Prevention and disposal technologies of gas hydrates in high-sulfur gas reservoirs containing CO2

•Gas hydrate will easily form in gas reservoirs with high content of H2S and CO2 during the producing process.•Gas hydrates will seriously affect the high-sulfur gas field efficiently and safely development.•The recommended hydrate inhibitor is methanol for Yuanba gas fields through the hydrate inhibitor screening experiments.•There are mainly three methods to prevent hydrate formation. It is especially effective to use these methods combinatorially.

Changxing gas reservoir is a lithologic formation with an ultra-deep and normal pressure system, which has a high content of H2S and medium content of CO2. This gas reservoir has the edge/bottom water locally and is controlled by the reef and beach body. Due to the high content of H2S, gas hydrate formation temperature is relatively high, which is easy to form hydrate. Wellbore and gathering pipelines belong to frequent site of hydrate formation in the process of production and transportation. Once the gas hydrates are formed, which will seriously affect the well production performance, so it's important to understand the forming conditions of hydrates for a specific gas reservoir. In this paper, through the hydrate inhibitor screening experiments by measuring the hydrate formation temperature under 13 groups of pressures and the hydrate formation temperature of 9 groups of methanol, ethylene and glycol at different concentrations under two pressures, we recommend the methanol as the priority hydrate inhibitor for Yuanba gas fields. The case study shows that all these methods must be used combinatorially in order to prevent gas hydrates formation and disposal gas hydrates effectively.