Optimization of Corrosion Inhibitor for a Gas and Condensate Field

Qualification of a new corrosion inhibitor was carried out for both tubing and flowline services in a gas and condensate field because the production condition changed. The methodology and result of the inhibitor evaluation under a sweet condition was summarized. The depth of production well is 4,500 m and the bottom hole temperature and pressure are 180 °C and 50 MPa respectively. Two brands of corrosion inhibitors had been used for production tubing and flowline respectively in the field. A new inhibitor was investigated for the both applications. The performance of corrosion inhibitor efficiency was evaluated with a rotating cage autoclave. In order to evaluate the tendency of emulsion forming, Oil, brine and an inhibitor were poured into a centrifuge tube and it was shaken intensely. Gas chromatograph - mass spectrometer (GC-MS) and Fourier transform infrared spectroscopy (FT-IR) were studied to measure the residual amount of inhibitor. Finally the field trial was carried out with the new inhibitor. The new inhibitor was adopted successfully for the both services. The GC-MS analysis showed the flow back lasted more than two hours. The risk of emulsion forming became lower because the mixing of two brands of inhibitors was avoided. Reducing the number of the chemicals contributed to reduction of the operation cost too.