Corrosion Influencing Factors of Sour Gas Wells in Chuandongbei, China

摘要

Based on the results of this investigation, one may draw the following conclusions: H_2S and CO_2 partial pressure, Cl~- content in the water, temperature, and elemental sulfur are the main factors that influence the corrosion of down- hole materials through the combined effects of H_2S and CO_2. Temperature influences the corrosion of the materi als slightly in the range of 60 to 120 deg C. The corrosion products are FeS and FeS_(0.9). In the experiment, the corrosion rate of AC80 was 0.273 to 2.677 mm/y. The higher the H_2S and CO_2 partial pressures are, the higher the corrosion rate is; the higher the Cl~- content in the water is, the faster the corrosion rate is. Moreover, the general and localized corrosion of AC80 is accelerated in the presence of elemental sulfur and the maximum pitting corrosion depth is 41.4 mm/y. Close attention should be paid to producing water or precipitation of elemental sulfur on downhole materi als in the course of gas field exploita tion. If there exists such a well that produces formation water with a high content of Cl~- or one that has precipi tated elemental sulfur on the surface of the downhole equipment, the well may be corroded seriously and proper measures should be taken to remove the elemental sulfur or control the corrosion of formation water. Further investigations should be carried out to simulate such downhole high-pressure corrosion because the downhole high-pressure environ ment is not simulated completely at present.