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

蒸汽辅助重力泄油（SAGD）是一种经常应用于加拿大西部油砂地区的提高采收率技术。重油的生产需要大量的水，这些水被转化为蒸汽，最终被泵入地下以动员重油。重油排到生产井中，从中提取重油。如果只在产油位置注入蒸汽，则可以降低与蒸汽生产相关的成本，但SAGD油藏的监测通常仅限于每隔一年进行一次的四维地震调查。我们建议结合两种创新的监测技术，重力梯度法和介子层析成像，以比地震采集低得多的成本补充监测选择。这可以大大节省成本，并减轻与层外流动相关的环境风险，即石油从控制的储层中流出，流入附近的含水层。μ子是由宇宙辐射和上层大气相互作用产生的高能粒子。μ子比电子重200倍，这使它们能够穿透物质，并通过衰减感知物质密度的变化。重力测量集成了传感器周围的所有质量或密度分布。因此，这两种技术都是通过非常不同的机制来感知地下的密度。介子层析成像以极局部化解决密度异常，但深度分辨率较低，而重力测量以有限的局部化感知势场，但深度分辨率较好。结合起来，这允许μ子和重力观测的联合反演，这将产生前所未有的地下密度分布及其随时间变化的细节。Queen’s University的重力梯度测量技术和CRM GeoTomography Technologies的介子断层扫描技术的结合，将使一项创新技术能够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和所需的蒸汽生产，为加拿大带来额外的环境效益。

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.