Study on H2S monitoring technique for high risk wellsite

摘要

During petroleum exploitation, deleterious gases, such as hydrogen sulphide, often present at wellsites, leading to dangers like creature death and explosion. Wellsite H2S can come from several ways with different diffuse concentration respectively, and the most practical defending method is rational monitoring and emergency measures. Aiming at the wellsite safety when exploiting reservoirs with high pressure, high temperature and high H2S component, studies are made in three steps. Firstly, the sources, possible overflow points and overflow quantity of H2S are summarized according to field steps including well testing, workover and production. The concept of alarm-weight for H2S concentration is proposed and weight values corresponding to different alarm level are proposed. Secondly, H2S leakage and diffusion are modeled by commercial software, with wellsite equipment, wind and gas leaking rate considered. Thirdly, position and number of monitors are recommended according to operation procedure, and emergency measures are proposed in response to industry standards and field experience. Parts of the results have been used in wellsite deleterious gas defense in eight wells in Yuanba district, Sichuan province.