Investigation of protein hydrolyzates ( PHs ) for green mitigation of hydrate blockage in deep‐sea oil and gas pipelines

Abstract

To address the severe environmental pollution caused by conventional chemical hydrate inhibitors in deep‐sea oil and gas pipelines, this study developed a biodegradable green kinetic hydrate inhibitor (KHI) based on silk protein hydrolyzates (PHs). Fourier transform infrared spectroscopy and ¹ H nuclear magnetic resonance were first employed to systematically characterize the amphiphilic oligopeptide structure of PHs, confirming the presence of abundant hydrophilic amide groups and hydrophobic alkyl side chains. The inhibitory performance of PHs against structure II (sII) gas hydrates and their synergistic effect with monoethylene glycol (MEG) were evaluated in a high‐pressure mechanically stirred reactor (1000 rpm) simulating pipeline high‐shear conditions. Results showed that PHs prolonged hydrate induction time in a concentration‐dependent manner: 2.0 wt.% PHs achieved an induction time of 4.85 h, which was 3.45 h longer than deionized water (1.4 h) and comparable to or slightly better than the commercial inhibitor polyvinylpyrrolidone (PVP, 4.6 h) at the same concentration. Notably, PHs exhibited excellent solubility in MEG, and the 2.0 wt.% PHs + 2.0 wt.% MEG composite system achieved a synergistic induction time of 5.55 h, reducing the total inhibitor dosage by 90% compared with single MEG. Additionally, PHs significantly reduced gas conversion efficiency at high concentrations. This study reveals that the amphiphilic oligopeptide structure is the key to PHs' inhibitory activity, providing a promising eco‐friendly alternative for hydrate blockage control in deep‐sea pipelines.