Volume 55, Nº 1 (2019)

Advances in volumetric thermal expansion in-line with complex physicochemical investigation allowed to introduce and rigorously test novel inexpensive transition metal oxide-based catalysts with varying shapes, which proved valuable against toxic compounds of flue and exhaust gases of various origin. Since the investigated processes can be described with high confidence by well-known diffusion models, the possibility of mathematical prediction of the structure and composition of the proposed catalysts is considered. The target product should be suitable for loading into different types of reactors and have a number of competitive advantages over the known commercial catalysts for gas purification, which are based on noble and rare metals. The possibility of eliminating the chemical, structural and phase history of the starting compounds by means of controlled synthesis to improve the consumer characteristics of the product is investigated. The advantages of the obtained molded catalysts are high activity and selectivity in combination with an increased life cycle and low hydraulic resistance in the catalytic bed.

The technology of CO₂ injection into oil reservoirs contributes to a significant increase in oil production effectively reducing greenhouse gas emissions into the atmosphere. The mechanism of enhanced oil recovery was studied on the example of large formations of the Ordos Basin. The Ordos shale oil field is characterized by low porosity, low permeability and high reservoir heterogeneity. In this paper; based on an experimental model, a mechanism of filtration of fluid in a formation rock is proposed. To verify the model, oil recovery parameters were studied experimentally during CO₂ injection for the conditions of the YanChang field of the Ordos Basin. In the course of the experiments, on models of long cores of the rock, the effect of the rate and intensity of injection, the exposure time and well parameters on the displacement efficiency during cyclic injection were measured. The paper concludes that it is possible to use CO₂ injection technology to improve the efficiency of oil recovery on reservoirs using the example of the YanChang field.

Carbonate reservoir is one of the important reservoirs in the world. Because of the characteristics of carbonate reservoir, vertical well and acid fracturing have become a key technology for efficiently developing a carbonate reservoir. Establishing corresponding mathematical models and analyzing transient pressure behaviors of this type of well-reservoir configuration can provide a better understanding of fluid flow patterns in formation as well as estimations of important parameters. A mathematical model for a fractured vertical well in triple media carbonate reservoir by conceptualizing vugs as spherical shapes is presented in this article. A semi-analytical solution is obtained in the Laplace domain by using source function theory, Laplace transformation, and the superposition principle. Analysis of transient pressure responses indicates that several characteristic flow periods of fractured vertical wells in triple media carbonate reservoir can be identified. Parametric analysis shows that the fracture length can significantly influence the transient pressure responses of fractured vertical wells in triple media carbonate reservoir. The model presented in this article can be applied to obtain important parameters pertinent to reservoir or fracture by type curve matching, and it can also provide useful information for optimizing fracture parameters.

In horizontal well drilling, the success of the drilling operation mainly depends on optimal selection of the drilling trajectory. In this paper-, we propose a method for optimizing horizontal well trajectory design based on the numerical optimization methods PSO (particle swarm optimization) and AHP (analytic hierarchy process). We selected four functions as the parameters which affect the selection of the optimal solution: the shortest length of the well trajectory, the highest target hitting accuracy, the lowest cost of drilling, and the least drilling string friction. The key parameters for a horizontal well (the KOP (kick-off point), BUR (buildup rate), and hold angle) were calculated by ththe PSO method in Matlab. Applying the AHP mathematical tool for a systematic approach to decision-making, we ranked the solutions according to the engineering and design requirements. The new method proposed in this paper lets us overcome the limitations of the optimization algorithm and to recast empirical judgments of experienced analyzers in mathematical language, thus avoiding subjectivity in selecting the best solution. The method was applied to and tested on conditions of the Yanchang field. As shown by the experimental study, the proposed method is a simple and reliable method for selecting the optimal trajectory.

Isomerization of n-hexane on Pt-catalysts supported on activated Tagan montmorillonite in the Na-form is studied as a function of the method for introducing TiO₂ into the catalyst. The textural properties of the obtained catalysts and their acidic characteristics and x-ray phase and elemental compositions were determined. The isomerization properties of Pt-catalysts supported on pillared TiNaHMM and prepared by mixing TiO₂ and NaHMM were compared. A simplified method was developed for preparing Pt/NaHMM + TiO₂ catalyst that had stronger isomerizing activity than Pt on pillared TiNaHMM. The maximum conversion of n-hexane was shown to be 57%; maximum total yield of C₆ + C₇ isomers, 51.6% on Pt/NaHMM + TiO₂ + HM at 400°C.

A device is proposed for contactless measurement of density profile in oil refining, chemical, and mining industries. The device consists of a γ-radiation source, a shield, and a proportional counter with xenon accumulation and counting with charge separation. The device is capable of measuring distribution of density of a substance behind a steel wall with a thickness up to 50 mm in the 1-1.5 m height range depending on the specific goal. The operation principle and the results of modeling using GEANT simulation software toolkits are described.

The aim of this study was to evaluate the impact of modeled drilling wastes on planktonic and benthic organisms of the Tuapse trough of the Black Sea. The extension of shelf turbidity area due to drilling is calculated using VOSTOK software package for water-oil- and water-based drilling muds (WODM and WDM). The maximum impact on the diatom (Phaedactylum tricornutum) population was achieved after 96 h of incubation at 20 mg/liter drilling wastes concentration. Acute lethal effect on water fleas (Daphnia magna) was observed only at high concentrations of suspension of drilling wastes (above 1 g/liter) in the seawater. In real conditions, such a concentration is attained only in the immediate proximity of the waste disposal site. Delayed effects, namely, fertility decline and maturation and growth delay, which resulted from short-term impact in the area of increased turbidity, were established. Mollusks (mussels) exhibited resistance to the impact of drilling wastes, but a marked deterioration occurred in their physiological state.

Damage to the cement sheath during well completion, stimulation, and production leads to sealing failure in the well and poses a significant risk to safe operation and the environment. In this paper, based on a predictive model for sustained casing pressure, we propose a method for quantitative evaluation of the extent of cement sheath sealing failure. The composite permeability is selected to characterize the extent of sealing failure. Based on the calculation results for sustained casing pressure, we obtain pressure dependences of the permeability. The composite permeability is calculated based on substituting field data into the proposed model. We analyze and compare the results of the predictive model for the casing pressure in constant annular volume and annular volume expansion scenarios. The results show that the time dependences of the permeability have the shape of an inversely proportional function. The composite permeability of the cement sheath for constant annular volume is 1.90% higher than for the annular volume expansion scenario. With an increase in the time required to establish the sustained pressure (the stabilization time), the permeability decreases and consequently the extent of cement sheath sealing failure decreases. The study results are of practical importance for a quantitative evaluation of the extent of sheath sealing failure for the well and a predictive evaluation of the casing pressure.

The title of the article should read

Effect of Solvent Phase State on Solvent Deasphalting of Vacuum Residue with n-Pentane

The second author’s name should read

A. V. Pripahaylo

End products of n-hexane cracking in a displacement fixed-bed catalytic reactor (Pt + Re + In + Ti)/γ-Al₂O₃ with specific surface area 193 m²/g were investigated. The catalytic system was crystalline γ -Al₂O₃ with lattice constants 8 Å and average crystallite size 4.8 nm. The degree of conversion of n-hexane doubled and the selectivity for methyl-substituted benzene increased by 33.2% as the temperature was increased from 400 to 450°C. The amount of carbonaceous reaction products was unaffected by the increased process temperature although the yield of gaseous products increased significantly. The isobutane content in n-hexane catalytic cracking gases exceeded 30 vol.%. The elemental and phase compositions of the catalytic system did not change during the experiment.