As the main source gas reservoir of the West to East Gas Pipeline Project, the Yaha Gas Condensate Field was a condensate gas reservoir located in the Tarim basin in the northwestern China that started to supply gas in 2000. The gas produced by the field contained about 0.7–1.3 volume percent CO₂ and Clion concentration as much as 116,000ppm. Initially, 16Mn steel was adopted to construct the pipelines. By May of 2006, there were as many as fifty failures. The investigations on corrosion of flow line at simulated internal service conditions found the high corrosion rate was due to the multiphase flow induced erosion and CO₂ corrosion. Considering severe corrosion environments in the Yaha Gas Condensate Field, bimetallic lined pipes, with a liner pipes made of CRA and an outer pipes made of low-cost steel, might be a potential anticorrosion solution. In this paper, the outcome of a comprehensive program of work to establish suitability of bimetallic lined pipe for gathering lines in Yaha Gas Condensate Field was presented. Manufacturing technique of bimetallic lined pipe, assessment of girth welding procedure, corrosion performance in the simulated condition and analysis on economics advantages of bimetal lined pipe were all discussed. Fit-for-purpose analysis showed that bimetal lined pipes could be an economic and effective solution to the corrosion problem in the Yaha Gas Condensate Field.

The release rate of liquid core material from microcapsules is crucial for the surface properties of self-protective metal/liquid microcapsule composite plating coating. However, there is no method to accurately predict the release rate of microcapsules. In this paper, the permeability experiments of different shell membranes and core materials were carried out using the weight loss method, and the permeability model of liquid microcapsules was studied based on a multiple linear regression method. The results show that three-variable mathematical model C, including membrane porosity, the viscosity of core material, and membrane thickness is suitable to describe permeability, and the membrane thickness is the most significant influence factor. Additionally, the accuracy of model C was experimentally verified, and the error of the permeation rate is about 2.06% between predictive and experimental values.

With further development of oil and gas resources, corrosion environment of gathering lines became more serious. Designers must consider H₂S cracking and H₂S corrosion, especially in oil and gas fields with H₂S and CO₂ rich gas. In this severe, sour environment, carbon steel with inhibition was not ineffective or infeasible in combating corrosion and cracking. Nickel-based, corrosion-resistant alloy (CRA) could resist corrosion, but its expensive price often makes it difficult to provide the economic justification for its use. Therefore, bimetallic-lined pipe, which has a liner pipe made of CRA and an outer pipe made of low-cost steel, might be an effective solution to the corrosion problem. Application of bimetallic-lined pipe in oil and gas field environments has been a topic of signification interest, involving both performance and economic questions. This paper analyzes four anti-corrosion measures: (1) carbon steel with corrosion allowance, (2) carbon steel with inhibitor, (3) CRA and bimetallic-lined pipe from technical and economic perspectives. The results showed that bimetallic-lined pipe had the greatest advantages in technology and economics. So far, however, bimetallic-lined pipe has not been used as gathering lines for sour service in China. There are still many questions to deal with. The paper describes three primary questions and puts forward some proposed solutions, including: (1) material selection and performance control; (2) manufacturing technique of pipe fitting; and (3) assessment of girth weld procedure. Ultimately, the obtained conclusion is that bimetallic-lined pipe owned a higher performance price ratio and must be widely used in highly corrosive oil and gas fields.

A self-protective metal/ liquid microcapsule composite plating coating has been prepared in our previous research. The release speed of liquid core material from microcapsules is crucial for the coating surface properties. The aim of this paper is to study the permeability rule of liquid microcapsules within composite coatings. According to permeability experimental data’s linear characteristics, multiple linear regression is firstly used to set up permeability model of liquid microcapsules. The results show that a reliable mathematical model about membrane porosity, viscosity of core material and membrane thickness is established under ambient temperature and moisture. Meanwhile, the predictive capacity and reliability of this model are analyzed carefully.