TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractProduction of Hydrogen Sulfide (H 2 S) gas in oil and gas wells has increased over the last few years. These sour (H 2 S Producers) wells have been successfully acid stimulated for many years. Wellbore acid washes, high rate squeeze treatments and acid fracs have been the norm for stimulating wells in carbonate formations. However, to accomplish this there are many problems related to the interaction of the treatment fluids and the H 2 S. These can result in excessive corrosion, unwanted precipitants, metal cracking, etc.In recent years, the practice of drilling horizontal wells has led to the technique of underbalanced acid washing. Controlling corrosion, metal fatigue and unwanted precipitants when using this technique in sour formations presents a special challenge. The resulting interaction of the H 2 S and acid additives, especially corrosion inhibitors has been the primary focus of concern. This paper describes test equipment and procedures designed to investigate H 2 S and acid additive interactions. Test results with a range of inhibitors and additives designed to minimize formation damage and protect coiled tubing and tubular steels are provided. Specifically, weight loss, pitting and precipitation products are listed.

No abstract