scholarly journals The Influence of Coupled Thermomechanical Processes on the Pressure and Temperature due to Cold Water Injection into Multiple Fracture Zones in Deep Rock Formation

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-14 ◽  
Author(s):  
Bruno Figueiredo ◽  
Chin-Fu Tsang ◽  
Auli Niemi
Keyword(s):  
Pore Pressure ◽  
Cold Water ◽  
Injection Pressure ◽  
Initial Permeability ◽  
Fracture Zones ◽  
Maximum Increase ◽  
Rock Formation ◽  
Deep Rock ◽  
The Mean ◽  
Fluid Pore Pressure

A technique to produce geothermal energy from deep rock formations at elevated temperatures consists of drilling two parallel deep boreholes, the second of which is directed so as to intersect a series of fractures produced by hydraulic fracturing in the first borehole. Then, the first borehole is used for injection of cold water and the second used to produce water that has been heated by the deep rock formation. Some very useful analytical solutions have been applied for a quick estimate of the water outlet temperature and injection/production pressures in this enhanced geothermal system (EGS), but they do not take into account the influence of thermomechanical and hydromechanical effects on the time evolutions of the pressure and temperature. This paper provided help for the engineering design of the EGS based on these analytical solutions, by evaluating the separate influences of the thermal (T), hydromechanical (HM), thermo-hydro-mechanical (THM) effects on the fluid pore pressure and temperature. A thermo-hydro-mechanical (THM) model was developed to simulate the heat extraction from multiple preexisting fracture zones in the hot rock formation, by considering permeability changes due to the injection pressure as a function of changes in the mean effective stress. It was found that the thermal effects (without coupling with mechanical effects) led to a decrease of the transmissivity of the fracture zones and a consequent increase in the injection pressure, by a maximum factor of 2. When the temperature is constant, the influence of the hydromechanical effects on the fluid pore pressure was found to be negligible, because in such scenario, the variation of the mean effective stress was 3 MPa, which was associated with a maximum increase in the initial permeability of the fracture zone only by a factor of 1.2. Thermo-hydro-mechanical effects led to a maximum increase in the permeability of the fracture zones of approximately 10 times the initial value, which was associated with a decrease in the fluid pore pressure by a maximum factor of 1.25 and 2, when hydrological and thermohydrological effects were considered, respectively. Changes in temperature were found not to be affected significantly by the thermomechanical and hydromechanical effects, but by the flow rate in the fracture zones. A sensitivity analysis was conducted to study the influence of the number, the initial permeability, the elastic modulus and the residual porosity of the fracture zones, and the elastic modulus of the confining intact rock, on the simulation results. The results were found to be the most sensitive to the number and the initial permeability of the fracture zones.

Thermoregulatory responses to cold water at different times of day

1999 ◽  
Vol 87 (1) ◽  
pp. 243-246 ◽  
Author(s):  
John W. Castellani ◽  
Andrew J. Young ◽  
James E. Kain ◽  
Michael N. Sawka
Keyword(s):  
Cold Water ◽  
Water Immersion ◽  
Early Morning ◽  
Cold Water Immersion ◽  
Time Of Day ◽  
Mean Skin Temperature ◽  
Mean Body Temperature ◽  
Metabolic Heat ◽  
Body Temperature Change ◽  
The Mean

This study examined how time of day affects thermoregulation during cold-water immersion (CWI). It was hypothesized that the shivering and vasoconstrictor responses to CWI would differ at 0700 vs. 1500 because of lower initial core temperatures (Tcore) at 0700. Nine men were immersed (20°C, 2 h) at 0700 and 1500 on 2 days. No differences ( P > 0.05) between times were observed for metabolic heat production (M˙, 150 W ⋅ m−2), heat flow (250 W ⋅ m−2), mean skin temperature (T sk, 21°C), and the mean body temperature-change in M˙(ΔM˙) relationship. Rectal temperature (Tre) was higher ( P < 0.05) before (Δ = 0.4°C) and throughout CWI during 1500. The change in Tre was greater ( P < 0.05) at 1500 (−1.4°C) vs. 0700 (−1.2°C), likely because of the higher Tre-T skgradient (0.3°C) at 1500. These data indicate that shivering and vasoconstriction are not affected by time of day. These observations raise the possibility that CWI may increase the risk of hypothermia in the early morning because of a lower initial Tcore.

