Linear Inferential Modeling: Theoretical Perspectives, Extensions, and Comparative Analysis

Inferential models are widely used in the chemical industry to infer key process variables, which are challenging or expensive to measure, from other more easily measured variables. The aim of this paper is three-fold: to present a theoretical review of some of the well known linear inferential modeling techniques, to enhance the predictive ability of the regularized canonical correlation analysis (RCCA) method, and finally to compare the performances of these techniques and highlight some of the practical issues that can affect their predictive abilities. The inferential modeling techniques considered in this study include full rank modeling techniques, such as ordinary least square (OLS) regression and ridge regression (RR), and latent variable regression (LVR) techniques, such as principal component regression (PCR), partial least squares (PLS) regression, and regularized canonical correlation analysis (RCCA). The theoretical analysis shows that the loading vectors used in LVR modeling can be computed by solving eigenvalue problems. Also, for the RCCA method, we show that by optimizing the regularization parameter, an improvement in prediction accuracy can be achieved over other modeling techniques. To illustrate the performances of all inferential modeling techniques, a comparative analysis was performed through two simulated examples, one using synthetic data and the other using simulated distillation column data. All techniques are optimized and compared by computing the cross validation mean square error using unseen testing data. The results of this comparative analysis show that scaling the data helps improve the performances of all modeling techniques, and that the LVR techniques outperform the full rank ones. One reason for this advantage is that the LVR techniques improve the conditioning of the model by discarding the latent variables (or principal components) with small eigenvalues, which also reduce the effect of the noise on the model prediction. The results also show that PCR and PLS have comparable performances, and that RCCA can provide an advantage by optimizing its regularization parameter.

Superpositions of Laguerre-Gaussian Beams in Strongly Nonlocal Left-handed Materials

We present beam solutions of the strongly nonlocal nonlinear Schrodinger equation in left-handed materials(LHMs). Different Laguerre-Gaussian (LG) necklace beams, such as symmetric and asymmetric single layer andmultilayer necklace beams are created by the superposition of two single beams with different topological charges. Suchsuperpositions are then propagated through LHMs, displaying linear diffraction. It is found that the superposition oftwo LG_(nm) beams with opposite topological charges does not show rotational behavior and that there exists rotation forother topological charge combinations. Our theory predicts that the accessible solitons cannot exist in LHMs,

Alternative and Potential Uses for the Sulfur Byproducts Produced from Oil and Gas Fields

Along with oil and gas operations, huge amounts of sulfur byproducts are produced. For example, in the State of Qatar which has the third largest proven reserves of natural gas, an incredible amount of sulfur is produced as byproduct from its natural gas processing facilities. The amount of produced sulfur surpasses by far the amount that can be utilized currently in the country. Hydrogen sulfide (H2S) existing in natural gas extracted from Qatar’s North Field is converted to elemental sulfur using the conventional Claus process. Managing byproduct sulfur from natural gas processing is a key aspect of economic development and environmental protection in many countries with oil and gas facilities. Therefore, new markets must be found to utilize sulfur to avoid disposal crises. Sulfur byproduct from natural gas can be utilized for various applications. This paper discusses alternative potential uses for sulfur in addition to the current practices of sulfur utilization. Some of these alternative applications of sulfur byproducts include the potential usage for medicinal uses, road construction, batteries, hydrogen production, structural additives, solar energy, waste treatment, arsenite removal, and production of maize.

Importance of Water Chemistry in Oil and Gas Operations—Properties and Composition

In the oil and gas industry, water is essential element since it exists in most of the stages, starting from drilling operations, then production processes including injecting in the reservoir to maintain the pressure, and finally disposing the produced water from the reservoir. Therefore, it is very important to understand the water in the petroleum industry with its different types and study its effects on the reservoirs as well as the downhole and surface equipment. Most of the studies and literature reviews focused on the oil and gas properties. In fact, understanding the properties of the water is as important as the oil and gas properties. Water is always present in the oil and gas fields during production, injection or disposal. Therefore, it has a direct impact on the productivity and overall efficiency of the field and the entire development project. This paper is going to illustrate and focus on several objectives. First, it elaborates the importance of the water in the oil and gas fields. Then, it includes a comprehensive overview of different types of water in the petroleum industry including a summary about of their properties. The main two types that the paper focuses on are the produced water and the injected water. It clarifies the effects of both of them on the reservoir, well completions and facilities. After that, the paper touches bases on the common problems and issues caused by water along with a brief summary of steps needed by the operators to follow in order to solve them. In addition to that, the common monitoring procedures and tests that are usually followed to observe the quality of the water are going to be presented. Finally, couples of solutions used by operators are reviewed to solve the problem of excessive water production after the water breakthrough in the field.

