Evaluation of a New Liquid Breaker for Polymer Based In-Situ Gelled Acids

A solid breaker is used to reduce the viscosity of the gel at pH range of 4-5 for in-situ gelled acids with Zr4 cross-linkers utilize. However, the literature survey confirmed that solid breakers caused a premature reduction in the fluid viscosity resulting in a less than desirable productivity. Therefore, an effective liquid breaker that is based on tetrafluoroboric acid was developed. This study was conducted to evaluate this new breaker system under the following conditions: breaker concentration (0-200 ppm), and acid injection rate (0.5-10 cm3/min). The major findings from the performed viscosity measurements and single coreflood experiments can be summarized as follows: the crosslinking of the polymer occurred at a pH value of 1.8. At a pH of less than 2, doubling the breaker concentration did not affect the viscosity of the acid. However, at a pH of greater than 2, the viscosity of acid was reduced by 30 percent. At a breaker concentration of 0 ppm, the appearance of Zr in the core effluent sample was delayed by 0.25 PV compared to the reaction product, while at 100 ppm, Zr was delayed by 0.75 PV. At 200 ppm breaker, no Zr ions were detected in the effluent samples. Additionally, it was observed that as the breaker concentration increased, more Zr remained inside the core, as ZrF4, which is water-insoluble. Increasing the breaker concentration from 100 to 200 ppm reduced the final normalized pressure drop by 50 percent at injection rate of 2.5 cm3/min. Permeability reduction due to gel was reduced by increasing the acid injection rate

Corneal biomechanical properties in thyroid eye disease

AbstractThe purpose of this study is to investigate the effect of thyroid eye disease (TED) on the measurement of corneal biomechanical properties and the relationship between these parameters and disease manifestations. A total of 54 eyes of 27 individuals with TED and 52 eyes of 30 healthy control participants were enrolled. Thyroid ophthalmopathy activity was defined using the VISA (vision, inflammation, strabismus, and appearance/exposure) classification for TED. The intraocular pressure (IOP) measurement with Goldmann applanation tonometer (GAT), axial length (AL), keratometry, and central corneal thickness (CCT) measurements were taken from each patient. Corneal biomechanical properties, including corneal hysteresis (CH) and corneal resistance factor (CRF) and noncontact IOP measurements, Goldmann-correlated IOP (IOPg) and corneal-compensated IOP (IOPcc) were measured with the Ocular Response Analyzer (ORA) using the standard technique. Parameters such as best corrected visual acuity, axial length, central corneal thickness, and corneal curvature were not statistically significant between the two groups (p > 0.05). IOP measured with GAT was higher in participants with TED (p < 0.001). The CH of TED patients was significantly lower than that of the control group. There was no significant difference in the corneal resistance factor between groups. However, IOPg and IOPcc were significantly higher in TED patients. CH and VISA grading of TED patients showed a negative correlation (p = 0.007). In conclusion, TED affects the corneal biomechanical properties by decreasing CH. IOP with GAT and IOPg is found to be increased in these patients. As the severity of TED increases, CH decreases in these patients

Impact of crossover and decision variable coding forms on the performance of genetic algorithm optimization a case study on pump and treat remediation design

Genetic algorithms (GAs) are robust methods applied especially for complex optimization problems. However, selection of some GA parameters may play a vital role on the efficacy of the method. This study investigates the impacts of crossover type and form of coding on the performance of optimization by genetic algorithms. For this purpose, two pump-and-treat remediation design problems were considered with different levels of complexity determined by the number of decision variables. The efficiencies of GA for these problems were compared for two different crossover operators (two-point and uniform) and decision variable coding forms (binary and gray). First problem seeks the best pump and treat system design by optimizing the location of the pumping wells and pumping rate at active wells while minimizing the system cost. The second problem is simpler such that it aims to minimize the remediation time while achieving the cleanup goals for a fixed remediation policy. Results show that uniform crossover operator outperforms two-point crossover and gray coding is superior to binary coding for the complex problem with higher number of decision variables. On the other hand, when a simpler problem was solved, the efficiency of GA was independent of the crossover and coding types

Evaluation of the genetic algorithm parameters on the optimization performance: a case study on pump-and-treat remediation design

Optimization, Genetic algorithms, Uniform crossover, Two-point crossover, Binary coding, Gray coding, 90B90, 90C27,

