Showing papers on "Overpressure published in 2019"
TL;DR: The results of this study provide the theoretical basis of the suppression technology for gas explosion by providing the groundwork for the design of gas explosion suppression system.
71 citations
TL;DR: In this paper, a fan-jet-stirred spherical explosion vessel with different hydrogen fractions (λ) and different turbulent intensities (u'rms) in a stoichiometric hydrogen/methane/air mixture was analyzed.
69 citations
TL;DR: In this paper, the authors evaluated the explosion overpressure behaviors of premixed methane-hydrogen/air mixtures in a duct, while the flame propagation behaviors in the duct and the vented explosion region were captured by a highspeed schlieren camera and a high-speed video camera, respectively.
66 citations
TL;DR: In this article, a numerical simulation of transient hydrogen-natural gas mixture flow in a looped network is studied based on a mathematical model that considers the variation of the compressibility factor of the gas mixture with pressure under isothermal gas flow.
59 citations
TL;DR: In this article, the authors used microthermometric and Raman spectroscopic techniques, PVT and basin modeling to investigate overpressure generation and evolution in the O3w-S1l shales.
52 citations
TL;DR: Based on the study of natural gas resource, low buried hill trap formation mechanism, high quality reservoir control factors and natural gas preservation conditions, the formation conditions and reservoir accumulation characteristics of Bozhong 19-6 large condensate gas field were summarized in this article.
39 citations
TL;DR: In this paper, the authors discussed the use of nitrogen to prevent the propagation of an explosion in a horizontal duct in an effort to reduce the damage caused by gas explosions, where the vent is set on the top surface of the duct and two nozzles are set near the vent and at a downstream location.
37 citations
TL;DR: Wang et al. as mentioned in this paper established a transversal pipe network methane explosion experimental system and experimentally studied the explosive pressure wave propagation laws of premixed gases of three different methane concentrations (8, 9.5, and 11%).
34 citations
TL;DR: In this article, the authors analyzed the distribution characteristics of multi-overpressure peak structures and the formation mechanisms of typical peak structures in vented gas explosion pressure curves and proposed a quantitative method for evaluating the correlation between influencing factors and peak structures.
Abstract: Explosion venting of flammable gases within confined spaces, which may be an explosion hazard or a hazard mitigation measure, has gained widespread attention from researchers in various fields. A substantial number of scientific studies have found that complex initial and boundary conditions lead to complex and diverse peak structures in vented gas explosion pressure curves. This poses major challenges for the accurate prediction and scientific research on vented gas explosion overpressures as well as incident prevention and control. By reviewing the existing literature, we analysed the distribution characteristics of multi-overpressure peak structures and the formation mechanisms of typical peak structures in vented gas explosion pressure curves. On this basis, the influence of different factors on various peak structures are described in detail, and a quantitative method for evaluating the correlation between influencing factors and peak structures is proposed. Our analysis revealed that peaks Pb, Pext, Pmfa, and Pac had the highest occurrence frequencies in the vented explosion pressure curves and were the dominant peaks during a vented gas explosion process. Influencing factors with the highest degrees of correlation with Pb, Pext, Pmfa and Pac include vent opening pressure, ignition location, obstacles, and gas concentration. In particular, gas concentration was identified as a key condition that influenced all typical pressure peak structures. Our conclusions may serve as a reliable theoretical basis for future research on safety relief theories and prevention of gas explosion incidents.
32 citations
TL;DR: In this paper, a two-dimensional (2D) basin model has been used to explain the mechanisms of overpressure in the Baikouquan Formation and to establish a hydrocarbon accumulation model of high pressure and high production oil pools.
29 citations
TL;DR: In this paper, the authors investigated the explosion characteristics of DME-blended LPG mixtures with different DME contents and equivalence ratios using a closed vessel and found that the explosion hazard increased with increasing DME content, reaching peak values at the equivalence ratio of 1.2.
TL;DR: A full-scale manhole model was established, in which the explosion overpressure of methane/air mixtures were studied experimentally, and it was found that when the methane concentration was close to stoichiometric ratio, the ignition location was further away from the manhole head, and the weight of manhole cover increased, the peak over pressure of blast wave caused by explosion increased.
TL;DR: In this paper, a combination of fluid inclusion analyses and basin numerical modeling, combined with measured pore pressures (drill stem and wireline formation tests), well loggings, gas geochemistry, and casting thin section data, was used to identify four oil inclusion types, exhibiting different API gravities and hydrocarbon gas inclusions.
