Short-term and long-term behaviour of clay shale as caprock for in situ thermal (heavy oil) recovery processes

蒸汽吞吐是阿尔伯塔深层油砂油藏开采稠油的可行方法之一。为了实现可持续发展，油砂储层上方必须有一个合格的盖层，以防止任何向上的水力和热迁移进入覆盖层。盖层的水力和结构完整性必须保持，因为这些原位热采过程会引起盖层的短期和长期变形。建议研究的主要目标是制定定量方法，评估页岩和泥岩等天然地质层作为原位热蒸汽刺激过程的盖层。天然盖层岩心将在野外遇到的短期和长期环境变化下进行实验室测试。短期环境变化包括剪切变形、高温加热和孔压升高。将利用一个新的高温高压试验设施研究盖层在这些恶劣环境条件下的短期结构和水力特性。还将研究长期行为，如孔隙流体化学变化下的膨胀和持续剪切和加热下的蠕变。盖层结构-水力完整性的长期退化是研究的重点。将开发新的创新加速测试方法，以缩短测试时间。从这项研究调查中，将制定新的结构和水力完整性标准，用于热采过程中页岩和泥岩作为盖层的性能评价。这项研究调查的结果可以转移到其他研究活动，如碳储存和废水处理。

Steam stimulation is one of the viable in situ methods to recover heavy oil from deep oil sand reservoirs in Alberta. For sustainable development, a competent caprock must exist above the oil sand reservoir to prevent any upward hydraulic and thermal migration into the overburden. The hydraulic and structural integrity of the caprock must be maintained as these in situ thermal recovery processes induce significant short-term and long-term deformation in the caprock. The main objectives of the proposal research are to develop quantitative methodologies in assessing natural geological formations such as shale and mudstone as caprock for in situ thermal steam-stimulated processes. Natural caprock cores will be tested in laboratory under the short-term and long-term environmental changes encountered in the field. The short-term environmental changes include shearing deformation, high temperature heating, and pore pressure elevation. The short-term structural and hydraulic behaviour of the caprock subjected to these severe environmental conditions will be studied using a new high temperature and pressure testing facility. The long-term behaviour such as swelling under pore fluid chemistry alteration and creep under sustained shearing and heating will be also investigated. Long-term degradation in caprock structural-hydraulic integrity is the key research subject. New innovative accelerated testing methods will be developed to shorten the test duration. New criteria on structural and hydraulic integrity will be developed from this research investigation for performance evaluation of shale and mudstone as caprock for thermal recovery processes. The findings from this research investigation can be transferred to other research activities such as carbon storage and waste water disposal.