The CCEIC has standardised protocols for analysis and testing of Corrosion Inhibitors (CI) for investigating and evaluating their performance. Some of the standard tests performed in the laboratory are as follows:
The bottle test is a useful method to screen a large number of CI’s or to investigate different test variables. Small weight loss coupons are placed inside a sealed glass bottle with pre-sparged test fluids (brine/hydrocarbon/MEG etc.) The bottles are rotated in a wheel oven to simulate a high mixing/turbulent flow regime.
Standard bubble test
The standard bubble test uses a set up of three electrodes to conduct electrochemical corrosion rate measurements in an aqueous test fluid. Corrosion measurements are made on a rotating cylinder electrode. This test is used to determine the blank corrosion rate and CI’s level of inhibition and efficiency. The test is performed in a CO2 saturated fluid at atmospheric pressure and at 80° C.
Emulsion tendency testing
This test is used for evaluating the effect of CI’s on emulsion formation. It is also used to screen candidate emulsion breakers.
Foaming tendency testing
This test is used to evaluate the extent of foaming caused by the inclusion of CI in a system.
This is a simple test to investigate the solubility of the CI in the hydrocarbon and aqueous phase.
The chemical compatibility test is used to investigate adverse effects by mixing of various chemicals including CI formulations.
The CI is heated to the desired temperature either in a sealed pressure (pipe autoclave or in an open glass vessel) CI is then inspected to find out the extent of solid formation, discolouration or solvent loss. Further investigations include infra-red analysis to assess structural break-down of the active components and to assess the impact on inhibition properties. The thermally treated CI can be used in emulsion and foaming testing.
The partitioning tendency of a CI can be performed in different ways. Generally, a pre-partitioning step is conducted before a corrosion test. This involves mixing of hydrocarbon and aqueous phase following the addition of the CI to the hydrocarbon phase. The aqueous phase is utilised and CI with little tendency to partition into the aqueous phase results in poor corrosion inhibition. The partitioning tendency can also be investigated in-situ by conducting corrosion measurements in an aqueous phase with an overlying hydrocarbon phase filled with CI.
Rotating blade autoclave test
The Rotating Blade Test (RBT) is used to simulate high shear stress associated with the turbulent flow. The test is performed in a 2 litre autoclave and at high pressure (50 bars) and high temperature (200° C) Weight loss coupons with a mixture of field-sourced or synthetic fluids are rotated at 500-1000 rpm within the autoclave. This test is useful for evaluating CI performance in simulated conditions.
Jet impingement test
The Jet Impingement Cell (JIC) is used to conduct electrochemical measurements at high pressure and temperature under well-defined hydro-dynamic conditions. The laboratory has 2 stainless steel cells and has acquired a ‘Hastelloy C276’ cell of 1.5L capacity. The Hastelloy cell can perform electrochemical measurements (ELS/LPR etc.) at high pressure (50 bars) and high temperature (200° C) and at high shear stress (200 Pa).