TL;DR: In this paper, a pressure field model of oil&gas wellbore during perforating shaped charge (PSC) explosion is presented and its important parameters are discussed by numerically simulating the evolution process of perforation overpressure using the nonlinear finite element software LS-DYNA combined with the ALE and AMR techniques.
TL;DR: In this paper, a new pore pressure prediction technique based on the concept of hydro-mechanical specific energy (HMSE) is proposed, which is the combination of axial, rotary and hydraulic energies required to break and remove a unit volume of rock.
TL;DR: In this paper, the authors presented a basic mathematical model for estimating peak overpressure attained in vented explosions of hydrogen in a previous study, which was not applicable for realistic accidental scenarios like presence of obstacles, initial turbulent mixture, etc.
TL;DR: Wang et al. as mentioned in this paper investigated the characteristics of gas explosion in a natural gas compartment of urban utility tunnel based on FLACS (Flame Acceleration Simulator) simulations and found that the flame profile undergoes two unstable flame stages.
Abstract: With the rapid urbanization in China, directly buried municipal pipelines have been gradually replaced by urban utility tunnels due to a serious shortage of urban underground spaces and weak disaster prevention of traditional municipal pipelines. The urban utility tunnels normally contain electricity pipelines, natural gas pipelines, heat pipelines, sewer pipelines, etc. If a natural gas pipeline leaks, a fire and explosion might occur and lead to serious consequences. In this study, the characteristics of gas explosion in a natural gas compartment of urban utility tunnel are investigated based on FLACS (Flame Acceleration Simulator) simulations. The results revealed that the flame profile undergoes two unstable flame stages. When the ignition position is set at the middle area (100.25, 1.2, 1.4 m) of the 200 m-long natural gas compartment, the maximum overpressure of the gas explosion in the 200 m-long natural gas compartment is 25.17 bar, which is the largest maximum overpressure under all gas explosion simulation setups. It is also found that the length of the natural gas compartment and different ignition positions have slight effects on the maximum overpressure. This study could provide technical support for structural strength design and division of the fireproofing area of the natural gas compartment in the utility tunnel, which is of great significance to improve urban safety during sustainable development.
TL;DR: The TNT equivalence concept for bare charges using Pentaerythritol tetranitrate (PETN) is discussed, which finds that a single value can be used to convert the charge mass of PETN to TNT in the far field, which is confirmed by a series of free field air blast measurements.
TL;DR: In this paper, the authors investigated the effects of cylinders placed parallel to the venting direction on vented hydrogen-air deflagrations and the structural response of the vessel wall to an explosion.
TL;DR: In this article, the authors measured the pressure behind a shock wave and its influence on spontaneous ignition during high-pressure hydrogen release through a tube are measured by pressure transducers and light sensors, and found that the minimum value of pressure behind the shock wave (Pshock) required for spontaneous ignition decreases with the increase in axial distance to the diaphragm.
TL;DR: In this article, the authors proposed a mathematical model of the whole waveform of the explosion under free-field air explosion, which was expressed as the product of the three factor functions of peak, attenuation and oscillation.
TL;DR: The results indicate that heptafluoropropane has a good suppression effect on the flame propagation speed and the explosion overpressure, which will be valuable for further understanding ethanol gasoline explosion mitigation and designing optimum heptAFluoroplane explosion mitigation systems.
TL;DR: In this article, a new approach was proposed for predicting lightning-induced mechanical damage using the shock wave overpressure (SWO) due to lightning arc channel expansion and also its equivalent air blast overpressure due to an explosion of chemical potential energy in AS4/3506 carbon/epoxy laminates.
TL;DR: In this paper, a series of tests were performed to study the wave diffraction behavior of a hemispherical structure by changing the nearest distance between the charge and structure and TNT equivalent.
Abstract: It is necessary to master the propagation and distribution of the overpressure on a building under an explosive load before an anti-explosion design is achieved. However, there is very less available test data which can be applicable to multi-curved large-span space structure under a surface burst. In this work, a series of tests were performed to study the wave diffraction behaviour of a hemispherical structure by changing the nearest distance between the charge and structure and TNT equivalent. The purpose of the experiment was to develop an experimental dataset which could evaluate the accuracy and efficiency of the numerical model. A simplified method to study the blast load distribution on the hemispherical structure was proposed by numerical and geometric analysis. The numerical results showed that the peak overpressure, impulse, blast wave front arrival time, and positive phase duration were highly dependent on the span–distance ratio and span–charge ratio, which affect the significance of the reflecting and shielding effects. For a convenient engineering application, a series of pseudo-analytical formulas were suggested to estimate the pressure–time histories for an ideal hemisphere structure.
