Aquathermolysis Reaction Research Articles

A modified model for aquathermolysis and its application in numerical simulation

Steam injection can significantly reduce the viscosity of heavy oil. In addition to physical effects, chemical reactions such as aquathermolysis also make a difference. However, the current numerical simulators do not include the characterization for the aquathermolysis reactions, making it unable to analyze directly the effect of the aquathermolysis reactions using numerical simulation. To solve this problem, a basic model of aquathermolysis reactions for numerical simulation is established in this paper. After dividing the oil components reasonably, a modified chemical equation is well defined. And the pre-exponential factors and activation energies are also calculated. Afterwards, this model is implemented into the numerical simulator CMG-STARS, and the results with and without the model are compared, to analyze the mechanisms of aquathermolysis reaction for increasing production. The results indicate: (1) the numerical simulation results with the aquathermolysis reaction model are more consistent with field results (2) aquathermolysis reactions can further reduce the viscosity of heavy oil, increase oil production, and reduce the water saturation near the well bore area.

Preparation of phase transfer functional catalysts and their application in viscosity reduction of heavy oils

Four kinds of nanosilica-supported metallic and metatitanic acid nanocatalysts were synthesised as potential phase transfer catalysts for enhancing heavy oil recovery via a liquid-reduction method. The catalysts were carried by water and transferred into oil phase, and the catalytic performance of catalysts for the aquathermolysis reaction and viscosity reduction of the extra-heavy oil recovered at Shengli Oilfield (Dongying, China) was investigated. At a mass fraction of 1%, an aquathermolysis reaction temperature of 150°C and an aquathermolysis time of 36 h, the as-synthesised silica/zero valence iron and nickel (denoted as SiO2/Fe/Ni) catalyst was able to reduce the apparent viscosity of the two kinds of heavy oils by 79.3 and 77.6%, showing promising application in the industrial production of heavy crude oil.

Catalytic Aquathermolysis of Heavy Crude Oil Using Surface-Modified Hematite Nanoparticles

The ability of both bare and surface-modified hematite nanoparticles to reduce the viscosity and upgrade the quality of heavy crude oil via aquathermolysis reaction was investigated in this study. The surface of hematite nanoparticles was modified using oleic acid to improve its hydrophobicity. First, a desulfurization study of thiophene was carried out to study the effect of hydrophobicity on the catalytic activity of the nanoparticles. Results showed that the catalytic activity could be improved by changing hydrophobicity of the nanoparticles from hydrophilic to slightly more hydrophobic. However, reduction of catalytic activity was observed when more oleic acids were attached due to blockage of the catalytic sites. In such a relatively mild aquathermolysis reaction, both untreated and surface-modified hematite nanoparticles were able to reduce effectively the viscosity of heavy crude oil by 61.52% and 74.33%. Additionally, the amount of large hydrocarbon molecules such as asphaltene and resin fractions...

Methanol enhanced catalytic viscosity-reduction of heavy oil by transition metal-Mannich base complex under low temperature

A series of transition metal-Mannich base complex was synthesized and screened for catalytic aquathermolysis of heavy oil and the results showed that the Ni(II)-Mannich base complex is the most effective one. The structure of catalyst was characterized by Fourier transform infrared (FTIR), ultraviolet and visible spectrophotometer (UV), and the group compositions C/H/N elemental analysis (EL), and thermogravimetric analysis (TGA) of the heavy oil were also conducted. The viscosity of the heavy oil can be decreased by 82.6% using 1.0 wt % catalyst with 15 wt % methanol in a reaction under 180°С for 24 h, and the composition analysis shows that 9.0% asphaltene is converted to resin and saturated HC. The group composition and the element content of the heavy oil before and after the aquathermolysis reaction were tested and analyzed.

Reservoir Simulation of Hydrogen Sulfide Production During a Steam-Assisted-Gravity-Drainage Process by Use of a New Sulfur-Based Compositional Kinetic Model

