289-3 Measurements of lithium in highly-saline brines: a cautionary tale.

Session: Estimating Natural Resources Using Geoscience Data

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Abstract:

The exploration interest in brine-hosted lithium from sedimentary basins continues. Exploration companies and academic researchers are attempting to understand lithium source and distribution and to build predictive models for data-poor and/or new areas. This commercial and scientific effort should be based on accurate measurements of lithium concentrations in the saline brines that host the resource. Yet data and studies continue to be published that contain avoidable errors in lithium concentrations.

There are two major categories of potential problems when it comes to accurate measurement of lithium concentrations in highly-saline brines. The first is due to the imperfect nature of the connection between the surface and subsurface: the wells used to produce the brine that hosts the lithium. Issues that can lead to non-representative lithium concentrations can include one or more of: i) wells sampled before complete purging of completion/stimulation fluids; ii) producing wells treated with fresh water or chemicals (continuously or batch) to manage salt buildup, corrosion, or other operational concerns; iii) wells producing from a zone with a nearby waterflood or water-disposal facility in the same zone; iv) producing wells with low water to gas ratio, where the produced fluids might be water condensed out of the produced gas; or simply v) wells producing stray (out of zone) fluids. The second category of problems arises from the lithium concentration measurements themselves. It is difficult to accurately and precisely measure 10’s to 100’s of mg/L of lithium in a saline brine with Total Dissolved Solids of typically 300,000+ mg/L (i.e., often <0.001%). Historical data are at most risk of this problem, but there remain challenges even using the most modern ICP-OES or ICP-MS instruments. When both of these categories of problems are combined, it is possible to obtain lithium concentrations that are significantly higher, or lower, than actual in-situ values. Sadly, numerous examples exist in the current literature with inaccurate lithium concentrations. These inaccurate data are being further incorporated into source studies, exploration models, and resource estimates.

This talk will review some examples of the problems of measuring lithium in highly-saline brines, and propose some possible solutions.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-11000

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