Chemistry and Technology of Fuels and Oils最新文献

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.

This paper addresses the challenge of accurately describing the boundary of deep cavern-type reservoirs. A method is developed to extract diffraction information from the cavern and its boundaries from full wavefield seismic data using PCA wavefield separation technology. The paper describes a method for extracting diffraction information based on post-stack seismic data, and demonstrates the validity of this method in identifying cavern’s boundaries via forward modeling. Subsequently, the method is applied to actual seismic data to extract diffraction information from deep caverns. By separating wavefield information at different scales, the extracted diffraction information can effectively identify the characteristics of cavernous reservoirs and their boundaries. It is verified by examples that the diffraction wave information separation method can provide a more accurate description of the distribution of deep cavern-type reservoirs, which can provide a basis for predicting this type of reservoir.

TIn order to solve the problem of water lock blockage in the wellbore of Daniudi gas field, the main surfactant APG and CG-1, CG-2, WR and other surfactants were used to produce co-energy and synergistic effect through the combination of multiple surfactants. The static properties of the agent were evaluated by measuring the interfacial tension, surface tension and contact Angle of the surfactant system. According to the physicochemical mechanism of the synergistic action of compound surfactants, the water lock of the combination of anionic surfactants and non-ionic surfactants is preferred. A new water unlocking agent system for tight gas reservoirs was developed: APG (0.3%) +CG-1(0.2%) +SYH (0.1%) +KCl (2%). The interfacial tension between the system and simulated oil was 9.61·10^-4 mN/m, the surface tension was 18.2 mN/m, and the gas/liquid/solid three-phase contact antenna was 99.4°. Daniudi tight core (core No. 602-14) was used to simulate the process of high temperature and high-pressure water lock damage. The permeability recovery rate after injection of waterproof lock agent is 25.36% compared with water lock damage.

The large-scale exploitation and wanton use of fossil energy have led to the increasing global warming and environmental pollution. The development and utilization of clean energy urgently need to be put on the agenda. At the same time, the development of Internet technology and big data technology is constantly promoting the development and popularization of clean energy. However, Internet information security is the number one factor threatening the development and supply of clean energy in today’s society. Therefore, based on the relevant theories of statistical learning, an evaluation model of information security reliability of clean energy internet based on statistical learning is constructed. At the same time, the reliability of the evaluation model is tested and analyzed. Finally, the role of the evaluation model in the carbon sequestration of natural gas hydrate, the reduction of greenhouse effect and the development of clean energy is analyzed. It is expected to lay a foundation for the efficient development and environmental protection of clean energy (natural gas) through this research. It is found that the predicted results of data transmission by coaxial cable are completely consistent with the actual results, and neither will generate hydrate within 2.5 m from the entrance. Moreover, the reliability of data transmission using coaxial cable is higher than that of wireless transmission. The study also found that the increase of carbon dioxide injection rate will accelerate the decomposition and gas production of hydrate, and it is more obvious in the small range of carbon dioxide injection rate. Considering the development efficiency and burial efficiency, the carbon dioxide injection rate is designed as 20·104 m³/day is the best. At the same time, the greenhouse effect of carbon dioxide will become more and more significant with the increase of its concentration, and based on the prediction of the built model, it is found that the replacement rate of natural gas in hydrate by carbon dioxide can reach 92.35%.

Chemical ways of utilising carbon dioxide in the oil and chemical industries to reduce CO₂ emissions and the carbon footprint of the products at various stages of their life, both those tested and used on an industrial scale and those currently under development and pilot testing, are discussed. Authors discuss the prospects for development of appropriate technologies aimed at decarbonization and sustainable development, and the critical factors for deciding on the direction for the production of “green” products using CO₂.

The apatite and zircon fission track (FT) analysis offers the opportunity to reveal the chronology records for Meso-Cenozoic tectonic events in the Northeast of Ordos Basin, China: the Indosinian Epoch tectonic events mainly occurred at (245-235 Ma±) with a peck-age of 240 Ma and (205-195 Ma±) with a peck-age of 200 Ma, corresponding to the parallel unconformity during the Middle and Lower Triassic to Upper Triassic, the angular unconformity during the Late Jurassic to its underling layers. Middle Yanshanian tectonic events occurred at (155-115 Ma±) with a peck-age of 135 Ma, and corresponded to the angular unconformity during Lower Cretaceous to its underling layers. Late Yanshanian to Himalayan tectonic events included at least two episodes, peak-age respectively is (65Ma±) and (20 Ma±). On this basis, we further complete their main elements geochemical analysis. The contents of TiO₂, Fe₂O₃+MgO, Lg (SiO₂ / A1₂O₃) in samples was 0.18-1.02%, 1.23-8.55%, and 0.59-1.04%, respectively. The average was 0.53%, 4.5%, 0.71%, respectively. Based on the discriminant plate of the main element, the transition events of the important sedimentary structure environment in phase two were obtained. The relationship analysis of the tectonic event and the mineralizing chronology revealed that the key tectonic events control reservoir forming time or mineralization time of the coupling coexistence of multiple energy resources in the Northeast of Ordos Basin, and show the collaborative and coupled relationship between the tectonic events and accumulation (mine).