Presented by Yong Xu
April 24th, 2007
11:45 to 1 pm (lunch provided)
Suite 2600, 111 - 5th Ave SW, East Petro-Canada Tower
Limited seating, click here to RSVP

This is the fifth in a series of lunch & learn seminars, see the sidebar for information on the other topics.

It is well known that the bitumen bearing McMurray formation in the Athabasca oil sand area is highly heterogeneous. High risks exist for SAGD projects if the reservoir heterogeneity is not understood well. As the lithology may vary from sand-dominated to mud-dominated in just a short distance, inference from core to core may not be reliable. Surface seismic, with its ability to image subsurface laterally and vertically, has the potential to help describe reservoir heterogeneity, and such applications can be found in the literature over the past decade. From the published case histories demonstrating the applications of seismic for understanding oil sand reservoir heterogeneity, one can find that the statistical approaches, mainly artificial neural network, were emphasized (Tonn, Dumitrescu et al, Gray et al, and Anderson at al). One of the reasons is the difficulty to solve for reliable attributes deterministically from surface seismic, which may be strongly correlated to lithofacies variation. On the other hand, deterministic seismic interpretation of reservoir heterogeneity is also hindered by the lack of understanding of the relationship between lithology and traditional seismically derived elastic parameters. This study shows that reliable and deterministic mapping of oil sand reservoir heterogeneity is possible by understanding the petrophysics, using more reliable inversion, and adapting the right interpretation strategy. Three aspects will be presented in the talk.

1. Petrophysical study to find out the sensitivity of seismically derived elastic attributes to lithofacies variation. Well logs from two plays in the Athabasca oil sands area are studied. The study shows that a number of seismically derived elastic attributes exhibit strong or weak abilities to separate lithology, although ambiguity exists by using a single attribute to separate high quality sand from other facies. The study suggests that two or more attributes be chosen to describe the lithology heterogeneity.

2. Reliable inversion strategy to estimate density information from seismic data. Density is a lithology sensitive attribute; however, density information may not be resolved reliably by traditional inversion approaches. To extract density information from seismic, a reliable inversion approach is required. The study evaluated the inversion approaches used in the industry to solve density from pre-stack seismic data and developed a new reliable inversion approach.

3. Discussion on the heterogeneity mapping strategy. As heterogeneity is a crucial element in the oil sand reservoirs, layer boundaries and horizons are difficult to define and may cause wrong characterization when they are used improperly in the seismic inversion. The use of seismic reflection attributes with a more general constraint will be addressed in the discussion.

To learn more, attend the lunch & learn session on April 24. Click here to RSVP.

This course is available as a free in-house seminar. For more information contact Florence Janzen, 781-1437 or email fjanzen@arcis.com.