Abstract Details
(2020) A Systematic Study of Element Mobilisation from Gas Shales during Hydraulic Fracturing
Otalega I, Apte S, King J, Dobson K, Shipton Z & Renshaw J
https://doi.org/10.46427/gold2020.2002
The author has not provided any additional details.
08e: Room 3, Tuesday 23rd June 00:30 - 00:33
Izabella Otalega
Simon C. Apte View all 4 abstracts at Goldschmidt2020
Josh King
Katherine Dobson View all 2 abstracts at Goldschmidt2020
Zoe Shipton View abstracts at 3 conferences in series
Joanna Renshaw View all 3 abstracts at Goldschmidt2020 View abstracts at 10 conferences in series
Simon C. Apte View all 4 abstracts at Goldschmidt2020
Josh King
Katherine Dobson View all 2 abstracts at Goldschmidt2020
Zoe Shipton View abstracts at 3 conferences in series
Joanna Renshaw View all 3 abstracts at Goldschmidt2020 View abstracts at 10 conferences in series
Listed below are questions that have been submitted by the community that the author will try and cover in their presentation. To submit a question, ensure you are signed in to the website. Authors or session conveners approve questions before they are displayed here.
Submitted by Basu Sudeshna on Monday 22nd June 09:36
The presentation is very interesting. I am curious to know how your leach tests might be affected by the solid:fluid ratio. Also, how do you explain the higher amount of leached Si for SGW than SHFF? Is it possible that they are leached but form complexes and is retained by the shale? This is in reference to the secondary precipitates of Ca, S, K and Cl you mentioned- Is it possible to know their composition more specifically? Thanks
Hi, thank you for the questions! To answer your first question, we did some preliminary investigations on the solid:fluid ratio with a carbonate-poor Kimmeridge Clay sample using SGW, leached for 5 hours at 80 C at four different solid:fluid ratios - 1:100, 1:50, 1:25 and 1:10. Major elements typically increased in concentration with higher ratios albeit non-linearly. On the other hand, most of the detectable trace elements seemed not particularly affected by it (e.g. As, Pb, V). However, this could be due to the gentle nature of the fluid, essentially just warm water. I suspect if investigated with SHFF, the results could show more pronounced differences. The estimated solid:fluid ratio during hydraulic fracturing is at least four orders of magnitude higher (100:1) ((Renock et al., 2016) than the ratios used by us and other studies. We ended up using 1:50 due to sample availability. It is likely we may be observing more diluted solutions, at least for some elements, than what could occur during actual hydraulic fracturing operation. Regarding the higher amount of Si leached by SGW than SHFF, it’s a consistent trend we observed for samples containing a considerable carbonate component. I am not yet sure how to explain this, but secondary precipitation is definitely a possibility. At this point we don’t know the specific composition of the secondary precipitates beyond what I shared in the presentation. I’m hoping that further SEM and EDX work, delayed due to Covid-19, will shed light on this as well as the Si trend. Thank you!
The presentation is very interesting. I am curious to know how your leach tests might be affected by the solid:fluid ratio. Also, how do you explain the higher amount of leached Si for SGW than SHFF? Is it possible that they are leached but form complexes and is retained by the shale? This is in reference to the secondary precipitates of Ca, S, K and Cl you mentioned- Is it possible to know their composition more specifically? Thanks
Hi, thank you for the questions! To answer your first question, we did some preliminary investigations on the solid:fluid ratio with a carbonate-poor Kimmeridge Clay sample using SGW, leached for 5 hours at 80 C at four different solid:fluid ratios - 1:100, 1:50, 1:25 and 1:10. Major elements typically increased in concentration with higher ratios albeit non-linearly. On the other hand, most of the detectable trace elements seemed not particularly affected by it (e.g. As, Pb, V). However, this could be due to the gentle nature of the fluid, essentially just warm water. I suspect if investigated with SHFF, the results could show more pronounced differences. The estimated solid:fluid ratio during hydraulic fracturing is at least four orders of magnitude higher (100:1) ((Renock et al., 2016) than the ratios used by us and other studies. We ended up using 1:50 due to sample availability. It is likely we may be observing more diluted solutions, at least for some elements, than what could occur during actual hydraulic fracturing operation. Regarding the higher amount of Si leached by SGW than SHFF, it’s a consistent trend we observed for samples containing a considerable carbonate component. I am not yet sure how to explain this, but secondary precipitation is definitely a possibility. At this point we don’t know the specific composition of the secondary precipitates beyond what I shared in the presentation. I’m hoping that further SEM and EDX work, delayed due to Covid-19, will shed light on this as well as the Si trend. Thank you!
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