Chemistry and Technology of Fuels and Oils最新文献

Tight oil has become one of the important energy sources for increasing reserves and production in China’s oil and gas field. Chang 8 Member of Ordos Basin shows great exploration potential, and the classification and evaluation of tight reservoirs are critical to reservoir optimization and reserve evaluation. However, the classification and evaluation of tight reservoirs in Chang 8 Member of Ordos Basin have not been unified. Therefore, on the basis of previous research results, this paper systematically studied the petrological characteristics, physical properties and microscopic pore throat structure characteristics of tight sandstone reservoirs by means of rock slice observation, overburden porosity and permeability test and high-pressure mercury injection test. On this basis, the weight coefficient of the correlation between the key parameters and the oil-bearing property of the reservoir is determined by screening the key parameters, and the mathematical model of reservoir classification evaluation is established by using the analytic hierarchy process. The research results show that the reservoir composition maturity of Chang 8 Member in Ordos basin is medium, and the lithology is mainly lithic arkose and feldspathic lithic sandstone. The physical property of Chang 8 reservoir is poor, and it belongs to low porosity, low permeability ultra-low permeability reservoir as a whole. The reservoir space is dominated by intergranular pores and dissolution pores, and micro fractures are developed locally. The pore throat structure of the reservoir is fine, and the pore type is smaller than 10 μm, and the throat and micro throat are dominant with 0.2 μm. Considering porosity, permeability, displacement pressure, average pore throat radius and other parameters comprehensively, normalize each parameter, and determine the weight of each parameter according to its correlation with oil saturation. The reservoir classification and evaluation model were established by using the analytic hierarchy process (AHP), and the reservoir quality index (RMI) is used to classify the reservoirs of Chang 8 Member in Ordos Basin into 4 types. This study can provide a basis for efficient exploration and development of tight oil.

A complete analysis of the existing methods of synthesis of polyhydroxylated fullerenes using direct chemical interaction, as well as alternative methods of creation has been carried out in order to identify the optimal methods of obtaining, for their implementation in various technological and biomedical fields. The scientific literature on this field of research is summarized and classified, and a comparative assessment of the efficiency and feasibility of practical implementation of the developed synthesis methods is given on the basis of a comprehensive review of literature and patent documents.

Molecular dynamics modelling was carried out for polyethylene terephthalate and composite materials derived from this polymer with different single‑walled carbon nanotubes as a filler. The effect of the supramolecular structure of this polymer composite material on some of its physicochemical and mechanical properties was studied. The interphase intermolecular interaction of the polymer matrix‑filler system was found to be the major factor determining the physicochemical and mechanical properties. Therefore, consideration of this interaction is necessary for predicting the properties of such materials.

The article discusses the special features of operation of hydroejector vacuum-creating systems. The flow diagram of a two-stage hydroejector vacuum-creating system is described and a calculation algorithm is given. The dependence of the yield of the components of the vapor-gas mixture on the temperature of the working fluid was analyzed and the required heating temperature of the working fluid was determined. A two-stage hydroejector vacuum-creating system was calculated and the dependence of the flow rate of the working fluid on the pressure and power consumption of the pumps was determined.

On the basis of the characteristics of low-density polyethylene determined experimentally from the geometric dimensions of the extruder parts and COMSOL MULTIPHYSICS software a digital model of the apparatus was created, and the flow rate of the polymer melt from the extruder nozzle was calculated hydrodynamically. The agreement between the experimentally measured polymer flow rate and the value obtained from the model lies within the permissible error. This establishes the adequacy of the digital twin model, which will be used to predict the viscosity characteristics of composite materials based on low-density polyethylene and the technological regimes of their production by blending in the extruder.

Stable water-oil emulsions are formed due to the strong armor layer at the oil/water interface able to prevent the coalescence of water droplets in oil. The stability of water-oil emulsions obtained by mixing solutions of asphaltene in toluene and in heptol (a mixture of n-heptanol and toluene) with distilled water was found to be a function of two asphaltene fractions, namely, a fraction soluble in heptol enriched with ester fragments and a fraction tending to form aggregates in heptol. The surfactant properties of the first fraction permit the formation of a thin shell with low mechanical strength at the oil/water interface. The asphaltene aggregates adsorbed onto this thin shell are compacted over time, imparting rigidity and mechanical strength to the oil/water interface layer.

