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Significant resources of viscous heavy oil exist in Canada and Venezuela and much of these resources require thermal recovery methods to recover the oil efficiently. Early thermal schemes employed steamflooding with vertical wells (especially in the USA), which suffered from steam override. The large thermal commercial projects currently underway in Canada plan to use SAGD (steam assisted gravity drainage) schemes with dual horizontal well pairs. In SAGD, the upper horizontal injects steam which is allowed to rise and drain towards the lower horizontal well which produces the mixture of condensed steam and oil collected though gravity drainage. The expected recovery of SAGD schemes is in the order of 60%.
Epic provides reservoir studies for both steamfloods and SAGD and is familiar with the requirements of thermal simulations such as geological characterization, fine scale gridding (typical 1 m dimensions), steam trap control and geomechanical effects. We also provide assesments of the thermal potential of undeveloped properties for acquisitions.
In the example shown, our client was considering the acquisition of an oilsands property with a small pilot. The thermal profiles acquired from 4D seismic suggested an uneven sweep of steam within the reservoir (with implications for ultimate recovery). The model created also matched the unusual declining steam oil ratio of one injector-producer pair by modeling the interference.
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Idealized SAGD Drainage
Actual thermal profile (areal view) shows uneven conformance of steam in reservoir
Declining SOR due to interference
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