One seismic source and receiver couple to detect steam effects on legacy data in Surmont, Canada
Paper presented at the EAGE 2021 – Annual Technical Conference and Exhibition, Amsterdam, Netherland, November 2021, and co-written by Victoria Brun, Elodie Morgan, Brad Gerl, Luis Cardozo, Jeremie Batias.
Surmont is a heavy oil field located in northeast Alberta currently being developed by a joint venture between ConocoPhillips and Total. A pilot project started in 1997 using Steam Assisted Gravity Drainage (SAGD) as improved oil recovery method to develop the field. This technique utilizes a pattern of horizontal well pairs that continually inject steam into the reservoir to mobilize the heavy oil so it can be produced (Byerley et al., 2009). To monitor the enhanced oil recovery process, highly repeatable 4D seismic surveys have been completed every 6 months over the years. Apart from the 600km² of 3D seismic, there are now about 1500 wells, most of which are covered by the 3D: a very dense and well-known area that has cost millions of dollars of investment.
In order to maximize the value of information while controlling costs, a novel light seismic monitoring approach has been “blind-tested” on existing well and 4D data. The concept requires the use of only one source and one receiver location optimally placed in the field to monitor a spot in the subsurface, using time lapse shots to detect 4D changes in the zones of interest. Subsurface changes linked to variations of constraints, temperature, pressure and saturation can be tracked in the non-migrated domain by comparing seismic traces acquired over time by each source/receiver couple.
The objective of this blind test was to see if the steam had reached one zone and not another without knowing previous reservoir history. The results obtained after the survey have then been compared to existing 4D vintages and well data to (in)validate said approach. The bigger picture was to see if this focused detection approach could complement or help space 4D campaigns in specific locations where the uncertainty remains high while controlling costs. In a never-ending fluctuating Oil & Gas environment, such solution could represent an affordable alternative to conventional monitoring techniques.