Application of Polymer Gelation Method to Blockage of Gaseak from CO2-Sequestered

在地质CO2封存中，假定注入的CO2气体被非渗透地层盖层完全封存在含水层中。然而，存在通过天然裂缝和高渗透条纹向上部区域泄漏的可能性。本研究通过实验研究了我们提出的聚合物凝胶化方法在封堵co2封存油藏气体泄漏中的适用性。将聚丙烯酰胺、NaA2O和NaOH的水溶液注入玻璃珠填充岩心的实验结果如下：(1)该喷胶工艺可实现CO2气体的堵塞。反复注入凝胶剂后，岩心的渗透率降至初始渗透率的1/16 ~ 1/115。(2)凝胶形成对气阻的影响取决于凝胶溶液中聚合物分子的浓度、分子量和水解程度，以及岩心渗透率。实验表明，通过注入含有250ppm NaAIO2, 250ppm NaOH和500 ppm聚丙烯酰胺（其分子量为1300万，水解率为30%）的凝胶溶液，气体泄漏可以通过约10达西的岩心停止。(3)岩心1 m长间隔内形成的凝胶可以承受2.0 MPa左右的气体压力，防止气体泄漏。为了实际应用该方法，还需要进一步模拟现场含水层的实验，但由于实际沉积物的渗透率远低于实验的岩心渗透率，因此该方法被认为是一种有希望阻止地质CO2封存中的gal渗漏的措施。单独的报告详细总结了实验结果和对未来研究的建议。

In geological CO2 sequestration, the injected CO2 gasis assumed to be completely trapped into the aquifer by the cap rock of non-permeable formation. However, there is some possibility of gasleak to the upper zone through natural fractures and high-permeability streaks. This studlexperimentallyinvestigated the applicability of our proposed polymer gelation methotd the blockage of gasleak from CO2-sequestrated resenoirs.The following results are obtained from the experiments injecting the gelant (aqueous solution of polyacrylamide, NaA2O and NaOH) into glass-bead packed cores. (1) The blockage of CO2 gas was possible by this gelant injection process. The gas permeabilities of the cores reduced to 1/16 to 1/115 of their initial permeabilits by gel formation after repeating injection of the gelant. (2) The effect of gas-blockage by gel formation depends on concentration, molecular weight and hydrolysis of polymer molecules in the gelant solution, and core permeability. The experiments revealed at the gas-leak was stopped through about 10-darcy core by injecting the gelant solution having 250ppm NaAIO2, 250-ppm NaOH, and 500-ppm polyacrylamide(its molecular weigh is 13 million and 30percent hydrolysis). (3) Gel formed in a 1-m long interval of the core could hold the gas pressure of about 2.0 MPa for preventing galseakage.The further experiments simulating insitu condition of the field aquifer is necessary fo real application of this gelation method, but this method is considered to be promising for a measure to block galseak in the geological CO2 sequestration because the permeability of real sediments is much lower thathe core permeabilityof the experiments. The separate report summarizes the experimental results in detail anthe recommendations to future studies.