Effect of Test Mode on Stress Sensitivity Evaluation of Full-Diameter Volcanic Rock

2013 ◽  
Vol 718-720 ◽  
pp. 525-531
Author(s):  
Juan Wang ◽  
Ping Guo ◽  
Cai Zhen Peng ◽  
Fang Wang
Keyword(s):  
Internal Pressure ◽  
Volcanic Rock ◽  
Confining Pressure ◽  
Stress Sensitivity ◽  
The Other ◽  
High Permeability ◽  
Pore Connectivity ◽  
Test Mode ◽  
Sensitivity Evaluation ◽  
Study Results

some reservoir property change which occurs during reservoir development has been studied, however, the study about the effect of test mode on stress sensitivity evaluation of full-diameter volcanic rock is few since the volcanic gas reservoir in Da-qing is buried deeply and the properties and flow mechanics are extremely complex. Therefore, there are two different test modes for stress sensitivity to study the effect of test mode on stress sensitivity evaluation. One of the test modes is to keep the internal pressure constant and change the confining pressure and the other is to change the internal pressure and keep the confining pressure constant. The study results are as follows: (a) the permeabilitys variation law at different test mode is similar when the net stress varies. There are two type, one is sensitive with high permeability since for well development of micro-fracture and pore connectivity, the other is not sensitive with high permeability since for the weak pore connectivity and micro-fracture; (b) the permeability could decrease with times of pressure cycling , so, the times of flow/shut in operation should be decreased as few as possible; (c) the relative variation of permeability in the mode of changing confining pressure is smaller than it in changing internal pressure, which means the stress sensitivity of changing confining pressure is weaker; (d) the results of changing internal pressure should be used since the test mode is more similar with the actual operation. The results are significant for gas-water RPs accurate determination and efficient development of volcanic reservoirs.

Stress-sensitive permeability of matrix cores and artificially fractured cores with non-proppant-filled fractures under high-pressure conditions

Geophysics ◽  
2021 ◽  
pp. 1-102
Author(s):  
Ren-Shi Nie ◽  
Zheng Wang ◽  
Zhangxin Chen ◽  
An-Cheng Wang ◽  
Chang-Hong Zhou ◽  
...  
Keyword(s):  
High Pressure ◽  
Internal Pressure ◽  
Confining Pressure ◽  
Stress Sensitivity ◽  
Curve Analysis ◽  
Test Method ◽  
Gas Reservoirs ◽  
Gas Reservoir ◽  
Permeability Damage ◽  
Fractured Sandstone

Stress-sensitive permeability (SSP) influences gas well productivity and is a crucial element influencing gas reservoir development. SSP for high-pressure fractured gas reservoirs with an initial reservoir pressure of more than 20 MPa has never been comprehensively evaluated to the best of our knowledge. SSP experiments with special procedures were designed by adopting the variable confining pressure (VCP) and variable internal pressure (VIP) methods. VCP is a test method in which confining pressure is altered and a constant internal pressure is maintained for the experimental core holder. VIP is a test method in which internal pressure is changed and a constant confining pressure is maintained. A four-stage curve analysis method was developed to perform regressions on semi-logarithmic curves and exponential curves of experimental data. A method to evaluate the SSP was presented using stress sensitivity coefficients obtained via regressions. A calculation approach for determining the degrees of permeability damage and permeability recovery was also proposed. Six matrix cores and six cores with artificial fractures from a high-pressure fractured sandstone gas reservoir were tested using the two methods. The SSP curves for high-pressure reservoirs were characterized by four-stage variation trends, which differentiated with low-pressure reservoirs with an initial reservoir pressure less than 20 MPa. The stress sensitivity of the VCP method was stronger than that of the VIP method. The core samples mainly showed a “Medium” / “Medium-Strong” stress sensitivity under low/high effective stress conditions. Compared with matrix cores, fractured cores showed stronger stress sensitivity owing to its strong plasticity and weak elasticity. The maximum permeability damage degree reached 99.67% and the minimum permeability recovery was only 6.9%. The presented method of experimental design, four-stage curve analysis, stress sensitivity evaluation and the summarized findings in this paper can provide references for future studies on SSP in high-pressure fractured sandstone gas reservoirs.

scholarly journals Stress sensitivity evaluation of ultra-low permeability sandstone reservoir and its influence on oilfield development

2021 ◽  
Vol 292 ◽  
pp. 01027
Author(s):  
Xin Bai ◽  
Chunfen Guo ◽  
Xingli Yang ◽  
Xi Liu
Keyword(s):  
Water Injection ◽  
Confining Pressure ◽  
Stress Sensitivity ◽  
Low Permeability ◽  
Oil Well ◽  
Pressure Stage ◽  
Bottom Hole ◽  
Sensitivity Evaluation ◽  
Permeability Damage ◽  
Sandstone Reservoir

