Investigation of Fracture Width Change under Closure Pressure in Unconventional Reservoir Based on the Hertz Contact Theory

To describe the fracture width is crucial for the flow conductivity evaluation, which influences the exploitation efficiency of unconventional oil and gas resources. Commonly, as the proppants fill in the fracture, the deformation will happen under the closure pressure to resist the fracture width change. Therefore, it is significant to develop the theoretical model to predict the variation. In this work, the mathematical model for the propping behavior of proppants in the fracture under closure pressure is established based on the Hertz contact theory. Compared with the existing models, the developed model considers both the proppant insertion and the elastic compression among the proppants, which is closer to the actual physical process. Furthermore, the experimental cases with different proppant sizes are taken to verify the model, and the good conformity presents its rationality. The parameter sensitivity analysis of this model shows that the fracture width change increases with the increase of the average diameters of proppants ( D ) and it declines with the improving of proppant elasticity modulus ( E 1 ) and Poisson’s ratio ( v 1 ).

A bükkaljai vízfolyások kanyarulatfejlettségének vizsgálata szerkezetföldtani okok és következtetések

Rivers react relatively quickly to epirogenetic movements. This is also confirmed through laboratory experiments (Ouchi, S. 1985; Marple, R. T. – Talwani, P. 1993; Twidale, P. 1996, 2004). Many river-related surface-forming processes and forms are used for studying fault activity, for example: channel formation, channel braided, variation of channel width, change of channel depth and river terraces (etc.). However, these processes and forms can be caused by climate change, so the form alone does not prove the structural activity of the area (Schumm , S. A. 1986, 2005; Pinter, N. C. 1996; Petrovszki J. 2013). Such morphological change is the development of river sinuosity, which is often used to justify the activity of faults. Several Hungarian and foreign researchers have been investigating this phenomenon, but have mainly examinied larger rivers. The purpose of this work is to examine the sinuosity of the Bükkalja creeks. I tested and refined the procedure associated with scaling in order to explain the possible causes of changes in the sinuosity of the creeks.

Glucosamine sulphate: an umbrella review of health outcomes

Background and Aims: Glucosamine sulphate (GS) can be used as background therapy in people affected by knee osteoarthritis (OA). Knowledge regarding the efficacy and safety of GS is of importance since its use worldwide is increasing. Therefore, the present study aimed to map and grade the diverse health outcomes associated with GS using an umbrella review approach. Methods: Medline, Cinahl and Embase databases were searched until 1 April 2020. An umbrella review of systematic reviews and meta-analyses of randomized controlled trials (RCTs) was carried out. The evidence from the RCTs was graded using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) tool. Results: From 140 articles returned, 11 systematic reviews, for a total of 21 outcomes (37 RCTs; 3949 participants; almost all using 1500 mg/day), were included. No systematic reviews/meta-analyses of observational studies were included. Regarding the findings of the meta-analyses, 9/17 outcomes were statistically significant, indicating that GS is more effective than placebo. A high certainty of evidence, as assessed by GRADE, supported the use of GS ( versus placebo) in improving the Lequesne Index, joint space width change, joint space width change after 3 years of follow up, joint space narrowing and OA progression. No difference in terms of adverse effects was found between GS and placebo. In systematic reviews, GS was associated with a better glucose profile and a better physical function performance than placebo. Conclusion: GS, when used as a prescription drug (i.e. crystalline glucosamine sulphate) at 1500 mg daily dosage, can positively affect the cartilage structure, reduce pain, improve function and glucose metabolism in people with knee OA, without having a greater incidence of adverse effects than placebo.

Simplified mathematical model of the hydrothermal regime of the Krasnoyarsk reservoir

The scheme of the reservoir bed is applied to numerical study of the hydrothermal regime of the Krasnoyarsk Reservoir in the form of regions with continuous depth variation and abrupt width change. A numerical algorithm for the research of 2-D stratified currents in vertical plane in flowing reservoirs is considered taking into account Coriolis force. The numerical model determines the vertical distributions of water temperature in various areas of a reservoir real meteodata. There are given examples of water currents and temperature calculations in the Krasnoyarsk Reservoir. The results of the calculations are consistent with the observational data.

On the Time of Emergence of Tropical Width Change

The tropical belt is expected to expand in response to global warming, although most of the observed tropical widening since 1980, especially in the Northern Hemisphere, is believed to have mainly originated from natural variability. The view is of a small global warming signal relative to natural variability. Here we focus on the question whether and, if so when, the anthropogenic signal of tropical widening will become detectable. Analysis of two large ensemble climate simulations reveals that the forced signal of tropical width is strongly constrained by the forced signal of global mean temperature. Under a representative concentration pathway 8.5 (RCP8.5) emissions scenario, the aggregate of the two models indicates a regression of about 0.5° lat °C−1 during 1980–2080. The models also reveal that interannual variability in tropical width, a measure of noise used herein, is insensitive to global warming. Reanalysis data are therefore used to constrain the interannual variability, whose magnitude is estimated to be 1.1° latitude. Defining the time of emergence (ToE) for tropical width change as the first year (post-1980) when the forced signal exceeds the magnitude of interannual variability, the multimodel simulations of CMIP5 are used to estimate ToE and its confidence interval. The aforementioned strong constraint between the signal of tropical width change and global mean temperature change motivates using CMIP5-simulated global mean temperature changes to infer ToE. Our best estimate for the probable year for ToE, under an RCP8.5 emissions scenario, is 2058 with 10th–90th percentile confidence of 2047–68. Various sources of uncertainty in estimating the ToE are discussed.