Summary Steam injection is commonly used as a thermal enhanced-oil-recovery (EOR) method because of its efficiency for recovering hydrocarbons, especially from heavy-oil and bitumen reservoirs. Reservoir models simulating this process describe the thermal effect of the steam injection, but generally neglect the chemical reactions induced by the steam injection and occurring in the reservoir. In particular, these reactions can lead to the generation and production of the highly toxic and corrosive acid gas hydrogen sulfide (H2S). The overall objective of this paper is to quantitatively describe the chemical aquathermolysis reactions that occur in oil-sands reservoirs undergoing steam injections and to provide oil companies with a numerical model for reservoir simulators to forecast the H2S-production risks. For that purpose, a new sulfur-based compositional kinetic model has been developed to reproduce the aquathermolysis reactions in the context of reservoir modeling. It is derived from results gathered on an Athabasca oil sand from previous laboratory aquathermolysis experiments. In particular, the proposed reactions model accounts for the formation of H2S issued from sulfur-rich heavy oils or bitumen, and predicts the modification of the resulting oil saturate, aromatic, resin, and asphaltene (SARA) composition vs. time. One strength of this model is that it is easily calibrated against laboratory-scale experiments conducted on an oil-sand sample. Another strength is that its calibration is performed while respecting the constraints imposed by the experimental data and the theoretical principles. In addition, in this study no calibration was needed at reservoir scale against field-production data. In the paper, the model is first validated with laboratory-scale simulations. The thermokinetic modeling is then coupled with a 2D reservoir simulation of a generic steam-assisted gravity drainage (SAGD) process applied on a generic Athabasca oil-sand reservoir. This formulation allows investigating the H2S generation at reservoir scale and quantifying its production. The H2S- to bitumen-production ratio against time computed by the reservoir simulation is found to be consistent with production data from SAGD operations in Athabasca, endorsing the proposed methodology.

Experimental Measurements of Bitumen–Water Aquathermolysis during a Steam-Injection Process

Laboratory studies and pilot project tests have shown that appreciable amounts of H2S and CO2 could be generated as a result of the aquathermolysis reaction between bitumen and steam or hot water during thermal recovery operations. A detailed experimental study was carried out to investigate the H2S generation mechanism that occurs during the recovery processes. A laboratory setup was designed and assembled that allowed for aquathermolysis tests to be carried out under controlled pressure conditions and at temperatures to 250 °C. Aquathermolysis tests on a defined ratio of bitumen and water sample were carried out at 225 and 245 °C over 3, 10, and 30 day reaction periods. Phase sampling and analysis procedures were developed to quantify the amount of H2S and CO2 generated during the individual vapor and aqueous phases. Vapor- and liquid-phase composition and bitumen properties, including viscosity and density, were analyzed after each reaction. The results of the investigation showed that the amount of H2S and CO2 generated increased with the reaction time and temperature and the CO2 concentration tended to flatten out over the test period. Data generated during the study were used to develop a kinetic model on a laboratory scale for predicting the time and temperature effects on H2S and CO2 production during the bitumen–steam/hot water aquathermolysis.

Preparation of zirconia‐doped titania superacid and its application in viscosity reduction of heavy oil

Sulphated titania superacid (denoted as SO4 2−/TiO2) and sulphated zirconia-doped titania superacid (denoted as SO4 2−/ZrO2/TiO2) were prepared via a liquid-phase in-situ method. As-prepared SO4 2−/TiO2 and SO4 2−/ZrO2/TiO2 superacids were characterised by transmission electron microscopy, field emission scanning electron microscopy, X-ray diffraction and Fourier transform infrared spectrometry. Moreover, the catalytic performance of SO4 2−/TiO2 and SO4 2−/ZrO2/TiO2 for the aquathermolysis reaction and viscosity reduction of the extra-heavy oil recovered at Shengli Oilfield (Dongying, China) was investigated. It was found that SO4 2−/TiO2 and SO4 2−/ZrO2/TiO2 as the catalysts for the aquathermolysis process of the tested extra-heavy oil have good catalytic performance. Saturated hydrocarbon, aromatic hydrocarbon, resin and asphalt composition of the tested heavy oil sample before and after aquathermolysis reaction indicates that the amount of the saturated hydrocarbon and aromatic hydrocarbon are increased, while the amount of resin and asphalt are decreased, showing promising potential in the industrial production of heavy crude oil.

Initial steps in reactions of aquathermolysis of cyclohexyl phenyl sulfide by means of ab initio calculations

Aquathermolysis is often proposed as a method to reduce the viscosity of heavy oils. In the present work we have investigated the aquathermolysis reaction of cyclohexyl phenyl sulfide in water medium by means of density functional theory. The water molecule was considered as a reagent and as a catalyst. We have shown that ab initio quantum chemistry methods could be applicable for comparative analysis of chemical reaction pathways in aquathermolysis processes. The obtained results could be useful for the systems like tert-alkyl (secondary-alkyl) thiophenyl ethers, which could be formed in heavy oils at harsh conditions. The scheme of different reaction directions with corresponding calculated values of reaction barriers, which are correlated with experimental data, is presented and could be used for comparison with other reaction mechanisms.

