Effect of THPS on Discharge Water Quality: A Lessons Learned Study

Abstract

Biocides typically have an adverse impact on overboard water. THPS (tetrakishydroxymethyl phosphonium sulfate), one of the most commonly used biocides offshore has a similar effect on produced water. The effect of THPS on seawater used for hydrotesting and bulk storage is seldom studied and rarely documented. The effect of temperature, pH, water depth, dissolved oxygen concentration and various ions in the system is important to note. Once a certain volume of water is treated with any chemical, it is now deemed to be chemically treated seawater which cannot be discharged unless verified using the NOEC (No Observable Effect Concentration) testing method.This experience will provide a detailed understanding of the discharge of chemically treated seawater as well as the interaction of THPS with potential ions in the matrix. Additionally, regular sampling and associated analyses will be presented that demonstrate the degradation and half-life of the THPS molecule in varying temperatures.Periodic sampling of the THPS chemical in the seawater has provided a detailed understanding of the half-life degradation of the chemical. The interaction of the chemical with the cations present in the system and subsequent aversion to the neutralization reaction with hydrogen peroxide has also been studied and presented.

Effect of external wall defect growth on internal wall corrosion of oil pipelines under mechano‐electrochemical interaction

“…Thus, because of a large fluctuation in the elevation of the pipeline, water and oxygen will accumulate in the relatively low elevation section. [16,17] Pipeline degradation caused by corrosion varies with time. [18] The current evaluation method commonly used in the pipeline industry is based on the analysis of historical in-line inspection (ILI) data to quantitatively predict the growth of corrosion defects.…”