GISERA Community Webcast October 2022

Gas_Industry_Social_and_Environmental_Research_Alliance_Community_Webcast_18_10_2022

 

 

[Music plays and an image appears of a digital map, and the CSIRO logo and text appears on the left: Gas Industry Social and Environmental Research Alliance, Researching the environmental and socio-economic impacts of onshore gas activities, 18 October 2022]

 

[Image changes to show participants on the screen]

 

[Image changes to show Tsuey Cham talking to the camera on the main screen, and participants can be seen in the bar at the bottom of the screen]

 

Tsuey Cham: Hello, and welcome to the Gas Industry Social and Environmental Research Alliance’s community webcast. My name is Tsuey, and I’m your host for today. Firstly, I would like to acknowledge and pay my respect to Elders, past and present, and to members of the Aboriginal and Torres Strait Islander communities who are with us on this webcast today. I particularly want to acknowledge the Turrbal, Jagera, and Yugara peoples, the Traditional Custodians of the lands on which I work and live.

 

I would like to go through a couple of housekeeping items before we start. We will hold questions until the end of both presentations, and you can submit your questions in the Question section which can be found by clicking on the icon that has a speech bubble with a question mark on the right hand side of your screen.

 

[Image continues to show Tsuey talking to the camera, and participants can be seen in the participant bar at the bottom of the screen]

 

GISERA has been running for 11 years and since launching in 2011 it has grown to become nationwide. CSIRO researchers have undertaken a wide range of projects and there are more than 70 projects either completed or underway in Queensland, New South Wales, South Australia, Northern Territory, and Western Australia. The aim of this webcast is to highlight the relevance and impact of the research and hear directly from our researchers. It is also an opportunity for you to ask questions.

 

Today, we dive into our groundwater research. Our first set of speakers are our groundwater scientists, Drs Matthias Raiber, and Axel Suckow. Dr Raiber specialises in the integration of hydrogeological, hydrochemical, and isotype information to improve the understanding of the connections between deep and shallow groundwater aquifers and surface water systems. Dr Suckow manages the CSIRO Environmental Tracer Laboratory in Adelaide, South Australia, a world leading facility using noble gases in the geosciences. Concentrations of all stable noble gases and their isotype ratios in groundwater and soil gas are routinely measured, and this is the only facility in the southern hemisphere with this capability. To date the water cycle and ice, new applications of argon and krypton radioactive noble gas isotypes are being developed at the lab. Only four other research groups worldwide have this capacity.

 

[Image continues to show Tsuey talking to the camera, and participants can be seen in the participant bar at the bottom of the screen]

 

Our second set of presenters are groundwater modellers, Drs Rebecca Doble, and Sreekanth Janardhanan. Dr Doble’s research interests are in groundwater, hydrology – especially recharge and discharge, integrating groundwater models with remote sensing and geophysics data, and interactions between rivers and groundwater. Dr Janardhanan’s research focuses on groundwater modelling and uncertainty analysis for the assessment, monitoring and management of the impacts of onshore gas and mining developments on groundwater resource.

 

But before I throw to our researchers, I’ll hand you over to Dr Cameron Huddlestone-Holmes, a Principal Research Scientist within CSIRO. Cameron works on environmental, geological, and geotechnical problems in the Earth resources industry, and is a state leader for the, for GISERA. So, Cameron will provide you a quick overview about GISERA. Thank you Cameron.

 

[Image changes to show Dr Cameron Huddlestone-Holmes talking to the camera, and participants can be seen in the participant bar at the bottom of the screen]

 

Dr Cameron Huddlestone-Holmes: Thank you very much Tsuey, and I’m very glad to be able to be here and to talk to you about GISERA, and the excellent research that CSIRO has been doing through GISERA around the potential impacts of the onshore gas industry on water, the environment, and  communities that live in gas regions. So, the work that GISERA does is guided by the concerns of the communities that live and work in the regions where onshore gas development happens. So, we reach out to those communities and listen to what those concerns are, and then our research works to address those concerns.

