Special Issue on “Processing and Conversion of Oil and Gas: Modeling, Control, Simulation and Optimization”

1. Introduction

Petroleum is considered the black gold of the earth, but this treasure cannot be utilized without the usage of innovative and advanced technologies for its recovery and conversion. To the best of our knowledge, the crude oil extracted from wells is not in a pure form and is mainly composed of oil, gas, and water. Therefore, an oil processing plant to separate it from other fluids and impurities in an environmentally friendly manner must be employed. The residual contaminants can be highly problematic during oil transportation or handling, hence novel optimized methods are essential to improve oil processing. Nevertheless, natural gas is nowadays considered the main bond between existing fossil fuels and future resources. Natural gas is primarily composed of methane and may contain variable amounts of other higher alkanes. Besides, natural gas may have low amounts of chemicals such as hydrogen sulfide, carbon dioxide, nitrogen, and helium. Natural gas processing is designed to refine the raw gas by eliminating impurities, thus producing dry natural gas compliant to the pipeline gas quality specifications. Natural gas processing plants can remove several types of contaminants such as water, hydrogen sulfide, carbon dioxide, mercury, and other hydrocarbons. The application and enhancement of different operations including sweetening and dehydration make the raw natural gas ready for usage or conversion. The conversion of oil and gas is mainly conducted through refineries and chemical processing plants. Consequently, oil and gas refining leads through the combination of several physical, chemical, and thermodynamic processes to the formation of many valuable products including fuels, materials, chemicals, and/or heat and power. To note that even the polluting emissions of the refineries that can be formed at any stage of the oil or gas conversion process have a certain economic value and can be further processed or sold. Moreover, impurities removed during the oil and gas processing step are not always considered as waste, but rather potential by-products of that industry. The goal of refineries is generally to successfully implement an environmentally friendly process that provides an economic and environmental benefit.

This Special Issue on “Processing and Conversion of Oil and Gas: Modeling, Control, Simulation and Optimization” (https://www.mdpi.com/journal/processes/special_issues/oil_conversion, accessed on 21 January 2023) of Processes collects the recent work of leading researchers on modeling, control, simulation, and optimization of new and revamped petrochemical processes using proven software. Therefore, it offers novel illustrative examples, prospective applications, and solutions to improve these processes.

2. General Methods

Some papers employ general and practical methods of chemical process engineering through a holistic approach. The article by Al-Rabiah et al. [1] proposed the non-random two-liquid (NRTL) model in Aspen Plus to determine the vapor-liquid-liquid equilibrium by simulating the esterification reaction. This method was applied to design and model a membrane reactor-based process for an annual plant capacity of 92,500 metric tons of butyl acetate. Moreover, the UNIFAC method was applied as a thermodynamic model to simulate the pill particle discharge process test [2] and to develop a novel process for the production of methyl isobutyl ketone (MIBK) from hydrogen and acetone [3]. Lui et al. [2] studied the discharge process and its mechanism using the discrete element method (DEM) with self-developed annular corrosion pill particles and the discharge device to optimize the oil and gas field wellbore casing annular corrosion process. To simulate the pill particle discharge process simulation test, the EDEM software Hertz–Mindlin contact mechanics model was also employed. Additionally, Al Rabiah et al. [3] applied the UNIFAC method using CHEMCAD v.7.1 software to develop a process flow diagram for the production of methyl isobutyl ketone (MIBK) based on a production of 30,000 metric tons of MIBK per annum with 30 days assigned for maintenance. This study proposed a Generalized Additive Model based on 21 recognized dimensionless numbers to predict the pressure drop of gas–liquid two-phase flow based on 5011 records in the Tulsa Unified Fluid Flow Project (TUFFP) database. The process was heat integrated, resulting in a 26% and a 19.5% reduction in the heating and cooling utilities, respectively, leading to a 12.6% reduction in the total energy demand.

