Non-ionic surfactant loaded on gel capsules to protect downhole tubes from produced water in acidizing oil wells

Abstract

AbstractGel capsules of calcium alginate as a matrix stuffed with a non-ionic surfactant, namely 2-(2-(3,4-bis(2-methoxyethoxy)tetrahydrofuran-2-yl)-2-(2-methoxyethoxy)ethoxy)ethyl stearate, Tween-60, as an inhibitor was prepared by a piercing-solidifying method for corrosion protection of carbon steel tubes from produced water in acidizing oil wells. The Fourier transform infrared and thermal gravimetric analysis techniques were used to study the properties of the capsules. The release of the inhibitor from the solid capsules to the corrosive acidizing produced water was studied gradually using ultraviolet-visible spectroscopy. A heavy additive was used to promote the sinking of the capsules in the oil well downhole tubes. The inhibitive effect of the released inhibitor on carbon steel in the corrosive produced water in acidizing oil wells was investigated using weight loss measurement, potentiodynamic polarization, electrochemical impedance spectroscopy, and morphologically by scanning electron microscopy. It was found that the inhibition efficiency increases with the increase of inhibitor release. The increase in temperature leads to partial desorption of inhibitor molecules at the metal surface, which causes increase in the corrosion rate. The positive sign of the activation enthalpy (ΔHa) reflects the endothermic nature of the carbon steel dissolution process.