Viscosity Reduction of Heavy Oil Using Nanocatalyst in Aquathermolysis Reaction

Enhanced oil recovery (EOR) in the last several years has become an important factor in oil production due to the shortfall in high quality crude oil. Heavy oil as one of the unconventional hydrocarbons is still vastly abundant in nature and is hence frequently explored with EOR. The viscous characteristic of heavy oil necessitates further in-situ upgrading processes to be executed before extraction. An interesting upgrading method is through aquathermolysis under the addition of catalyst. This review focuses on presenting nanoparticle catalysts, such as nickel-, iron- and cobalt-based nanocatalyst. The explanation covers topics from synthesis methods and characterization up to the effect of reducing the viscosity of heavy oil. Lastly, concluding remarks and future perspectives are highlighted regarding the visibility and available approaches of developing nanofluids for EOR.

Enhance Oil Recovery for Steam Flooding: Low-Temperature Oxidative Decomposition of Heavy Oil with Air Injection

With the increasing demand of energy, technical research of how to enhance oil recovery of steam flooding for heavy oil reservoirs has attracted widespread attention at present. Air-injection is an effective technology that has been used to improve the development effect of steam flooding in heavy oil reservoirs. The low-temperature oxidation (LTO) reaction and the high-temperature combustion reaction are the main mechanisms of air-injection technology. The high-temperature combustion reaction can decompose the heavy component in heavy oil, but it requires a higher-temperature condition, which the steam flooding process cannot offer. In addition, the LTO reaction between air and heavy oil consumes the O2, so the safety risk of explosion caused by the mixture of O2 and hydrocarbon gas can be eliminated. Nevertheless, oil viscosity will increase. During the steam flooding process, an aquathermolysis reaction occurs between heavy oil and high-temperature water, which decreases the content of the heavy compon...

Synthesis of Fe<sub>3</sub>O<sub>4 </sub>Nanoparticles Using the Co-Precipitation Method and its Development into Nanofluids as a Catalyst in Aquathermolysis Reactions

Catalytic aquathermolysis is proposed as one of the potential methods which functions to reduce the viscosity of heavy oil for ease of extraction. In this research, we have developed a solution dispersed catalyst of Fe3O4 nanoparticles through a co-precipitation method. FeCl3·6H2O and FeCl2·4H2O were used to serve as an Fe source, with NaOH as a co-precipitator. The as-synthesized nanoparticles were characterized by X-ray diffraction (XRD) to verify materials. In order to be able to be used in the reservoir, the prepared powder was further dispersed into a base fluid with the addition of a dispersant by an ultrasonication for 2 hours. The stable nanofluid was achieved using the ratio of ethylene glycol/water mixture of 20%:80%. Dynamic light scattering (DLS) characterization results showed that the average size of the particle was about 309 nm, which is small enough to ensure its ability to pass through rock pores. Catalytic aquathermolysis of heavy oil in laboratory scale was employed under the addition of stable nanofluid at 200°C for 6 hours. The viscosity of heavy oil after the reaction could be reduced up to 71.3%.

Synthesis of silica/metatitanic acid nanocomposite and evaluation of its catalytic performance for aquathermolysis reaction of extra-heavy crude oil

A lipophilic silica/metatitantic acid (denoted as SiO2/H2TiO3) nanocomposite was synthesized by hydrothermal reaction with surface-modified SiO2 as the lipophilic carrier. As-synthesized SiO2/H2TiO3 nanocomposite was used as a catalyst to promote the aquathermolysis reaction of extra-heavy crude oil thereby facilitating the recovering from the deep reservoirs at lowered temperature. The catalytic performance of the as-synthesized SiO2/H2TiO3 catalyst for the aquathermolysis reaction of the heavy oil at a moderate temperature of 150 °C was evaluated in relation to the structural characterizations by TEM, FTIR, XRD and FESEM as well as the determination of the specific surface area by N2 adsorption–desorption method. Findings indicate that as-synthesized SiO2/H2TiO3 nanocomposite exhibits an average size of about 20 nm as well as good lipophilicity and dispersibility in various organic solvents; and it shows good catalytic performance for the aquathermolysis reaction of the extra-heavy oil extracted from Shengli Oilfield of China. Namely, the as-synthesized SiO2/H2TiO3 catalyst is capable of significantly reducing the viscosity of the tested heavy oil from 58,000 cP to 16,000 cP (referring to a viscosity reduction rate of 72.41%) at a mass fraction of 0.5%, a reaction temperature of 150 °C and a reaction time of 36 h, showing potential application in downhole upgrading heavy crude oils.

