Implementing a Robust Methodology: Experimental Designs and Optimisation

Valuable condensate in gas condensate reservoirs which will drop out and is left in the reservoir at reservoir pressure lower than dew point pressure can be recovered via CO2 injection by the mechanism of condensate re-vaporization as a result of pressurization. At the same time, part of the injected CO₂ can be sequestered in the reservoir, allowing the methodology to be attractive.The objective of this study is to investigate the application of CO₂ sequestration and enhanced condensate recovery in gas condensate reservoir for different flood design parameters and strategies using compositional reservoir simulation model. It is to better quantify the potential of reservoir condition over a wide variety of parameters and strategies with the need to find optimum operational strategies with the aid of Experimental Design and Response Surface Methodology. The parameters and strategies studied include permeability, injection scheme (water alternating gas vs. continuous CO₂ injection), injection and production well type (vertical vs. horizontal), vertical to horizontal permeability ratio, injection rate, well spacing, and injection time. The amount of CO₂ stored and condensate recovery factor are considered as two responses.The results show that 1000-md permeability gas condensate reservoir with high kv/kh has potential to implement. Optimum strategies are provided by Experimental Design with less time and cost compared to full runs of simulation.

Capsaicin (CAP) is a pungent alkaloid of chili peppers that is obtained from chili peppers that has a variety of pharmacological activities and can be used in various areas, such as functional foods, nutritional supplements and medical nutrition. Capsaicin has important anticancer, antioxidant and anti-inflammatory properties that allow to be applied as treatment for several diseases. However, its lack of water solubility, as well as its poor oral bioavailability in biological systems, show limiting factors for its successful application. Recently, the formulation of capsaicin for food and pharmaceutical use is limited. Therefore, the present study emphasized on preparation of capsaicin-loaded chitosan nanoparticles (CAP-CSNPs) and design and optimization of the formulation using Box-Behnken experimental design (BBD) and response surface methodology (RSM). The capsaicin-loaded chitosan nanoparticles were prepared by o/w emulsification and ionotropic gelification. The optimized formulation of capsaicin-loaded chitosan nanoparticles had a chitosan concentration of 0.11 (%w/v), a Tween 80® concentration of 1.55 (%w/v) and a CAP concentration of 1 mg/mL and that it should be stored at 4°C. Box-Behnken experimental design and response surface methodology was found to be a powerful technique for design and optimization of the preparation of capsaicin-loaded chitosan nanoparticles using limited number of experimental runs. Our study demonstrated that capsaicin-loaded chitosan nanoparticles can be potentially utilized as dietary supplements, nutraceuticals and functional foods.

Endogenous microorganisms isolated from the marigold flower (Tagetes erecta) were studied to understand the events taking place during its ensilage. Studies of the cellulase enzymatic activity and the ensilage process were undertaken. In both studies, the use of approximate second-order models and multiple lineal regression, within the context of an experimental mixture design using the response surface methodology as optimization strategy, determined that the microorganisms Flavobacterium IIb, Acinetobacter anitratus, and Rhizopus nigricans are the most significant in marigold flower ensilage and exhibit high cellulase activity. A mixed culture comprised of 9.8% Flavobacterium IIb, 41% A. anitratus, and 49.2% R. nigricans used during ensilage resulted in an increased yield of total xanthophylls extracted of 24.94 g/kg of dry weight compared with 12.92 for the uninoculated control ensilage.

History matching is an inverse problem, in which an engineer calibrates key geological/fluid flow parameters via fitting simulator's output to the real reservoir production history. It has no unique solution, because of insufficient constraints. History match solutions are obtained by searching for minima of an objective function below a pre-selected threshold value. Experimental design and response surface methodologies provide an efficient approach to build objective functions (OF) for history matching. The search for minima can then be easily performed on the reconstructed OF as long as its accuracy is acceptable. In this paper, we first introduce a novel experimental design methodology for semi-automatically selecting the sampling points, which are used to improve the accuracy of reconstructed non-linear OF. This method is based on derivatives of reconstructed response surfaces. We propose an iterative procedure for history matching, applying this new design methodology. To obtain the global optima, the objective functions are initially constructed on the global parameter space. The objective function is iteratively improved until adequate accuracy is achieved. We locate sub-spaces in the vicinity of the optima regions using a clustering technique to improve the accuracy of the reconstructed OF in these sub-spaces. We test this novel methodology and history matching procedure with two waterflooded reservoir models. One model is the Imperial College fault model1. It contains a large bank of simulation runs. The other is a modified version of SPE92 benchmark problem. We demonstrate the efficiency of this newly developed history matching technique.

