Characterization of microseismicity caused by pore‐pressure change laboratory study

2007 ◽  
Author(s):  
S. B. Turuntaev ◽  
E. V. Zenchenko ◽  
A. V. Novikov
Keyword(s):  
Pore Pressure ◽  
Laboratory Study ◽  
Pressure Change

Laboratory study of microseismicity spreading due to pore pressure change

2012 ◽  
Vol 17 (1) ◽  
pp. 137-145 ◽  
Author(s):  
S. B. Turuntaev ◽  
E. I. Eremeeva ◽  
E. V. Zenchenko
Keyword(s):  
Pore Pressure ◽  
Laboratory Study ◽  
Pressure Change

scholarly journals Characterization of complex pebble movement patterns in channel flow – a laboratory study

2015 ◽  
Vol 41 (1) ◽  
pp. 63 ◽  
Author(s):  
K. Becker ◽  
O. Gronz ◽  
S. Wirtz ◽  
M. Seeger ◽  
C. Brings ◽  
...  
Keyword(s):  
Channel Flow ◽  
Laboratory Study ◽  
Movement Patterns

The Effect of Capillary Condensation on the Geomechanical and Acoustic Properties of Tight Formations: An Experimental Study

2021 ◽  
Author(s):  
Aamer Albannay ◽  
Binh Bui ◽  
Daisuke Katsuki
Keyword(s):  
Pore Pressure ◽  
Capillary Condensation ◽  
Pore Space ◽  
Dew Point ◽  
Acoustic Properties ◽  
Point Pressure ◽  
Tight Formations ◽  
Dew Point Pressure ◽  
Compressional Velocity

Abstract Capillary condensation is the condensation of the gas inside nano-pore space at a pressure lower than the bulk dew point pressure as the result of multilayer adsorption due to the high capillary pressure inside the small pore throat of unconventional rocks. The condensation of liquid in nano-pore space of rock changes its mechanical and acoustic properties. Acoustic properties variation due to capillary condensation provides us a tool to monitor phase change in reservoir as a result of nano-confinement as well as mapping the area where phase change occurs as well as characterize pore size distribution. This is particularly important for tight formations where confinement has a strong effect on phase behavior that is challenging to measure experimentally. Theoretical studies have examined the effects of capillary condensation; however, these findings have not been verified experimentally. The main objective of this study is to experimentally investigate the effect of capillary condensation on the mechanical and acoustic properties of shale samples. The mechanical and acoustic characterization of the samples was carried out experimentally using a state-of-the-art tri-axial facility at the Colorado School of Mines. The experimental set-up is capable of the simultaneous acquisition of coupled stress, strain, resistivity, acoustic and flow data. Carbon dioxide was used as the pore pressure fluid in these experiments. After a comprehensive characterization of shale samples, experiments were conducted by increasing the pore pressure until condensation occurs while monitoring the mechanical and acoustic properties of the sample to quantify the effect of capillary condensation on the mechanical and acoustic properties of the sample. Experimental data show a 5% increase in Young's Modulus as condensation occurs. This increase is attributed to the increase in pore stiffness as condensation occurs reinforcing the grain contact. An initial decrease in compressional velocity was observed as pore pressure increases before condensation occurs which is attributed to the expansion of the pore volume when pore pressure increases. After this initial decrease, compressional velocity slightly increases at a pressure around 750 - 800 psi which is close to the condensation pressure. We also observed a noticeable increase in shear velocity when capillary condensation occurs, this could be due to the immobility of the condensed liquid phase at the pore throats. The changes of geomechanical and acoustic signatures were observed at around 750 - 800 psi at 27°C, which is the dew point pressure of the fluid in the nano-pore space of the sample at this temperature. While the unconfined bulk dew point pressure of carbon dioxide at the same temperature is 977 psi. Hence, this study marks the first measurement of the dew point of fluid in nano-pore space and potentially leads to the construction of the phase envelope of fluid under confinement.

Postural Control in Young and Elderly Adults When Stance is Challenged: Clinical versus Laboratory Measurements

1993 ◽  
Vol 102 (7) ◽  
pp. 508-517 ◽  
Author(s):  
Neil T. Shepard ◽  
Albert Schultz ◽  
Mian Ju Gu ◽  
Neil B. Alexander ◽  
Thomas Boismier
Keyword(s):  
Postural Control ◽  
Laboratory Study ◽  
Lower Limbs ◽  
Measuring System ◽  
Elderly Subjects ◽  
Dynamic Posturography ◽  
Clinical Interpretation ◽  
Healthy Elderly ◽  
Young Subjects

The use of dynamic posturography (EquiTest) for the characterization of postural control biomechanics would be aided by specific knowledge of what the measured data imply about body segment movements. To investigate this issue, the biomechanics of a group of 15 healthy elderly subjects were compared to those of healthy young subjects by using both dynamic posturography and a laboratory movement and force measuring system. The results from EquiTest were analyzed by 1) routine clinical interpretation of data and 2) a clinical research interpretation by subjecting the EquiTest parameters to additional statistical comparison of mean performance of the young and elderly groups. The young-elderly differences from the 2 EquiTest analyses were then compared to the young-elderly differences derived from the laboratory protocol. The routine clinical interpretation of EquiTest data identified the same increases in sway shown by the laboratory study, but did not reveal the more subtle differences indicated by the laboratory study. When the EquiTest data were subjected to additional statistical analysis, the characterization of difference between young and elderly subjects was the same as that of the laboratory study, with the exception of issues of head versus trunk movement, a measure not made by EquiTest. This essential similarity in the characterization of elderly compared to young subjects by both systems suggests 1) that EquiTest is able to detect subtle differences in biomechanics of postural control between young and elderly healthy adult groups and 2) that implied movements of center of gravity, trunk versus lower limbs, and strength of reaction measures are consistently detected by both EquiTest and the laboratory kinematics and dynamics measurement systems.

Reliability and Characterization of Micro-Packages in a Wafer Level Au-Si Eutectic Vacuum Bonding Process

2005 ◽  
Author(s):  
Jay S. Mitchell ◽  
Gholamhassan R. Lahiji ◽  
Khalil Najafi
Keyword(s):  
High Sensitivity ◽  
Pressure Change ◽  
Bonding Process ◽  
Wafer Level ◽  
Eutectic Solder ◽  
Packaging Process ◽  
Primary Mechanism ◽  
Airtight Seal ◽  
Over Time

A Au-Si eutectic vacuum packaging process was evaluated using high sensitivity poly-Si Pirani vacuum sensors. Encapsulation of devices was achieved by bonding a silicon cap wafer to a device wafer using a Au-Si eutectic solder at above 390°C in a vacuum bonder. The Au-Si eutectic solder encircled the devices, providing an airtight seal. The Pirani gauges were encapsulated and tested over a period of several months in order to determine base pressures and leak/outgassing rates of the micro-cavities. Packaged devices without getters showed initial pressures from 2 to 12 Torr with initial leak/outgassing rates of −0.073 to 80 Torr/year. Using getters, pressures as low as 5 mTorr have been achieved with leak/outgassing rates of <10 mTorr/year. Trends in pressure over time seem to indicate outgassing (desorption of atoms from inside of the microcavity) as the primary mechanism for pressure change over time.

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