X65碳钢在模拟油田采出水中的阴极保护研究

Cathodic Protection of X65 Carbon Steel in a Simulated Oilfield Produced Water

采用极化曲线、恒电位阴极极化和失重法,并结合SEM,EDS和XRD分析产物的形貌、成分和结构,研究了不同保护电位下X65碳钢的保护效果和机制。结果表明:该环境中,自腐蚀条件下的X65碳钢发生严重腐蚀,失重速率大,坑蚀严重;-800^-1000 mV的保护电位对X65碳钢的腐蚀均有明显抑制效果;-800 mV阴极保护电位下X65碳钢表面无良好的钙质沉积层形成,-900 mV下表面能生成牢固致密的钙质沉积层,有效降低保护电流密度,-1000 mV下沉积层容易因析氢反应而鼓泡脱落;相比于海洋环境,X65碳钢在油田采出水中的析氢电位偏正,沉积层中不含Mg(OH)2。

The effectiveness of cathodic protection for X65 carbon steel in a simulated oilfield produced water was examined by means of measurements of polarization curve, constant potential cathodic polarization and weight loss. Then the morphology, composition and constituent of the corrosion products were characterized by SEM, EDS and XRD. The result indicates: in the simulated oilfield produced water, X65 carbon steel suffered from serious pitting corrosion with a great weight loss rate; the cathodic protection potential in a range-800 mV to-1000 mV exhibits obvious inhibition effect on corrosion of X65 in the environment; a sound scale of calcareous deposits can't formed on the surface of carbon steel by the potential of-800 mV, a dense and good adhesive scale of deposits may formed by-900 mV on the steel surface, resulting effectively in reduction of the cathodic protection current density. The deposits blister and easily spall off due to hydrogen evolution by potential-1000 mV. In comparison with the circumstance in seawater, hydrogen evolution potential of X65 carbon steel is much positive in the simulated oilfield produced water and the deposits do not contain magnesium hydroxide.