The formation of corrosion inhibitor micelles in produced water can be used as an indicator of optimal dosage in a system. Prior to field use, tests are conducted in the laboratory on the relevant corrosion inhibitor, ideally in the presence of field hydrocarbon and other production chemicals. This ensures that the chemical and system are suitable and gives confidence that micelles will be detected, if present. During this pre-deployment testing, a corrosion inhibitor concentration series is created to determine the critical micelle concentration (CMC), i.e. the concentration at which micelles form for a given system. Other information is also provided, such as partitioning and potential influence of production chemicals on micelle formation.
Lab qualification testing of corrosion inhibitors require significant time, instrumentation, and skilled staff. Work has been conducted to determine if micelles can provide a higher throughput for compatibility testing so that more chemicals can be tested in the same timeframe, for the same cost; initial results are shown. The relationship between CMC and the field dose ultimately chosen is also considered. The usefulness of this approach, as a complementary qualification tool to those already used, is discussed in the context of being one that enables higher throughput testing and allows more chemicals to be screened for a more comprehensive and quicker process.
The prevention of internal corrosion remains a significant challenge during the production of oil and gas. The use of film forming corrosion inhibitors is an important and cost-effective means of protecting assets from corrosion. These chemicals operate by forming a protective layer between the corrosive species present in the produced fluids and the pipe surface1.
Prior to the use of film forming corrosion inhibitors in the field, the chemical must first undergo qualification testing in the laboratory. These chemical tests will inform the operator on the chemical performance, characteristics, and interactions with other production chemicals. Carrying out many of these tests can take a significant amount of time2. For example, a simple linear polarization resistance (LPR) test to determine corrosion inhibitor performance can run for up to 16 hours. If the dose rate is unknown, then many of these tests may be carried out to narrow down to the required concentration.