 

And the way that we, you know, select our research, and allocate funding to that is done through our Regional Advisory Committees which operate in each of the regions that we, we work in. These Regional Advisory Committees are responsible for approving the projects that we do and ensure that there is independence about the selection, the design of those research projects from our funders which include government, CSIRO itself, and industry.

 

[Image continues to show Dr Cameron Huddlestone-Holmes talking to the camera, and participants can be seen in the participant bar at the bottom of the screen]

 

All of our research is done in a way that makes it publicly accessible. So, right from the very point at which a research project is approved, the project’s order is available on our website so you can see the research that we’re doing, why we’re doing it, and then the final outcomes of that research is all publicly available through our research. All of the research that is done through CSIRO’s GISERA follows all of CSIRO’s normal quality control processes with our internal peer review. So, it’s the science that we do through CSIRO for GISERA is world class. So, I’m really excited to hear more from our researchers today, and I’ll hand back to Tsuey to introduce them.

 

[Image changes to show Tsuey talking to the camera, and participants can be seen in the participant bar at the bottom of the screen]

 

Tsuey Cham: Thank you Cameron. So, our first set of speakers as I said are Drs Matthias Raiber and Axel Suckow. Axel, over to you.

 

[Image changes to show Dr Axel Suckow talking to the camera, and participants can be seen in the participant bar at the bottom of the screen]

 

Dr Axel Suckow: Thank you Tsuey. I’m just trying to share this screen.

 

[Image changes to show a new slide showing a photo of a scrubby hillside, and text appears on the left: An overview on recharge and connectivity studies in NSW and Qld using environmental tracers and hydrochemistry, Dr Axel Suckow and Dr Matthias Raiber]

 

Can you give me please a hands up that everybody can see that? OK. So I’m, my role, as Tsuey said already is to run the Environmental Tracer Lab in Adelaide. We will give you an overview on recharge and connectivity studies both in New South Wales, and Queensland, using hydrochemistry and environmental tracers. And while I can probably assume that everybody knows what hydrochemistry is, I can probably not assume that everybody knows what an environmental tracer actually is. So, let me introduce that.  

 

[Image changes to show a new slide showing a photograph of footprints in the sand on a beach, and text appears: What are Environmental Tracers and how do they work?, Environmental Tracers are natural substances that are already in the water cycle and can be used to conclude on groundwater movement (flow velocity), on time scales long before human intervention (up to 1My), just like footprints in the sand (traces), Some of them are radioactive and decay at a well known and constant rate with time (and flow distance)]

 

[Image continues to show the same slide on the screen]

 

It is a little bit similar like these footprints that you see on the sand in this image. The footprints tell you something. It tells you there has been somebody walking. It’s not only somebody, so it was not a dog, it was a human being obviously from the shape of the footprint. But it tells you also that this person was walking there not too long ago because the next flood for instance would wash away the footprints.

 

Environmental tracers work a little bit similarly. They are natural substances that are already in the water cycle. So, we are not putting anything additional into it, and these tracers can be used to conclude on groundwater movement mainly, that means flow velocity. Some people talk about age dating of groundwater. I personally don’t like that expression. However, they can still conclude on time scales long before human intervention. We have tracers that work on decades, on centuries, on thousands of years up to one million year, or even further. Some of these tracers are naturally procuring radioactive substances and they decay at a well known constant rate with time.

 

[Image shows a curved line graph showing concentration and half lives in the bottom left corner of the screen]

 

So, that is displayed here in the red curve. If you have 100 at the beginning, then after one half life, you would have only 50 left. Or, after two half lives, you would only have 25 left. Whatever the unit is it’s quite unimportant. The important thing is that each tracer has a different half life, and each can be used on a certain timespan to deduce groundwater velocity.

