Optimization of direct assessment technology for internal corrosion of gathering and transmission pipelines in Changqing Gas Field

Abstract

For the operation mode of the production, gathering and transmission pipelines is diversified in the Changqing Gas Field, and the flow state and corrosion environment vary greatly, there is a large error between the actual detection and the detection using the prediction model specified in the technical standard of internal corrosion direct assessment. Considering the characteristics of the operating conditions of the gathering and transmission pipelines in Changqing Gas Field, a three-dimensional flow pattern distribution map was plotted based on the gas set, water-gas ratio and pipeline inclination with the Fluent and SolidWorks softwares. In addition, a corrosion prediction model suitable for the actual operating condition parameters was established and optimized based on the De WarrD and SwRI models. Through the detection and verification at 31 excavation points along 9 pipelines, it is shown that the prediction coincidence degree of the detection points is up to 86.67%, which basically satisfies the requirement of pipeline corrosion risk discrimination, and the measures to enhance the accuracy of pipeline elevation-mileage data and reduce the locating error of excavation, etc., are helpful to improve the prediction coincidence degree.

Keywords

• gas field
• pipelines
• internal corrosion
• direct assessment