Liwan 3-1 gas field project is China's first deepwater project, located in the eastern of South China Sea. This project is to build a new center platform to Gaolan island terminal pipes, pipe diameter is 30 "(OD 762mm), length is 261km, no valve chamber is in the middle , and center platform depth is 205m. Design pressure is 23.6Mpa and test pressure is 24.78Mpa.
The company contracts for the entire work of the sea pipe drainage, drying and inerting. The pipeline needed to be drained, dried and replaced with nitrogen is is ranging the entire pipeline from Zhuhai Gaolan onshore terminal (KP261.237) to the CEP (KP0), including of the platform rigid riser, PLET, water isolation valves, connecting pipe, overland uphill section pipe and risers. Drying requires to combine with dry air drying and chemical drying.
Liwan Sea pipeline drainage and drying has the following difficulties: (1) large diameter pipes, long distance, pipe capacity over 100000m 3, water depths at platforms up to 200m, and the pressure of pushing the ball high; (2) drying requiring high, requiring to combine with dry air drying and chemical drying method; (3) construction time of drainage and drying is short.
The project faced many difficulties, but the company developed targeted programs, made predicted pre-judgment and well targeted measures in the construction process which may appear difficult. The company deployed capable personnel, composed of Liwan sea pipeline drainage,drying and inerting project department, make special design for pigging and conduct production, in order to meet long-distance, high-pressure conditions to the end has the sufficient sealing performance; deployed more than 40 sets of large-discharge, high pressure compressor, supercharger, dryers, pumps and other large equipment, and leaving enough spare emergency equipment; in the process of drainage, drying and pigging, the onshore terminal and offshore platforms keep contacting in real time, according to the first end condition, make response timely and adjustments to ensure pigging train always in good condition and fully monitoring.
Liwan sea pipeline drying and drainage officially started to add ball since August 29, and finished nitrogen inerting to September 17, which lasted 20 days, guarantee quality and quantity, no HSE incidents, successful completion and acceptance by the Owner,obtained the owners and first party good reputation and high praise.
Platform Surveying
Construction site
Examinate carefully before inserting the pigs
Catch the time limit for this project
Take the ball from the platform
