Joint modelling of gravity gradiometry and muon tomography for monitoring of SAGD reservoirs

蒸汽辅助重力泄油（SAGD）是加拿大西部油砂地区常用的一种提高采收率技术。重油的生产需要大量的水，这些水被转化为蒸汽，并最终被泵入地下以调动重油。重油流入生产井并从中提取。如果仅在产油地点注入蒸汽，则可以降低与蒸汽生产相关的成本，但SAGD储层的监测通常限于每隔一年进行一次4D地震勘测。我们提出了两种创新的监测技术，重力梯度和μ子层析成像相结合，以补充监测方案，成本比地震采集低得多。这可以节省大量成本，并减轻与区域外流动相关的环境风险，即石油从控制的储层体积流入附近的含水层。μ子是宇宙辐射和高层大气相互作用产生的高能粒子。μ子比电子重200倍，这使得它们能够穿透物质并通过衰减来感知材料密度的变化。重量分析法对传感器周围的所有质量或密度分布进行积分。因此，这两种技术都能检测地下的密度，但机制截然不同。μ子层析成像解决密度异常与极端的本地化，但深度分辨率低，而重力感测有限的本地化，但良好的深度分辨率的位场。结合起来，这允许联合反演μ介子和重力观测，这将产生前所未有的细节的地下密度分布及其随时间的变化。加入女王大学的重力梯度测量专业知识和CRM GeoTomography Technologies的μ子断层扫描技术，将实现一种创新技术，允许更频繁地监测和改进蒸汽操作和生产周期的规划。最终，这项技术可以大大节省水的消耗，并需要蒸汽生产作为加拿大的额外环境效益。

Steam assisted gravity drainage (SAGD) is an enhanced oil recovery technique frequently applied to the oil sands region of western Canada. The production of heavy oil requires large amounts of water, which is turned into steam, and eventually pumped into the ground to mobilize heavy oil. Heavy oil drains into a producer well from which it is extracted. Costs associated with steam production could be reduced if steam would be injected only at locations which produce oil, but monitoring of SAGD reservoirs is often limited to 4D seismic surveys every other year. We propose a combination of two innovative monitoring techniques, gravity gradiometry and muon tomography, to complement the monitoring options at a much lower cost than seismic acquisitions. This could turn into significant costs savings as well as mitigate environmental risks associated with out-of-zone flow, where oil runs out of the controlled reservoir volume into nearby aquifers.Muons are high energy particles generated through the interaction of cosmic radiation and the upper atmosphere. Muons are 200 times heavier than electrons which allows them to penetrate through matter and sense variations in material density through attenuation. Gravimetry integrates over all masses or the density distribution surrounding the sensor. Both techniques therefore sense density in the subsurface, but through very different mechanisms. Muon tomography resolves density anomalies with extreme localization, but low depth resolution, while gravimetry senses a potential field with limited localization, but good depth resolution. In combination, this allows for joint inversion of muon and gravity observations which will yield unprecedented details of the subsurface density distribution and its change over time. Joining the expertise in gravity gradiometry at Queen's University and muon tomography at CRM GeoTomography Technologies will enable an innovative technology allowing for more frequent monitoring and improved planning of steam operations and production cycles. Ultimately, this technology could turn into significant savings in water consumptions and required steam production as additional environmental benefits to Canada.