Том 53, № 4 (2017)

In this work, we sought to find new efficient methods for reducing the sulfur content in crude petroleum coke. The action of reactive dichlorocarbene or chlorocarbene intermediates produced in the reaction of chloroform or methylene chloride and sodium hydroxide under phase transfer catalysis conditions was shown to cause the breakdown of C–S bonds of some individual sulfur compounds to give reaction products identifiable by classical methods. Furthermore, a series of experiments was conducted using crude petroleum coke with high sulfur content (4.3%) under phase transfer catalysis conditions, which showed that, under optimized conditions (by enhancing the mass transfer rate using phase transfer catalysis and/or ultrasound), the sulfur content in the original coke can be reduced to 2%, which comprises a reduction of more than 50% of the initial content.

The effect of micro- and nano-sized CeO₂ powder additives on acidic and catalytic properties of MFI (mordenite-framework-inverted) type of high-silicon zeolite in the process of production of high-octane motor fuel components from straight-run gasolines of gas condensate is studied. Addition of modifying agents to the original zeolite promotes its catalytic activity and concentration of acid centers. Addition of 1 wt. % of promoting additives of nano-sized CeO₂ powder to zeolite enhances yield of arenes in the liquid catalyzate by 4-7 wt. % and octane number (ON) of the obtained catalyzate by 2-3 points in terms of RON. It is shown that zeolite modified by micro-sized CeO₂ powder possesses similar catalytic and acidic properties as does zeolite modified by nano-sized CeO₂ powder.

Novel viscoelastic self-diverting acid (VDA) systems with and without cosurfactant (sodium dodecylbenzenesulfonate, SDBS) added to enhance reaction retardation and to improve the conventional VDA system are studied. The novel system viscosifies at a pH of ~0.6 and attains a viscosity of ~500 mPa·s. The system without added SDBS viscosifies at a pH of ~2.2 and reaches a final viscosity of 403 mPa·s. Studies of the limestone—acid reaction kinetics showed that the reaction rate fell from 1.37·10^–4 mol/(cm²·s) for 20 wt. % HCl solution to 13.2·10^–6 and 6.5·10^–6 mol/(cm²·s) for VDA solutions without and with added SDBS, respectively. The reaction rate constants (k) for the negative sample control and VDA systems I and II were 1.0740·10^–1 (mol/cm³)^(–0.3092)·(cm/s), 5.5221·10^–4 (mol/cm³)^(0.2822)·(cm/s), and 6.3154·10^–5 (mol/cm)^(0.5554)·(cm/s), respectively. A dual-core flow test showed that wormholes were produced in both cores for the VDA systems rather than a large single channel in a high-permeability core when 20 wt.% HCl solution is used. Thus, a smaller volume of SDBS is needed for flow formation when VDA solution is added. The studies revealed that the novel VDA system retards reaction considerably, improves acid diversion, and has tremendous potential for field applications.

Based on the rapidly varying casing pressure method and multiphase flow theory, we have constructed a transient mathematical model for managed pressure drilling (MPD) that combines kick with mud loss in a single fracture. The finite difference method was used to iteratively solve this model. The model calculated values agree well with the experimental results, which confirms the reliability of the model. Casing pressure, casing shoe pressure, pit gain, outlet flow, and choke opening during the entire well control process are analyzed. Experimental results show that equality of inlet flow and outlet flow may not imply influx stoppage when a kick is coupled with mud loss. In addition, the loss rate at the casing shoe initially increases linearly over time and then decreases exponentially, ultimately becoming constant. After completion of well control, drilling can be safely continued until loss is negligible. This study may provide a theoretical basis for better control of wells with complicated kick and circulation loss in managed pressure drilling (MPD).

The pore network (connected tunnels) can be used not only to describe pore geometry inside a rock but also to calculate various fluid flow properties on a micro scale. Based on a “digital core” extracted from micro computerized tomography (μ-CT), we have developed a simplified pore network model. This study simplifies the pore structure as a lattice of cubes. Pore size, pore distribution, tunnel connectivity, fluid viscosity, interfacial tension, and the external driving pressure gradient are considered for each adjacent cube to evaluate the flow capacity of the pore network. We calculated the permeability, effective permeability, and effective sweep efficiency. The results show that fluid flow initially starts in the largest tunnel, which corresponds to the threshold pressure of the rock sample (fluid flow onset pressure). Permeability changes nonlinearly before all the tunnels are involved in the flow. Changes in the microscopic residual oil saturation and the sweep efficiency were visualized based on the three-dimensional pore distribution. Visualization shows that more oil remains in the formation, the heterogeneity is greater, and the oil viscosity is higher.

The results of investigating gas hydrate decomposition processes in model porous media using a Micro-CT Test System were analyzed. The objects of the study were natural gas hydrates produced at a specified pressure and temperature using porous media consisting of sand with three particle size ranges (0.85-1.18, 1.18-2.85, and 2.85-4.8 mm). The microstructural characteristics and the porosity of the obtained gas hydrates in the decomposition process were studied. The dependence of microstructural characteristics of gas hydrates on the nature of the porous medium, based on which the hydrates were produced, was also investigated. The results indicate that the hydrate is distributed uniformly and fills the pores of the porous media almost completely.