 

[Image shows new text appearing on the slide: Others like helium increase with time and flow distance, Tracers provide information on groundwater flow that no other method can provide, Every time scale needs a different tracer, so we have to use several]

 

There are other tracers which are produced in the aquifers, things like helium for instance, and that is of course what I like most because I’m running the Noble Gas Lab, so they would follow this blue curve and increase with time. Important to know is that every time scale, I talk about days or decades, or centuries, millenia, or millions of years, each time scale needs a different tracer. So, we have to use a combination of different tracers to deduce groundwater flow in a certain area.

 

[Image changes to show a new slide showing text: Groundwater research in Qld and NSW, During the past 8 years, we have conducted several regional groundwater assessments with a focus on – Understanding recharge processes and estimating deep recharge to major aquifers of the Great Artesian Basin (GAB), Understanding how major GAB aquifers are connected to over- or underlying formations including coal seam gas (CSG) target units, Provide critical knowledge to assess the risks of CSG depressurisation for other industries]

 

What did we do? Our groundwater research in Queensland and New South Wales during the past eight years, we’ve conducted several regional groundwater assessments. The focus in this case is understanding recharge processes and trying to quantify deep recharge to the major aquifers of the Great Artesian Basin. Now, I have to stress a little bit that we are talking here about deep recharge because there are methods to estimate the amount of water that recharges into an aquifer that is happening on short time scales, and that uses things like the difference between the rainfall and the, what the plants consume. They are valid methods, but they are valid methods on short time scales. And what we look at is on flow scales of 100km or more, or on depth scales up to a few kilometres.

 

Another thing that we did here is, was trying to understand how major Great Artesian Basin aquifers are connected to the over and to the underlying formations. The overlying formations are typically where the industry like farming takes their water from, and the underlying formations are typically where the coal seam target units are. You can imagine that this is of course very critical knowledge to assess the risk of coal seam gas industry development on the area and on the water resources.

 

[Image changes to show a new slide showing a map of Australia on the left with the various Basins outlined, and text appears on the right: GAB and underlying basins, The GAB is one of the largest aquifer systems in the world, It includes multiple sub-basins (eg Surat Basin and Eromanga Basin), We have conducted assessment of recharge and connectivity with underlying basins in two areas – Northern Surat Basin (CSG areas in QLD), Hutton Sandstone and Precipice Sandstone, Coonamble Embayment (Narrabri Gas Project), Pilliga Sandstone]

 

Now where did we do that? We did that mainly in the Great Artesian Basin. I think I have to go to another pointer here. The Great Artesian Basin here is outlined by this violet line. It’s one of the largest aquifer systems in the world. It covers roughly a quarter of the Australian continent. It includes the Surat Basin which is here in light green, and it includes also the Eromanga Basin. The study areas today are all in the Surat Basin. It’s important to know that the Surat Basin is underlying by deeper aquifers which are outlined here in yellow. That for instance would be the Bowen Basin, or that would be the Gunnedah Basin here in green.

 

Our research areas are mainly the northern Surat Basin, and the southern Surat Basin, and the main aquifers that we investigated were the Hutton Sandstone, the Precipice Sandstone, and the Pilliga Sandstone in New South Wales.

 

[Image changes to show a new slide showing a pyramid hierarchy diagram on the right, and text appears on the left: Recharge and connectivity – a multi-disciplinary assessment, Iterative process – Integration of data from multiple lines of evidence to develop comprehensive conceptual hydrogeological models that describe recharge and connectivity processes, Identify knowledge gaps and uncertainties to inform further work]

 

And with this I head over, hand over to my colleague Matthias Raiber, who will tell you in detail what came out of these studies. Up to you Matthias.

 

Dr Matthias Raiber: Thanks Axel. Yeah, as Axel has already indicated, we have given all of you today on two examples of research, on aquifer recharge, and aquifer connectivity, that we have conducted as part of GISERA, and one is in Queensland and one in New South Wales.

