Direct Evaluation of Internal Corrosion of Gas Gathering Pipeline in Shale Gas Well Area

Abstract

In recent years, pipeline transportation has become an indispensable way of oil and gas transportation in China. However, with the frequent occurrence of pipeline accidents, the corrosion of natural gas gathering and transmission pipeline has become a great threat to the sustainable development of natural gas. Taking shale gas gathering pipeline as an example, a variety of corrosive substances such as CO2, dissolved oxygen, SRB and Cl- were detected in the transported gaseous and liquid substances, resulting in a very harsh corrosive environment, which caused varying degrees of corrosion damage to the gas gathering pipeline, and even led to rapid perforation of multiple gas gathering pipelines, resulting in serious economic losses and threatening the personal safety of staff. The direct evaluation of internal corrosion of shale gas wet gas pipeline can provide favorable guarantee for the safe operation of the pipeline. Therefore, based on the multiphase flow theory and the operating conditions of shale gas wet gas gathering and transmission pipeline in a gas field, the internal corrosion direct evaluation process was carried out according to MP-ICDA. The multiphase flow simulation and calculation were conducted by OLGA software to indirectly evaluate the corrosion in the pipeline. The corrosion sensitive areas in the pipeline were determined to be low-lying areas and uphill sections. The internal corrosion should be directly evaluated after the excavation detection should be conducted at the high-risk position of the pipeline. Excavation detection was conducted in high-risk locations of pipelines to verify the direct evaluation of internal corrosion. The post evaluation of the pipeline should be completed according to the detection results, and the re-evaluation time should be determined.

Keywords

• shale gas|gathering pipeline|internal corrosion|icda