Study On Hydrate Prediction And Control Technology Of A Natural Gas Pipeline Network In Bohai Oilfield

During the transportation process of natural gas, the formation of gas hydrate leads to the consequences ofplug inside pipelines or decommission of gas wells, which may cause serious safety accidents. In order to prevent the formation of gas hydrate duringthe production process of oil-gas fields,it is necessary to accurately predict the formation conditions of hydrate and draw up targeted preventive measures.Literature research shows that there were hydrate plug accidents in a certain natural gas system of Bohai oil field in the winter of the year 2010, which requires simulation of hydrate formation conditions and the corresponding prevention measures. The natural gas system is divided into two districts:BX district and BN district, and the schemes of positive and reverse transportation are developed. HYSYS is used to simulate the hydrate formation conditions in the system. Meanwhile, TGNET is used to simulate the operation parameters under various transportation scheme conditions. The simulation results indicate that the risk of hydrate formation happens in B, C, CB and Q platforms and BX district both in the positive and reverse transportation stage, yet as a result of dry gas transportation, there is no formation of hydrate in BN district. The results of agent adding methods demonstrates that the adding of methanol in B platform and glycol in C platform prevent the formation of hydrate effectively. A formula of the relationship between additive agent rate and throughput is presented, as well as the relationship between inhibitors concentration and additive agent rate is proposed for better operation in field.Due to the reasons such as no concern of dehydration in design, limited space of platform and the high cost of equipment and so on, dehydration in all process is rejected. The additive agent rate in C platform is calculated in the scheme of dehydration in B platform and agent adding in C platform. The prevention scheme of hydrate formation in a certain natural gas system of Bohai oil field is obtained through simulation calculation.