Baton Rouge, La — Juan Lorenzo, associate professor of geology & geophysics, and Arash Dahi Taleghani, assistant professor of petroleum engineering, recently received funding to simulate real fracturing treatments through the establishment of a hydraulics fracturing lab, the first of its kind at LSU.
The duo received this nationally competitive award through Research Partnership to Secure Energy for America, or RPSEA. Over the next two years, the Gas Technology Institute in Chicago will head a team of experts from Lawrence Berkeley National Laboratory, University of California at Berkeley, LSU and the private sector to develop advanced methods and techniques for design and execution of environmentally safe and economically efficient hydraulic fracturing.
The RPSEA award is not the first grant collaboration for Lorenzo and Taleghani. The award follows another grant the team received in 2010 from the Louisiana Board of Regents Industrial Ties Research Subprogram. Lorenzo and Taleghani were attempting to collect information on the frequencies of seismic waves emitted by hydraulic fractures as they grow.
“It turns out that when the oil and gas companies collect the data, they don’t do it scientifically. So we can’t verify our ideas,” said Lorenzo. “The next best thing would be to get a lot of money and break rocks in the field, but that’s not as efficient as doing it in a lab.”
The oil and gas industry uses hydraulic fracturing to break subsurface rock with pressurized fluid. The created cracks act like “highways” in which gas and petroleum can flow faster and easier. When not executed properly, this technique has the potential to limit the size of the fractures or run into aquifers exposing drinking water resources to hazardous chemicals.
Lorenzo and Taleghani plan to use the RPSEA award to recreate hydraulic fracturing in a lab on LSU’s campus, which will allow them to control all of the variables and test hypotheses to understand how and why the rocks break in a particular way. Using the right ratio of viscosity of fluids in the rock, Taleghani will be able to scale down the experiment to lab scale.
Lorenzo finds parallels between hydraulic fractures and the way magma flows through rock. Interestingly, magma has similar viscosity to the fluids used to break rocks in the oil and gas fields. Though micro seismic monitoring techniques are used in the field, there are many limitations to measuring tension among the cracks, including the frequency range of the sensors and environmental noise. The team plans to perform experiments under controlled laboratory conditions specifically designed to record and analyze various kinds of micro seismic events. In order to measure the data properly, a super computer and high frequency sensors are required in the hydraulics-fracturing lab.
The lab will supply two major components. The first component is a very small high-frequency sensor that is capable of listening to up to two and a half million hertz. Humans normally hear up to about 20 thousand hertz, meaning that these sensors are about 100 times more sensitive than the human ear. The lab will contain multiple sensors for extremely precise seismic monitoring. The second component is a super computer with capabilities of collecting the large amounts of data that the sensors will produce.
“We will have about 20 sensors placed around the block as listening devices and we will use the same methodology that earthquake scientists use, and from the sound we can locate where the crack is occurring,” said Lorenzo.
“It is important to determine the size and dimensions of fractures in order to predict hydrocarbon production in the future,” said Taleghani. “You can also use this for assessing fracture design. From a safety point of view, for example, you do not want to have a height growth into nonproducing zones or shallow aquifers.”
Lorenzo and Taleghani are trying to understand how they can locate the tip of fractures in order to improve fracture assessments in the future.
“For the students, it’s a fantastic learning environment,” said Lorenzo. “This sort of lab is very valuable because it gives students a unique experience in a controlled setting to understand the fundamentals of what goes on.”