluation are introduced. The oxide layer on the surface of the copper mesh is first removed by pickling, and then immersed in FeCl3 solution for chemical etching to make the surface rough, stearic acid (SA) is used for in-situ growth to reduce the surface energy, a superhydrophobic oil-water separation copper mesh is obtained. The water contact angle (WCA) of the copper mesh is more than 160°. The copper mesh is chemically stable and can effectively adsorb floating oil and separate the oil-water mixture. After several oil-water separation experiments, the oil-water separation efficiency can still be above 98%. The effects of the concentration of FeCl3 and SA on the contact angle and oil-water separation efficiency are investigated, the results show that when the concentration of FeCl3 is 2% and SA is 1.5%, the WCA and oil-water separation efficiency are the largest. The research used a simple and environmentally friendly method to prepare the oil-water separation copper mesh, which has important application significance for water quality restoration.

Fabrication of Superhydrophobic SA-CeO2@Cu Mesh and Its Application in Oil-Water Separation.

CeO2 was synthesized by the co-precipitation method on the Cu mesh substrate and modified the surface of CeO2@Cu mesh by stearic acid (SA). The superhydrophobic behavior was ascribed to the combination of hierarchical micro-nanostructure of CeO2 and the hydrophobic alkyl groups from SA. The SA-CeO2@Cu mesh had antiacid and base stability and excellent durability as well as high separation efficiency. The separation efficiency can be up to 98.0% after separating 30 times.

Fabrication of PDMS@Fe3O4/MS Composite Materials and Its Application for Oil-Water Separation.

The discharge of oily wastewater and oil spills at sea are the current difficulties in water pollution control. This problem often leads to terrible disasters. Therefore, the effective realization of oil-water separation is a very challenging problem. Superhydrophobic sponge is a promising oil-absorbing material. In this article, we reported a superhydrophobic sponge with nano-Fe3O4 for oil-water separation. The addition of nano-Fe3O4 allows the sponge to be recycled under the action of magnetic force. The sponge has the advantages of low cost, simple preparation and efficient oil-water separation. This kind of sponge is very worthy of promotion for the treatment of oily wastewater and marine oil spill accidents.

A Mini Review: Application Progress of Magnetic Graphene Three-Dimensional Materials for Water Purification.

Marine oil pollution, colored counterattacks, and heavy metal ions in the water will cause serious environmental problems and threaten human health. The three-dimensional material prepared by graphene, as a new nanomaterial, has a large specific surface area and surface chemical activity. Various impurities in the water can be absorbed, which is very suitable as a water purification material. Depositing Fe3O4 and other magnetic materials on graphene three-dimensional materials can not only increase recyclability but increase hydrophobicity. Therefore, magnetic graphene three-dimensional materials have a high potential for use in water purification. This article reviews the research progress and adsorption mechanism of magnetic graphene materials for water purification. Finally, the future research prospects of magnetic graphene materials have prospected.

Hydrophobic mesoporous silicon dioxide for improving foam stability.

In this study, mesoporous SiO2 nanoparticles (MSNs) were synthesized via a sol-gel method and modified with (3-chloropropyl) trimethoxysilane to make them hydrophobic (MMSNs). The material was characterized via SEM, TEM, FT-IR, DLS, BET and contact angle measurements. The MMSNs have good foam stability, so that the foam properties of the added particles have been increased by 38.4% in an oil/SDS solution. Simultaneously, it becomes a promising material for foam stabilization in order to enhance the oil recovery because it is bio-compatibile and environment friendly. Also, it provides a novel application-stable foam for mesoporous materials.

Correction: Hydrophobic mesoporous silicon dioxide for improving foam stability.

[This corrects the article DOI: 10.1039/D0RA02161J.].

Mechanism and modelling of CO2 corrosion on downhole tools.

The conditions surrounding oil and gas exploration are becoming more hazardous, especially in oil and gas fields with a high quantity of corrosive components such as CO2. CO2 causes localized corrosion of tools made from metal, rubber and other materials in humid environments; this leads to corrosion failure in metal equipment and downhole tools such as drills pipes, casings and oil pipes, thereby reducing their service life. In this study, the composition, lattice and crystalline forms of corrosion products and corroded materials were analysed using scanning electron microscopy, energy spectrum analysis, X-ray diffraction and polarization curves, in order to investigate the corrosion mechanisms and influential factors for several common tool materials. A CO2 corrosion model was established for two materials and the results were verified with optimal prediction values.

[Development of a wrist wearing and remote heart rate alarm apparatus].

We have developed a new wrist wearing heart rate monitoring alarm apparatus, which can detect the patients' real-time pulse waves. When the abnormal heart rate appears or pulse disappears, the monitoring alarm will sound and dial the remote telephone for help simultaneously. This apparatus uses the switch circuit to control the keyboard of mobile phone, and dials remote telephone in the help of mature technology and communication platform of mobile phones. The intelligent program can distinguish digital pulse signal, pick out the correct cycle of heartbeat intelligently. The new wrist wearing heart rate monitoring alarm apparatus will calculate an average heart rate when it captures consecutively five correct electrocardiograph waveforms. It really provides a simple, inexpensive and effective way for the patients with heart disease.

