ABSTRACT

In assessing the origin of fracture porosity a question arises as to the depths at which fractures develop and become openings that conduct fluid flow. Information bearing on this question can be gained by determining the homogenization temperature of gas-liquid inclusions in the mineral-filling which now occupies some of these fracture openings. Samples are taken from fractures in Cardium sandstone that outcrops in Foothills structure along South Ram River, from fractures in Cardium beds cored within the Ricinus field, and from wells east of this field, in the Foreland. For each locality fluid inclusions display ranges of homogenization temperatures which are interpreted as indicating that opening of fractures developed progressively as an accompaniment to tectonism, regional uplift and erosional unloading. The evidence also indicates that incipient fracture porosity at depth can develop gradually into a network of open fractures under conditions of continued uplift and erosional unloading.