 

But before moving on, the two examples I would just like to highlight that the way, how we study recharge and connectivity in sedimentary basins, is usually by integrating knowledge from multiple lines of evidence. So, that means that we, for example, include information from geology, as you can see on this pyramid. So, that’s the basis of our work. We include geological knowledge, hydrogeological knowledge, and geophysics together, with groundwater hydraulics, geochemistry, and as Axel has already indicated, environmental tracers, hydrogeochemistry. That then allows us to build conceptual hydrogeological models that integrate all the data and describe how recharge and connectivity work in a particular area.

 

It's also important I think to note that that’s an interactive process. So, it’s not a one way thing. So, the conceptual models and the numerical impact predictions are not necessarily endpoints, but they allow us to identify uncertainties and knowledge gaps that then can further, can inform further groundwater management, and further research needs. Thanks Axel. Next slide.

 

[Image changes to show a new slide showing a map of the North Surat Basin on the right, and text appears on the left: North Surat Basin – Hutton Sandstone, Tracers ¹⁴C (half-life of 5,700 years) and ³⁶CI (half-life of ~300,000 years) disagreed, we learned – the Hutton Sandstone is a dual porosity system, Only 2% of the recharge reaches the deeper system and is usable for the farms]

 

So, now I’m moving to the two examples, and starting with the example in the northern Surat Basin. So, we looked here at the Hutton Sandstone, and the Precipice Sandstone. So, the Hutton Sandstone is one of the major aquifers of the Great Artesian Basin. We have looked at the spatial viability of tracers such as Carbon 14, and Chlorine 36 to estimate deep recharge, or flow velocities within the Hutton Sandstone. So, Carbon 14 has a half life of about 5,700 years, and Chlorine 36 of 300,000 years.   So, you can see that Chlorine 36 allows us to identify very old groundwaters. This map that we have here shows the spatial distribution of Chlorine 36 where it’s used in the Hutton Sandstone in the northern Surat Basin.

 

So, the larger symbol sizes correspond to younger groundwater, whereas the smaller sizes correspond to, to older groundwaters. And Axel, maybe you can also highlight the recharge bits of the Hutton Sandstone. So, this area is the area where the Hutton Sandstone takes in the bed, takes in the water, and then as you move away from that towards the centre of the Basin it becomes deeper and disconnected from the, from the atmosphere obviously.

 

[Image continues to show the same slide on the screen]

 

So, in the, you can see as I said already, you have the very large symbols at the edge of the Hutton Sandstone, and you have the very small symbols in the centre. So, that means that the groundwater at the edge of the Hutton Sandstone, or within the recharge beds is very young or relatively young, and in the centre it is very old. So, that indicates that flow velocities are very, very slow here. Water moves very slowly through the Hutton Sandstone.

 

As Axel has already indicated, so we look, we always look at different tracers with different time scales. So they, they represent different age ranges. In this case the results of Carbon 14 and Chlorine 36 disagreed, but it was possible to reconcile. It is somewhat contradictory as I was describing the Hutton Sandstone as a dual porosity system in which a significant part of the tracer is not only lost by radioactive decay but also by diffusion into segment stones of, of the aquifer. So, we may have some portions of the aquifer that’s, for example, composed of sandstone, or core sandstone, and other parts of the aquifer may be more cleavage.

 

So, this indicates that only a small portion of, about 2% of the initial recharge reaches the deeper system and the flow velocity, sorry that flow within the Hutton Sandstone is limited to a small portion of the aquifer, whereas the rest is discharged to springs, or as baseflow to streams such as Dawson River. And you can see that there are quite a lot of springs in this area, so Axel maybe you can find them out here, and also the Dawson River.