Aquathermolysis of heavy oil: A review and perspective on catalyst development

Aquathermolysis process is one of the key and economical viscosity reduction technologies being considered for the successful exploitation of huge heavy oil deposits across the world. The paper substantially reviewed the progress made and the fundamental issues related to catalysts development. The most appropriate catalysts are those containing strong, active sites that can actively break the CC, CS, CO and related bonds in resins and asphaltenes, with a net increase in the concentration of saturates and lighter aromatic hydrocarbons. Solid catalysts based on natural zeolites, heteropoly acids and modified zirconia oxides have so far demonstrated excellent activities. Catalysts such as alloys of Mo, W, C and Ni, nano oxides of Cu and Fe, Ni-chelates, supported nano-Fe particles and Cu2+ and Fe3+ complexes of toluene sulfonic acid were also recently reported as good candidates for the aquathermolysis reactions. Hydrophobic zeolites prepared in the fluoride or organic silane routes, carbides of W and Mo are prospective catalysts for the future due to their excellent performance in related reactions. In all cases, further studies are required to explore the optimal catalyst synthesis procedures, operation conditions and actual reaction mechanisms.

Viscosity Reduction of Heavy Oil by Aquathermolysis with Coordination Complex at Low Temperature

To seek for new catalysts for the aquathermolysis of crude oil under relatively low temperature, in this paper, a series of Mannich base-transit metal coordination complexes was synthesized and used in aquathermolysis of heavy oil as catalyst. The results show an evident viscosity reduction by 84.2% for the heavy oil reacted at 180 °C for 24 h catalyzed by the Ni(II) coordination complex. The group compositions, the element content of the heavy oil and paraffin crystal morphology before and after the aquathermolysis reaction were analyzed, which are consistent with the viscosity reduction of the heavy oil. Besides the catalysts were also found to be widely applicable.

Quantum Chemical Study of Mechanisms of the Reaction of Cyclohexyl Phenyl Sulfide with Water

Some possible reactions of cyclohexyl phenyl sulfide with water are examined. Cyclohexyl phenyl sulfide was chosen as a model compound of heavy oils. Quantumchemical calculations of the difference in the energy of the products and reagents and the energy barrier of the reactions are performed and the temperature dependence of the change in Gibbs energy free energy is determined. It is shown that the data obtained using the density functional theory agree with the experimental data and could be used for more detailed study of the mechanisms of aquathermolysis reactions, including catalytic effects.

Aquathermolysis of Heavy Crude Oil with Amphiphilic Nickel and Iron Catalysts

Two amphiphilic catalysts (i.e., metal dodecylbenzenesulfonates, noted as C12BSNi and C12BSFe) were synthesized and characterized by Fourier transform infrared spectroscopy (FT-IR), element analysis (EA), atomic absorption spectroscopy (AAS), and thermogravimetric (TGA). Their interfacial activities were determined using a surface tensiometer and an interfacial tensiometer. Both catalysts are interfacial active and thermostable enough for heavy oil aquathermolysis. Their performance on heavy oil aquathermolysis was assessed in an autoclave. According to the viscosity reduction results, the synthesized amphiphilic catalysts are more effective than water-soluble or oil-soluble catalysts, with C12BSNi more efficient than C12BSFe. The average molecular weight, group compositions, and average molecular structure of heavy oil samples were analyzed using EA, FT-IR, and 1H nuclear magnetic resonance (1H NMR) before and after aquathermolysis reaction. And the results show that both catalysts caused the change of m...

