| With the development of the world, the global oil and natural gas consumption increasing greatly, but slowly in alternative energy technologies. At present, in the world more than 400 high sour oil gas fields which have the commercial value have discovered. The content of H2S in these fields ranges from tittle to more than 92%. As the requirement of oil and gas is increasing, some high sour oil gas fields that are difficult for exploitation now put on the agenda.After analyzing the problems in the exploitation of high sour oil gas well and the corrosion mechanism at home and abroad, a number of measures have been taken to prevent corrosion of hydrogen sulfide. Because the corrosion resistance performance of high alloy steel gets better with the content of alloys increasing, AISI4130 steel, 30CrMo steel in China, is used for wellhead material of Christmas tree by majority famous manufacturer in the world. 30CrMo alloy that is often used for valve body or valve cover of Christmas tree is choose as base metal and 4-5mm thick Inconel 625 nickel alloy is overlaid by the tungsten-arc inert-gas welding in the paper. Then, mechanical properties, microstructure and composition distribution of the overlay are studied. Uniform corrosion experiment is done and its corrosion rate is measured.The result showed that the combination between Inconel 625 nickel alloy and 30CrMo steel is good and no macroscopic surface defects are discovered. The plasticity and the tensile strength of the joint increases greatly than the base metal after welding. But, the yield strength nearly keeps same. However, the hardness decrease slightly and also meet the using requirements of equipment. Comparing with 30CrMo steel, Inconel 625 alloy have well resistant to pitting and corrosion of the sulfide. In the saturated hydrogen sulfide solution, the corrosion rate of Inconel 625 alloy is about 1/8 times of that of 30CrMo steel. Obviously, Inconel 625 nickel alloy have well resistant to corrosion of the sulfide.
|
PDF Full Text Request