Thermodynamic and kinetic effect of biodegradable polymers on carbondioxide hydrates

Polysaccharides Are Effective Inhibitors of Natural Gas Hydrate Formation

This review covers the types and applications of chemical inhibitors of gas hydrate formation in the oil and gas industry. The main directions of the development of new types of highly effective and environmentally safe “green” kinetic hydrate inhibitors (KHIs) based on biopolymers are analyzed. The structure, physicochemical properties, efficiency of gas hydrate formation inhibition, and commercial prospects of polysaccharides in preventing and controlling the formation of gas hydrates are considered. The criteria for their selection, current experimental data, and the mechanism of inhibition are presented. Recent research in the development of cost-effective, efficient, and biodegradable KHIs for industrial applications in the oil and gas industry is also presented.

Inhibitory influence of amino acids on the formation kinetics of methane hydrates in oil-water and oil-brine systems

This experimental study evaluates the inhibition performance of kinetic hydrates inhibitors (KHIs) of three amino acids, namely: glycine, proline, and alanine. It includes the performance comparison with the conventional inhibitor i.e., polyvinyl pyrrolidine (PVP) on methane (CH₄) hydrate in oil systems in two different systems, i.e., deionized and brine water systems. The experiments were conducted in a high-pressure hydrate reactor replicating subsea pipeline conditions, i.e., the temperature of 274 K, pressure 8 MPa, and concentration of 1 wt%, by applying the isochoric cooling technique. The formation kinetics results suggest that all the studied amino acids effectively worked as kinetic inhibitors by potentially delaying CH₄ hydrate formations due to their steric hindrance abilities. The interesting phenomenon was observed that the different studied amino acids behave differently in the brine-oil and deionized water-oil systems due to their side chain interaction. In a deionized water-oil system, glycine gives the highest inhibition performance by reducing the hydrate formation risk. On the contrary, in the brine-oil system, proline showed a significant inhibition effect. It should be noted that both glycine and proline were giving almost similar inhibition performance compared to the conventional hydrate inhibitor PVP, however glycine and proline significantly reduced CH₄ consumption into hydrate due to their high surface active under CH₄ conditions, which strengths the surface tension of the liquid/CH4 interface. Furthermore, according to the findings, it shows that increased side alkyl chain lengths of amino acids increase the efficacy of their kinetic hydration inhibition performance due to better surface adsorption abilities. The amino acids' ability to suppress growth is also linked strongly with hydrophobicity and alkyl side chain length. The findings of this study contribute significantly to current efforts to limit gas hydrate formation in offshore pipelines, particularly in oil-dominant pipelines.

A road map on synthetic strategies and applications of biodegradable polymers

Biodegradable polymers have emerged as fascinating materials due to their non-toxicity, environmentally benign nature and good mechanical strength. The toxic effects of non-biodegradable plastics paved way for the development of sustainable and biodegradable polymers. The engineering of biodegradable polymers employing various strategies like radical ring opening polymerization, enzymatic ring opening polymerization, anionic ring opening polymerization, photo-initiated radical polymerization, chemoenzymatic method, enzymatic polymerization, ring opening polymerization and coordinative ring opening polymerization have been discussed in this review. The application of biodegradable polymeric nanoparticles in the biomedical field and cosmetic industry is considered to be an emerging field of interest. However, this review mainly highlights the applications of selected biodegradable polymers like polylactic acid, poly(ε-caprolactone), polyethylene glycol, polyhydroxyalkanoates, poly(lactide-co-glycolide) and polytrimethyl carbonate in various fields like agriculture, biomedical, biosensing, food packaging, automobiles, wastewater treatment, textile and hygiene, cosmetics and electronic devices.

Kinetic Hydrate Inhibition of Natural Gels in Complex Sediment Environments

Natural gels are emerging as a hotspot of global research for their greenness, environmental-friendliness, and good hydrate inhibition performance. However, previous studies mostly performed experiments for simple pure water systems and the inhibition mechanism in the sediment environment remains unclear. Given this, the inhibition performance of xanthan gum and pectin on hydrate nucleation and growth in sediment environments was evaluated via hydrate formation inhibition tests, and the inhibition internal mechanisms were revealed via a comprehensive analysis integrating various methods. Furthermore, the influences of natural gels on sediment dispersion stability and low-temperature fluid rheology were investigated. Research showed that the sediments of gas hydrate reservoirs in the South China Sea are mainly composed of micro-nano quartz and clay minerals. Xanthan gum and pectin can effectively inhibit the hydrate formation via the joint effects of the binding, disturbing, and interlayer mass transfer suppression processes. Sediments promote hydrate nucleation and yet inhibit hydrate growth. The interaction of sediments with active groups of natural gels weakens the abilities of gels to inhibit hydrate nucleation and reduce hydrate formation. Nonetheless, sediments help gels to slow down hydrate formation. Our comprehensive analysis pointed out that pectin with a concentration of 0.5 wt% can effectively inhibit the hydrate nucleation and growth while improving the dispersion stability and low-temperature rheology of sediment-containing fluids.

Gas Hydrate in Oil-Dominant Systems: A Review

Gas hydrate risks minimization in deepsea hydrocarbon flowlines, especially in high water to oil ratios, and is critical for the oil and gas flow assurance industry. Although there are several reviews on gas hydrate mitigation in gas-dominated systems, limited reviews have been dedicated to the understanding and mechanism of hydrate formation and mitigation in oil-dominated systems. Hence, this review article discusses and summarizes the prior studies on the hydrate formation behavior and mitigation in oil-dominated multiphase systems. The factors (such as oil volume or water cut, bubble point, and hydrate formers) that affect hydrate formation in oil systems are also discussed in detail. Furthermore, insight into the hydrate mitigation and mechanism in oil systems is also presented in this review. Also, a detailed table on the various studied hydrate tests in oil systems, including the experimental methods, inhibitor type, conventions, and testing conditions, is provided in this work. The findings presented in this work are relevant for developing the best solution to manage hydrate formation in oil-dominated systems for the oil and gas industry.

Gas hydrates in sustainable chemistry

This review includes the current state of the art understanding and advances in technical developments about various fields of gas hydrates, which are combined with expert perspectives and analyses.