Effect of heterogeneity correlation scale on pump and treat remediation design

Pump-and-treat (P&T) remediation is a commonly used technology for the cleanup of contaminated groundwater. The long remediation time, high capital and operational costs are the most important problems associated with these systems. One of the determinants that affect the remediation design and its outcome is the spatial heterogeneity in the hydraulic conductivity (K) field. In this study, the effect of correlation scale (length) (lambda) of the heterogeneous K-field on P&T remediation design and costs was investigated. For this purpose, several synthetic K-fields of similar means and variances (sigma 2) but different lambdas were generated using a random field generator. Simulation-optimization approach was used in order to conduct the study. For this purpose, BIO2D-KE linked with a genetic algorithm library was used. Runs were conducted in order to determine the best pumping policies and costs for the heterogeneous fields. According to the initial results, lambda of the spatial variation in K impacted P&T remediation design and costs. The number of wells, pumping rates, and costs of remediation varied for different lambdas. This outcome was more pronounced for higher sigma 2 of the spatially variable K-field. © 2007 ASCE

Impact of time dependent sorption sites on optimal pump-and-treat remediation design

Kirlenmiş sahalarda kirleticilerin toprağa tutunmuş halde bulunabilmesi ve suya çözünmenin yavaş olması, pompaj ve arıtım yöntemiyle temizleme tasarımını ve maliyetlerini etkileyebilir. Bu çalışmada, 1-f faktörünün optimum temizleme tasarımı ve maliyeti üzerindeki etkileri incelenmiştir. f, zamana bağlı sorpsiyonu tanımlamak için sıklıkla kullanılan iki-siteli sorpsiyon modelinde yer alır ve 1-f zamana bağlı sorpsiyon sitelerinin oranını gösterir. Çalışmada benzetim-eniyileme yöntemi kullanılarak, 5 farklı f değeri (0,00, 0,25, 0,50, 0,75, ve 1,00) için farklı hidrolik iletkenlik (K) heterojenliğine sahip hipotetik bir akiferin temizlenmesi için optimum tasarımlar elde edilmiştir. Çalışmada elde edilen bulgular, küçük f değerlerinin temizleme için gerekli kuyu sayılarını ve/veya toplam pompaj miktarlarını arttırdığını göstermiştir. Buna paralel olarak toplam temizleme maliyetleri f değerleri düştükçe önemli ölçüde artmıştır. Bulgular, pompaj ve arıtım sistemi tasarımında yavaş sorpsiyonun doğru bir şekilde tanımlanmasının ve doğru f değerinin kullanılmasının gerekliliğini göstermiştir. Bu, temizleme sistemi tasarımını ve maliyet tahminlerini doğru yapabilmek için çok önemlidir.Presence of contaminants in sorbed phase and their slow desorption to aqueous phase in contaminated aquifers may impact pump-and-treat remediation design and cost. In this study, the impact of 1-f factor on optimum remediation design and cost is investigated. f is used in the two-site sorption model that is frequently used to account for time-dependent sorption and 1-f shows the fraction of time-dependent sorption sites. In the study, optimum remediation designs are obtained to cleanup a hypothetical aquifer that has different hydraulic conductivity (K) heterogeneity conditions using simulation-optimization method for 5 different f values (0.00, 0.25, 0.50, 0.75, ve 1.00). Results obtained in the study state that small f values increase the number of wells and/or total pumping rates required for cleanup. In parallel to these, remediation costs increase significantly as f values decrease. Results indicate the necessity of accurate determination of slow desorption and using the correct f value in the design of pump-and-treat system. This is very important for accurate realization of remediation design and cost predictions

Variation in time-to-compliance for pump-and-treat remediation of mass transfer-limited aquifers with hydraulic conductivity heterogeneity

In this study, the impact of correlation length (lambda) of hydraulic conductivity (K) heterogeneity on pump-and-treat (P&T) remediation period (time-to-compliance) for a mass transfer-limited aquifer is evaluated. Additionally, impacts of variance (sigma (2)), different distributions of high and low K zones and different initial contaminant masses are explored. Two different P&T policies including different number of wells pumping at different rates are employed for the investigation. Simulation-optimization approach in which a genetic algorithm (GA) is linked with a groundwater flow and contaminant transport model is used. Results show that K heterogeneity, in terms of lambda (ln K), sigma(2)(ln) (K) and respective locations of low and high K zones, significantly impacts the time-to-compliance. Contaminant presence at low K zones can increase the time required to clean up the aquifer. Lower variation is observed in time-to-compliance for the remediation design utilizing higher number of wells pumping at slower rates compared to the design with a single well pumping at a higher rate. Higher number of wells increases the robustness of P&T remediation system when aquifer is heterogeneous in K