Product Analysis of Supercritical Fischer-Tropsch Synthesis: Utilizing a Unique On-Line and Off-Line Gas Chromatographs Setup in a Bench-Scale Reactor Unit

The utilization of supercritical fluids (SCF) in the Fischer-Tropsch Synthesis (FTS) further complicates the hydrocarbon products identification and analysis process due to the dilution of hydrocarbon peaks by the predominant solvent peak. Therefore, in this project, a custom-made Gas Chromatography (GC) analysis system was designed and implemented to identify and quantify SCF-FTS products. The FTS products were identified using two different methods. The first was through retention time matching by injecting standard solutions, and the second was through the use of the GC/MS system. The quantification of CO and CH4 was achieved by using external standards, where the CO conversion was calculated by relating the peak area of CO to the peak area of an internal standard (argon) while the CH4 selectivity was calculated by relating the peak area of CH4 to that of CO. After setting and calibrating the GC system, two reaction conditions (gas phase: 240°C, 20 bar syngas with 2:1 H2:CO molar feed ratio and for the supercritical fluids FTS (SCF-FTS): 240°C, 65 bar with 20 bar syngas partial pressure and 2:1 H2:CO molar feed ratio) were used to compare the different FTS reaction media. The comparison between the gas phase FTS and the SCF-FTS showed the following: carbon monoxide conversion was improved by 14% in the SCF-FTS, while the hydrocarbon product profile SCF-FTS showed 78% reduction in light hydrocarbons (C1 - C4) products, 35% increase in middle distillates (C11 - C22) products compared to gas phase FTS. These improvements have resulted in higher chain growth probability for the SCF-FTS (α = 0.85) compared to the gas phase FTS (α = 0.76). These results are generally in agreement with previously reported enhancement in the SCF-FTS[1].

Water Chemistry in Oil and Gas Operations: Scales Properties and Composition

Oil and gas operations depend heavily on water in many different aspects. Water is present wherever there is hydrocarbon production. It is produced along with the hydrocarbons and helps in mobilizing them. It is also injected into the reservoirs to aid in mobilizing the hydrocarbons, maintain the pressure and increase the recovery of the development project. With water presence, some serious problems occur such as scaling. Scaling is a well-known problematic precipitation caused mainly due to mixing of two incompatible fluids, changes in temperature and pressure conditions and disturbance to thermodynamics and kinetics of reservoir fluids. They can be found at any point of the operations starting down at the formation up to the surface tanks. Scales are directly responsible for compromising the economics and safety of development projects. This review paper is going to include a recap of the importance of water in the oil and gas industry, then review the different types of scales as well as their properties including carbonate and sulfate scales. After that, famous scales from each type is going to be reviewed as well as their properties and precipitation conditions such as Calcium Carbonate CaCO3, Calcium Sulfate CaSO4, Barium Sulfate BaSO4 and Strontium Sulfate SrSO4. Moreover, common practices and precautions steps in the industry are going to be reviewed as well. Finally, the paper presents the common practices used by the operators for scale removal.

Direct Mass Spectroscopy Analysis and Comparison of Middle Eastern and Texas Crude Oils

We analyzed two types of crude oil samples: Middle Eastern crude oil and Texas crude oil by using a residual gas analyzer (RGA) based on the linear quadrupole principle. This portable mass analyzer is capable of measuring hydrocarbons with masses of up to 300 atomic mass units (amu) as well as low mass targets, such as methane and carbon dioxide at ppm level concentrations. The generated mass spectra revealed differences in the composition and signal intensity of hydrocarbons of Middle Eastern and Texas crude oil samples. Even if RGA 300 is manufactured to be served as a detailed gas analysis of vacuum systems, we have shown that it is sensitively capable of detection of hydrocarbons and it enables one to qualitative and quantitative analysis of the composition of the crude oils.

A Lumped-Parameter Model for Nonlinear Waves in Graphene

A lumped-parameter nonlinear spring-mass model which takes into account the third-order elastic stiffness constant is considered for modeling the free and forced axial vibrations of a graphene sheet with one fixed end and one free end with a mass attached. It is demonstrated through this simple model that, in free vibration, within certain initial energy level and depending upon its length and the nonlinear elastic constants, that there exist bounded periodic solutions which are non-sinusoidal, and that for each fixed energy level, there is a bifurcation point depending upon material constants, beyond which the periodic solutions disappear. The amplitude, frequency, and the corresponding wave solutions for both free and forced harmonic vibrations are calculated analytically and numerically. Energy sweep is also performed for resonance applications.

Bifurcation behaviors of an Euler discretized inertial delayed neuron model

This paper presents an Euler discretized inertial delayed neuron model, and its bifurcation dynamical behaviors are discussed. By using the associated characteristic model, center manifold theorem and the normal form method, it is shown that the model not only undergoes codimension one(flip, Neimark-Sacker) bifurcation, but also undergoes cusp and resonance bifurcation(1:1 and 1:2) of codimension two. Further, it is found that the parity of delay has some effect on bifurcation behaviors. Finally, some numerical simulations are given to support the analytic results and explore complex dynamics, such as periodic orbits near homoclinic orbits, quasiperiodic orbits, and chaotic orbits.