In the Western Canadian Sedimentary Basin (WCSB), abundant tight and light oil resources are locked in formations such as Bakken/Exshaw, Viking, Cardium and Lower Shaunavon. While new tight oil wells are highly productive when stimulated through hydraulic fracturing, this production declines rapidly from its initial peak. We can see declines at rates of more than 85 per cent per year, with ultimate primary recovery of only 3 to 10 per cent of the original oil in place.
Innovation for multi-stage hydraulic fracturing in horizontal wells has proven to be the key factor in the booming development of the light and tight oil fields over the last decade. Technology advancements enable oil producers to increase recovery factors while lowering decline rates, capital and operating costs. Even in the current price environment, light and tight oil formations are among the most economic oil plays in North America. However, gaps remain.
Significant work is needed to grow or even sustain the current level of production. Because of the micro- to nano-meter-scale flow channels in tight oil formations, their phase behaviour and multi-phase flow could be significantly different from those in conventional oil reservoirs. There are large local variations in permeability, lithology and mineralogy. This is further complicated by fluid flow and mass transfer between the matrix and fractures with extreme permeability contrast.
This presentation reviews the challenges associated with tight oil recovery and EOR. It assesses state-of-the-art IOR and EOR techniques, focusing on the gaps and challenges in our understanding of various mechanisms and processes important for the most popular techniques of improved oil recovery in tight reservoirs, such as waterflooding, gas flooding and chemical flooding.