Experimental study on hydration damage of anisotropic shale under high temperature

Auto-ignition and knocking combustion characteristics of iso-octane-ammonia fuel blends in a rapid compression machine

Investigation on laminar burning velocity measurements of premixed Ethane-Air mixture at higher pressure and temperature conditions

Creep behavior of the ZK60 magnesium alloy was investigated using impression creep technique. The tests were carried out under constant punching stress at high temperatures (175, 200 and 225 °C) under low stresses (25, 50, 75 and 100 MPa) and at low temperatures (100, 125 and 150 °C) under high stresses (100, 125, 150 and 175 MPa). The creep mechanism of the extruded ZK60 magnesium alloy is grain boundary sliding by dislocation climbing obtained at low temperature and high pressure. At high temperature and under low pressure, the creep mechanism of the extruded ZK60 magnesium alloy is grain boundary diffusion by grain boundary sliding. The initial microstructure of the extruded ZK60 magnesium alloy was composed of mainly Mg phase and a little MgZn phase. Under the conditions of low temperature and high pressure, MgZn2 phase precipitated during creep deformation. Under the conditions of high temperature and low pressure, MgZn2 phase and a small amount of Zr-Zn phase precipitated during creep deformation. The creep resistance of magnesium alloy ZK60 under the conditions of low temperature and high pressure is better than under the conditions of high temperature and low pressure.

Applying SANS technique to characterize nano-scale pore structure of Longmaxi shale, Sichuan Basin (China)

Pore connectivity characterization of shale using integrated wood’s metal impregnation, microscopy, tomography, tracer mapping and porosimetry

Evaporation of solid cyanuric acid particles suspended in argon

Calculation of hydrogen adsorption isotherms and Henry coefficients with mixed CO2 and CH4 gases on hydroxylated quartz surface: Implications to hydrogen geo-storage

Temperature affects sexual maturation through the control of kisspeptin, kisspeptin receptor, GnRH and GTH subunit gene expression in the grass puffer during the spawning season

The high temperature and high in-situ stress geological environment can significantly affect the mechanical properties, failure modes, and deformation characteristics of deep shale reservoirs. In this study, real-time high temperature triaxial compressive tests simulating the deep shale formation environment (temperature: 25–150 °C, confining pressure: 0–100 MPa) are carried out. The GSI-strength degradation and constitutive models are derived based on the Hoek–Brown criterion. The results show that in low confining pressure conditions, the mechanical behavior of shale is greatly influenced by temperature. Compared with shale at 25 °C, the compressive strength of shale at 150 °C decreases by up to 13.7%, and the elastic modulus decreases by up to 36.9%. The peak strain was increased by a factor of up to 1.4, and the yield stress level was advanced by as much as 7.4%. However, in high confining pressure conditions, the shale plasticity characteristics are significantly enhanced and the failure mode is relatively single. The GSI-strength degradation model can well characterize the variation law of shale strength with confining pressure under high temperature conditions. The statistical damage constitutive model matches the actual stress–strain curve very well, and it can fully reflect the deformation and failure characteristics of deep shale. The findings of this study can help us better understand the variation of mechanical properties of deep shale.

The results of a study of the effects of the temperature and pressure conditions in high temperature/high pressure wells on drilling fluid equivalent circulating density and consequently bottom-hole pressure are presented in this paper. High temperature conditions cause the fluid in the wellbore to expand, while high pressure conditions in deep wells cause fluid compression. Failure to take these two opposing effects into account can lead to errors in the estimation of bottom-hole pressure. The rheological behavior drilling fluids is also affected by the temperature and pressure conditions. A simulator called DDSimulator was developed to simulate the wellbore during circulation. A Bingham plastic model was employed to express the rheological behavior of the drilling fluids studied, with rheological parameters expressed as functions of temperature and pressure. The Crank-Nicolson numerical discretizing scheme was employed in the DDSimulator for the evaluation of the wellbore temperature profile. The results of the simulation show that higher geothermal gradients lead to lower bottom-hole pressure. The inlet pipe temperature did not have a significant effect on the bottom-hole temperature and pressure, and higher circulation rates result in lower bottom-hole temperature and higher bottom-hole pressure.

Seismic signals induced by the Metasomatism of mantle wedge by siliceous melts: Insights from the elasticity of orthopyroxene at high pressure and temperature

Iron doped TiO2 nanoparticles were prepared under the high temperature and pressure conditions by mixture of metal nitrates solution and TiO2 sol. Fe doped TiO2 particles were reaction at the temperature range of 170°C–200°C for 6 h. The microstructure and phase of synthesized particles were studied by SEM(FE-SEM), TEM and XRD. Thermal properties of the synthesized particles were investigated by TG-DTA analysis. Also, Specific Surface Area of synthesized particles were studied by BET analysis. X-ray diffraction pattern shows that the synthesized particles shows the coexistence of anatase and rutile reaction at the temperature range of 170°C to 200°C for 6 h. The amount of rutile phase on the synthesized particles increased with decreasing Ag concentration in solution because the less a content of the transposition metal, the easier to phase transition in the same temperature condition. The average size and distribution of the synthesized particles was about 10nm and narrow, respectively. The average size of the synthesized particles increased as reaction temperature increased. Also, BET surface areas of synthesized particles by a hydrothermal process were found to be larger than that of pure TiO2 which is synthesized by a sol-gel process.

