The Mitsue field, in north-central Alberta, produces large quantities of oil and minor gas from the Middle Devonian Gilwood Sandstone Member of the Watt Mountain Formation. This sandstone is generally clean, well sorted, fine to medium grained, and quartzose. The average oil column at the field is 4 m, and porosity averages 15-20 percent.
In retrospect, it seems surprising that for more than a decade explorationists condemned the Gilwood as being either “tight” or water bearing. The Gilwood is an excellent example of the type of widespread sandstone units common in sedimentary basins throughout the world. Many such units have not been explored fully and undoubtedly contain petroleum reservoirs awaiting discovery.