F22 carbon steel has been widely used in subsea field development due to enhanced mechanical properties. However, commonly used scale inhibitors have been shown to be very corrosive against F22, and therefore cannot be injected continuously subsea to control mineral scales. In this paper, inhibition performances of several scale inhibitor intermediates tested under subsea conditions for controlling CaCO3 and BaSO4 scales were presented, and several formulations containing tailored corrosion inhibition packages were evaluated. The corrosivity of those formulations against F22 was assessed using static immersion coupon corrosion tests. The test results revealed most of the formulations had corrosion rates against F22 above 40 mpy and only two of the formulations passed the criterion of <4 mpy. The most promising formulation was selected for deepwater qualification and was ultimately qualified for downhole chemical injection. The additional material compatibility testing data show this new product is compatible with various metals and elastomers/plastics.
Additionally, to study the compatibility between this new product and a commonly used corrosion inhibitor, scale inhibition performance of the product with and without a corrosion inhibitor was assessed, and high-pressure autoclave corrosion inhibition tests in the presence of the corrosion inhibitor were conducted with and without the new scale inhibitor.