This work aims to removing anionic food dyes, Acid Red18 (E124) and Quinoline Yellow WS (E104), from their aqueous solutions. The Emulsion Liquid Membrane (ELM) technique was used. ELM consists of diluent (kerosene), nonionic surfactant (0.5 wt. % Triton X-45), Aliquat 336 as an extractant. Sulfuric acid (H2SO4) solution was used as an internal aqueous phase. The key parameters impacting the stability of liquid membrane and the efficiency of dye removal were investigated; Almost 98% of E124 at 50 mg/L are successfully extracted under optimum conditions. The extraction of a mixture of the two dyes at equal concentrations (25 mg/L) was conducted and their extraction showed more than 95% of efficiency. The experimental results of dye mixture (E124, E104) extraction were expressed by the following three quantities: The concentration of Triton X-45, the concentration of Aliquat 336, and the internal phase concentration of H2SO4, represented on three dimensional plots using the Box-Behnken design and the response surface methodology. For each of the parameters, the values of which were determined by experimental design, these results were subjected to empirical smoothing. The values, thus calculated, are consistent with the measurements.

Experimental design for estimating the power potential of the Wairakei geothermal field, New Zealand: A retrospective analysis

The determination of benzene, toluene, p-xylene, tetrachloroethene, chlorobenzene, and dibromomethane in water by headspace analysis combined with gas chromatography-mass spectrometry (HS-GC-MS) has been investigated. An optimization strategy for the analysis of the six volatile organic compounds (VOCs) is presented with the experimental design and response surface methodology aid. Thermostatting time, temperature, and salt quantity were optimized by using a central composite design, and quadratic models relating peak areas to the three factors were built. The mathematical models were tested on a number of simulated data set and had a coefficient of R2>0.98. The factor effects were visualized as three-dimensional response surfaces and contour plots. The optimal conditions were achieved in 36.8 min, at 90 degrees C, and with 6 g of NaCl. The method showed a good agreement between the experimental data and predictive values throughout the studied parameter space, and was suitable for optimization studies of the VOCs in water by the HS-GC-MS method.

The main focus of this study was to use an experimental design to and the response surface statistical technique to predict and optimize the dielectric properties of hydrated ethanol-sodium chloride blends. Several samples of these blends were prepared considering the following variables: hydrated ethyl alcohol concentration, sodium chloride concentration and temperature. The main dielectric properties of these blends, i.e., the dielectric constant, dielectric loss factor and dissipation factor, were measured in a calibrated device suitable for liquid or pasty substances. For this study, experimental tests were carried out according to a Central Composite Design (CCD). Response surface techniques were used to predict the magnitude of the effect of the input variables on the responses investigated, particularly on the dissipation factor. This factor represents the ability of the substance to convert electromagnetic energy into heat. Within the experimental range studied here, the values of the variables that optimized the response were as follows: sodium chloride concentration of 2.21%, hydrated ethanol concentration of 4.64% and temperature of 87 °C.

Optimization of nutrient medium containing agricultural wastes for xylanase production by Aspergillus niger B03 using optimal composite experimental design

