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省深部油砂油藏开采稠油的可行方法之一。为了可持续开发，油砂储层上方必须有一层合适的盖层，以防止任何向上的水力和热运移进入上覆层。必须保持盖层的水力和结构完整性，因为这些原位热采过程会导致盖层发生显著的短期和长期变形。提案研究的主要目标是开发定量方法，以评估天然地质构造，如页岩和泥岩，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、高温加热和孔隙压力升高。在这些恶劣的环境条件下，盖层的短期结构和水力行为将使用新的高温高压测试设备进行研究。研究了孔隙流体化学变化下的膨胀和持续剪切和加热下的蠕变等长期行为。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。本研究将为页岩和泥岩作为热采盖层的性能评价提供新的结构和水力完整性标准。本研究调查的结果可以转移到碳储存和废水处理等其他研究活动中。

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.