Modern heavy oil projects typically use SAGD (Steam Assisted Gravity Drainage) or CSS (Cyclic Steam Stimulation “huff-and-puff”) technologies. CSS involves injection of steam into a well for weeks to months, then the well is shut in to heat and soak for days or weeks and later the hot oil is pumped out of the well. Being lighter than water, oil floats above water in a permeable reservoir. Ideally the oil is produced leaving the water in place. Due to the large capital investment required for the surface facilities and high production costs, heavy oil projects must be completed on a large scale to be economical. A full understanding of the reservoir is required in order to ensure the play is commercial prior to investing significant capital is critical.
Thin (2 – 3m) inter-layered bitumen and water legs were confirmed with recovered core samples. Husky needed to determine if the oil could be produced though CSS. In order for the project to be viable the oil needed to be produced, while leaving the water in place. Calculating the permeability (k) of the water leg was critical in order to determine if the water was mobile.
Northstar isolated the two metre water leg with an Inflate Straddle DST string. Bottom hole pressure data was recovered during multiple flow and shut-in periods. A fluid flow rate was calculated and Reservoir analysis determined the water zone permeability.
An Open Hole DST recovered the essential data to help characterize Husky’s heavy oil reservoir and provided the information Husky’s engineers and managers required to determine if a CSS project was feasible.