As worldwide demand of hydrocarbon is growing fast, the oil and gas companies have been forced to explore reservoirs with more hostile conditions, such as High-pressure, High-temperature conditions. Improved technology, material selection and testing procedures are required to overcome the common problems in these conditions. One of the main phases of well construction is cementing job. Appropriate selection of cementing material can guarantee a successful cementing job. Many researchers investigated the required cement properties for applications in High-pressure, Hightemperature conditions. However, the focus of their work was on the mechanical properties of set cement, while the other properties have not been studied enough. The purpose of this work is to produce a High resistant cement system, which can satisfy the other essential requirements at the same time. The main other requirements include free fluid content, thickening time and expansion capability, which have been investigated in this work. The results show that although some cement systems have High mechanical resistant, but their application is limited due to undesirable values of other properties. Therefore, different additives have been used to adjust the properties of the final cement system. The High-resistant cement is produced by adding siliceous material. Free fluid content, thickening time and expansion capability of the High-resistant cements are adjusted by adding polyvinyl alcohol, lignosulfonate and MgO, respectively. The combined effect of these additives is investigated to develop a High-resistant system, which has optimum values of other essential properties too.

pressure-dependent first-order phase transition, mechanical, elastic, and thermodynamical properties of cubic zinc blende to rock-salt structures in 3C silicon carbide (SiC) are presented. An effective interatomic interaction potential for SiC is formulated. The potential for SiC incorporates long-range Coulomb, charge transfer interactions, covalency effect, Hafemeister and Flygare type short-range overlap repulsion extended up to the second-neighbour ions, van der Waals interactions and zero point energy effects. The developed potential including many body non-central forces validates the Cauchy discrepancy successfully to explain the High-pressure structural transition, and associated volume collapse. The 3C SiC ceramics lattice infers mechanical stiffening, thermal softening, and ductile (brittle) nature from the pressure (temperature) dependent elastic constants behaviour. To our knowledge, These are the first quantitative theoretical predictions of the pressure and temperature dependence of mechanical and thermodynamical properties explicitly the mechanical stiffening, thermally softening, and brittle/ductile nature of 3C SiC and still awaits experimental confirmations.

Reliability science is based on statistics and probability, and the possibility representation of healthiness of the product. Understanding the likeliness of health or deterioration of the product is very valuable. Hence, in recent years reliability engineering has become very important for researchers and designers. Nowadays one of the most important parameters in the industry is High reliability products and this is because of its direct link to the user's health and well-functioning industrial products. Working with systems that have a low reliability are very dangerous. The oil and gas are very important industries and one of the most important elements in the installation of a refinery are pipes. Hence, in this study the dynamic stress and reliability analysis of a piping under gas with High pressure and temperature will be discussed. Therefore, the finite element and Monte-Carlo methods were used to compute stress and reliability in the pipe with High pressure and temperature. In order to verify this presented code and its results were compared with ANSYS software and other existing results.

pressure- and temperature-dependent mechanical, elastic, and thermodynamical properties of rock salt to CsCl structures in semiconducting SrX (X=O, S, Se, and Te) chalcogenides are presented based on model interatomic interaction potential with emphasis on charge transfer interactions, covalency effect, and zero point energy effects apart from long-range Coulomb, short-range overlap repulsion extended and van der Waals interactions. The developed potential with non-central forces validates the Cauchy discrepancy among elastic constants. The volume collapse (VP/V0) in terms of compressions in SrX at Higher pressure indicates the mechanical stiffening of lattice. The expansion of SrX lattice is inferred from steep increase in VT/V0 and is attributed to thermal softening of SrX lattice. We also present the results for the temperature dependent behaviors of hardness, heat capacity, and thermal expansion coefficient. From the Pugh’s ratio (f=BT/GH), the Poisson’s ratio (n) and the Cauchy’s pressure (C12–C44), we classify SrO as ductile but SrS, SrSe, and SrTe are brittle material. To our knowledge these are the first quantitative theoretical prediction of the pressure and temperature dependence of mechanical stiffening, thermally softening, and brittle nature of SrX (X=O, S, Se, and Te) and still await experimental confirmations.

In this paper, we make a brief overview of the maintenance procedures and condition monitoring methods. The WKL32 model High pressure pump made in Iran Pump Co, be evaluated by the vibration analysis and sound tests, based on the proactive maintenance procedure. We study the effect of electric current leakage which is made of using the pump chassis as the welding connection cable (NULL) and check the effect of the ambience temperature on the grease lubricant viscosity and on the corrosion of the pump’ s bearings. Finally, we make appropriate cures according to the proactive maintenance procedure.

In this paper, the drain-source current, transconductance, and cutoff frequency in AlGaN/GaN High electron mobility transistors have been investigated. In order to obtain the exact parameters of AlGaN/GaN High electron mobility transistors such as the electron density, wave function, band gap, polarization charge, effective mass, and dielectric constant, the hydrostatic pressure and temperature effects are taken into account. It has been found that the drainsource current decreases as the temperature increases and increases as the hydrostatic pressure increases. The increase in temperature is equivalent to a negative virtual gate while an increase in the hydrostatic pressure is equivalent to the positive virtual gate voltage. Moreover, the temperature, hydrostatic pressure, and effective mass dependence in High electron mobility transistor structures are investigated. It is observed that the increase of hydrostatic pressure decreases the effective mass as the wave function penetrates through the quantum barrier AlGaN. In general, the process of increasing and decreasing the cutoff frequency and transconductance is similar to the variations in the drain-source current. The calculated results are in good agreement with the existing experimental data.

The gas-liquid supersonic separator is a convergent-divergent nozzle in which condensation and phase change at speeds Higher than sound are the characteristics of this device. The fluid flow, mass, and heat transfer in supersonic separators are not understood well due to the complicated interaction of the supersonic flow and phase change. In this research, the virial gas equation of state and a mathematical model have been used to accurately predict spontaneous condensation using nucleation and droplet growth theories. The droplet average radius and pressure distribution obtained from the numerical model are well consistent with the experimental data. The results showed that with a 3.5% decrease in inlet temperature at constant pressure, the average radius of the outlet droplets increased by more than 40%. Also, with about a 40% increase in inlet pressure at a constant temperature, the maximum liquid mass fraction increased by more than 90%. Therefore, low temperature and High pressure at the inlet are necessary to improve the separation efficiency. Also, the lowest entropy generation rate due to temperature changes is related to the Highest pressure and the lowest temperature, and the lowest entropy generation rate due to pressure changes is related to the lowest temperature and pressure. The Bejan number calculation showed that irreversibility is affected by the effects of fluid friction compared to heat transfer.