scholarly journals Experimental Investigation of Permeability Evolution on Sandstone in Triaxial and Long-Term Dissolution Experiment

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Ji Shi ◽  
Jianhua Zhang ◽  
Chunyang Zhang ◽  
Tingting Jiang ◽  
Gang Huang
Keyword(s):  
Room Temperature ◽  
Flow System ◽  
Initial Permeability ◽  
Low Permeability ◽  
Average Increase ◽  
Permeability Evolution ◽  
Dissolution Experiment ◽  
Permeability Increase ◽  
The Relationship

The temporal permeability and damage evolutions of low-permeability sandstone cores during triaxial and long-term dissolution experiments were measured using a triaxial-flow system. Three triaxial experiments were performed on sandstone cores having initial permeability ranging from 78 × 10 − 18   m 2 to 120 × 10 − 18   m 2 . Two sets of long-term dissolution experiments were conducted on cracked sandstone cores. All dissolution experiments were performed at room temperature and using a 10 g/L H2SO4 and 0.2 g/L H2O2 input solution. Permeability evolution was determined using Darcy’s law. The cores experienced an average increase of 25% in permeability in the dissolution experiment and 900%~1500% increase at the end of the experiment. The dissolution was fairly homogeneous during the long-term experiments whether on the 1 mm scale or the 10 μm scale. The relationship between damage and permeability was speculated and its correlation coefficient has been proved to be close to 1. These results suggest that hydraulic fracturing works well in permeability increase in low-permeability sandstone reservoir.

scholarly journals Long-term evolution of fracture permeability in slate as potential target reservoirs for Enhanced Geothermal Systems (EGS)

2021 ◽  
Author(s):  
Chaojie Cheng ◽  
Johannes Herrmann ◽  
Erik Rybacki ◽  
Harald Milsch
Keyword(s):  
Room Temperature ◽  
Time Dependent ◽  
Emission Spectrometry ◽  
Intermittent Flow ◽  
Fracture Aperture ◽  
Enhanced Geothermal Systems ◽  
Permeability Reduction ◽  
Permeability Evolution ◽  
Fracture Permeability

<p>The long-term sustainability of fractures in Variscan metamorphic rocks will determine whether it is reasonable to utilize such formations as potential unconventional EGS reservoirs. During long lasting fluid flow within fractures, dissolution, precipitation, and chemical reactions between the fluid and the rock matrix may alter the flow pathway structure and flow properties. Within the framework of the European Union's Horizon 2020 initiative "MEET (Multi-Sites EGS Demonstration)", we performed long-term fracture permeability experiments on saw-cut slate samples from the Hahnenklee drill site, Harz Mountains, Germany, under constant pressure and temperature conditions. Two experiments were performed using deionized water as pore fluid with intermittent flow for more than one month at 10 MPa confining pressure and 1 MPa pore pressure. Three sequential investigations were performed, including (1) an initial continuous flow tests at room temperature, (2) temperature cycles between room temperature and up to 70 °C or 90 °C, and (3) measurement of the time-dependent permeability evolution at 70 °C or 90 °C. During stage (3), the effluents were sampled in time intervals of 6 days and analyzed using inductively coupled plasma optical emission spectrometry (ICP-OES). The results show that (1) sample permeability first continuously decreases, but progressively converges within about three days, (2) increasing temperature leads to an additional permeability decline that is irreversible, and (3) the time-dependent permeability reduction is much more pronounced at 90 °C in comparison to that at 70 °C. The effluents are enriched with Na, Fe, K, Ca, Si, where the Na concentration is always an order of magnitude higher than the others. Except for Si, concentrations are progressively decreasing with time. During the entire experimental period, sample permeability was reduced by approximately 90% at 90 °C and 60% at 70 °C compared to their initial values. In contrast, both samples showed a negligible permeability decline with time at room temperature after cooling. Our results demonstrate that thermally-enhanced fluid-rock interactions lead to a permanent and at least partial closure of fracture aperture, which is unfavorable for geothermal exploitation. However, the degree of permeability reduction may strongly depend on initial fracture roughness, which remains to be investigated.</p>

Comparative Labelling and Biokinetic Studies of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn)

1977 ◽  
Vol 16 (01) ◽  
pp. 30-35 ◽  
Author(s):  
N. Agha ◽  
R. B. R. Persson
Keyword(s):  
Complex Formation ◽  
Significant Influence ◽  
Room Temperature ◽  
Ph Value ◽  
Maximum Activity ◽  
Reduction Step ◽  
Labelling Yield ◽  
Different Temperatures ◽  
Kinetics Of

