含硫化氢气井钻井过程中的腐蚀因素与防护研究

在含硫气井的钻井过程中对于HRC大于22的钻具钢材除了腐蚀疲劳之外，在pH值小于9的环境中会发生硫化物应力腐蚀破裂，这种破坏比腐蚀疲劳更突然、更快，使钻杆大量损坏。含硫气井在钻井过程中，由于湿硫化氢的出现，常常会出现油管、套管、钻井设备、钻井仪器以及对支持保护管柱的水泥环柱等腐蚀和损坏问题，为此，阐述了湿硫化氢的腐蚀特点、机理，归纳总结了影响腐蚀的因素，综述了如何在这些方面防止其腐蚀，使损失减小，为指导油管、套管防腐工程实践提供了依据。建议在钻井过程中采用碱性钻井液，其pH值可到9或更高(至pH值12)，以减缓或防止钻井过程中电化学从硫化物应力腐蚀破裂；含硫气井用的钻杆应该间歇使用。钻杆停用堆置时间可使其放氢，使钻杆恢复韧性，防止硫化物应力腐蚀断裂。

STUDY ON CORROSION FACTORS AND RELATED PREVENTIVE MEASURES FOR DRILLING OF H2S-CONTAINING GAS WELLS

During drilling of H_2S gas wells, H_2S will cause corrosion fatigue to drilling tools with HRC over 22, and also SSC damage when ambient PH value is below 9. The SSC destruction is quicker than the corrosion fatigue, resulting in large amounts of drill pipe damage. The hardness along the length of the drill pipe varies a lot, the cold wrought area is more sensitive to the hydrogen infiltration. In H_2S medium, especially when under high stresses, only API D drill pipe is safe. The high strength tool joints will be damaged in a very short period when used in H_2S environment. In this paper, the basic characteristics, mechanism and main influential factors of corrosion are expounded, which offers a reliable base for deciding preventive measures to be adopted to minimize the corrosion. It is recommended to adopt alkaline drilling fluid, and the drill pipes be used and then stored alternately to prevent SSC effects.