Vol 55, No 3 (2019)
- Year: 2019
- Articles: 15
- URL: https://journals.rcsi.science/0009-3092/issue/view/14658
55 Years of Chemmotology
Gas-Chromatographic Identification and Determination of the Content of Normalakanes in Fuels for Jet Engines
Abstract
A new method was developed for the identification and quantitative determination of normal alkanes in jet fuels and kerosene fractions on the basis of simulated distillation. Normal alkanes were identified on the chromatogram by their retention times, and their concentrations were calculated by absolute calibration, the results of which correspond to the results obtained by standard addition and internal standard methods. The developed method is simple and productive and can be carried out using standard analytical equipment.
Article
A Method for Investigating Tendency of Diesel Fuels to Form High-Temperature Deposits
Abstract
A quick inexpensive method for investigating the tendency of diesel fuels to form high-temperature deposits in the engine cylinder zone is proposed. The method can be used to model the dynamics of the deposit formation process that depends on the factors governing this process and to establish the quantitative characteristics of the influence of composition and conditions of use of fuels on deposit formation.
Feasibility Study for Using Jet Fuel in Diesel Engines
Abstract
We have determined the primary jet fuel performance properties that have the greatest impact on how effectively they can be used in diesel engines, requiring improvement with the help of functional additives. We have studied the effect of a cetane improver additive based on 2-ethylhexyl nitrate and an antiwear additive based on higher carboxylic acids on the performance properties of jet fuels when they are used in diesel engines, and we have optimized their composition. We present the results of a study of the proposed fuel compositions based on jet fuel and functional additives, using laboratory and qualification methods and indicator properties for the D-245.125 engine cycle.
Use of Transformer Oil and “Dry Water” to Store and Transport Methane Hydrate
Abstract
In this paper a new system is proposed for the storage and transportation of gas in the hydrate form (for the case of methane hydrate). The use of solid particles (Aerosil ® R202) is most effective as promoters of hydrate formation for the intended purposes. The ratio of water to transformer oil in the initial systems was constant (1:1 by weight); the content of Aerosil® R202 in “dry water” was 5 wt. %. From the obtained results it follows that the presence of “dry water” in the system accelerates the formation of the hydrate, while the transformer oil provides a self-preservation effect and thereby slow decomposition of the hydrate phase. The proportion of methane hydrate subjected to self-preservation in the presence of transformer oil is 80 times higher than for the hydrate obtained from “dry water” without any additives. The obtained data can be used in the development of hydrate methods of gas storage and transportation.
Studies of Flammable Liquid Boilover at Low Pressure and High Altitude
Abstract
Contact of a flammable liquid and water can cause hazardous boilover because of their different boiling points. The dependence of the initial boilover point of a flammable liquid on atmospheric pressure was studied at different geographic locations with different altitudes, i.e., at HeFei (alt., 0 m; P, 101 kPa) and on Lhasa plateau (alt., 3650 m; P, 64 kPa). The temperatures in the bulk and at the interface of the flammable liquid and water, flame temperature, thermal radiation, sound level, and mass loss at ambient temperature were experimentally measured using identical transparent quartz pans for each measurement. The experimental results showed that boilover was delayed or diminished at low pressure and disappeared completely at pressures lower than a certain critical value for this pan surface area. The pan size was shown not to affect the boilover onset or intensity.
Improved Model for Characterization of Fractal Features of the Pore Structure in a High-Rank Coalbed Methane Formation
Abstract
In this paper, we propose a theoretically derived improved model for characterizing the fractal features of coalbed methane reservoirs, and we compare with previously published models for conventional reservoirs. The model was verified by mercury intrusion porosimetry. The results have shown that there is no linear relationship between the normalized wetting phase saturation, wetting phase saturation, or mercury saturation vs. the capillary pressure on a log-log plot. Therefore existing models are inapplicable for a high-rank CBM formation, which is characterized by low permeability and porosity. The improved model lets us calculate the multi-interval fractal features characterizing the physical properties of the formation. We show that higher fractal dimensions mean poorer physical properties of the formation.