SummaryGelchromatography column scanning has been used to study the fractions of 99mTc-pertechnetate, 99mTcchelate and reduced hydrolyzed 99mTc in preparations of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn). The labelling yield of 99mTc-EDTA(Sn) chelate was as high as 90—95% when 100 μmol EDTA · H4 and 0.5 (Amol SnCl2 was incubated with 10 ml 99mTceluate for 30—60 min at room temperature. The study of the influence of the pH-value on the fraction of 99mTc-EDTA shows that pH 2.8—2.9 gave the best labelling yield. In a comparative study of the labelling kinetics of 99mTc-EDTA(Sn) and 99mTc- DTPA(Sn) at different temperatures (7, 22 and 37°C), no significant influence on the reduction step was found. The rate constant for complex formation, however, increased more rapidly with increased temperature for 99mTc-DTPA(Sn). At room temperature only a few minutes was required to achieve a high labelling yield with 99mTc-DTPA(Sn) whereas about 60 min was required for 99mTc-EDTA(Sn). Comparative biokinetic studies in rabbits showed that the maximum activity in kidneys is achieved after 12 min with 99mTc-EDTA(Sn) but already after 6 min with 99mTc-DTPA(Sn). The long-term disappearance of 99mTc-DTPA(Sn) from the kidneys is about five times faster than that for 99mTc-EDTA(Sn).

Multi-Center Calibration of the Second Reference Material for Thromboplastin, Rabbit, Plain, Coded CRM 149R

1991 ◽  
Vol 65 (03) ◽  
pp. 263-267 ◽  
Author(s):  
A M H P van den Besselaar ◽  
R M Bertina
Keyword(s):  
Reference Material ◽  
Standard Error ◽  
Standard Errors ◽  
Sensitivity Index ◽  
Long Term Stability ◽  
Significant Bias ◽  
The Mean ◽  
The Relationship ◽  
International Sensitivity Index

SummaryIn a collaborative trial of eleven laboratories which was performed mainly within the framework of the European Community Bureau of Reference (BCR), a second reference material for thromboplastin, rabbit, plain, was calibrated against its predecessor RBT/79. This second reference material (coded CRM 149R) has a mean International Sensitivity Index (ISI) of 1.343 with a standard error of the mean of 0.035. The standard error of the ISI was determined by combination of the standard errors of the ISI of RBT/79 and the slope of the calibration line in this trial.The BCR reference material for thromboplastin, human, plain (coded BCT/099) was also included in this trial for assessment of the long-term stability of the relationship with RBT/79. The results indicated that this relationship has not changed over a period of 8 years. The interlaboratory variation of the slope of the relationship between CRM 149R and RBT/79 was significantly lower than the variation of the slope of the relationship between BCT/099 and RBT/79. In addition to the manual technique, a semi-automatic coagulometer according to Schnitger & Gross was used to determine prothrombin times with CRM 149R. The mean ISI of CRM 149R was not affected by replacement of the manual technique by this particular coagulometer.Two lyophilized plasmas were included in this trial. The mean slope of relationship between RBT/79 and CRM 149R based on the two lyophilized plasmas was the same as the corresponding slope based on fresh plasmas. Tlowever, the mean slope of relationship between RBT/79 and BCT/099 based on the two lyophilized plasmas was 4.9% higher than the mean slope based on fresh plasmas. Thus, the use of these lyophilized plasmas induced a small but significant bias in the slope of relationship between these thromboplastins of different species.

Risk Attitude and Corporate Investment under Output Market Uncertainty: Evidence from The Mekong River Delta, Vietnam

2016 ◽  
pp. 59-70
Author(s):  
Ninh Le Khuong ◽  
Nghiem Le Tan ◽  
Tho Huynh Huu
Keyword(s):  
Negative Relationship ◽  
Risk Attitude ◽  
Business Strategies ◽  
Risk Averse ◽  
Market Uncertainty ◽  
Firm Investment ◽  
Output Market ◽  
The Impact ◽  
The Relationship

This paper aims to detect the impact of firm managers’ risk attitude on the relationship between the degree of output market uncertainty and firm investment. The findings show that there is a negative relationship between these two aspects for risk-averse managers while there is a positive relationship for risk-loving ones, since they have different utility functions. Based on the findings, this paper proposes recommendations for firm managers to take into account when making investment decisions and long-term business strategies as well.

Financial Folly and Spain’s Black Legend

2017 ◽  
Author(s):  
Mauricio Drelichman ◽  
Hans-Joachim Voth
Keyword(s):  
Seventeenth Century ◽  
Economic History ◽  
Military Power ◽  
Great Flexibility ◽  
Loan Contracts ◽  
Historical Tradition ◽  
Black Legend ◽  
Contractual Obligations ◽  
The Relationship

This epilogue argues that Castile was solvent throughout Philip II's reign. A complex web of contractual obligations designed to ensure repayment governed the relationship between the king and his bankers. The same contracts allowed great flexibility for both the Crown and bankers when liquidity was tight. The risk of potential defaults was not a surprise; their likelihood was priced into the loan contracts. As a consequence, virtually every banking family turned a profit over the long term, while the king benefited from their services to run the largest empire that had yet existed. The epilogue then looks at the economic history version of Spain's Black Legend. The economic history version of the Black Legend emerged from a combination of two narratives: a rich historical tradition analyzing the decline of Spain as an economic and military power from the seventeenth century onward, combined with new institutional analysis highlighting the unconstrained power of the monarch.