 

[Image changes to show a new slide showing a new map of the Surat Basin on the right, and text appears on the left: North Surat Basin – Precipice Sandstone, Tracers ¹⁴C and ³⁶CI agreed, The Precipice Sandstone has larger flow velocity than the overlying Hutton Sandstone, It will provide the fresh water for the farms and can be used to inject (clean) CSG process water]

 

So, going to the next slide. For the Precipice Sandstone, which is the deepest agriculturally used aquifer in the Surat Basin in this region, the spatial patterns of tracers look very different from the Hutton Sandstone. So, you can immediately here think, see the, whereas we had only big symbol sizes in the outer margin of the Hutton Sandstone, we have big symbol sizes everywhere in the Precipice Sandstone. So, that indicates that recharge rates in the Precipice Sandstone are much higher than in the Hutton Sandstone. And that’s, that’s somehow a little bit counterintuitive because the Precipice Sandstone is located underneath the Hutton Sandstone so it’s deeper, and usually we would think that while most are slow flow velocities in deeper sandstones, and deeper formations, but that’s not the case here. So, this water in the Precipice Sandstone can provide the freshwater for the farms, and can be used to inject clean CSG process water. So, next slide Axel.

 

[Image changes to show a new slide showing a map of the Coonamble Embayment on the right, and text appears on the left: Coonamble Embayment (Surat Basin), Tracers suggest the presence of a faster southern and a slower northern flow path, Along the northern flow path, salinity increases in the Pilliga Sandstone from the recharge beds to the deeper basin, New conceptual hydrogeological and hydrochemical models describe how the major aquifers (Pilliga SS) interact with adjacent formations (underlying Gunnedah Basin)]

 

 

So, the second example that we provide to you today is from the Coonamble Embayment. So, the Coonamble Embayment is a sub-basin of the Surat Basin in New South Wales, and it’s also the area where the Narrabri Gas Project area is present, shown by the purple outline near Narrabri that acts as a highlight here. So, we have looked here at a spatial patterns of tracers such as Chlorine 36 within the Pilliga Sandstone, which is the major GAB aquifer in this region to understand recharge processes and also to understand connectivity of aquifers with coal, coal seam gas reservoirs. The recharge beds of the Pilliga Sandstone are shown by the light blue outline, that acts as highlighting here. And our flow is then occurring towards the west away from this area. So, we have two flow paths here.

 

[Image shows the northern and southern flow path being marked on the map by a blue and a red arrow]

 

We have a northern flow path that’s outlined by that blue colour, and we have a southern flow path that’s outlined by that red, by that red line. Along the southern flow path, which is approximately 300km long, we can see that Chlorine 36 values corresponding to relatively young groundwaters, so larger symbol sizes continue far to the west, and only at about halfway along the flow path Chlorine 36 starts to significantly decrease. By integrating, by integrating various other sources, as I showed you in the preliminary bit earlier, we have refined existing conception models. So, Axel, next slide please.

 

[Image changes to show a new slide showing a cross-section diagram showing the Southern Flow Path of the Surat Basin, and text appears: Conceptual model (south vs. north), Southern Flow Path]

 

So, I would like to show you now the conceptual model of the southern flow path. So, that’s putting the Chlorine 36 values into the spatial context. So, you can see the vertical scale here is about 1,500m, and the east-west extension is about 300km. So, this conceptual hydrogeological model highlights the complex geological setting where we have a volcanic aquifer of the Warrumbungle National Park that Axel’s highlighting here, overlying the Surat Basin aquifers. Axel, can you show them as well thanks. And in the east we have the Gunnedah Basin underneath the Surat Basin. In the west as you can see the Gunnedah Basin which hosts the coal seams is absent. So, it does not appear to extend further west than the Warrumbungle’s National Park here.

 

So, the high Chlorine 36 areas on the flow path indicate that this is a relatively fast, fast moving flow path, and by combining the recharge from most of the tracers we have been able to submit groundwater flow velocities of approximately 30cm to 60cm per year. And the northern flow path, next slide please.