Luohe ultra-low permeability sandstone reservoir is a hot block in Yanchang oilfield, which is a potential point for increasing production and reservoir. In view of the current situation that there is no unified stress sensitivity evaluation standard for ultra-low permeability sandstone in the study area, taking the ultra-low permeability sandstone in Luohe district as the research object, the stress sensitivity evaluation of ultra-low permeability sandstone is carried out by using experimental analysis as the main means. The results show that it is more accurate to evaluate porosity by using pore stress sensitivity coefficient instead of pore compressibility coefficient. With the increase of net overburden pressure, the porosity stress sensitivity decreases gradually; the permeability stress sensitivity is evaluated by variable confining pressure. With the increase of confining pressure, the permeability damage decreases. With the decrease of confining pressure, the permeability damage increases, but it can not recover to the original value, so the permeability damage is irreversible; in the low bottom hole pressure stage, stress sensitivity has a greater impact on oil well productivity, while in the high bottom hole pressure stage, stress sensitivity has a smaller impact on oil well productivity; advanced water injection can reduce the adverse effect of stress sensitivity on the development of ultra-low permeability sandstone and maximize the economic benefits. The research results clarify the method of stress sensitivity evaluation, and provide guidance for efficient water injection in the next step.

Computational and experimental studies of the strength of full-scale samples of pipes with defects "metal loss" and "dent with groove"

2020 ◽  
Vol 10 (3) ◽  
pp. 226-233
Author(s):  
Dmitry A. Neganov ◽  
◽  
Victor M. Varshitsky ◽  
Andrey A. Belkin ◽  
◽  
...  
Keyword(s):  
Internal Pressure ◽  
Experimental Studies ◽  
Full Scale ◽  
The Other ◽  
Metal Loss ◽  
Calculation Methods ◽  
Reliable Operation ◽  
Sufficient Stability ◽  
Comparative Results ◽  
The Moment

The article contains the comparative results of the experimental and calculated research of the strength of a pipeline with such defects as “metal loss” and “dent with groove”. Two coils with diameter of 820 mm and the thickness of 9 mm of 19G steel were used for full-scale pipe sample production. One of the coils was intentionally damaged by machining, which resulted in “metal loss” defect, the other one was dented (by press machine) and got groove mark (by chisel). The testing of pipe samples was performed by applying static internal pressure to the moment of collapse. The calculation of deterioration pressure was carried out with the use of national and foreign methodical approaches. The calculated values of collapsing pressure for the pipe with loss of metal mainly coincided with the calculation experiment results based on Russian method and ASME B31G. In case of pipe with dent and groove the calculated value of collapsing pressure demonstrated greater coincidence with Russian method and to a lesser extent with API 579/ASME FFS-1. In whole, all calculation methods demonstrate sufficient stability of results, which provides reliable operation of pipelines with defects.

scholarly journals Management of accounting information resources security in Polish entities – study results

2018 ◽  
Vol 2018 (97 (153)) ◽  
pp. 115-139
Author(s):  
Elżbieta Szczepankiewicz
Keyword(s):  
Empirical Research ◽  
Accounting Information ◽  
Information Resources ◽  
The Other ◽  
Three Dimensions ◽  
Accounting System ◽  
External Threats ◽  
Study Results ◽  
Cyber Space ◽  
Business Entities

The presence of contemporary entities in the cyber-space shows that IT offers unlimited possibilities of running a business and developing an organisation. On the other hand, it involves a greater number of internal and external threats in the area of accounting information resources security. The objective of the paper is to diagnose the current level of accounting information resources security (AIRS) assurance in Polish business entities. The paper analyses two research hypotheses. In accordance with the first one, the AIRS assurance level in various entity groups may be different, even though all entities should have implemented the same requirements of the Accounting Act in the analyzed area. The identified differences may result from the effect of additional, industry-specific regulations. The other hypothesis claims that in the private business area, accounting and auditing companies adhere to AIRS regulations more strictly than other small and medium enterprises. The paper defines the fundamental factors affecting the functioning of corporate accounting systems in the three dimensions of the cyber-space. Subsequently, the author presents the results of empirical research on how corporate information security is ensured in the context of internal accounting control systems and the requirements of the Polish Accounting Act. The results of the empirical research show how the management of the analysed entities crafts the basic elements of their internal environment as well as internal communication and control processes connected with ensuring information resources security. The results also show the management’s approach to various aspects of risk management of accounting information resources security, as well as to adherence to organisational and administrative procedures, and to hardware and software safeguards in the IT environment of the accounting system. The issues analysed in the present paper open a scholarly discussion that should lead to the development of theoretical models, recommendation of efficient methods and tools, as well as indication of adequate legislative initiatives. Research methods used by the author include analysis of literature and legislation, analysis of survey results, deduction and inference.

