Improvement and Application of Segmented Pigging Process for Gathering and Transportation System in Puguang Gas Field, China

摘要

Gathering-transferring Pipeline 1 of the Puguang Gas Field employs a procedure that mixes gas and liquid for transportation. The inner wall of the pipeline is coated with a 0.1-mm-thick corrosion inhibitor film. Implementation of the corrosion inhibitor film procedure requires pigging during operation of the pipeline to sweep effusion and impurities out and ensure that the inner wall is fully coated. In on-site operations, pigging and filming are performed alternately. During "pigging + filming," the range of gas transmission fluctuation is 120-530x10(4) m(3)/day. These fluctuations severely affect the purification effect of the acidic gas remover in the purification plant and even affect the quality of the sulfur content. Therefore, an optimal pigging approach is proposed to decrease pigging and filming time and minimize the influences of these two operations on subsequent purification. It requires completion of pigging within the shortest time possible and simultaneous deposition of the corrosion inhibitor film on upstream and downstream pipelines. These requirements reduce the time for these operations to 15.38 h and the time for gas transmission fluctuation to 6.16 h. With the proposed optimal pigging approach, the amount of effusion in the downstream pipeline rises, enabling throttling in some low-lying areas which induces ice blockage. For smooth optimal pigging, use of a portable device that can drain the effusion from low-lying areas to prevent ice blockage is recommended. (C) 2021 American Society of Civil Engineers.