The undrained equilibrium behaviour of gassy sediments

1984 ◽  
Vol 21 (3) ◽  
pp. 439-448 ◽  
Author(s):  
J. C. Sobkowicz ◽  
N. R. Morgenstern
Keyword(s):  
Pore Pressure ◽  
Oil Sands ◽  
Predictive Accuracy ◽  
Gulf Coast ◽  
Saturation Pressure ◽  
Deep Ocean ◽  
Model Parameters ◽  
Pore Pressure Response ◽  
Soil Behaviour

Gassy soils are defined as those soils which contain a relatively large amount of gas dissolved in the pore fluid. Examples include the Alberta Oil Sands, marine sediments from deep ocean locations, geopressure reservoirs along the Gulf Coast, and other naturally occurring, gas-charged reservoirs.The equilibrium behaviour during unloading with undrained boundary conditions is examined. Contrary to conventional experience with soils containing only a small amount of gas, gassy soils exhibit an equilibrium pore pressure response close to zero. Effective stress, and hence strength, decrease commensurately with total stress at the soil boundary.Laboratory observations of gassy soil behaviour are presented, which confirm the predictive accuracy of the theoretical model. Parameters important to the determination of gassy soil behaviour include the in situ state of stress (σ0 and u0), the liquid/gas saturation pressure (ul/g), the gas solubility (H), saturation (S), and the soil and liquid compressibilities (βT and βL). Key words: undrained, pore pressure, compressibility, gas, shear strength, unloading, laboratory, ex-solution.

scholarly journals Stratigraphic profiling, slip surface detection, and assessment of remolding in sensitive clay landslides using the CPT

2021 ◽  
Author(s):  
Joshua Potvin ◽  
David Woeller ◽  
James Sharp ◽  
W. Andy Take
Keyword(s):  
Pore Pressure ◽  
Slip Surface ◽  
Progressive Failure ◽  
Cone Penetration ◽  
Cone Penetration Testing ◽  
Tip Resistance ◽  
Sensitive Clay ◽  
Pore Pressure Response ◽  
Soil Behaviour ◽  
Intact Soil

A multi-year cone penetration testing program was initiated at a landslide subject to episodic retrogression in Mud Creek, Ottawa, to assess whether a hand-operated mobile CPT could yield new insights into the current degree of remoulding under progressive failure in metastable areas of a landslide where conventional tracked rigs are unable to gain access. The mobile CPT rig permitted tests to be performed through the entire thickness of the Champlain Sea deposit at a penetration rate of 0.5 cm/s, with similar results to tests performed at the standard 2 cm/s. Measurements of pore pressure varied considerably with cone size, with the magnitude of pore pressure response decreasing with cone size. The elevation of the slip surface was identified in the tip resistance as the point of transition between the remolded soil above the slip surface and the intact soil below the slip surface, whereas a further 0.5 m of penetration was required to elevate pore pressures to values indicative of the intact soil behaviour. In-situ measurements of shear strength of corresponding layers between the intact and remolded profiles to be compared indicating that the soil above the slip surface had remolded to 50% of its fully remolded strength.

Experience with the IMMa tyre test bench for the determination of tyre model parameters using genetic techniques

2005 ◽  
Vol 43 (sup1) ◽  
pp. 253-266 ◽  
Author(s):  
J. A. Cabrera ◽  
A. Ortiz ◽  
E. Carabias ◽  
A. Simón
Keyword(s):  
Test Bench ◽  
Model Parameters ◽  
Tyre Model ◽  
Genetic Techniques

Examination of Silk Fibers from a Deep Ocean Site: SEM, EDS, & DSC

1996 ◽  
Vol 462 ◽  
Author(s):  
R. Srjnivasan ◽  
K. A. Jakes
Keyword(s):  
Glass Transition ◽  
Central America ◽  
Deep Ocean ◽  
Structural Data ◽  
Silk Fibers ◽  
Melting Endotherm ◽  
Historic Silk

ABSTRACTThe research reported herein is directed toward the determination of the microstructure of silk fibers recovered from the shipwreck site of the S.S. Central America. The structural data obtained from examination of these silk materials using SEM, EDS, and DSC was compared to data obtained from the examination of historic silk fibers (ca. 1860–1880) not exposed to the deep-ocean and of modern silk fibers. Marine silks appear more degraded than historic and modern silk when viewed under the SEM and the fiber surfaces are partially obscured by inorganic deposits. The melting endotherm of marine, historic, and modern silk fibers are comparable to each other, but the glass transition observed in the modern silk is not apparent in the DSC trace of any of the marine silks.