scholarly journals Perturbation Solution for One-Dimensional Flow to a Constant-Pressure Boundary in a Stress-Sensitive Reservoir

2021 ◽  
Author(s):  
Amarjot Singh Bhullar ◽  
Gospel Ezekiel Stewart ◽  
Robert W. Zimmerman
Keyword(s):  
Approximate Solution ◽  
Pore Pressure ◽  
Constant Pressure ◽  
Initial Permeability ◽  
Order Perturbation ◽  
Zeroth Order ◽  
One Dimensional ◽  
First Order ◽  
Outflow Boundary ◽  
Perturbation Solutions

Abstract Most analyses of fluid flow in porous media are conducted under the assumption that the permeability is constant. In some “stress-sensitive” rock formations, however, the variation of permeability with pore fluid pressure is sufficiently large that it needs to be accounted for in the analysis. Accounting for the variation of permeability with pore pressure renders the pressure diffusion equation nonlinear and not amenable to exact analytical solutions. In this paper, the regular perturbation approach is used to develop an approximate solution to the problem of flow to a linear constant-pressure boundary, in a formation whose permeability varies exponentially with pore pressure. The perturbation parameter αD is defined to be the natural logarithm of the ratio of the initial permeability to the permeability at the outflow boundary. The zeroth-order and first-order perturbation solutions are computed, from which the flux at the outflow boundary is found. An effective permeability is then determined such that, when inserted into the analytical solution for the mathematically linear problem, it yields a flux that is exact to at least first order in αD. When compared to numerical solutions of the problem, the result has 5% accuracy out to values of αD of about 2—a much larger range of accuracy than is usually achieved in similar problems. Finally, an explanation is given of why the change of variables proposed by Kikani and Pedrosa, which leads to highly accurate zeroth-order perturbation solutions in radial flow problems, does not yield an accurate result for one-dimensional flow. Article Highlights Approximate solution for flow to a constant-pressure boundary in a porous medium whose permeability varies exponentially with pressure. The predicted flowrate is accurate to within 5% for a wide range of permeability variations. If permeability at boundary is 30% less than initial permeability, flowrate will be 10% less than predicted by constant-permeability model.

scholarly journals Effect of Injection Pressure of Infiltration Anesthesia to the Jawbone

2016 ◽  
Vol 63 (3) ◽  
pp. 131-138 ◽  
Author(s):  
Kenji Yoshida ◽  
Eri Tanaka ◽  
Hiroyoshi Kawaai ◽  
Shinya Yamazaki
Keyword(s):  
Local Anesthetic ◽  
White Male ◽  
Injection Pressure ◽  
Time Interval ◽  
Time Intervals ◽  
Lidocaine Concentration ◽  
The Mean ◽  
High Concentrations ◽  
Infiltration Anesthesia ◽  
Local Anesthetic Infiltration

To obtain effective infiltration anesthesia in the jawbone, high concentrations of local anesthetic are needed. However, to reduce pain experienced by patients during local anesthetic administration, low-pressure injection is recommended for subperiosteal infiltration anesthesia. Currently, there are no studies regarding the effect of injection pressure on infiltration anesthesia, and a standard injection pressure has not been clearly determined. Hence, the effect of injection pressure of subperiosteal infiltration anesthesia on local anesthetic infiltration to the jawbone was considered by directly measuring lidocaine concentration in the jawbone. Japanese white male rabbits were used as test animals. After inducing general anesthesia with oxygen and sevoflurane, cannulation to the femoral artery was performed and arterial pressure was continuously recorded. Subperiosteal infiltration anesthesia was performed by injecting 0.5 mL of 2% lidocaine containing 1/80,000 adrenaline, and injection pressure was monitored by a pressure transducer for 40 seconds. After specified time intervals (10, 20, 30, 40, 50, and 60 minutes), jawbone and blood samples were collected, and the concentration of lidocaine at each time interval was measured. The mean injection pressure was divided into 4 groups (100 ± 50 mm Hg, 200 ± 50 mm Hg, 300 ± 50 mm Hg, and 400 ± 50 mm Hg), and comparison statistical analysis between these 4 groups was performed. No significant change in blood pressure during infiltration anesthesia was observed in any of the 4 groups. Lidocaine concentration in the blood and jawbone were highest 10 minutes after the infiltration anesthesia in all 4 groups and decreased thereafter. Lidocaine concentration in the jawbone increased as injection pressure increased, while serum lidocaine concentration was significantly lower. This suggests that when injection pressure of subperiosteal infiltration anesthesia is low, infiltration of local anesthetic to the jawbone may be reduced, while transfer to oral mucosa and blood may be increased.