The tight shale matrix has the structural characteristics of low porosity and low permeability. It is easy to cause water sensitivity damage, water lock damage and solid phase damage during fracturing, which greatly affects the gas reservoir transportation process of core. At the same time, fracturing fluid will invade the reservoir matrix, causing permeability damage and reducing gas production efficiency. This study analyzes the process and mechanism of fracturing fluid damage to shale matrix in the process of fracturing fluid retention, and proposes fracturing fluid damage control methods. Taking a tight sandstone reservoir in the ZJ block in South Sichuan as the research object, the mineral type, viscosity content and various physical parameters of shale gas reservoir are analyzed, and the quantitative index of fracturing fluid damage index is calculated. Using HPG as the precursor fluid, KW-1 and KDF as the drainage aids to prepare the fracturing fluid for experiment, the viscosity of the gel breaker reached 1.3 mPa·s, the interfacial tension between the gel breaker and kerosene reached 1.05 mN/m, and the surface tension was 22.8 mN/m. The fracturing fluid has good flowback performance. By collecting 4 core samples from ZJ block, the gas permeability of core samples is selected as three permeability sections 0.05·10^–3 μm², 0.15·10^–3 μm² and 0.25·10^–3 μm². And the correlation experiments of water sensitive damage, water lock damage and solid damage are carried out. The results show that when the permeability of the fracturing fluid decreases from 0.25·10^–3 μm² to 0.05·10^–3 μm², the damage value of the permeability section of the JS experimental group also increases from 8.25% to 18.35%, the movable water retention also increases from 0.032 PV to 0.046 PV, and the bound water increase increases from 0.032 PV to 0.086 PV. Therefore, the smaller the osmotic pressure is, the greater the retained amount of movable water and the increased amount of bound water are, and the greater the damage value of fracturing fluid is. In addition, when the mass fraction of XJHX in this experiment reaches 0.8%, its anti-swelling rate can reach 85%, which has excellent anti-swelling performance and can effectively reduce the permeability damage caused by fracturing fluid to shale formation.

The formation, storage and seepage characteristics of shale gas reservoirs are significantly different from those of conventional oil and gas reservoirs, and their in-depth study is extremely important for improving energy security and promoting sustainable development. In this paper, based on the nonlinear seepage theory of shale gas reservoirs and the capacity analysis of test wells, a steady state capacity model integrating the apparent permeability model and the multi-scale transport mechanism is constructed to investigate the influence of various factors on the apparent permeability and the capacity of shale gas fractured horizontal wells, as well as to predict the production of shale gas wells. It is found that: apparent permeability is significantly affected by pore radius, and the non-Darcy effect is particularly significant under low-pressure and small-scale pore conditions; when the reservoir pressure is lower than 15 MPa, the sensitivity of apparent permeability to temperature and Langmuir volume increases, but decreases with the increase of Langmuir pressure; and the production capacity analysis of shale gas reservoirs shows that the production rates of fractured wells that consider the multiscale transport mechanism are generally higher than those considering Darcy flow only, especially in the case of low wellbore pressure and large pore radius; the effects of Langmuir volume and pressure on the production capacity are relatively small, and mainly noticeable in the range of wellbore flow pressure from 1 MPa to 15 MPa. The number of fracture bars has a significant effect on production, but too many fractures can lead to gap interference, which slows down production growth. The results of this research provide theoretical support for the scientific development of shale gas reservoirs and have important research and application value for the efficient and rational development of actual well sites.

Aiming at the hazards caused by drilling into fractured formations during oil drilling, linear prediction of physical properties of CO₂/H₂S under different well depths are carried out, based on Fluent to simulate gas-liquid placement in near-critical, critical and supercritical states of gas. The results show that when the well depth is small, the CO₂/H₂S near-critical state and the initial bottom hole pressure of the critical state invading the annulus are lower than the formation pressure, and the gas invading the annulus is suspended in the annulus until the hydrostatic pressure of the missing drilling fluid is supplemented for about 1s and 1.2 s respectively, the formation pressure can be balanced before the upward return can be continued; the bottom hole pressure of the supercritical state invades the annulus rapidly drops within 2 s; the gas-liquid replacement rate in the supercritical state is slower than that in the non-supercritical state, with a difference of 60-80 s. During the drilling process, it can be judged according to the bottom hole pressure change whether it has encountered a fractured formation and the state of the gas contained, and well control measures should be taken in time.

The study of fluid inclusions in petroliferous basins is an effective method to understand hydrocarbon migration and accumulation. In this paper, the fluid inclusions in the Ordovician carbonate rock samples taken from the TS3, TP18, YQ8 and YJ2-3 wells in Tahe Oilfield are analyzed by experiments, the purpose is to explore the accumulation period of the Ordovician oil and gas reservoirs in the Tahe area and the reasons for the differences between different blocks.The results show that the Ordovician Yingshan Formation and the Yifangfang Formation in the Tahe area are rich in fluid inclusions, and there are only a single phase of oil, gas and brine in the phase. There are also two phases of oil, gas and water mixed with each other. According to the fluorescence characteristics and homogenization temperature of hydrocarbon inclusions, combined with the burial history-thermal evolution history of the study area, it is determined that the Tahe oil and gas reservoir is filled in the fourth stage, in the middle of the Caledonian period (454-446 Ma), and in the late Hercynian-Indosinian period (255-217 Ma), late Yanshanian period(143-99 Ma), Himalayan period (25-5 Ma).Among them, the middle of Caledon is mainly filled with low-mature oil, with a small amount of mature oil; the late high-mature oil in the late Hercynian is filled with some mature oil; the late Yanshan is mainly filled with high mature oil; during the Himalayan period, as the depth of burial continues to increase, the cracking of the accumulated hydrocarbons has occurred, mainly the migration of gas hydrocarbons. The four wells selected in this study belong to different tectonic units, after analysis, the author believes that the difference between single wells is on the one hand the influence of hydrocarbon thermal evolution and the other is influenced by tectonic movement.