Use of Gas Meters for Determination of Pay Strata in Oil Sands

1925 ◽  
Vol G-25 (01) ◽  
pp. 183-195 ◽  
Author(s):  
C.V. Millikan
Keyword(s):  
Oil Sands

Determination of Bubble-Point and Dew-Point Pressure Without a Visual Cell

2014 ◽  
Author(s):  
R.. Hosein ◽  
R.. Mayrhoo ◽  
W. D. McCain
Keyword(s):  
Oil And Gas ◽  
Saturation Pressure ◽  
Volatile Oil ◽  
Phase Region ◽  
Gas Condensate ◽  
Dew Point ◽  
Bubble Point ◽  
Point Pressure ◽  
Dew Point Pressure

Abstract Bubble-point and dew-point pressures of oil and gas condensate reservoir fluids are used for planning the production profile of these reservoirs. Usually the best method for determination of these saturation pressures is by visual observation when a Constant Mass Expansion (CME) test is performed on a sample in a high pressure cell fitted with a glass window. In this test the cell pressure is reduced in steps and the pressure at which the first sign of gas bubbles is observed is recorded as bubble-point pressure for the oil samples and the first sign of liquid droplets is recorded as the dew-point pressure for the gas condensate samples. The experimental determination of saturation pressure especially for volatile oil and gas condensate require many small pressure reduction steps which make the observation method tedious, time consuming and expensive. In this study we have extended the Y-function which is often used to smooth out CME data for black oils below the bubble-point to determine saturation pressure of reservoir fluids. We started from the initial measured pressure and volume and by plotting log of the extended Y function which we call the YEXT function, with the corresponding pressure, two straight lines were obtained; one in the single phase region and the other in the two phase region. The point at which these two lines intersect is the saturation pressure. The differences between the saturation pressures determined by our proposed YEXT function method and the observation method was less than ± 4.0 % for the gas condensate, black oil and volatile oil samples studied. This extension of the Y function to determine dew-point and bubble-point pressures was not found elsewhere in the open literature. With this graphical method the determination of saturation pressures is less tedious and time consuming and expensive windowed cells are not required.

scholarly journals The seven sisters DANCe

2018 ◽  
Vol 612 ◽  
pp. A70 ◽  
Author(s):  
J. Olivares ◽  
E. Moraux ◽  
L. M. Sarro ◽  
H. Bouy ◽  
A. Berihuete ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Model Comparison ◽  
Precise Determination ◽  
Model Parameters ◽  
Data Sets ◽  
Adequate Model ◽  
Comparison Results ◽  
Bayesian Evidence ◽  
Mass Segregation

Context. Membership analyses of the DANCe and Tycho + DANCe data sets provide the largest and least contaminated sample of Pleiades candidate members to date. Aims. We aim at reassessing the different proposals for the number surface density of the Pleiades in the light of the new and most complete list of candidate members, and inferring the parameters of the most adequate model. Methods. We compute the Bayesian evidence and Bayes Factors for variations of the classical radial models. These include elliptical symmetry, and luminosity segregation. As a by-product of the model comparison, we obtain posterior distributions for each set of model parameters. Results. We find that the model comparison results depend on the spatial extent of the region used for the analysis. For a circle of 11.5 parsecs around the cluster centre (the most homogeneous and complete region), we find no compelling reason to abandon King’s model, although the Generalised King model introduced here has slightly better fitting properties. Furthermore, we find strong evidence against radially symmetric models when compared to the elliptic extensions. Finally, we find that including mass segregation in the form of luminosity segregation in the J band is strongly supported in all our models. Conclusions. We have put the question of the projected spatial distribution of the Pleiades cluster on a solid probabilistic framework, and inferred its properties using the most exhaustive and least contaminated list of Pleiades candidate members available to date. Our results suggest however that this sample may still lack about 20% of the expected number of cluster members. Therefore, this study should be revised when the completeness and homogeneity of the data can be extended beyond the 11.5 parsecs limit. Such a study will allow for more precise determination of the Pleiades spatial distribution, its tidal radius, ellipticity, number of objects and total mass.

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