Analysis of the Assessment of Storage Capacity of a Gas Reservoir with an Oil Rim and Underlying Aquifier
Abstract
Due to the complexity of fluid composition and the dynamic characteristics of a gas reservoir with an underlying aquifer and an oil rim, estimating the storage capacity of such a reservoir is a complex problem. In this work, the method of numerical simulation is used to calculate the dynamic characteristics of such reservoirs. The obtained data on the distribution of the three phases in the reservoir show the expansion of the gas cap and the penetration of the underlying water into the oil rim, resulting in a three-phase transition zone which increases seepage resistance. The capacity of the reservoir is calculated by the method of numerical simulation taking into account the seepage resistance of the three phases, and the material balance method without taking into account the seepage resistance. The results of calculations show that the storage capacity calculated by the first method is 74% of the value calculated by the second method. Thus, we can conclude that the three-phase transition zone is the main parameter affecting the calculated reservoir capacity, and the effect of the transition zone cannot be neglected when estimating the storage capacity of the reservoir.
The Effect of Thermochemical Factors on Fracturing Pressure in Shale Rock Characterized by Tensisle Strength Anisotropy
Abstract
Drilling mud characteristics affect the stress distribution around the borehole, while anisotropic tensile strength determines the fracture behavior of the formation, but the combined effect of these factors is rarely considered in the prediction of fracture pressure. In this work, tensile strength anisotropy of shale rock was analyzed based on the Brazilian disc test (BDT), and the corresponding anisotropic tensile criteria were reviewed and contrasted with experimental results. The N-Z (Nova – Zaninetti) criterion is adopted to describe tensile strength anisotropy of shale rock. Based on the stress distribution model and the N-Z criterion, a model of shale rock fracture under the combined action of thermal and chemical factors was constructed. The solution of the model shows that chemical and thermal factors have a different effect on pore pressure distribution around the borehole. The effect of sedimentary layers, tensile strength anisotropy, in-situ stress and pore pressure on equivalent density of fracture pressure (EDFP) was also investigated. It is shown that the EDFP decreases with increasing dip angle at a given strike of the bedding plane and reaches a minimum value when the strike of the bedding plane is along the direction of the minimum horizontal stress. The decrease in EDFP caused by tensile strength anisotropy reaches or exceeds 10% of the value calculated for isotropic conditions. The more pronounced the anisotropy of strength, the smaller the possible value of EDFP. The higher the ratio of horizontal stresses and pore pressure, the more significant the effect of anisotropy on EDFP. It is also notable that increasing the temperature of the wellbore can improve EDFP parameters and enlarge the SMDW.
A New Model for Predicting Pressure Fluctuations for a Robertson-Stiff Fluid in a Vertical Well
Abstract
Determination of the reasonable and safe speed for tripping or running casing to avoid downhole problems requires the development of a methodology for modeling the rheology of drilling fluid and pressure fluctuations. Based on the model of flow in a narrow channel, a new calculation model of pressure fluctuations for a Robertson-Stiff (RS)fluid in a vertical well is derived in this paper. Unlike the simplified pressure fluctuations prediction method based on flow in a narrow channel, this model considers the actual difference in stresses between the wall of the moving drill string and the borehole wall, yielding more reliable prediction values. Results indicate that pressure fluctuation values calculated by this model are in good agreement with the values measured under field cjnditions: the average deviation corresponds to 2%, the maximum deviation does not exceed 7%. The pressure gradient directly depends on the hipping speed, rheological parameters of the fluid, and the ratio of the inner and outer diameters of the annular space, i.e. the gradient increases with an increase in any of these parameters. The findings presented in this paper may be of interest for determining safe operation modes for wells with enhanced safety requirements, such as drilling with casing or in deep-water drilling, including selecting the tripping speed, the rheological parameters of drilling mud, and the optimal sequence of casing installation.