[Development of a digital cardiac pacemaker for animals and its application in medical research].

In this research and development project, we used the general microprocessor as a core to constitute the animal cardiac pacemaker in vitro. Control of the pacemaker's settings was carried out by transmitting parameters through a serial communication interface. Finally, our pacemaker reaches a satisfying test result in activating the cardiac outer membrane of the rabbits. Full digital pacemaker has high precision, good stability, and has an intuitive way to set parameters. Owing to its smaller size, lower cost, and easier mass production, the digital pacemaker is a good candidate to replace costly medical pacemakers for activating the animal's heart.

Poly[[(N,N-dimethyl-formamide-κO)(µ(3)-pyrazine-2,3-dicarboxyl-ato-κN,O:O:O)copper(II)] monohydrate].

In the title compound, {[Cu(C(6)H(2)N(2)O(4))(C(3)H(7)NO)]·H(2)O}(n), the Cu(II) atom is coordinated by an N,O-bidentate pyrazine-2,3-dicarboxyl-ate (pzdc) dianion, two O atoms from two other pzdc anions and one O atom from the dimethlyformamide ligand, forming a distorted square-pyramidal CuNO(4) geometry. The polymeric character of the structure is established by the formation of layers parallel to (100) via bridging pzdc ligands. O-H⋯O hydrogen bonding between water mol-ecules and uncoordinated carboxyl-ate O atoms leads to additional stabilization of the structure.

Poly[aqua-[µ(2)-cis-1,2-bis-(4-pyrid-yl)ethyl-ene-κN:N'](µ(2)-5-nitro-isophthalato-κO:O',O'')nickel(II)].

In the title compound, [Ni(C(8)H(3)NO(6))(C(12)H(10)N(2))(H(2)O)](n), the Ni(II) atom is octa-hedrally coordinated by two cis N atoms from two different 1,2-bis-(4-pyrid-yl)ethyl-ene (bpe) ligands, two O atoms from one chelating carboxyl group of the 5-nitro-isophthalic acid (nip) ligand, one O atom from another monodentate nip ligand and one O atom from a water mol-ecule, forming a three-dimensional network structure. Inter-molecular O-H⋯O hydrogen bonding stabilizes this arrangement. The asymmetric unit of the structure contains one Ni(II) atom, one water mol-ecule, one nip ligand and two half-mol-ecules of the bpe ligand with an inversion centre at the mid-point of the central C=C bond.

[The design of an instrument furnished with hydrogen clearance technique for measuring local blood-flow and the microcomputer analysis curve on hydrogen clearance].

A new instrument, furnished with hydrogen clearance technique for measuring local blood-flow, was designed by use of new electronic components and a microcontroller. The corresponding program was developed. The curve of hydrogen clearance was sampled automatically by microcomputer, fitted into an exponential function by least square method, and then the local blood-flow was calculated. The cerebral blood-flow in the rat's striatum had been measured using the system. The fitted curve corresponds with the curve of hydrogen clearance and the obtained parameter was correct. The design of the instrument was reasonable. It can work reliably and stably. The calculated results are more accurate and they can be acquired more quickly, because the curve of hydrogen clearance is automatically sampled and analyzed by the microcomputer.

[A simple and new type of drop recorder mainly applied in the experiment of frog heart].

AIM: To introduce the manufacture and use of a simple, new type of drop recorder of frog heart. METHODS: To improve the perfusion device of (see text for symbol) and Straub method. Two electrodes of drop recorder were fixed in an injector of 20 ml. The input tube, output tube and resistance tube were all made of plastic material. RESULTS: This device could be used to observe effects of preload, after-load, hormone and electrolyte on the cardiac output in isolated frog heart. CONCLUSION: The new type of drop recorder was economical and could be easily operated, it could be also connected to computer. Using the new type of drop recorder, effects of various physical and chemical factors on cardiac function could be observed directly, accurately.

[Electrophysiological effects of phytoestrogen genistein on guinea pig papillary muscles].

The cardiac electrophysiological effects of genistein (GST) were examined in guinea pig papillary muscle using intracellular microelectrode technique. The results obtained are as follows. (1) Duration of action potential (APD) in normal papillary muscles was decreased by GST (10 100 micromol/L) in a concentration-dependent manner. (2) In partially depolarized papillary muscles, 50 micromol/L GST not only reduced APD, but also decreased the amplitude of action potential, overshoot and maximal velocity of phase 0 depolarization. (3) Pretreatment with N( )-nitro-L-arginine (L-NNA, 5 mmol/L) failed to affect the above effects of GST (50 micromol/L)on papillary muscles. (4) 17beta-estradiol (E(2), 5 micromol/L) or GST (10 micromol/L) alone did not affect action potential, while GST combined with E(2) at the same doses shortened APD significantly. All these results indicate that the effects of GST on papillary muscles are likely due to a decrease of calcium inflow which is not mediated by NO and that GST has a facilitative or synergetic action with E(2).