通过模拟井下环境的均匀和局部腐蚀试验,结合电化学测试分析,研究了J55 套管钢的腐蚀行为和腐蚀机理.结果表明:随着温度的升高,J55 套管钢的CO2 均匀腐蚀速率逐渐增大,当温度达到 60℃时,其腐蚀速率达到最大值,即 1.0175 mm/a,并且局部腐蚀最为严重.SRB、TGB导致J55 套管钢的均匀腐蚀速率明显增大,局部腐蚀程度显著增强.在单独CO2 腐蚀环境中,J55 套管钢的阴极和阳极均表现为活化反应,自腐蚀电位下的腐蚀电流密度为阴极反应过程所控制.随着温度的升高,其电化学腐蚀热力学趋势增强,当温度达到 60℃时,J55 套管钢动力学阻力达到极小值点,自腐蚀电流密度最大.SRB、TGB使J55 钢在CO2 腐蚀环境中的自腐蚀电位明显降低,并显著促进了CO2 腐蚀的阴极氢去极化过程,导致J55 钢的阳极溶解加速.
为解决低渗透油藏CO 2 驱气体窜流影响开发效果的问题,以泡沫综合值为评价指标,通过搅拌法优选发泡剂,建立了CO 2 响应性增强泡沫体系,配方为0.1%发泡剂AOS+4.0%小分子胺+水。该体系在接触CO 2 前黏度与水接近,与CO 2 作用后黏度可升高18倍以上。性能评价结果显示:CO 2 响应性增强泡沫体系的泡沫综合值可达到常规泡沫体系的11倍以上;具有明显的剪切稀释特性,流变方程符合幂律流体流变模式;比常规泡沫体系具有更强的黏弹性,可以封堵优势渗流通道,抑制非均质低渗透油藏CO 2 驱气体窜流,提高低渗透油藏CO 2 驱的采收率。研究结果表明,CO 2 响应性增强泡沫体系可以解决低渗透油藏CO 2 气体窜流问题,提高CO 2 驱的开发效果。
The channeling of CO2 seriously affects the development effect of CO2 flooding technology. In response to this problem, the construction of the CO2 responsive enhanced foam system and the evaluation of its channeling performance have been carried out. The foaming agent is optimized by the stirring method, the CO2 responsive enhanced foam system is constructed based on the optimization of foam agent, and the rheological performance test and the enhanced oil recovery experiment are carried out to study the stability mechanism and channeling plugging performance of the responsive enhanced foam system. The developed responsive enhanced foam system formula is 0.1 wt% AOS foaming agent + 4 wt% small molecule amine. The viscosity of this system is close to that of water before exposure to CO2, and the viscosity can increase by more than 18 times corresponding to CO2. The CO2 responsive enhanced foam system has obvious shear thinning characteristics, and its rheological equation conforms to the power law fluid rheological model. The enhanced foam system has stronger viscoelasticity than conventional foams. The foam comprehensive value of the enhanced foam system can reach more than 11 times that of the conventional foam system, which can effectively inhibit the CO2 channeling of heterogeneous low permeability reservoirs and improve the development effect of CO2 flooding in low permeability reservoirs.
通过对模拟工况环境中耐温铝合金牺牲阳极的电化学腐蚀行为和性能参数测试,探讨其在井筒环境中的适用性.结果表明:随着温度升高,耐温铝合金阳极自腐蚀电位明显负移,自腐蚀速率增大,在20、40、60和80℃时的自腐蚀速率分别为0.1097、0.1235、0.1378、0.1835 mm/a.耐温铝合金阳极在20、40、60和80℃条件下的活化电位分别为-1108、-1105、-1082、-1022 mV;工作电位则分别为-1100、-1080、-1060、-990 mV,其值高于相应温度下的破钝电位,并且在高达80℃的条件下,工作电位也低于有效阴极保护电位,电流效率仍保持在70％以上.耐温铝合金阳极不仅能够提供良好的阴极保护效果,而且自腐蚀腐蚀速率较低.