SummaryHistory matching is an inverse problem in which an engineer calibrates key geological/fluid-flow parameters by fitting a simulator's output to the real reservoir production history. It has no unique solution because of insufficient constraints. History-match solutions are obtained by searching for minima of an objective function below a preselected threshold value. Experimental design and response surface methodologies provide an efficient approach to build proxies of objective functions (OF) for history matching. The search for minima can then be easily performed on the proxies of OF as long as its accuracy is acceptable.In this paper, we first introduce a novel experimental design methodology for semi-automatically selecting the sampling points, which are used to improve the accuracy of constructed proxies of the nonlinear OF. This method is based on derivatives of constructed proxies.We propose an iterative procedure for history matching, applying this new design methodology. To obtain the global optima, the proxies of an OF are initially constructed on the global parameter space. They are iteratively improved until adequate accuracy is achieved. We locate subspaces in the vicinity of the optima regions using a clustering technique to improve the accuracy of the reconstructed OF in these subspaces.We test this novel methodology and history-matching procedure with two waterflooded reservoir models. One model is the Imperial College fault model (Tavassoli et al. 2004). It contains a large bank of simulation runs. The other is a modified version of the SPE9 (Killough 1995) benchmark problem. We demonstrate the efficiency of this newly developed history-matching technique.

In the range of engine operating speed, a reasonable variable strategy based on variable valve timing and lift can be adopted to improve the engine intake flow, power, and torque. In this study, a 1D engine system model was established, and the accuracy of the simulation model was checked through the bench test results. The intake and exhaust pulsations at the high and low typical speeds were further discussed, and the low speed (4000 rpm) was determined as the boundary for the optimization of relevant parameters. Plackett-Burman (PB) experimental design and variance analysis were used to screen out the important valve timing parameters that affect the output torque of the engine. We further explored these significant variables and their correlation effects through the full factor experiment, and a response surface regression model based on response surface method (RSM) was established. Three-dimensional and contour map analysis was conducted for the four factors with interactive effects to study their interaction effects and optimization direction. The optimized combination level of parameters was evaluated, and the simulation results showed that the torque increased by 5.84%, which was completely matched with the prediction and was accurately located within the confidence and prediction intervals. Therefore, the optimization of engine valve timing parameters based on PB experimental design and RSM can effectively predict and improve engine performance..

Chemometric assessment and investigation of mechanism involved in photo-Fenton and TiO2 photocatalytic degradation of the artificial sweetener sucralose in aqueous media

Isomaltulose was obtained from sucrose solution by immobilized cells of Erwinia sp. D12 using a batch and a continuous process. Parameters for sucrose conversion into isomaltulose were evaluated using both experimental design and response surface methodology. Erwinia sp. D12 cells were immobilized in different alginates, and the influence of substrate flow rate and concentration parameters to produce isomaltulose from sucrose were observed. Response surface methodology demonstrated that packed bed columns containing cells immobilized in low-viscosity sodium alginate (250 cP) presented a mean isomaltulose conversion rate of 47%. In a continuous process, both sucrose substrate concentration and substrate flow rate parameters had a significant effect (p < 0.05) and influenced the conversion of sucrose into isomaltulose. Higher conversion rates of sucrose into isomaltulose, from 53-75% were obtained using 75 g of immobilized cells at a substrate flow rate of 0.6 mL/min.

In the present study, high throughput extraction of three highly polar opium alkaloids, namely morphine, oxymorphone, and methylmorphine (codeine), was investigated using electromembrane extraction. Each alkaloid migrated from 24 mL of the sample solution through a supported liquid membrane containing di-(2-ethylhexyl) phosphate as the anionic carrier, dissolved in 2-nitrophenyl octyl ether, and into 10 μL of the acidic aqueous acceptor solution present inside the fiber lumen. Experimental design and response surface methodology were used for optimization of fundamental parameters affecting the extraction efficiencies of alkaloids including extraction voltage, extraction time, and pH of the donor and acceptor phases. After the microextraction process, the extracts were analyzed by high-performance liquid chromatography with ultraviolet detection. Under optimal conditions, alkaloids were extracted from various samples with enrichment factors in the range of 114–308 and 37–176 in water and urine samples, respectively. The proposed technique provided good linearity with correlation coefficient values higher than 0.9886. Limits of detection were in the range of 0.5–2.0 and 10.0–50.0 μg L−1 in water and urine samples, respectively. Also, limits of quantification were found in the range of 2.0–5.0 and 25.0–125.0 μg L−1 in water and urine samples, respectively. The maximum intra- and inter-day precisions (n = 3) were less than 9.5% and 12.4%, respectively.

Adsorption heat pump optimization by experimental design and response surface methodology