TL;DR: In this paper, the authors focused on the effects of hydrogen concentration and film thickness on the explosion venting in a small obstructed rectangular container and used high speed schlieren photography to obtain the flame fine structure and velocity.
TL;DR: In this paper, a series of experiments designed to establish hydrogen-air explosion overpressures in a well-defined and well understood 3m × 3m x 2m (high) repeated pipe congestion were conducted with the objective of gaining a better understanding of the potential explosion hazard consequences that could be associated with a high-pressure leak from a hydrogen vehicle refuelling system.
TL;DR: In this article, the authors investigated the dominant mechanism for overpressure in the mudstones of the Shahejie Formation in the Chezhen depression and found that the overpressure was caused by pressure transmission from the source rocks.
Abstract: The Chezhen depression, located in the south of Bohai Bay Basin, is an oil-producing basin in China. The third and fourth members of the Shahejie Formation (Es3 and Es4) are the main source rock series in the Chezhen depression. Widespread overpressures occurred in the Es3 and Es4 from the depths of approximately 2 000 to 4 600 m, with the maximum pressure coefficient of 1.98 from drillstem tests (DST). Among the sonic, resistivity and density logs, sonic-log is the only reliable pressure indicator and can be used to predict the pore pressure with Eaton’s method. All the overpressured mudstones in the source rock series have higher acoustic traveltimes compared with normally pressured mudstones at a given depth. The overpressured mudstones in the Es3 and Es4 units are characterized by a normal geothermal gradient, high average density values up to 2.5 g/cm3, strong present-day hydrocarbon generation capability, abundant mature organic matter and high contents of residual hydrocarbons estimated by the Rock-Eval S1 values and chloroform-soluble bitumen “A” values. All suggest that the dominant mechanism for overpressure in the mudstones of source rock series in the Chezhen depression is hydrocarbon generation. A comparison between the matrix porosity of the normally pressured sandstones and overpressured sandstones, the quantitative evaluation of porosity loss caused by compaction and the conventional thin section inspection demonstrate that the sandstones in the Chezhen depression were normally compacted. The high contents of hydrocarbons in the overpressured reservoirs prove that the overpressure in the sandstones of the source rock series was caused by pressure transmission from the source rocks.
TL;DR: In this paper, the explosion characteristics of premixed LPG/DME/Air mixture in an obstructed confined pipeline of length 3.5m and diameter 0.1m under a wide range of initial pressures and temperatures (−20 to 200°C).
TL;DR: In this paper, the relationship between the flame propagation and external overpressure is summarized, and the variations in the pressure peaks of the internal pressure curves are also discussed in a 2-m-long cylindrical tube under the influences of the hydrogen concentration and vent burst pressure.
TL;DR: In this article, a temperature-dependent kinetic diagenesis model is formulated and implemented within a hydromechanical framework to simulate the macroscopic effects of diagenetic reactions on porosity loss, sediment strength, sediment stiffness and compressibility, change in elastic properties, increase in tensile strength due to cementation and overpressure generation.
Abstract: Forward basin modelling is routinely used in many geological applications, with the critical limitation that chemical diagenetic reactions are often neglected or poorly represented. Here, a new, temperature‐dependent, kinetic diagenesis model is formulated and implemented within a hydromechanical framework. The model simulates the macroscopic effects of diagenesis on: 1) porosity loss, 2) sediment strength, 3) sediment stiffness and compressibility, 4) change in elastic properties, 5) increase in tensile strength due to cementation and 6) overpressure generation. A brief overview of the main diagenetic reactions relevant to basin modelling is presented and the model calibration procedure is demonstrated using published data for the Kimmeridge Clay Formation. The calibrated model is used to show the implications of diagenesis on prediction of overpressure development and structural deformation. The incorporation of diagenesis in a uniaxial burial model results in an increase in overpressure of up to 9 MPa due to both stress‐independent porosity loss and overpressure generated by disequilibrium compaction caused by a reduction in permeability. Finally, a compressional model is used to show that the incorporation of diagenesis within geomechanical models allows the transition from ductile to brittle behaviour to be captured due to the increase in strength that results in an over‐consolidated stress state. This is illustrated by comparison of the present day structures predicted by a geomechanical‐only model, where a ductile fold forms, and a geomechanical model accounting for diagenesis in which a brittle thrust structure is predicted.