scholarly journals Cost-Effectiveness Analysis of Biopharmaceuticals for Treating Rheumatoid Arthritis: Infliximab, Adalimumab, and Etanercept

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Ahmad Gholami ◽  
Jassem Azizpoor ◽  
Elham Aflaki ◽  
Mehdi Rezaee ◽  
Khosro Keshavarz
Keyword(s):  
Rheumatoid Arthritis ◽  
Sensitivity Analysis ◽  
Cost Effectiveness ◽  
Cost Effective ◽  
The Other ◽  
Cost Data ◽  
Fars Province ◽  
Study Results ◽  
The Mean ◽  
The Cost

Introduction. Rheumatoid arthritis (RA) is a chronic progressive inflammatory disease that causes joint destruction. The condition imposes a significant economic burden on patients and societies. The present study is aimed at evaluating the cost-effectiveness of Infliximab, Adalimumab, and Etanercept in treating rheumatoid arthritis in Iran. Methods. This is a cost-effectiveness study of economic evaluation in which the Markov model was used. The study was carried out on 154 patients with rheumatoid arthritis in Fars province taking Infliximab, Adalimumab, and Etanercept. The patients were selected through sampling. In this study, the cost data were collected from a community perspective, and the outcomes were the mean reductions in DAS-28 and QALY. The cost data collection form and the EQ-5D questionnaire were also used to collect the required data. The results were presented in the form of an incremental cost-effectiveness ratio, and the sensitivity analysis was used to measure the robustness of the study results. The TreeAge Pro and Excel softwares were used to analyze the collected data. Results. The results showed that the mean costs and the QALY rates in the Infliximab, Adalimumab, and Etanercept arms were $ 79,518.33 and 12.34, $ 91,695.59 and 13.25, and $ 87,440.92 and 11.79, respectively. The one-way sensitivity analysis confirmed the robustness of the results. In addition, the results of the probabilistic sensitivity analysis (PSA) indicated that on the cost-effectiveness acceptability curve, Infliximab was in the acceptance area and below the threshold in 77% of simulations. The scatter plot was in the mentioned area in 81% and 91% of simulations compared with Adalimumab and Etanercept, respectively, implying lower costs and higher effectiveness than the other two alternatives. Therefore, the strategy was more cost-effective. Conclusion. According to the results of this study, Infliximab was more cost-effective than the other two medications. Therefore, it is recommended that physicians use this medication as the priority in treating rheumatoid arthritis. It is also suggested that health policymakers consider the present study results in preparing treatment guidelines for RA.

scholarly journals Examining Distance Learners in Hybrid Synchronous Instruction: Successes and Challenges

2017 ◽  
Vol 21 (4) ◽  
Author(s):  
Enilda Romero-Hall ◽  
Cristiane Rocha Vicentini
Keyword(s):  
Data Analysis ◽  
Focus Group ◽  
The Other ◽  
Distance Learners ◽  
Electronic Journals ◽  
Face To Face ◽  
Individual Interviews ◽  
Study Results ◽  
Successes And Challenges

This paper reports on a case study investigating distance learners participating in graduate-level hybrid synchronous instruction. This research helps inform the design of hybrid synchronous instruction in which face-to-face and distance learners engage in class sessions. Data were collected using electronic journals, individual interviews, and a focus group. The results of the data analysis provide evidence that in this case, hybrid synchronous instruction improved the study habits of distance learners. On the other hand, the case study results also revealed that there are challenging pedogogical aspects which the distance learners had to overcome during hybrid synchronous instruction. Among such challenges were the interactions, relationships, and communication exchanges between distance learners, their face-to-face counterparts, and the instructor.

scholarly journals ROLE OF EARLY LAPAROSCOPIC CHOLECYSTECTOMY IN PREVENTING COMPLICATIONS OF ACUTE CHOLECYSTITIS

2020 ◽  
pp. 1-3
Author(s):  
Mukesh Kumar ◽  
Sanjay Kumar Suman ◽  
Pawan Kumar Jha ◽  
Debarshi Jana
Keyword(s):  
Laparoscopic Cholecystectomy ◽  
Bile Duct ◽  
Conservative Treatment ◽  
Common Bile Duct ◽  
Acute Cholecystitis ◽  
Common Bile Duct Stone ◽  
Bile Duct Stone ◽  
The Other ◽  
Study Results ◽  
Delayed Group

Background: Cholecystectomy is the standard and the only curative treatment for acutecholecystitis. The complications of acute cholecystitis are disastrous to the patients; on the other hand, conservative treatment is associated with recurrence of symptoms and other complications as common bile duct stone. The aim of this study is to weight out the complication of emergency surgery against the complications of conservative treatment in patients with acute cholecystitis. Materials andmethods: A total of 80 patients were included in the study. All Patients underwent early laparoscopiccholecystectomy or interval laparoscopic cholecystectomies for acute calcularcholecystitis from October 2017 to September 2019 were included in the study. Results: The overall complication rate was 15% (6 of 40 in early group and 10% (4 of 40) in the delayed group. One case of delayed group suffering recurrent acute attack and the other one suffering common bile duct stone, there was no major bile duct injury in the delayed group. Conclusion: Laparoscopic cholecystectomy is a safe and cost-effective approach for the treatment of acute cholecystitis within 72 h after the onset of attack.

