| Gas hydrate plugging is a common problem encountered in the process of gathering and handing in gas fields.For the gas gathering pipeline,due to the complexity of the fluid composition in the well,water and impurities are more,so The hydrates would be easily produced in pipes under the complex and changing external environment and flow conditions.The local accumulation of hydrates may reduce the flow area of pipelines,decrease the capacity of pipeline gas transmission,and damage pipe elbows,valves,cleaning ballings and other equipments,even cause the occurrence of shutdown accidents.So hydrates seriously affects the normal production and safe operation in the fields.At present,the gas fields often inject methanol inhibitors into pipelines to inhibit the formation of hydrates at the wellhead position through injection lines which are laying in the same ditch with the gas gathering pipeline.Two key issues need to be focused during the process of inhibitor injections: the time of methanol injection and the reasonable amount of injection,that is,what time the methanol inhibitor is injected and how much should be injected.At present,the gas production plants can not achieve fine management of the inhibitors injection and lack of scientific basis by means of manual estimation,which leads to the excessive consumption of methanol,which seriously increases the running cost of the gas production plants.Although the design institutes can use some chemical process simulation software to calculate such as Hysys and Pro II,the complexity of their operation and the additional configuration makes it difficult for field operators to master and use skilfully.The higher cost of the commercial software which undoubtedly increases the operating cost of gas production plants.Based on the study of pipeline hydrate freezing problem of Changqing Oilfield 5th gas production plant,This paper has established the optimal hydrate formation prediction model: gas and solid phase equilibrium model by analysing and solving the hydrate phase equilibrium model and comparing with other prediction methods.At the same time,the methanol content in the aqueous phase,the gas phase and the condensate liquid phase has been calculated according to the distribution of the methanol inhibitor under the temperature and pressure of the pipeline,and the total amount of the methanol inhibitor has also been determined.then,based on the C ++ builder6.0 platform,the Windows version of hydratePro software has been developed in C ++ object-oriented programming language.At the same time,in order to facilitate the use of the field operators and expand the scope of software,this paper has also developed the Android version of HydratePro software,so that People can get a good solution through different ways.Finally,the software has been applied to the production practice of Changqing Oilfield 5th Gas production plant.The comparison between the calculated methanol consumption by HydratePro and the methanol consumption in the previous year has been carried out to verify the economic and rationality of the software. |
