De Rerum Fractura. These days it is much in the mind of petroleum seismic researchers to get into the “fracture game.” This is driven by the remarkable rise in natural gas reserves from shale reservoirs, primarily in the US for now but quickly being exported worldwide. Shale formations have long been of interest as source rock and reservoir seal, but in the last 20 years shale has taken center stage as a reservoir in its own right. Gone are the days when we would drill through shale and get a gas kick, ignore it, then drill on down to conventional reservoirs. Gas shale is considered an unconventional reservoir, mainly because of very low porosity and permeability compared to those Swiss cheese sandstones and limestones. For a 25% porosity conventional reservoir, you need only to punch a hole through it, open the choke, and production will scream out for decades. But shale, like tight gas sand, must be modified to open channels for production. Wells must be horizontally drilled to expose more reservoir rock and they must be fractured.

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