We have conducted numerical simulation studies with the goal of improving recovery efficiency. Utilizing results obtained in pilot testing on the target reservoir, which was done previously using polymer gel flooding and cyclic steam injection, in this paper we give the results of a study on optimization of the injection – production parameters. “Injection – production” refers to a combination operation involving polymer gel flooding and steam injection (for simplicity, we call this a “heating plus maintaining pressure” process). The study result shows that this process is affected by many factors, including the steam temperature, the injection rate, the soak time in the formation, the injected steam volume, and the cyclic soak time; the polymer concentration, the polymer gel slug size, the polymer flooding time interval; and the well production factor. Considering the development results, we obtained the order of importance for these factors: cyclic steam injection time > production factor > cyclic steam injection volume > soak time > steam temperature > polymer injection concentration > polymer gel slug size > polymer gel flooding time interval > steam injection rate.

The distinctive features of the structure and composition of hydrocarbon disperse systems in various types of heavy oils after steam-heat treatment, including use of low-boiling hydrocarbons, are determined. Methodological approaches are developed to determine the stability of heavy hydrocarbon resources as a function of composition and structure of the hydrocarbon disperse systems. Based on theoretical concepts of oil disperse systems, the composition of the latter is characterized quantitatively. A notable feature of low-viscosity oils is greater affinity of the components of the solvate shell and the dispersion medium. As a result, the dispersion medium participates in cross-linking of the oil disperse system significantly, which leads to a decrease in the dispersivity of the system and in its viscosity.

Coking and regeneration of a hydrofining catalyst activated by various sulfidizing agents are analyzed. The procedures for activating the catalyst in a high-pressure catalysis unit by tert-butyl polysulfide and dimethyl disulfide are described. The activation energy for catalyst regeneration by oxygen is calculated for different heating rates using differential scanning calorimetric data.

A technological procedure has been developed for the production of succinimide additives possessing detergent dispersant and anticorrosion properties, which can be used in lubricating oils for the reduction of carbonaceous deposits on internal combustion engine parts. New alkylenimidosuccinimides derived from N,N–bis–(β–aminoethyl)piperazine and terephthalic acid production waste materials have been synthesized. Tests showed that the new additives meet the technical specifications for succinimide additives.

Esters of vicinal dicarboxylic acids are synthesized. Their structural specifics are studied. The thermooxidative stability of the vicinal dicarboxylic acid esters is estimated. It is established by IR spectroscopy that the oxidation proceeds along the C–H bond of a tertiary carbon atom. The C=C bond of alkenes does not participate in the oxidation process.

The results of laboratory experiments on modeling of heavy oil oxidation processes in an air-oxygen environment using cobalt (III) acetylacetonate as catalyst at temperatures and pressures typical of thermal production methods are presented. It is established that the high-molecular components of the heavy oil are degraded in the air-oxygen environment at temperatures above 250°C in the presence of the catalyst with formation of low-boiling hydrocarbon fractions and oxygen-bearing compounds, and this reduces the density and viscosity of the transformed oil. In addition, the products obtained in the experiments show an increased asphaltene content and the presence of finely disperse carbonaceous substances, indicating the occurrence not only of cracking, but also of condensation processes. The experimental data indicate the main directions of the reactions and transformations of heavy oil hydrocarbon components in the studied systems, which provides the possibility of using cobalt acetylacetonate as a catalyst in the in-situ low-temperature oxidation of heavy oil in carbonate reservoirs.

The known technical solutions for regeneration of used fuels and oils are generalized. A new extractant based on orthophosphoric acid is studied and a method for extractive cleaning (refining) of waste industrial oils and diesel fuel is proposed. A technological scheme and a laboratory experimental procedure of refining (clarifying) waste petroleum products as a hydrocarbon stock are proposed.

A new method of quantitative appraisal of adhesion properties of lubricants and their dispersion media, which is based on determination of the forces of adherence between the lubricant and the metallic surface as well as between the elements of the structural framework of the lubricant under the destructive impact of centrifugal force, is described. The results of the investigation on the influence of the base oil type and the nature of the thickener on the adhesion properties of the lubricants are reported.

Drilling faces many complex design and multiobjective optimization problems. Solving these problems is also a critical and complicated part of drilling optimization as part of well trajectory design and optimization. Many researchers have developed many algorithms, but they have some disadvantages. We take the shortest total borehole length, the highest target shooting accuracy, the lowest cost, and the minimum friction as the multiobjective function, and we use a fish swarm algorithm for trajectory optimization. In this paper, we present the idea of using a nondominant relation for sorting in the algorithm and we also use an optimization program in the Matlab software to obtain all numerical solutions satisfying the constraints. Therefore it is quite adaptable for introducing the idea of nondominant sorting into appropriate multiobjective optimization problems based on a fish swarm algorithm. We give an example of the calculation, and also show that the algorithm and the calculation procedure are accurate and reliable. The algorithm has a simple structure, a small number of calculations, and good convergence.

The second author’s affiliation should read Key Laboratory of Enhanced Oil & Gas Recovery under Ministry of Education, Northeast Petroleum University, Daqing, China