A study of the variability in the febrile responses of rabbits to endogenous pyrogen

1985 ◽  
Vol 59 (4) ◽  
pp. 1254-1257 ◽  
Author(s):  
J. T. Stitt
Keyword(s):  
Standard Dose ◽  
Intravenous Route ◽  
Intracerebroventricular Administration ◽  
Endogenous Pyrogen ◽  
Maximum Increase ◽  
Putative Receptor ◽  
Receptor Sites ◽  
New Zealand White Rabbits ◽  
The Mean ◽  
Fever Response

The range of body temperature increases elicited by a standard dose of endogenous pyrogen (0.5 ml/kg iv) was examined in a population of 26 male New Zealand White rabbits. Although the mean maximum increase in rectal temperature was 0.88 +/- 0.06 degree C (SE), individual responses varied from 0.4 degree to 1.5 degree C. Three representative animals that responded to the standard dose of pyrogen with small, intermediate, and large febrile responses were selected and challenged with the same dose of pyrogen on eight separate occasions, and the variability of these responses was examined. There was little variability within the characteristic responses of any particular animal to the repeated challenges. The variability of the febrile responses elicited by both intravenous and intracerebroventricular administration of the same pyrogen was examined and compared using another group of 11 rabbits. The variability in response to the intravenous route was similar to that found in the larger population, whereas the variation in response to the intracerebroventricular route was smaller, and all 11 animals had fevers that were greater than 1 degrees C. It is concluded that the variability of the febrile responses of rabbits to intravenous pyrogen was due to differences between individual sensitivities of animals to the intravenously administered pyrogen. This difference in sensitivity may be due to a difference in the amount of pyrogen that reaches the putative receptor sites, or to a difference in the density or effectiveness of receptor sites in translating the pyrogenic stimulus into a fever response.

Drained/Undrained-Zones Boundary in Steam-Assisted-Gravity-Drainage Process

SPE Journal ◽  
2016 ◽  
Vol 21 (05) ◽  
pp. 1721-1742 ◽  
Author(s):  
Mazda Irani ◽  
Ian Gates
Keyword(s):  
Pore Pressure ◽  
Volume Change ◽  
Injection Pressure ◽  
Point Of View ◽  
Gravity Drainage ◽  
Oil Sand ◽  
Steam Assisted Gravity Drainage ◽  
Shear Dilation ◽  
Temperature Front ◽  
Undrained Conditions

Summary Li et al. (2004) described three zones at the edge of steam chambers on the basis of drainage conditions: drained, partially drained, and undrained. In the drained zone, the pore pressure is controlled by injection pressure, and fluid mobility within this region is sufficient to drain additional pore pressures because of shear dilation and pore-fluid thermal expansion. The undrained zone lies beyond the partially drained zone and extends to virgin reservoir far beyond the chamber. In this zone shearing behaves under undrained conditions; by this, Li et al. (2004) mean no volume change occurs but shear lead to changes in pore pressure. Li et al. (2004) proposed that the boundaries of these zones are dependent on bitumen viscosity, which relates to the temperature distribution beyond the steam interface. Because drained/undrained conditions affect the geomechanics at the edge of the chamber, we investigate whether the assumption of Li et al. (2004) that there is no volume change within the sheared zone is correct and is supported by field data. Here, we establish the physics associated with the undrained zone at the edge of steam-assisted gravity-drainage steam chamber and explore the pressure front vs. temperature front of different oil-sand field projects. The results reveal that the drained zone governed by pressure-front advancement is greater in extent than the sheared zone. The thermodynamics of the undrained zone are discussed to derive a new theory for mechanothermal phenomena at the edge of the chamber. The results from the theory show that the drained zone extends beyond the temperature front and thus, from a geomechanical point of view, the system solely consists of the drained and partially drained zones.