scholarly journals Tasa de preñez post vitrificación en los embriones de équidos producidos in vivo. Revisión

2020 ◽  
Vol 11 (4) ◽  
pp. 1142-1149
Author(s):  
Christian Urías-Castro ◽  
Ana Myriam Boeta
Keyword(s):  
The Other ◽  
Dramatic Reduction ◽  
High Permeability ◽  
Vitreous State ◽  
Preservation Method ◽  
Two Factors ◽  
Cryo Preservation ◽  
Transfer Index ◽  
Year 2000

Vitrification is a cryo-preservation method often used in embryos obtained from mares or jennies. It consists in the dramatic reduction of temperature to levels close to -196 °C, that allows the cryopreserving solution containing the embryo to pass from liquid to vitreous state. Several improvements to vitrification protocols have made possible to cryo-preserve embryos with different sizes; since during the first decade after the year 2000, only small embryos were successfully vitrified.  Embryos collected at the sixth day post ovulation (PO) are usually smaller or equal to 300 micrometers in diameter (≤ 300 µmØ) and can be  routinely vitrified following simple protocols; they have a higher post vitrification pregnancy rate (PVPR) when compared to large embryos which have more than 300 micrometers in diameter (˃ 300 µmØ).  The high PVPR of embryos ≤ 300 µmØ is due to an embryo capsule (EC) that is not fully developed yet and has a high permeability to cryo-preserving solutions. At present time, embryos collected either the seventh or eighth day PO are ˃ 300 µmØ and are characterized to have a low post vitrification survival; in order to increase their PVPR their EC might be punctured to make it permeable to cryopreserving solutions. Additionally, there are at least two factors that can be manipulated to increase the PVPR of embryos ˃ 300 µmØ; one is to reduce their size by aspiring their blastocoelic liquid (BL), and the other is to induce a high temperature transfer index (TTI) to rapidly reach -196 °C. 

scholarly journals Development of gypsy moth (Lymantria dispar L) on the foliage of Quercus cerris L., Q. Petraea (matt) Liebl. and Q. Robur L. in the controlled conditions

2007 ◽  
pp. 55-67 ◽  
Author(s):  
Slobodan Milanovic
Keyword(s):  
Relative Humidity ◽  
Host Plant ◽  
Gypsy Moth ◽  
Lymantria Dispar ◽  
Environmental Conditions ◽  
Quercus Robur ◽  
Quercus Petraea ◽  
The Other ◽  
Study Results ◽  
Quercus Cerris

The development of Gypsy moth (Lymantria dispar L) was monitored in laboratory conditions, on the foliage of the species Quercus cerris L. Quercus petraea (Matt) Liebl. and Quercus robur L. The experiment was established in the controlled environmental conditions, at the temperature of 25?C, photoperiod 14:10 (day: night) and relative humidity 70%. The objective of the research was to determine the suitability of the study host plant species for gypsy moth development. The study results show that Gypsy moth caterpillars cultivated on Q. petraea foliage had a lower survival, higher number of moultings, longer preadult development and lower fecundity, which makes this species less suitable compared to the other two. Gypsy moth caterpillars cultivated on Q. cerris foliage had the highest survival degree the lowest number of moultings, the shortest preadult development and the highest fecundity, which makes this species the most favourable for gypsy moth development. Q. robur was between the former two species in this respect.

14 Treaty Entry into Force, Exceptions, Modifications, and Terminations

2021 ◽  
Author(s):  
Salacuse Jeswald W
Keyword(s):  
Internal Pressure ◽  
International Law ◽  
The Other ◽  
Foreign Investors ◽  
Labour Unions ◽  
Pressure Groups ◽  
Civic Organizations ◽  
Other Hand ◽  
Investment Treaties

This chapter discusses the entry into force, exceptions, modifications, and terminations of investment treaties. While enunciating rules of international law governing foreign investors and investments, investment treaties at the same time incorporate various devices to regulate and limit the applicability of those rules and thereby allow contracting states to mediate tensions between demands of treaty partners and of internal pressure groups, such as labour unions, local manufacturers and merchants, and civic organizations. Such devices include treaty provisions on four matters: the entry into force of the treaty; treaty exceptions; treaty modifications; and treaty terminations. States employ the first two as part of the treaty negotiating process. On the other hand, states usually employ the latter two devices as a result of their unsatisfactory experience with a treaty that has entered into force.

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