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

蒸汽吞吐是艾伯塔省深层油砂油藏开采稠油的可行方法之一。为了可持续发展，必须在油砂储层上方存在一个合格的盖层，以防止任何向上的水力和热迁移进入覆盖层。必须保持盖层的水力和结构完整性，因为这些就地热开采过程会在盖层中引起重大的短期和长期变形。该提案研究的主要目标是制定定量方法，以评估页岩和泥岩等自然地质构造作为就地热蒸汽刺激过程的盖层。天然盖层岩心将在实验室进行测试，在野外遇到短期和长期环境变化。短期环境变化包括剪切变形、高温加热和孔压升高。将使用一种新的高温和压力测试设备来研究盖层在这些恶劣环境条件下的短期结构和水力行为。还将研究其长期行为，如在孔隙流体化学作用下的膨胀、在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目前的重点研究课题。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关于结构和水力完整性的新标准，以评估页岩和泥岩作为热采过程盖层的性能。这项研究调查的结果可以转移到其他研究活动中，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.