A pair of inventive companies are working on a way to allow microseismic tests to visualize the otherwise silent process of propping fractures.
The project brings together a French creator of a microdevice designed to create a distinct sound when the hollow structure collapses after reaching its destination—Fluidion—and an inventor in California who created an ultrasensitive in-well seismic receiver array, which is the only one capable of recording and locating that faint pop—Björn Paulsson.
“We believe that with our sensor…we can more precisely locate where microfracturing is happening and where the proppant is going,” said Paulsson, founder and chief executive officer of Paulsson Inc.
The project brings together a French creator of a microdevice designed to create a distinct sound when the hollow structure collapses after reaching its destination—Fluidion—and an inventor in California who created an ultrasensitive in-well seismic receiver array, which is the only one capable of recording and locating that faint pop—Björn Paulsson.
“We believe that with our sensor…we can more precisely locate where microfracturing is happening and where the proppant is going,” said Paulsson, founder and chief executive officer of Paulsson Inc.
The joint effort is one of several research efforts backed by the US Department of Energy to develop improved ways of measuring the impact of fracturing. While others are working on using electromagnetic imaging to show the volume of propped rock, this project is aimed at mapping fracturing by locating points of sound from tiny devices collapsed by natural pressure, like squeezing the bubbles in a protective wrap.
The microdevices, which Fluidion calls acoustic microemitters, will be mass-produced using 3D printing techniques in large sheets, which are then cut into tiny bits.
Each emitter has a hollow core and includes a tiny version of a water clock that is activated when the device has been exposed to reservoir pressure. The microelectromechanical device delays the collapse long enough to ensure it reaches its destination in the ground before imploding. Testing verified that the vast majority of the emitters could survive a trip through a pump, Paulsson said.
The plan is to create emitters in two sizes: about 2 mm across or 4 mm across, each of which will produce a different sound. The number to be used per test is under consideration, but a working estimate is about 1,000 acoustic microemitters per stage, he said. That would create “a cloud of these microemitters and we could listen to them and locate where they are in space,” Paulsson said. The different sounds of the large and small microemitters could help identify the fracture size, as well as their extent and orientation.
If all components meet specifications, the plan is to place the receiver in an idle well in the middle of a six-well pad, and observe the sounds in the other five as they are fractured.
A couple of years of work are expected before in-ground tests are possible, he said. The time is required for building a protective steel shell for the 2,500 ft-long string that will house the 100-level receiver array, and to develop the system needed to dependably mass-produce the microemitters.