We are excited to announce that our speaker for this month is Dr. Adam Jew, who is an associate staff scientist at the Stanford SLAC National Accelerator Laboratory. The title of his presentation is: Understanding the Geochemical Impact of Injection Fluids on Unconventional Shale Systems. An abstract of the talk and a short bio of Dr. Jew are shown below.
Title: Understanding the Geochemical Impact of Injection Fluids on Unconventional Shale Systems
When: Wednesday, March 16, 2022 (11AM Pacific)
Where: Online via Zoom
Meeting Link: Zoom Meeting - SPEGGS March 2022 Link
Meeting ID: 859 4944 2697
Abstract
Unconventional oil/gas shale production has led to US energy independence and is a major contributing factor to the reduction in CO2 emissions over the past decade. In spite of these successes, unconventional stimulation practices remain highly inefficient. Though current injection practices use a wide array of chemicals for a variety of purposes to promote production, these chemicals can prime the system for later mineral scale precipitation. This mineral scaling can lead to decreased production and requires a multi-faceted approach to understanding the important chemical reactions occurring. By blending laboratory- and synchrotron-based laboratory techniques with reactive transport modeling it has been shown that mineral scaling is occurring by both mineral scaling on fracture surfaces derived solely from injected chemicals and in the internal shale matrix caused by transformation of the naturally occurring minerals caused by the injection fluids.
Producing shale plays encompass clay-rich (> 25 wt.%) and carbonate-rich (> 20 wt.%) lithologies. Most unconventional stimulations begin with extremely low pH (pH -0.3) with later steps in the injection process being as high as pH = 10. These wide pH ranges coupled with the large range of lithologies result in different mineral scaling rates and phase behaviors. Regardless of these lithological variations, Fe(III)-(hydr)oxides are a universal scaling problem in the shale matrix while sulfates primarily precipitate on the surfaces. The degree to which sulfate scaling occurs is controlled by the composition of the both the additives and the base fluid used. The sourcing of the base fluid is critically important and needs to be taken into account when selecting additives to minimize sulfate scaling. Besides the interactions between additives and base fluids, the disequilibrium caused by the base fluid alone can cause mineral scaling as well. This disequilibrium covers a wide range of chemical parameters (pH, redox, ionic strength, dissolved organics). In some situations, mineral transformation/scaling is so rapid that additives added to control scaling are arriving too late to mitigate the problems. The insights garnered through studies of injection fluids with the minerals in the stimulated rock volume provides the necessary knowledge that allow for important incremental changes to the chemical aspects of stimulations.
About the Speaker
Dr. Adam Jew is an associate staff scientist at SLAC National Accelerator Laboratory with a focus on mineralogy and geochemistry of various earth systems using a combination of laboratory- and synchrotron-based methods. He received his PhD in surface and aqueous geochemistry from Stanford University and has worked in a variety of research fields from mercury in the environment to coal and unconventional oil/gas shales. His current focus is on geochemistry of unconventional oil/gas shales, enhanced geothermal systems, and critical material geochemistry.
Next Meeting
Our speaker for next month is Varadarajan Dwarakanath. Stay tuned for our next meeting announcement!