Nov
8
Getting Every Last Drop
November 8, 2011 | Leave a Comment
University of Alberta researchers have developed ROC as a way to replicate oil trapping rock layers and show energy producers the best way to recover every last bit of oil from these reservoirs.
Mechanical engineering professor Sushanta Mitra leads a team of University of Alberta researchers using an actual core sample from oil drilling sites to make 3D mathematical models of the porous rock formations that can trap huge quantities of valuable oil.
Recovering the oil trapped in porous layers of sandstone and limestone is a tricky and costly operation for energy exploration companies the world over. But they all have core samples of their reservoirs.
Mitra explains, “The process starts with a tiny chip of rock from a core sample pulled from porous rock where oil has become trapped. That slice of rock is scanned by a Focused Ion Beam-Scanning Electron Microscopy machine, which produces a 3D copy of the porous rock. The replica is made of a thin layer of silicon and quartz at Nanofab, the U of A’s micro/nanofabrication facility.”
Reservoir on a Chip Sample. Click image for the largest view.
The team calls the finished little 3D model a Reservoir on a Chip.
Mitra continues, “The hugely expensive process of recovering oil in the field is re-created right in our laboratory. The researchers soak the ROC in oil and then water under pressure is forced into the chip to see how much oil can be pushed through the microscopic channels, and recovered.
“ROC replicas can be made from core samples from oil trapping rock anywhere in the world,” said Mitra. “Oil exploration companies will be able to use ROC technology to determine what concentration of water and chemicals they’ll need to pump into layers of sandstone or limestone to maximize oil recovery.”
The new chip represents the individual pore structure of a naturally occurring oil-bearing reservoir rock. The pore-network has been etched in a silicon substrate and bonded with a glass-covering layer to make a complete microfluidic chip. That makes it possible to perform traditional waterflooding experiments in a ROC. Oil is kept as the resident phase in the ROC, and waterflooding is performed to displace the oil phase from the network. The flow visualization provides specific information about the presence of the trapped oil phase and the movement of the oil/water interface/meniscus in the network.
The Alberta team is a little further along than a first glance suggests. The paper contains the first indication that this oil-recovery trend realized at chip-level can be correlated to the flooding experiments related to actual reservoir cores.
Mitra and his team have successfully demonstrated that the conceptualized ‘Reservoir-on-a-Chip’ has the features of a realistic pore-network and in principle is able to perform the necessary flooding experiments that are routinely done in reservoir engineering.
This is no small thing – most of the oil, more than half, perhaps 75% or more is still in the ground. The huge oil consumption to date could be only about a third of the inventory already at hand. The University of Alberta team’s new reservoir modeling based on the actual rock below plus the new ways to describe the shape and circumstances of the oil and how the rocks are laid out may well discover even more reversions than current understood.
This is a great idea already on its way to being a proven working concept. Great work folks.
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