Abstract

As offshore deepwater oil production is reaching new high levels, producers and service companies are challenged with harsher conditions of temperature (> 177°C/350°F), shear (> 25Pa) and high-pressure systems (> 1000psi). Therefore, the demand for new technologies and production chemistries under these extreme conditions are on the rise. This paper discusses the development of high temperature stable, water soluble corrosion inhibitors for slightly sour deepwater systems. These corrosion inhibitors exhibit thermal stabilities at high temperatures for lengthy periods of time and are extremely effective for general and localized corrosion. This paper describes various laboratory corrosion testing techniques used to simulate field conditions and the results obtained from these testing are presented.

The chemical injection via umbilical plays a vital role in deepwater and ultra deepwater chemical applications. Therefore, the chemical cleanliness is extremely important in these harsher environments for umbilical applications. Exceptional measures are taken to ensure the corrosion inhibitor performance are not compromised due to these harsher conditions. Furthermore, the rigorous qualification process of qualifying chemicals for deepwater application are discussed1,2,3.

Introduction

With increasing world energy demands and total supply getting lowered, petroleum industry has been forced to drill deeper into much more hostile subsea environments. This created a large number of high-temperature and high-pressure oil and gas wells around the globe. Hence the demand for high temperature stable and umbilical deliverable corrosion inhibitors increased. The demand is even higher for high-temperature effective, environmentally acceptable corrosion inhibitors4,5,6.

Examples reported for high-temperature effective corrosion inhibitors are few in the literature. However, most of the publications are on oil soluble, filming corrosion inhibitors. Lindsay et al., studied amine, polyamines and amino alcohols as corrosion inhibitors at very high temperatures. These amines are added to neutralize the carbonic acid formed from residual CO2 and to provide a basic environment to prevent acid corrosion. However, at higher temperatures (above 177°C/350°F) most water-soluble corrosion inhibitors would decompose. The effectiveness of most chemicals reduces to less than 50% indicating possible polymerization or decomposition, which can be attributed to particulate formation or gunking inside the tubbing and flowlines. Therefore, it is important to use high-temperature effective and stable products for these conditions.

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