Subcritical Crack Growth and Long-Term Strength in Rock and High-Strength and Ultra Low-Permeability Concrete

2009 ◽  
Vol 58 (6) ◽  
pp. 525-532 ◽  
Author(s):  
Yoshitaka NARA ◽  
Masafumi TAKADA ◽  
Daisuke MORI ◽  
Hitoshi OWADA ◽  
Tetsuro YONEDA ◽  
...  
Keyword(s):  
Crack Growth ◽  
Subcritical Crack Growth ◽  
High Strength ◽  
Low Permeability ◽  
Term Strength

QUALITY OF LIFE PROBLEMS OF GYNECOLOGICAL CANCER PATIENTS

2017 ◽  
Vol 63 (3) ◽  
pp. 368-374
Author(s):  
Olga Churuksaeva ◽  
Larisa Kolomiets
Keyword(s):  
Quality Of Life ◽  
Gynecological Cancer ◽  
Social Aspects ◽  
Cancer Data ◽  
Life Problems ◽  
Anticancer Treatment ◽  
Short And Long Term ◽  
The Relationship

Due to improvements in short- and long-term clinical outcomes a study of quality of life is one of the most promising trends in oncology today. This review analyzes the published literature on problems dealing with quality of life of patients with gynecological cancer. Data on quality of life with respect to the extent of anticancer treatment as well as psychological and social aspects are presented. The relationship between quality of life and survival has been estimated.

The Effects of P75NTR on Learning Memory Mediated by Hippocampal Apoptosis and Synaptic Plasticity

2020 ◽  
Vol 26 ◽  
Author(s):  
Jun-Jie Tang ◽  
Shuang Feng ◽  
Xing-Dong Chen ◽  
Hua Huang ◽  
Min Mao ◽  
...  
Keyword(s):  
Synaptic Plasticity ◽  
Learning And Memory ◽  
Neurological Diseases ◽  
Neurotrophin Receptor ◽  
P75 Neurotrophin Receptor ◽  
Negative Effects ◽  
Apoptotic Effect ◽  
New Ideas ◽  
The Relationship

: Neurological diseases bring great mental and physical torture to the patients, and have long-term and sustained negative effects on families and society. The attention to neurological diseases is increasing, and the improvement of the material level is accompanied by an increase in the demand for mental level. The p75 neurotrophin receptor (p75NTR) is a low-affinity neurotrophin receptor and involved in diverse and pleiotropic effects in the developmental and adult central nervous system (CNS). Since neurological diseases are usually accompanied by the regression of memory, the pathogenesis of p75NTR also activates and inhibits other signaling pathways, which has a serious impact on the learning and memory of patients. The results of studies shown that p75NTR is associated with LTP/LTD-induced synaptic enhancement and inhibition, suggest that p75NTR may be involved in the progression of synaptic plasticity. And its pro-apoptotic effect is associated with activation of proBDNF and inhibition of proNGF, and TrkA/p75NTR imbalance leads to pro-survival or pro-apoptotic phenomena. It can be inferred that p75NTR mediates apoptosis in the hippocampus and amygdale, which may affect learning and memory behavior. This article mainly discusses the relationship between p75NTR and learning memory and associated mechanisms, which may provide some new ideas for the treatment of neurological diseases.

The Relationship between Human Development and Economic Growth

2018 ◽  
Author(s):  
Frances Stewart ◽  
Gustav Ranis ◽  
Emma Samman
Keyword(s):  
Economic Growth ◽  
Human Development ◽  
Human Development Index ◽  
Econometric Analysis ◽  
Complementary Relationship ◽  
Development Index ◽  
The Relationship ◽  
Intervening Variables

This chapter explores the interactions between economic growth and human development, as measured by the Human Development Index, theoretically and empirically. Drawing on many studies it explores the links in two chains, from economic growth to human development, and from human development to growth. Econometric analysis establishes strong links between economic growth and human development, and intervening variables influencing the strength of the chains. Because of the complementary relationship, putting emphasis on economic growth alone is not a long-term viable strategy, as growth is likely to be impeded by failure on human development. The chapter classifies country performance in four ways: virtuous cycles where both growth and human development are successful; vicious cycles where both are weak; and lopsided ones where the economy is strong but human development is weak, or conversely ones where human development is strong but the economy is weak.

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