Analysis on Failure of an Oil and Gas Gathering Pipeline in Tahe Oilfield

Abstract

In order to ensure the safe operation and production of oilfield gathering pipelines and to provide corrosion protection in advance,a failed oil and gas gathering pipeline in Tahe Oilfield was analyzed.The macro morphology observation of the corrosion perforation of such pipeline,the material composition analysis by direct reading spectrometer,the micro morphology observation of the sample corrosion by scanning electron microscope,the corrosion products analysis by X-ray diffractometer and energy disperse spectrometer,and the electrochemical testing were carried out to determine the cause of the perforation of the oil and gas gathering pipeline.Results showed that the highly mineralized corrosion medium,the crude oil containing a lot of CO2 and H2S,and the injected water poured into the stratum led to an CO2 corrosion inside the pipe wall.There were a lot of soluble calcium salts in the medium,and the chemical reaction between calcium salts and CO2 resulted in calcium carbonate scaling.The scaling and corrosion products were deposited on the uphill section of the pipeline,which led to serious corrosion of the metal matrix under scaling.The high-chloride ion accelerated the corrosion,and finally caused the perforation failure at the bottom of the pipeline.

Keywords

• gathering pipeline|corrosion|failure|scaling|perforation