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

在CO2地质封存中，注入的CO2气体假定完全被非渗透性地层的盖层围困在含水层中。然而，有一定的可能性通过天然裂缝和高渗透条纹向上层泄漏气体。本研究从实验上考察了我们提出的聚合物凝胶方法在封堵CO2封存油层气体泄漏中的适用性。通过将凝胶(聚丙烯酰胺、NaA2O和NaOH的水溶液)注入玻璃微珠填充岩心的实验，获得了以下结果。(1)这种凝胶注入工艺可以封堵CO2气体。重复注入凝胶后，岩心的气体渗透率下降到初始渗透率的1/16~1/115。(2)凝胶堵气效果与凝胶溶液中聚合物分子的浓度、相对分子质量和水解度以及岩心渗透率有关。通过注入含有250ppm NaAlO2、250ppm NaOH和500ppm聚丙烯酰胺(其相对分子质量为1300万和30%水解度)的凝胶溶液，通过约10-Darcy岩心阻止了气体泄漏。(3)在1米长的岩心间隔内形成的凝胶可以保持2.0 Mpa左右的气体压力以防止盖尔塞克，模拟现场含水层的现场条件的进一步实验是该凝胶法真正应用的必要条件，但由于实际沉积物的渗透率远低于实验的岩心渗透率，该方法被认为是一种在地质二氧化碳封存中封堵盖尔塞克的措施。单独的报告详细总结了实验结果，并对未来的研究提出了建议。

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.