A New Mathematical Model of Tight Formation for Productivity Transient Analysis with Additional Gas Driving

During the gas injection development of low-permeability carbonate reservoirs, due to the complexity of the reservoir and the complexity of the fluid phases, the current productivity evaluation methods are no longer applicable. In this paper, considering factors such as fracture characteristics, stress sensitivity, and phase distribution, a low-permeability carbonate reservoir gas injection development productivity transient analysis model is established. The results of the study show that the larger the value of permeability damage coefficient, the stronger the curve of the production curve will bend toward the pressure axis. This is because the larger the value of permeability damage coefficient, the more severe the stress sensitivity of the formation is, which shows that rock deformation has an important impact on production. When two phases appear at the bottom of the well, the seepage resistance increases due to the two-phase flow, which in turn causes the productivity of a single well to rapidly decrease. With the decrease of bottom hole pressure, this resistance will increase significantly and the productivity of a single well will decline rapidly.

Assessment of the Ecological Risks of Landslide Damages in the Carpathian Region

The dynamism of the landslides within the Carpathian region of Ukraine is because of the difficult engineering and geological conditions. High landslide den sity and significant population density contribute to the fact that environmental parameters worsen and require rational management. Permanent natural factors like clay flysch formation, fault tectonics, high seismic activity, and dense network of rivers mostly facilitate the active development of landslides in the Carpathian region. However, it is triggered by extreme long-term precipitation. The numerical parameters of population density, the landslide damage coefficient, and the predictive range of landslide intensification were selected to assess the ecological risk of damages in the area. The landslide dam age coefficient characterizes the tendency of the area to landslide development, considering all the factors contributing to the landslides. Risk, as a multifunctional calculated complex, includes the calculation of damage, according to which we can assess the possibility of risk for the human being while assuming the equal distribution of the population within the study area. The integral components of the risk are calculated based on the data gathered to assess the growth of risks in the future, considering the area distribution and predictive time series of the landslide intensification. This analysis has identified engineering and geological areas having the greatest risk to human life.

The choice of cap-and-trade and carbon tax regulations in a cap-dependent carbon trading price setting

PurposeThe purpose of this paper is to analyze the operational decisions of a manufacturer who produces multiple products and the government's selection of cap-and-trade and carbon tax regulations.Design/methodology/approachThis paper explores the production decisions of a multi-product manufacturer under cap-and-trade and carbon tax regulations in a cap-dependent carbon trading price setting and compares carbon emission, the manufacturer's profits and social welfare under the two regulations. Game theory and extreme value theory are used to analyze our models.FindingsFirst, the authors find that the optimal profit of the manufacturer (the optimal cap) increases and then decreases with the cap (the unit carbon emission of product). Second, if the environmental damage coefficient is moderate, the optimal cap of unit environmental damage coefficient is independent of the product carbon emission or other related product parameters. Ultimately, cap-and-trade regulation always generates more carbon emission than carbon tax regulation. And cap-and-trade regulation (carbon tax regulation) can generate more social welfare if the environmental damage coefficient is low (high), and the social welfare under the two regulations is equal to each other, or otherwise.Originality/valueThis paper contributes the prior literature by considering the inverse relationship of the allocated cap and the carbon trading price and discusses the social welfare under cap-and-trade and carbon tax regulations. Some important and new results are found, which can guide the government's implementation of the two regulations.

Frost resistance of cement-sand and concrete beams during unilateral freezing

The work investigates changes in the beam structure under the action of local freezing, which leads to a change of the mechanical properties of the material and, consequently, of the beam structure. Two types of beam samples were used: from cement-sand mortar and from concrete. The work investigates the change in the development of deformations depending on the conditions of freezing of samples. The second accelerated method for assessing frost resistance was chosen according to DSTU B В.2.7-47-96. An accelerated method was chosen for assessing frost resistance at the temperature of -20 ±2 C°. After every five freeze-thaw cycles, the following changes were monitored: mass, water absorption, ultrasound transmission rate, damage coefficient, tensile bending strength, splitting strength, compressive strength, carbonization depth. The results showed that both in concrete and in mortar samples, the compressive strength after freezing was lower by 8% and 15% accordingly. The experimental results obtained confirm the assumptions made that the frost resistance of the material depends on the conditions of exposure of negative temperatures on products and structures and it can be used in a wider range of construction which will push regional development.

Monitoring internal corrosion in steel pipelines: a two-step helical guided wave approach for localization and quantification

This article presents a two-step approach for the assessment of internal corrosion in cylindrical structures using helical guided ultrasonic waves. The approach consists of two steps such as (1) localization and (2) estimation of the size of the corroded area. Localization is performed with the algebraic reconstruction technique where the energy ratio of the two fundamental Lamb modes S0 and A0 is used as input damage coefficient. Using the output of the localization step, the size of the corroded area is estimated by iteratively solving the eikonal equation using a finite-difference approach. The proposed approach is validated by an accelerated corrosion test. Furthermore, numerical simulations are carried out to study the interaction of the energy ratio and the phase velocity travel time with various thickness profiles acquired from the experiment. The proposed approach is validated against the experimental data up to approximately 50% thickness loss.

