N80钢的CO_2腐蚀行为试验研究

我国中西部的油田，大多面临严重的CO2腐蚀危害。为更清楚了解油管套管常用的N80钢在现场条件下腐蚀形貌、腐蚀速率等腐蚀行为，为油田选材提供依据，进行了模拟现场环境的腐蚀试验研究。研究结果表明，在温度为92℃、介质流速为12m/s、CO2分压为29648kPa、总矿化度为346g/L的水介质中，N80钢的平均腐蚀速率为08224mm/a，按NACE RP—0775—91标准属于极严重腐蚀；腐蚀试样表面除了存在大面积凹陷外，还有较深的腐蚀坑；金属表面腐蚀产物分为三层，各层形态和成分不同，但都不很致密；腐蚀产物主要是碳酸的复盐和Fe3C。

Experimental investigation in CO2 corrosion behavior of N80 steel

s Most of the oil fields in the midwest of China face the harm of serious CO2 corrosion． To make clear the corrosion behavior of the N80 steel for casing and tubing in field conditions a simulation test is made． Water with a flow rate of 1．2m／s and total salinity of 34．6g／L is taken as test medium． When the test temperature is 92℃ and the partial pressure of CO2 is 296．48kPa the mean corrosion rate of N80 steel is 0．8224mm／a． This corrosion is very serious according to the standard NACE RP－0775－91． There exist not only large local depression on the surface of the coupons but also deep corrosion pits． The corrosion products on the metal surface mainly compound carbonates and Fe3C can be divided into three layers with different shapes and compositions but they are not very compact．