 

[Image changes to show a new slide showing a cross-section diagram showing the Northern Flow Path of the Surat Basin, and text appears: Conceptual model (south vs. north), Northern Flow Path]

 

And the northern flow path, you can see again the Surat Basin. Axel can you point it out please. And you can see the Gunnedah Basin underneath the Surat Basin in the east. So, the Gunnedah Basin hosts the primary coal seam gas target. That’s the bottom formation here, which is the most green formation. All under this green formation as you can see on the right we have several infilled aquitards, and then further in the top of the vertical sequence we have the Pilliga Sandstone, which is the major aquifer in this region.

 

So, in this latest project we have also assessed the extent and the continuity of these aquitards, and whether faults are likely to connect deep, causing gas target formations with shallow aquifers in some areas. Unlike on the southern flow path along the northern flow path we can see that the patterns are very different. So, Chlorine 36 starts to, Chlorine 36 values start to decrease much earlier along the flow path than the south, so much closer to the outcrop that’s in the south. And we think that this could indicate that there’s a small outputs discharge at the western edge of the Gunnedah Basin into the Pilliga Sandstone.

 

So, it’s important to remember that groundwater in the Gunnedah Basin, so the deeper basin here is very saline, whereas groundwater in the Pilliga Sandstone is very fresh. So, it would only require a very small contribution from the Gunnedah Basin to explain those sort of patterns. So, this also meant that we are not able to use environmental tracers in this instance to determine reliable flow velocities in the northern area. But it’s also important to note that in the actions between different aquifers, in between different aquifers in the sedimentary basin is very complex and there are often, there are often different multiple possible explanations to, to explain the sort of patterns. So, if we move right on, if we go back quickly to the next slide. Yeah thanks.

 

[Image changes back to show the Southern Flow Path Conceptual model again]

 

So, you can see, as I mentioned earlier, we have these large symbol sizes moving quite fast to the west, and then we all of a sudden have quite a sharp decrease of the symbol sizes which indicates a change in groundwater age of flow velocities. And you can see that the Gunnedah Basin is not present in this area where this change occurs. So, that means that while we in the northern area thinks that, I think that this change is due to some upper discharge from the Gunnedah Basin, other explanations may also be possible and in the next project that we have proposed we will fully examine those processes. Next slide Axel.

 

[Image changes to show a new slide showing text on a white screen: Conclusions, Surat Basin (Qld), Recharge of the Hutton Sandstone is much less (40 times less) than what earlier models indicated, The Precipice Sandstone shows much higher flow velocities than the Hutton (counter-intuitive, because it is deeper), and where this water ends up is still unknown, The Precipice Sandstone is the target formation for farmers water supply and CSG-water re-injection, Coonamble Embayment (NSW), There is a southern flow path in the Pilliga Sandstone with fast flow (evidenced by ³⁶CI ) from the Warrumbungle Volcanics, On the northern flow path our tracer methods failed due to a small amount of mixing from underlying groundwater]

 

So finally, in the Surat Basin, as we have shown the recharge of the Hutton Sandstone is much less, probably about 40 times less than what earlier models indicated, and I think that’s largely accepted now. So, that also, I think, it’s an agreement with research that has been done by other researchers from, for example from the University of Queensland. The Precipice Sandstone shows much higher flow velocities than the Hutton Sandstone. That’s as I said counter-intuitive because it is deeper and where there’s water in the Precipice Sandstone, it’s obviously still a bit unknown. So, the Precipice Sandstone is the target formation for farmers in this area for water supply and also for CSG water reinjection. Next please.

 

In the Coonamble Embayment, you could see that as a clear separation. There’s a southern flow path in the Pilliga Sandstone with fast flow evidenced for example by Chlorine 36 from the run, that starts approximately from the Warrumbungle Volcanics. On the northern flow path our tracer methods failed. So, they didn’t really fail but we were not able to, we were not able to determine the flow velocity but they still gave us very valuable insights into the groundwater processes, and that’s due to potentially a small amount of mixing from underlying groundwater. Thank you.

