High Temperature Geochemistry

EESA’s Geochemistry Department scientists have developed geochemical experimental capabilities at temperatures and pressures beyond the ambient conditions characteristic of environmental geochemistry. Our geochemists have the expertise to quantify high temperature, high pressure rock-water-gas interactions that play critical roles in controlling the behavior and fate of CO2 injected into deep subsurface formations, geochemical interactions occurring within geothermal systems, and mineral-aqueous fluid interfacial geochemical processes.

Our experimental geochemistry capabilities now span from the bench-scale to the nanoscale. Current research topics:

  • Rock-water-gas interactions that control the behavior and fate of CO2 injected into deep sedimentary basins, oil fields, and elsewhere within the shallow crust
  • Geochemical interactions occurring within geothermal systems
  • Geochemical impact of various strategies employed in Enhanced Geothermal Energy recovery approaches
  • Fundamental research into mineral-aqueous fluid interfacial geochemical processes.

Our bench-scale studies use hydrothermal geochemical reactors of various types that permit experiments at temperatures up to 400°C and pressures up to 200MPa. Instrumentation:

  • Four rocking furnaces equipped with flexible gold bag (Dickson-type) reaction cells and super-alloy pressure vessels
  • Associated digital controllers, an analogue/digital datalogging system
  • A piston accumulator (for reinjecting fluid into the gold bags during a run)
  • Two air-driven (Sprague) high pressure pumps
  • Two ISCO 500D HPLC pumps (one dedicated to CO2 delivery using a chiller jacket)
  • A Quizex computer-controlled precision high pressure two-piston metering pump

Fluid samples can be acquired throughout an experiment without disturbing the experiment’s temperature and pressure.

Our nanoscale studies use a custom-built (homemade, one of a kind) Hydrothermal Atomic Force Microscope (HAFM) capable of real-time subnanometer (crystal monolayer) scale imaging of crystal growth and dissolution at up to 150°C and 10 b pressure under flowing conditions (gas or liquid), including aqueous fluids spanning a range in pH (pH1 – pH10) and fluid composition. A Picostage X-Y translator allows precise sample positioning over a ±1mm range. A modified (for cooling) Digital Instruments Top View © optical head also permits simultaneous video microscopy —ideal for crystal growth/dissolution catalysis/inhibition mechanistic studies. Recently, we have built a minibending jig for use inside the HAFM, permitting simultaneous geomechanical/geochemical studies, e.g., subcritical crack growth, frictional force measurements.

We work closely with the Geochemical Transport group and use a variety of geochemical simulators to both design and interpret experiments.

Current research is funded by the DOE: Office of Basic Energy Science, Office of Fossil Energy, and the Office of Energy Efficiency & Renewable Energy- Geothermal Program Office. We participate in the LBNL EFRC Center for Nanoscale Control of Geologic CO2.