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

在CO2地质封存中，注入的CO2气体被假定为被非渗透地层的盖层完全截留在含水层中。但天然气也有可能通过天然裂缝和高渗条带漏到上部。本文通过将聚丙烯酰胺、NaA_2O和NaOH的水溶液注入玻璃珠填充岩心的实验，研究了聚合物凝胶法封堵CO_2封存气藏漏失的适用性。(1)CO2气体的堵塞是可能的，通过这种胶凝剂注入过程。在重复注入胶凝剂后，通过形成凝胶，岩心的气体渗透率降低到其初始渗透率的1/16至1/115。(2)凝胶堵气效果取决于凝胶剂溶液中聚合物分子的浓度、分子量、水解程度和岩心渗透率。实验表明，通过注入含有250 ppm NaAlO_2、250 ppm NaOH和500 ppm聚丙烯酰胺（其分子量为1300万，水解度为30%）的胶凝剂溶液，可以阻止通过约10达西岩心的气体泄漏。(3)在岩心1 m长的井段内形成的凝胶可保持约2.0MPa的气体压力，防止漏失，这种凝胶方法的真实的应用还需要进一步模拟现场含水层条件的实验。但这种方法被认为是有希望的一种措施，以阻止在地质CO2封存Galseak，因为真实的沉积物的渗透率是低得多的核心实验的渗透性。单独的报告总结了实验结果的细节和建议，以未来的研究.

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.