Case Study: Kl-3866 Inhibitor Reduces Costs, Controls Corrosion in 15-Year-Old High-Pressure Sour Pipelines

Quarterly application reduces corrosion rate to 1 mil per year, Alberta

Challenge: Prevent further integrity losses in an extensive network of 15-year-old pipelines in high-pressure, high-H2S field.

Solution: Apply KI-3866 corrosion inhibitor on a quarterly basis.

Result: Reduced program costs and corrosion rate to less than 1 mil per year (0.025 mm/a)

Combating severe corrosion risks

The Dunvegan field is approximately 9 mi [15 km] southeast of Fairview, Alberta and includes oil and gas wells with some zones producing H2S. The H2S and high pressures posed a severe corrosion risk in the extensive network of more than 15-year-old pipelines transporting production from 11 satellites to the processing plant.

Testing for optimal utilization

Extensive autoclave corrosion testing determined the proper batch corrosion chemistry for the Dunvegan field. Because of excessive chemical use by a previous chemical vendor, M-I SWACO also tested to determine the maximum dilution ratio for the selected batch corrosion inhibitor. All testing was performed at worse-case system conditions by a third-party laboratory. The unmitigated corrosion rate for the field was determined to be approximately 21 mil per year (0.51 mm/a).

Reducing corrosion rate by 97%

KI-3866 inhibitor outperformed the previous product and was able to reduce the blank corrosion rate to less than 1 mil per year (0.025 mm/a), a decrease of approximately 97%. Testing also indicated that a maximum diesel dilution of 1:3 still provided effective corrosion control.

The customer began using KI-3866 inhibitor as the main batch corrosion inhibitor for the Dunvegan field, and the 24 lines were batched every quarter. The next year, M-I SWACO installed flush mounted coupons at the high-pressure sour gas inlet and the lower-pressure sour inlet. Since then, no pitting has been observed on the coupons. General corrosion rates have not exceeded the recommended NACE corrosion rate of 1 mil per year (0.025 mm/a). The coupon data also indicated that KI-3866 inhibitor is still present on the coupons after a three-month period, demonstrating the effectiveness of a quarterly treatment program. M-I SWACO was able to reduce the program cost by increasing the dilution ratio of some of the batch pills to 1:3 with diesel instead of adding chemical to ensure the correct pill size.

Download: Kl-3866 Inhibitor Reduces Costs, Controls Corrosion in 15-Year-Old High-Pressure Sour Pipelines (0.11 MB PDF)

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