Fig. 2—Images taken through the window in the rocking cell during experiments using an uncoated surface (left) and a surface with the omniphobic coating (right). Hydrates deposited on the uncoated surface but did not deposit on the omniphobic surface. CS=carbon steel. When certain thermodynamic conditions exist in oil- and gas-production flowlines, gas-hydrate plugs can form and greatly restrict flow. One potential strategy for hydrate management involves allowing hydrates to form but mitigating their ability to deposit on the flowline walls by deploying a low-adhesion, protective surface coating on the inside wall of the flowline. In this study, two coatings were produced and evaluated to determine their effect on hydrate adhesion onto carbon-steel surfaces. In order to test the adhesion of hydrates to the two low-surface-energy coatings, micromechanical-force (MMF) apparatuses were used at low and high pressures. MMF apparatuses have been used historically to investigate both hydrate/hydrate interparticle forces and hydrate/surface interactions. The primary mechanism of hydrate cohesion and adhesion has been determined to be capillary bridging. Many of the parameters in capillary bridge theory can be altered through the modification of the system (e.g., the addition of surfactants or other chemicals or modification of the hydrate or solid surface). Hydrate/surface interactions have been studied previously; however, the surfaces used in these previous adhesion studies were always either stainless-steel or mineral surfaces, such that surface degradation by corrosion was not taken into account. In addition to MMF studies measuring adhesion forces, experiments were performed in a rocking cell to observe more-macroscopic effects of the coatings on deposition. Rocking-cell tests give a simulated flow environment and may provide insight into how the coatings respond in the bulk, rather than single-particle measurements performed with an MMF apparatus. This article, written by Special Publications Editor Adam Wilson, contains highlights of paper , “Low-Adhesion Coatings as a Novel Gas-Hydrate-Mitigation Strategy,” by SPE, and Colorado School of Mines; and SPE, Oceanit Laboratories; and SPE, Colorado School of Mines, prepared for the 2017 Offshore Technology Conference, Houston, 1–4 May. The paper has not been peer reviewed. Copyright 2017 Offshore Technology Conference. Reproduced by permission. ... This article is reserved for SPE members and JPT subscribers. If you would like to continue reading, please , or
Houston scientists have developed improved coatings for the inside surface of oil and gas lines to reduce the likelihood of hydrates sticking to them and restricting the flow. The researchers from the Colorado School of Mines created a composite polymer coating that was designed to be applied to previously worn and corroded surfaces, and a second coating created with the addition of nonpolar nanomaterials. In tests, the coating showed good results in preventing hydrates sticking to the surfaces.