Using hydrogen donor with oil-soluble catalysts for upgrading heavy oil

With self-made oil-soluble organic cobalt salt as catalyst and formamide as hydrogen donor, we studied the aquathermolysis reaction of heavy oil through simulating the condition of thermal recovery of oil reservoir with autoclave. In the paper, we explored the effect of the hydrogen donor added into catalytic aquathermolysis reaction on the viscosity of heavy oil, group composition and component contents. Moreover, FTIR spectrum was employed to analyze the structural change of heavy oil after hydrogen donor catalytic aquathermolysis. The obtained data are validated that when the mass fraction of added hydrogen donor was increased, the viscosity reduction rate and the contents of saturated hydrocarbons and aromatic hydrocarbons were increased and the contents of resin and asphalt were decreased. Under the synergic action of catalysts and hydrogen donor, the content of carbon in heavy oil was decreased and the content of hydrogen was increased. Thus, the ratio of H/C rose and the content of sulfur was reduced. Analysis result of infrared spectrum validated that hydrogen donor catalytic aquathermolysis underwent decarboxylation and that the number of aromatic rings was reduced.

Kinetics of the In-Situ Upgrading of Heavy Oil by Nickel Nanoparticle Catalysts and Its Effect on Cyclic-Steam-Stimulation Recovery Factor

Summary The effect of nickel nanoparticles on in-situ upgrading of heavy oil (HO) during aquathermolysis and the effect of this process on the recovery through cyclic steam injection were studied. High-temperature experiments were conducted with a benchtop reactor to study the kinetics of the reactions among oil, water, and sandstones in the presence and absence of the nickel nanoparticles. Eighteen experiments were conducted at three different temperatures and at three different lengths of time, and the evolved hydrogen sulfide during the reaction was analyzed. The kinetic analysis showed that nickel nanoparticles reduce the activation energy of the reactions corresponding to the generation of hydrogen sulfide by approximately 50%. This reaction was the breakage of C-S bonds in the organosulfur compounds of the HO. The maximal catalysis effect was observed to be at a temperature of approximately 270°C. Also, the simulated-distillation gas-chromatography (GC) analysis of the oil sample, after the aquathermolysis reactions, confirmed the catalysis effect of nickel nanoparticles. According to this analysis, by catalytic process, the concentration of the components lighter than C30 increased whereas the concentration of heavier components decreased. Next, the effect of the catalytic aquathermolysis on the recovery factor of the steam-stimulation technique was studied. The stimulation experiments consisted of three injection/soaking/production phases. The results showed that the nickel nanoparticles increased the recovery factor by approximately 22% when the nanoparticles were injected with a cationic surfactant and xanthan-gum polymer. This increase of recovery was approximately 7% more than that of the experiment conducted with the surfactant and polymer only.

On in situ hydrogen sulfide evolution and catalytic scavenging in steam-based oil sands recovery processes

In the SAGD (Steam-Assisted Gravity Drainage) process, high temperature saturated-steam is injected into an oil sands reservoir to lower the viscosity of the bitumen hosted within the reservoir. Typical steam temperatures range from 200 to 260 °C. Under these conditions, the bitumen, in presence of steam–condensate, undergoes aquathermolysis yielding H2S and CO2. Current SAGD simulation models take into account complex spatial heterogeneity of geology and oil composition and the physics of heat transfer, multiphase flow, gas solubility effects, and viscosity variations with temperature; however, few have taken the chemistry of SAGD into account. Here, we have added aquathermolysis reactions to a simulation model to understand H2S reactive zones in SAGD. Given the requirement to constrain sulfur emissions from thermal recovery processes, it is necessary to reduce H2S production to surface. The results demonstrate that injecting small amount of SO2, along with steam, initiates the Claus reaction in the reservoir which converts H2S into liquid sulfur. Thus, sulfur emissions are reduced below that of the original operation without SO2 co-injection. The ability to use in situ Claus reaction-based H2S scavenging offers an elegant way to reduce sulfur emissions from thermal oil sands recovery processes.

Use of unsupported, mechanically alloyed NiWMoC nanocatalyst to reduce the viscosity of aquathermolysis reaction of heavy oil

Ni, W, Mo and C catalysts were mixed and mechanically processed at room temperature for different grinding times: 0, 40, 80, 120, 160, 200 and 240h. The phases at every stage of milling were studied by X-ray diffraction (XRD). The powders were used in the catalytic aquathermolysis reaction of heavy oil. X-RD showed by increasing the milling time from 0 to 240h, nanostructured carbide phases were synthesized with a crystallite size ranging from 125.6 to 10.1nm, which was confirmed by high resolution transmission electron microscopy (HRTEM). The performance of the nano-catalysts in the heavy oil before and after the reaction was analyzed by Fourier transform infrared spectroscopy (FT-IR). As the milling time increased, the ratio of the viscosity reduction of the heavy oil increased from 80.4% to 97.1% by using the catalyst milled for 240h.