大牛地低含H2S/CO2气井腐蚀规律及主控因素研究

Study on corrosion law and dominant control factors for low H2S and CO2 containing gas wells in Daniudi gasfield

大牛地奥陶系风化壳气藏含有不同程度的硫化氢,整体属于低微含硫范围,目前对H2S/CO2共存条件下腐蚀规律认识不清,气藏安全生产存在一定风险。通过静态失重法探究温度、压力、硫化氢浓度对气井油套管腐蚀规律的影响。结果显示:N80和P110两种钢材的腐蚀速率随硫化氢浓度降低、压力升高呈升高趋势;随温度升高腐蚀速率先升高后降低,80℃时达到最大值1.4521 mm/a和1.8915 mm/a。初步确定大牛地气田腐蚀主控因素为H2S浓度,研究结果为该气田井筒管材优选及腐蚀防治提供了依据。

The Daniudi Ordovician weathering crust gas reservoir contains different degrees of hydrogen sulfide,which belongs to the range of low and micro sulfur.At present,the corrosion law under the condition of H2S/CO2 co-existence is unclear,and there are certain risks in the safe production of gas reservoir.The influence of temperature,pressure and concentration of hydrogen sulfide on the corrosion of gas well casing was studied by static weight loss method.The results showed that the corrosion rate of N80 and P110 steel increased with the decrease of hydrogen sulfide concentration and the increase of pressure,and the corrosion rate first increased and then decreased with the increase of temperature,reaching the maximum value of 1.4521 mm/a and 1.8915 mm/a at 80℃.It is preliminarily determined that H2S concentration is the dominant control factor of corrosion in Daniudi gasfield,and the research results provide a basis for the optimization of wellbore pipe and corrosion prevention of the gasfield.