 

[Image changes to show a new slide showing a close photo of a person looking through a microscope, and text appears: A decade of groundwater modelling research for GISERA, Sreekanth Janardhanan, Rebecca Doble, 18/10/22]

 

Tsuey Cham: Thanks Axel and Matthias. I’ve got a better understanding of tracers, and better understanding of the conceptual groundwater models in the Surat area. We’ll move on to Sreekanth and Rebecca. We’ll just have to make up a bit of time as we don’t, we’ve eaten into some of our time. So, over to you Sreekanth and Rebecca.

 

Dr Sreekanth Janardhanan: Thanks Tsuey, and good afternoon everyone. I hope you can hear me. Yeah, we have been doing modelling research for GISERA for the last ten years. So, what we would like to do in the next ten minutes is to give a very brief overview like Matthias and Axel of examples of groundwater modelling work that we have doing during this period.

 

Before the expansion of coal seam gas in Queensland, we haven’t been doing a lot of modelling of very deep groundwater systems in Australia, particularly to understand the movement of water vertically between different formations, like for example, in the Great Artesian Basin that Axel and Matthias talked about, where there are different groundwater units separated by rock formations or aquitards. So, we didn’t have a lot of data about the characteristics of these formations deep in the ground, particularly of those aquitards, so rock formations that separates different groundwater units. This makes it very difficult to make a correct prediction using numerical models.

 

So, one of the particular questions was, can we quantify impacts of onshore gas on our groundwater resources, acknowledging the limited data and resulting uncertainties, and still make predictions that can inform decision-making. So, the philosophy we followed in GISERA and other related projects of groundwater modelling, it was not focussed on accurately predicting what is going to happen in the future, but it focuses on whether we can quantify the likelihood of some bad or undesirable outcome happening, and its confidence or uncertainty bounds. Where we cannot confidently exclude a bad thing happening, can we inform risk based management strategies to be put in place in the meanwhile, so that, and collect more data to refine the predictions at a later point in time?

 

And we do this iteratively to improve predictions and management like the pyramid that Matthias was showing. I would see it more of a cycle rather than a pyramid where data collection followed by modelling followed by data collection is an iterative process of improving our predictions and management. Axel could you please go on to the next slide please.

 

[Image changes to show a GISERA groundwater modelling research slide flashing up for a short time]

 

So, the first… sorry I’m done with that. Please go to the next one.

 

[Image changes to show a new slide showing a cross-section of the Great Artesian Basin, and text appears: CSG impacts to the Pilliga Sandstone aquifer, The challenge – Community concerns about impacts to groundwater in GAB aquifer – Pilliga Sandstone due to CSG development from the Gunnedah Basin, Our response – Predictive modelling for maximum drawdown impacts and volume of water lost from the GAB aquifer, The results – Less than 0.2m of expected GW level drawdown for most of areas and expected loss of groundwater volume for the aquifer is about 0.3% of the Long-term Annual Average Extraction Limit for this source]

 

OK, so the first example is from New South Wales where we had a modelling project to quantify the groundwater impacts of the Narrabri gas project. When we did this work a couple of years ago the project was still a proposed project and there was widespread concerns about potential impacts of the projects on water resources in the Namoi Alluvium [27.57] the Pilliga Sandstone, the Great Artesian Basin aquifer in the area. The project location is also close to what is considered as intake beds of the Great Artesian Basin and hence there was concern that fresh recharge into the Great Artesian Basin aquifer in the region may be lost due to gas development resulting from the lower water pressures in the underlying Gunnedah Basin resulting in some of the water moving down as shown in the picture there.