scholarly journals Experimental Methodology and Facility for the J69-Engine Performance and Emissions Evaluation Using Jet A1 and Biodiesel Blends

Energies ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 4530 ◽  
Author(s):  
Gabriel Talero ◽  
Camilo Bayona-Roa ◽  
Giovanny Muñoz ◽  
Miguel Galindo ◽  
Vladimir Silva ◽  
...  
Keyword(s):  
Fossil Fuels ◽  
Fuel Injection ◽  
Engine Performance ◽  
Injection Pressure ◽  
Experimental Tests ◽  
Experimental Methodology ◽  
Injection System ◽  
Small Scale ◽  
Gas Temperature ◽  
Maximum Increase

Aeronautic transport is a leading energy consumer that strongly contributes to greenhouse gas emissions due to a significant dependency on fossil fuels. Biodiesel, a substitution of conventional fuels, is considered as an alternative fuel for aircrafts and power generation turbine engines. Unfortunately, experimentation has been mostly limited to small scale turbines, and technical challenges remain open regarding operational safety. The current study presents the facility, the instrumentation, and the measured results of experimental tests in a 640 kW full-scale J69-T-25A turbojet engine, operating with blends of Jet A1 and oil palm biodiesel with volume contents from 0% to 10% at different load regimes. Findings are related to the fuel injection system, the engine thrust, and the emissions. The thrust force and the exhaust gas temperature do not expose a significant variation in all the operation regimes with the utilization of up to 10% volume content of biodiesel. A maximum increase of 36% in fuel consumption and 11% in injection pressure are observed at idle operation between B0 and B10. A reduction of the CO and HC emissions is also registered with a maximum variation at the cruise regime (80% Revolutions Per Minute—RPM).

One-Dimensional Consolidation Modelling for Unlayered Soil

2014 ◽  
Vol 580-583 ◽  
pp. 123-128
Author(s):  
Issam Hanafi ◽  
Fouad Dimane ◽  
Francisco Mata Cabrera ◽  
José Tejero Manzanares
Keyword(s):  
Numerical Solution ◽  
Pore Pressure ◽  
Effective Stress ◽  
Finite Strain ◽  
Total Stress ◽  
Linear Solution ◽  
One Dimensional ◽  
Soil Skeleton ◽  
Fluid Pore Pressure ◽  
Extra Stress

In this work, one-dimensional problem has a well-known linear solution and, thus, provides a simple verification of the consolidation capability using numerical solution. The coupling is approximated by the effective stress principle, which treats the saturated soil as a continuum, assuming that the total stress at each point is the sum of an effective stress carried by the soil skeleton and a pore pressure in the fluid permeating the soil. This fluid pore pressure can change with, and the gradient of the pressure through the soil that is not balanced by the weight of fluid between the points in question will cause the fluid to flow: the flow velocity is proportional to the pressure gradient in the fluid according to Darcy's law. A typical case is a consolidation problem. Here the addition of a load to a body of soil causes pore pressure to raise initially; then, as the soil skeleton takes up the extra stress, the pore pressures decay as the soil consolidates. The Terzaghi problem is the simplest example of such a process. For illustration purposes, the problem is treated with and without finite-strain effects. The numerical solution agrees reasonably well with the analytical solution, with some loss of accuracy at later times.

Permeability heterogeneity during sandstone compaction

2020 ◽  
Author(s):  
Philip Meredith ◽  
Nicolas Brantut ◽  
Patrick Baud
Keyword(s):  
Pore Pressure ◽  
Fluid Pressure ◽  
Initial Permeability ◽  
High Porosity ◽  
Pressure Measurements ◽  
Permeability Heterogeneity ◽  
Compaction Bands ◽  
Local Permeability ◽  
Spatially Distributed ◽  
Cylindrical Samples