CURRENT PROBLEMS. Alternative feedstock
Gasification Behavior of Biomass—Tar Mixtures
Abstract
Gasification of mixtures of biomass (sunflower seed shells, corn cobs) and heavy oil residues (tar) with added water and preliminary mechanochemical activation of the feedstock is investigated. The influence of the gasification conditions on the yield and composition of the obtained syngas is studied.
Technology
Optimal Composition of Crude Oil for Atmospheric Petroleum Distillation
Abstract
Results are given for a study on the optimization of the composition of crude oil consisting of petroleum, fuel oil, and gas condensate to improve atmospheric distillation at an installation of the Gazprom Neftekhim Salavat Atmospheric and Vacuum Distillation Company. The results of a determination of the size of dispersed phase particles and the stability factor were used to predict the effect of the gas condensate in the crude oil on the major physicochemical properties and yield of light petroleum products. An active state of the dispersed system in the mixed crude oil was found at 40 wt.%. Atmospheric distillation of the activated crude oil permits an increase in the yield of light petroleum products by 28 wt. %.
Research
Oxidative Methods for the Study of the Structural Group Composition of Organosulfur Compounds
Abstract
The composition of the organosulfur compounds of the oil fraction of Arlan oil was studied using a method involving the two-step oxidation of these compounds with 30% hydrogen peroxide in the presence of an acid catalyst at 80° and 100°C. Vacuum distillation of the organosulfur compounds into narrow fractions showed that the sulfoxides obtained by oxidation of the organic sulfur compounds of the oil fraction are thiamono-, thiabi-, and thiatricycloalkanes, aliphatic sulfides, and alkylcycloalkyl sulfides. No aromatic compounds were detected in the sulfoxides. Sulfones in the narrow fractions are mainly represented by thiaindanes, alkylcyclano- and alkylbicyclanobenzthiophenes with long alkyl substituents containing from 10 to 15 carbon atoms.
Methods of Analysis
Method for Isolating Asphaltenes from Petroleum by Their Precipitation from Supercritical Carbon Dioxide
Abstract
A study was carried out on the precipitation of heavy fractions and the isolation of asphaltenes from a petroleum sample using supercritical carbon dioxide (SC-CO2) as the antisolvent. The experiments were carried out in a laboratory supercritical fluid extraction device using a GAS (gas antisolvent) procedure at from 50 to 140°C and pressure from 10 to 30 MPa. We determined the effects of temperature and pressure as well as of the addition of a hydrocarbon diluent on the yields of the isolated fractions. The elemental and microelement composition was determined as well as the structural properties of the components isolated in the SC-CO2 medium at various temperatures. An increase in temperature at pressures above 20 MPa as well as the addition of small amounts of toluene to the starting petroleum sample gave greater isolation selectivity, greater concentration of asphaltenes in the precipitated fractions, and drier solid particles. In contrast to C7-asphaltenes, CO2-asphaltenes have lower aromaticity, polarity, and metal content. The proposed analytical method permits the isolation of asphaltenes in only a few hours, does not require large volumes of organic solvents, and yields asphaltenes in amounts sufficient for subsequent detailed study of their composition and properties.
Innovative Technologies of Oil and Gas
Application of Multi-Vertical Well Synchronous Hydraulic Fracturing Technology for Deep Coalbed Methane (DCBM) Production
Abstract
In this paper, we propose a method for multi-vertical well synchronous hydraulic fracturing and compare with synchronous fracturing technologies used in shale. Based on theoretical analysis and triaxial fracturing experiments, we have shown that “face interference” in multi-vertical well synchronous fracturing helps to connect the cleats and generate complex fracture networks. The developed three-step method for designing synchronous fracturing technology was tested under field conditions. The results showed that application of synchronous fracturing decreases the gas breakthrough time in the wells and increases DCBM (deep coalbed methane) production. Furthermore, stress interference generated by synchronous fracturing has a positive impact on the production rate of wells adjacent to the experimental area.