This study aimed to investigate the combined effects of temperature and light conditions on tomato maturation. Tomato fruits that had completed volumetric growth at the mature green stage were harvested and matured in growth chambers composed of two temperature conditions (daytime–nighttime: 30–20 °C or 20–15 °C) and two light conditions (0 µmol·m−2·s−1 or 400 µmol·m−2·s−1), which were set for 12 h each day and night. Our findings indicate that tomato ripening was significantly influenced by both light and temperature. Tomatoes that matured under low-temperature conditions in the absence of light took more than three times longer to transition from the green stage to the breaker stage compared to those matured under high-temperature conditions with light exposure. Notably, tomato fruit maturation occurred at a faster rate under low-temperature and light conditions than under high-temperature and dark conditions. Changes in chlorophyll a fluorescence parameters were observed throughout the ripening process of tomato fruits. Tomato fruits ripened under low-temperature and dark conditions exhibited significantly lower NPQ (non-photochemical quenching) and RFD (relative fluorescence decrease) values compared to other treatments, while their FO (initial fluorescence) and FM (maximum fluorescence) values were higher. The accumulation of sugar in tomato fruits was observed to be more influenced by light than temperature. On the other hand, the highest levels of phenolic content and lycopene were observed in tomato fruits matured under high-temperature and light conditions. Antioxidant activities, as measured by ABTS and DPPH assays, were highest in mature tomato fruits under high-temperature and light conditions, while they were lowest in fruits under low-temperature and dark conditions. In conclusion, this study highlights the critical role of temperature and light as crucial environmental factors influencing tomato maturation. Understanding these factors can contribute to optimizing postharvest conditions and enhancing fruit quality in the tomato industry.

The article presents the results of the influence of carbon nanotubes on the mechanical parameters of cement stones under high temperature and pressure conditions (150°C, 90 MPa). The tests used multi-walled carbon nanotubes (MWCNTs) with an external diameter of 10–20 nm and a length of 10–30 μm. Cement slurries contained 0.1% of CNTs bwoc (by the weight of cement). Laboratory tests of cement slurries were carried out at the Oil and Gas Institute – National Research Institute. The tests were carried out under conditions of increased pressure and temperature at 150°C, 90 MPa. Cement slurries were prepared on the basis of class G drilling cement. Developing recipes were guided by the requirements to be met by cement slurry for the cementing of casing in the conditions of high temperature and reservoir pressures. The densities of tested slurries ranged from 1900 kg/m3 to 2250 kg/m3 (slurries with the addition of hematite). The cement slurries were tested for density, fluidity, rheological parameters, filtration and thickening time. Compressive strength tests and measuring adhesion were carried out after 2, 7, 14 and 28 days. Cement slurry recipes with very good technological parameters were developed and after curing (after 28 days of hydration) had very high values of compressive strength, reaching up to 45 MPa. Cements were characterized by high values of adhesion to pipes reaching up 7 MPa after 28 days. The research showed significant information about possible applications of carbon nanotubes to modify the cement slurry under conditions of high temperature and pressure. The conducted tests confirmed that the addition of even small amounts of CNTs improves the mechanical parameters of the cement stone compared to the base sample without such addition, and also reduces the thickening time of cement slurries and reduces filtration. It is investigated that CNTs addition increases the viscosity and yield point of cement slurry. As a result, slurries with the addition of MWCNTs will more effectively displace the mud from the borehole and significantly affect the quality of cementation.

Micro- and nano-pores and micro-fractures in shale reservoirs provide storage spaces and main permeability pathways for migration of natural gas molecules, which directly determines the accumulation and dissipation of shale gas. However, investigations about the pore-fracture structure of shales were mainly focused on nano-submicron pores, while the contribution of micrometer-scaled pores and micro-fractures to pore system of shale reservoirs lack sufficient attention. Here, using a combination of field-emission scanning electronic microscopy (FE-SEM), gas adsorption (N2 and CO2) and CT scanning (Nano-CT and Micro-CT), the Longmaxi shale cored from JYA well, in the Fuling area, was selected to comprehensively evaluate the characteristics of the pore-fracture structure at different scales. The results show that the Longmaxi shale samples mainly contain organic pores, inorganic pores, and micro-fractures. The forms of organic pores are diverse in shapes including slits, irregular polygons, discrete distributed sponge-shaped and ellipses. The shale pore diameters range from 0.305 nm-98.5 μm, mainly between 0.305-1.5 nm, 2-10 nm and 1-2 μm. The proportion of micro-pore (0.305-2 nm), meso-pore (2-50 nm), macro-pore (50 nm-2 μm) volume account for 33.59%, 36.28%, and 14.04% of the total pore volume, respectively, and that of micro-fracture (2-98.5 μm) is 16.09%. Moreover, shale permeability and specific surface area were calculated to be 0.005 mD and 39.44 m2/g, respectively, based on the full-scaled pore splicing. About 92% of specific surface area is contributed by pores with diameter of 0.305-5 nm. Micro-fractures connect with each other and form net-shaped structure with great connectivity, and their permeability account for more than 90% of the total permeability. Micro-pores and small meso-pores in shale reservoirs provide large adsorption space for adsorbed gas, while micro-fractures enhance the seepage capability of shale gas, which are favorable for shale gas accumulation and production. The integration of CO2 and N2 adsorption, Nano-CT and Micro-CT scanning studies provided an effective way to the comprehensive characterization of complex pore-fracture system in unconventional tight shale reservoirs, which might be helpful for accurate evaluation of engineering sweet spots and reduce exploration risks.