Pathologic correlates of the magnetization transfer ratio in multiple sclerosis

ObjectiveTo identify pathologic correlates of magnetization transfer ratio (MTR) in multiple sclerosis (MS) in an MRI–pathology study.MethodsWe acquired MTR maps at 3T from 16 fixed MS brains and 4 controls, and immunostained 100 tissue blocks for neuronal neurofilaments, myelin (SMI94), tissue macrophages (CD68), microglia (IBA1), B-lymphocytes, T-lymphocytes, cytotoxic T-lymphocytes, astrocytes (glial fibrillary acidic protein), and mitochondrial damage (COX4, VDAC). We defined regions of interest in lesions, normal-appearing white matter (NAWM), and cortical normal-appearing gray matter (NAGM). Associations between MTR and immunostaining intensities were explored using linear mixed-effects models (with cassettes nested within patients) and interaction terms (for differences between regions of interest and between cases and controls); a multivariate linear mixed-effects model identified the best pathologic correlates of MTR.ResultsMTR was the lowest in white matter (WM) lesions (23.4 ± 9.4%) and the highest in NAWM (38.1 ± 8.7%). In MS brains, lower MTR was associated with lower immunostaining intensity for myelin (coefficient 0.31; 95% confidence interval [CI] 0.07–0.55), macrophages (coefficient 0.03; 95% CI 0.01–0.07), and astrocytes (coefficient 0.51; 95% CI 0.02–1.00), and with greater mitochondrial damage (coefficient 0.31; 95% CI 0.07–0.55). Based on interaction terms, MTR was more strongly associated with myelin in WM (coefficient 1.58; 95% CI 1.09–2.08) and gray matter (GM) lesions (coefficient 0.66; 95% CI 0.13–1.20), and with macrophages (coefficient 1.40; 95% CI 0.56–2.25), astrocytes (coefficient 2.66; 95% CI 1.31–4.01), and mitochondrial damage (coefficient −12.59; 95% CI −23.16 to −2.02) in MS brains than controls. In the multivariate model, myelin immunostaining intensity was the best correlate of MTR (coefficient 0.31; 95% CI 0.09–0.52; p = 0.004).ConclusionsMyelin was the strongest correlate of MTR, especially in WM and cortical GM lesions, but additional correlates should be kept in mind when designing and interpreting MTR observational and experimental studies in MS.

Parametric Study of Polymer-Nanoparticles-Assisted Injectivity Performance for Axisymmetric Two-Phase Flow in EOR Processes

Among a wide range of enhanced oil-recovery techniques, polymer flooding has been selected by petroleum industries due to the simplicity and lower cost of operational performances. The reason for this selection is due to the mobility-reduction of the water phase, facilitating the forward-movement of oil. The objective of this comprehensive study is to develop a mathematical model for simultaneous injection of polymer-assisted nanoparticles migration to calculate an oil-recovery factor. Then, a sensitivity analysis is provided to consider the significant influence of formation rheological characteristics as type curves. To achieve this, we concentrated on the driving mathematical equations for the recovery factor and compare each parameter significantly to nurture the differences explicitly. Consequently, due to the results of this extensive study, it is evident that a higher value of mobility ratio, higher polymer concentration and higher formation-damage coefficient leads to a higher recovery factor. The reason for this is that the external filter cake is being made in this period and the subsequent injection of polymer solution administered a higher sweep efficiency and higher recovery factor.

Damage Evaluation of the Paving around Manholes under Vehicle Dynamic Load

It is very important for pavement engineers to know which factors are the main reasons for the damage of the paving around manholes. Based on the investigation on the damage of paving around manholes, a vibration model with multidegree of freedom for the vehicle-manhole cover was established and analyzed. After that, the Matlab software was used to obtain the variation law of impact load over time, and the 95% fourth power of the aggregate force was used as the index to evaluate the pavement damage. Finally, many influencing factors on pavement damage were analyzed by the method of grey correlation entropy. The results indicated that the impact load reached the maximum for the first time when the vehicle reached the top of the manhole cover, which was 1.29 times that of the static load, and the pavement damage coefficient was 2.12 times that of the static load. The influencing factors had different degrees of influence on the pavement damage; from large to small, they were change of road longitudinal slope > driving speed > damping of tire > stiffness of tire > height difference from the pavement damage > height difference from the manhole settlement > stiffness of the manhole cover.