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

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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.