&lt;p&gt;Compaction of porous sandstones is generally associated with a reduction in permeability. Depending on porosity and other microstructural characteristics, compaction may be diffuse or localised in bands. Compaction bands have been shown to act as barriers to fluid flow and therefore reduce permeability perpendicular to the band orentiation, and thus also introduce permeability anisotropy. Additionally, the localised nature of compaction bands should also introduce strong permeability heterogeneity. We present new experimental data on sandstone compaction combining acoustic emission monitoring and spatially distributed pore fluid pressure measurements, allowing us to establish how permeability heterogeneity develops during progressive compaction. Three sandstones were tested in the compactant regime: Locharbriggs sandstone, which is microstructurally heterogeneous with beds of higher and lower initial permeability; a low porosity (21%) Bleurville sandstone, which is microstructurally homogeneous and produces localised compaction bands; and a high porosity (24%) Bleurville sandstone, which is also homogeneous but produces compaction in a more diffuse pattern. At regular intervals during compactive deformation, a constant pore pressure difference was imposed at the upper and lower boundaries of the cylindrical samples, and steady-state flow allowed to become established. Following this, local pore pressure measurements were made at four locations, allowing us to derive estimates of the local permeability. In all samples, progressive compaction produced overall reductions in permeability. In addition, localised compaction also produced internal reorganisation of the permeability structure. Localised compaction bands caused local decreases in permeability, while more diffuse compaction produced a more homogeneous overall reduction in permeability.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;

Simulation on THM Coupling Process of Deep Rock Roadway with Aquifer in Coalmine

2013 ◽  
Vol 671-674 ◽  
pp. 1131-1134
Author(s):  
Jian Guo Yang ◽  
Li Chuan Chen ◽  
Hong Liang Liao ◽  
Fan Yang
Keyword(s):  
Rock Mass ◽  
Pore Pressure ◽  
Surrounding Rock ◽  
Stress Fields ◽  
Important Process ◽  
Governing Equations ◽  
Coupling Process ◽  
Deep Rock ◽  
Rock Roadway

THM coupling is an important process in engineering rock mass. In order to study the mechanism of THM coupling in surrounding rock of deep rock roadway in coalmine, the interactions between THM fields were analyzed, and the governing equations of THM coupling were given. Finally, a model of rock roadway with aquifer is simulated, and the distribution of pore pressure as well as the thermal and stress fields were obtained after some steps of calculation.

scholarly journals Efficacy of hand washing beeswax food wrap in household use

2019 ◽  
Author(s):  
Celine Hsin ◽  
BCIT School of Health Sciences, Environmental Health ◽  
Dale Chen
Keyword(s):  
Cold Water ◽  
Intervention Group ◽  
P Value ◽  
Cross Contamination ◽  
Post Intervention ◽  
Food Residue ◽  
Specific Category ◽  
Single Use ◽  
The Mean ◽  
Post Intervention Group

  Background: Over the years, many reusable products have been invented to replace single-use disposable items to reduce waste. One of such products is the reusable beeswax food wrap, which aims to replace plastic film wraps to store food. According to manufacturer instructions, the beeswax wrap can only be washed with cold water and detergent. This presents the question whether the beeswax wrap can be effectively cleaned, as continuous reuse may present cross contamination issues. This study examines if manufacturer instructions is effective in cleaning the beeswax wrap. Methods: ATP analysis was used to determine the level of cleanliness on the beeswax wrap between the pre-intervention and post-intervention treatments. Pre-intervention samples are the new beeswax wraps. Post- intervention samples are wraps that have been contaminated with avocado, washed, and dried. ATP counts (RLU) were measured with Hygiena SystemSURE Plus ATP monitoring system. Paired T-Test was done on NCSS to analyze the results. Results: The mean of the pre-intervention group was measured at 8 RLU, which is considered clean under the Hygiena standard. The mean for the post-intervention group was measured at 67 RLU, which is considered a fail on cleanliness under the Hygiena standard. This shows that the manufacturer instructions on washing the beeswax wrap does not effectively clean the beeswax wrap. Statistical analysis show p-value is 0.000, therefore one can conclude there is a statistically significance difference in the mean ATP count between pre-intervention and post-intervention beeswax wrap samples. Conclusion: Results show that some food residue remained on the wrap after washing. This means manufacturer instructions cannot effectively clean beeswax wrap. Therefore, it is recommended that manufactures should put a label on their packaging to let their customers know that the wrap can’t be thoroughly cleaned, and certain foods should be avoided for its use. During its use, the wraps should be labeled for the specific category of food it is used for. BCCDC can also use this result to add into the reusable container guideline.  

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