Corrosion Research, Oil And Gas Within The Two-phase Flow Pipeline

By contrast, internal corrosion of oil-gas mixed flowing pipelines is much severe than single-phase pipeline. Internal corrosion of oil and gas flow pipeline will impact the transportation efficiency, the equipment safety and the reliability of pipeline. To the multiphase pipeline, there is often one or several oil, gas and water phase in the mediums transported by pipelines, in which corrosive gases such as oxygen, carbon dioxide and sulfureted hydrogen may be dissolved. So multiphase mixture transportation is very complicated. Nearly 20 years, scientists from our country and overseas have been researching on the multiphase flow corrosion. According to a great deal of investigations and researches of the related literatures, and based on real conditions of internal corrosion of the gathering and transportation pipelines, the mechanism of several types of oil and gas flow pipeline internal corrosion are analyzed. The influencing factors about corrosion are discussed. And the oil and gas pipeline internal corrosion prediction and analysis software is developed. In a word, this paper includes several parts as follows:This paper analyzes the corrosion mediums of oil and gas flow, studies the mechanism of internal flowage corrosion of multiphase oil and gas pipelines such as CO₂ corrosion, H₂S corrosion, erosion-corrosion.Emphasis has been put on summarizing the mechanism of flowage corrosion, analyzing the main influencing factors of oil and gas flow pipeline corrosion rate. Three kinds of oil and gas flow pipeline internal corrosion rate prediction model are built based on the consideration of several physical and chemical factors. By solving the parameters included in the models, this paper generally studies the calculation methods of physical parameters, oil and gas flow holdup, flow pattern, pressure drop and temperature, programmed relevant computer program to calculate the internal corrosion rate of oil and gas flow pipelines. Several calculate examples show that the corrosion rate of oil and gas flow pipeline is related to flow pattern, the pipeline will under the worst corrosion condition when the flow pattern is slug flow.As a specific flow type in oil and gas flow, slug has been detailed in this paper. This paper deeply analyzes the occurring and existing condition of slug, the mechanism of slug flow corrosion of oil and gas pipelines, and the physical model of slug flow. According to the formulas such as the mass conservation, momentum conservation, and conservation of energy, the steady and transient models are built. The transformation trends of slug flow technological parameters along with the distance of pipeline are provided with concrete calculation example. The corrosion rate of slug flow could be calculated by the slug flow corrosion rate prediction model. Mean influencing factors such as shear stress of slug flow are discussed too.In the end, oil and gas flow pipeline internal corrosion prediction and analysis software is developed. This software has many features, such as powerful calculating function, simply operation and accurate calculation result. It can be used to provide data and information for oil and gas flow pipeline internal corrosion prediction.