麻豆传媒

Variations in porosity and permeability are common concerns when analyzing formations for reservoir quality. The Cretaceous Bluesky Formation of Whitecourt Alberta is a tight gas formation where average permeability is > 0.1 mD. The Bluesky Formation in Whitecourt was deposited during a regional transgression and shows three main depositional well log signatures. "Bluesky A" is regionally extensive and interpreted as a channel mouth to shoreface deposit containing several characteristic ichnofacies and ranging in thickness from 1-4 m. "Bluesky B" is a channel deposit and or barrier bar system trending NE-SW, located primarily in the western portion of the study area near Edson, and ranging in thickness from 7-18 m. "Bluesky C" is an estuary deposit and contains several metres of mud draped sand lenses and is moderately to heavily bioturbated.

Samples taken from 6 cored Bluesky wells have been studied to investigate why porosity and permeability vary from well to well but also within a single well. Stratigraphic columns show the Bluesky Formation fits into 3 depositional environments. Representative gamma log signatures have been identified for each of the depositional environments and are used to identify the sands in well logs. Porosity and permeability data collected using the Accumap database, and from thin sectioned samples have been studied extensively. This has allowed a comparison of the collected data for porosity and permeability with thin sections and the stratigraphic logs. By sampling and photographing sections of high and low porosity/permeability the causes for the variations became more evident. The changes in porosity and permeability are attributed to the depositional environment, sedimentary features, and the diagenetic processes the formation has undergone since it was deposited.

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Pages: 127
Supervisors: Martin Gibling