Volume 52, Nº 4 (2016)

The salient technological properties of coal slurries are studied using fusel oil as the dispersion medium. The distinctive features of the rheological behavior and flow pattern of coal slurries as a function of the nature of coal are ascertained. It is shown that the effective viscosity of coal slurries decreases as the coal passes from the lignite to the anthracite stage. The calorific value and degree of combustion of coal slurries in fusel oil are higher than those of the original coal.

Bio-oil production from giant leucaena wood was performed by liquid-phase pyrolysis in the presence of decane as the solvent. Three different types of catalyst (ZSM-5, NiMo/Al₂O₃ and Pt/Al₂O₃) were evaluated in terms of the bio-oil production yield and quality in an autoclave reactor at a reaction temperature of 350°C and initial hydrogen (H₂) pressure of 1 MPa with decane as the solvent. Although the yield was not significantly affected by the catalyst type, CHN analysis revealed that the NiMo/Al₂O₃ catalysts yielded bio-oil with the lowest oxygen content (10.0 wt. %) in 4.30 wt. % yield so that it was selected as the optimal catalyst. Optimization of the reaction temperature (at 250, 300, 350, and 400°C) and the initial H₂ pressure (at 0.5, 1, 2, and 3 MPa) by sequential univariate analysis revealed that the reaction temperature had the greatest influence on the oil yield and oxygen content, reaching a yield of 8.60 wt. % with the lowest oxygen content of 8.50 % at 400°C. Increasing the initial H₂ pressure diminished only slightly the oil and char yield and decreased the gas yield.

Silica sol was used for the first time to stabilize sodium dodecylsulfate (SDS) foams in order to avoid aggregation of nanoparticles in aqueous solutions. The stabilities and rheological properties of SDS foams stabilized by silica sol and silica nanoparticles were characterized using a Waring blender, an R/S plus rheometer, and an extensional viscoelasticity meter in order to illustrate the better performance of the former. The results showed that the foam stability (liquid drainage half-life) increased by 29.3% and 21.1% after addition of 0.05 wt% silica sol and silica nanoparticles, respectively. The rheological properties of foams with added silica sol were the best, followed by those with added silica nanoparticles and those without additives. Both the viscosity and elasticity of the liquid film were increased better after addition of silica sol rather than silica nanoparticles. The better dispersity of silica sol may have been the main reason for these results.

The qualitative and quantitative composition of hydrocarbons formed during oxidative-hydrolytic treatment of Kuzbas and Mongolian sapropelic oil shales under hydrous pyrolysis conditions was determined by chromato-mass spectrometry. It was shown that oxidative-hydrolytic transformations of the organic mass of these sapropelites at 400°C in aqueous-alkaline solution are due to the extent of 30-40% to the formation of paraffinic-naphthenic hydrocarbons, primarily normal C₁₀- C₃₁ alkanes and normal C₁₄- C₂₈ alkenes. It was found that, in contrast to the anhydrous pyrolysis products, the destructive oxidation-hydrolysis products contain more monounsaturated olefins with the double bond in a different position. The composition of the hydrocarbon biomarkers confirms the marine origin of the original biomass of the studied oil shales.

The results of experimental studies on preparation of oil shale and oil residue blend for gasification to produce synthesis gas of the desired composition are reported. The feasibility of preparation of stable oil shale suspension in aqueous emulsion of high-viscosity residual fuel oil having structural-rheological characteristics that ensure unhindered pumping of gasification feedstock through the gas generator nozzle and uniform distribution in the combustion chamber is shown.

Loss of drilling fluid in fractured reservoirs impedes drilling operation and may cause great damage to reservoirs. A new technique has been developed for temporary scaling (sediment forming) sealing protection of fractured reservoirs that combines the advantages of chemical, bridge, and shield sealing methods. Laboratory results indicate that (1) the plugging effect of the scaling agent is excellent with an average scaling rate of 96.14%, (2) bridging fiber materials exhibit high capacity for absorption of the scaling products, which facilitates aggregation of scaling products, (3) the plugging zone can withstand up to 6 MPa pressure, and (4) the sealing product erosion rate is great, averaging 95.48%, which can reduce the damaging effect of plug removing agents on reservoirs.

The process of development of a gelatinous plugging agent usable in heterogeneous formations at high temperatures is discussed. The static and dynamic properties of the agent and its optimal concentration are determined by variation. To optimize the plugging process, the experimental data are integrated with the numerical modeling data obtained by CMG software. The plugging agent contains 0.03% coagulant, 2.75% crosslinking agent I, 2.1 % crosslinking agent II, and 8% main heat-resistant agent. Gel viscosity is 2000-5000 mPa⋅sec, pH is 6-8, degree of plugging > 90.39%, and the working temperature >280 °C. The optimum injection control profile radius at which oil recovery is increased and flooding is reduced is 20 m.

The wear and score resistance of different types of plastic lubricants infused with additives based on sulfur-containing molybdenum compounds are studied. It is shown that the tribological properties of all the studied lubricants are improved by infusion with 2-8 wt. % of molybdenum dithiocarbamate and that the additives are most active in the lubricants containing polyurea thickener.

It is demonstrated by mechanochemical conversion of high-molecular oil components that degradation of oil hydrocarbons by mechanical treatment in the presence of quartz is accompanied by formation of gaseous hydrocarbons. Upon mechanochemical treatment in the presence of quartz, asphaltene content decreases in Zuunbayan oil, but increases in Stolbovoi oil. Mechanical treatment reduces solid paraffin content in Stolbovoi oil, but increases it in Zuunbayan oil. Mechanochemical treatment of oil in the presence of quartz causes accumulation of poorly soluble organic substances consisting essentially of heteroatomic compounds on the surface of solid phase particles. Obtained data can be used to develop a mechanochemical oil treatment flow chart.

Poorly recoverable oils are typified on the basis of analysis and generalization of the published data. An oil quality index that allows investigation of the characteristics of poorly recoverable oil reserves is proposed. Types of poorly recoverable oils are classified in terms of quality index into three classes, namely, low-, medium-, and high-quality oils. The peculiarities of physicochemical properties of poorly recoverable low-, medium-, and high-quality oils are determined by analyzing data on 18,000 specimens of oils having anomalous properties and 9000 specimens of oils bedded under complex conditions. A comprehensive classification of oils based on physicochemical properties is proposed, taking account of the density, viscosity, sulfur, resin, asphaltene, solid paraffin, vanadium, nickel, and light fraction content, gas saturation of the oil, etc. The investigation results can be used for optimizing the routes of transporting oils having anomalous physicochemical properties through pipelines.

We propose a model for predicting the response time of a production well responding to a change in pressure in the injection well while developing a low-permeability oil reservoir. The governing equation is derived based on a nonlinear seepage law and the method of successive substitution of steady states, and takes into account the anisotropy of the oil formation. We show that this model permits more accurate calculation than the conventional model.