Cepeda-Vega et al. [4] proposed a Generalized Additive Model (GAM) to calculate the pressure drop in a gas–liquid two-phase flow at horizontal, vertical, and inclined pipes based on 21 different dimensionless numbers. The GAM non-parametric method achieved a high prediction capacity and permitted a good degree of interpretability describing each predictor’s marginal effects, unlike in other machine Learning methods. A mean relative error of at most 19.98% for stratified flow and 12.93% for all the data points in a randomly sampled test set was obtained. Guo et al. [5] develop a mathematical model for the stability of a viscous liquid jet in a coaxial twisting compressible airflow. This model considers several factors such as the twist and compressibility of the surrounding airflow, the viscosity of the liquid jet, and the cavitation bubbles within the liquid jet, to be able to analyze the effects of aerodynamics caused by the gas–liquid velocity difference on the jet stability.

3. Processes Optimization

Several articles study certain processes to promote specialized models to improve their performance by examining and modifying the operating parameters. Therefore, the related studies will be described in the following. Oil quality improvement is investigated. Complex reaction extraction methods have been usually used to reduce nitrogen-containing compounds (NCs) from a coal tar fraction. Su Jin Kim [6] reduce NCs contained in wash oil by applying a batch equilibrium extraction. Wash oil and an aqueous solution of formamide is employed as the raw material and the solvent, respectively. The formamide extraction method is efficient with results to reduce the NCs of wash oil, and it is expected to be an alternative to the complex reaction extraction methods that have been applied. Al Rabiah et al. [7] present a promising novel industrial scheme for the synthesis of Dimethyl carbonate (DMC) via the oxidative carbonylation of vaporized methanol with dimethyl oxalate (DMO) as a byproduct. DMC and DMO are produced on a copper chloride catalyst in an isothermal FBR. A MeOH conversion rate of 81.86% and a DMC selectivity of 83.47% are reached. DMO purification is achieved through conventional distillation at 99.9 mol%. The pressure-swing technique is applied to separate the DMC-H₂O azeotropic mixture and a 99.78 mol% pure DMC product is obtained.

Encinar et al. [8] evaluate the usage of rapeseed oil as a starting point for a biorefinery. Biolubricant production through double transesterification is studied by modeling and designing the kinetics of the second transesterification and the reactor. A SAE 10W30 biolubricant suitable for Diesel engines, is obtained. A batch reactor, with a pseudo-first reaction order and a reactor volume of 9.66 m³ is selected to produce this biolubricant in Spain.

Optimizing cleaning performance of reactors seems to be as important as process optimization. Therefore, Zhang et al. [9] studied the structure of self-excited oscillation pulsed jet nozzles (SOPJNs) to optimize cleaning and energy efficacies. The jet performance of a SOPJN was investigated and modeled based on computational fluid dynamics considering a large eddy simulation and homogeneous cavitation. The investigation includes several parameters such as inlet diameter, cavity diameter, cavity length, wall reflection angle, and inlet pressure on the jet’s peak velocity, oscillation frequency, and cavitation number, cavity length, and wall reflection angle produced a jet with a high peak velocity and strong cavitation.

4. Processes Safety

Moreover, one article deals with pipelines risk. In fact, the shale gas collection and transportation pipeline causes significant risk due to certain geographical conditions and climatic conditions. Chen et al. [10] proposed a methodology that considers several failure scenarios including third-party damage, corrosion, design and construction defects, mis-operation, and natural disasters. Since the used method employs subjective and objective data from different sources, an improved analytic hierarchy process was applied to process data and minimize subjectivity.

5. Economic Aspect

Finally, Ahmed et al. [11] analyzed the unexpected fuel price changes for the first time in Pakistan. The study aims to understand whether the fuel price driver is demand driven or whether it is exuberant consumer behavior that prevails and contributes to a sudden spike in the fuel price series. The empirical analysis is performed using a novel state-of-the-art generalized sup ADF (GSADF) approach on six commonly used fuel price series, such as LDO (light diesel oil), HSD (high-speed diesel), petrol, natural gas, kerosene, and MS (motor spirit).

6. Conclusions

To conclude, a broad variety of papers were presented. Many studies deal with general methods applicable to certain processes to improve the methods of process engineering. Other proposed studies are dedicated to improving and optimizing processes performance by examining and modifying the operating parameters, and improving the cleaning performance of reactors. One article analyzes safety risk of pipelines in China by studying several risk factors. Finally, the economic aspect was treated to understand the sudden fluctuation in fuel price in Pakistan.