 

So, in this project we considered a broad range of coal seam gas water extractions, and a broad range of values for the characteristics of the deep formations in the Surat as well as the Gunnedah Basin to bracket the potential maximum drawdown, or groundwater level change, and water loss from the Great Artesian Basin Pilliga Sandstone aquifer. The study found that the expected volume of water lost from the GAB aquifer is about 0.3% of the Long-term Annual Average Extraction Limit set for the groundwater source in the region. I think it’s the southern recharge source. And in terms of the change in groundwater pressures, it was found that the groundwater pressure drawdown in the Pilliga Sandstone aquifer could be around 0.2m for most of the area. So, that’s like an expected value or a median value. So, there’s a 50% chance that groundwater level drawdown in most parts of the GAB aquifer would be less than 0.2m whereas there is a 5% chance that the drawdown might be up to 10m, particularly in locations very close to the gas wells.

 

Next slide please Axel.

 

[Image changes to show a new slide showing a photo of an injection well on the right, and text appears on the left: Reinjection of CSG produced water, The Challenge – Feasibility and impacts of large-scale reinjection of CSG produced water; injection trials revealed small amount of arsenic mobilisation, Our response – Applied a modelling framework to investigate arsenic mobilisation and upscale information from injection trials and assess contamination risks, The results – Modelling studies demonstrated that arsenic could be prevented by adjusting the pH of the injected water and deoxygenation and contamination risks are very low – reinjection is currently operational]

 

Is that there?  I can’t see it. Hopefully it changed for you. Oh yeah. And we had a few projects in the initial phase of GISERA in Queensland looking at the feasibility and impacts of free injection of coal seam gas produced water. The CSG proponent, APLNG, was planning a large scale injection of CSG produced water after reverse osmosis treatment into the aquifer called Precipice Sandstone which is around 1km underground at that particular location. We had a project look at the pressure distribution resulting from this large scale reinjection and also the injection trials that APLNG conducted in the initial phase revealed that there could be increased arsenic levels close to the injection wells where the arsenic levels would slightly go above the potable water limit for, in the aquifer. So, one of the GISERA projects we did looking at geochemical modelling took to investigating this particular problem. The study found that arsenic mobilisation could be prevented by adjusting the pH of the water and de-oxygenating it, removing oxygen from the injected water.

 

Also we did a risk assessment project to look at contamination to farmers both in the regions should this kind of arsenic mobilisation continue for a period of time, and it was found that the risk was low, and more importantly the geochemical modelling study found that the arsenic mobilisation could be fixed by making these amendments to the injected water. The reinjection project is now operational and is one of the largest managed aquifer recharge schemes in Queensland and Australia.

 

[Image changes to show a new slide showing a photo of a monitoring station, and text appears: Informing data collection and monitoring, The challenge – Where, when and what type of data to collect to maximise the ‘bang for the buck’ to improve monitoring and reduce uncertainties, Our response -  Developed and applied methods for improved data collection and monitoring impacts, The results – Identified injection tracers that provided maximum value for informing reinjection, Developed monitoring design for Narrabri Gas Project (NSW)]

 

Next slide Axel. Yeah, as I said before the biggest challenge, challenge in all of these studies is the data sparsity. Given a reasonably developed conceptual model and a numerical model, mathematical methods can be used for identifying sensitivities of different measurement types, and locations of data collection to a particular prediction of interest. This approach can be used to inform future data collection. For example, in Queensland we used this method to identify the type of tracers for injection trials to maximise the value of investment in data collection. We investigated a few different tracers like bromides and chlorides and found that the bromide tracer was found to be superior to pressure data and other tracers like chloride in informing the transport characteristics of the aquifer.

 

In New South Wales we also used a similar approach to identify the locations and target formations for putting, monitoring those, that would give maximum useful data to inform propagation of drawdown from the Gunnedah Basin into the GAB aquifer. It was found that monitoring the formation immediately underneath the Pilliga Sandstone, the below level formation I guess, within the footprint of the predicted drawdowns in the initial ground of modelling give the maximum useful data for refining and reducing uncertainty in predicted impacts. Next slide please.

 

[Image changes to show a new slide showing a cross-section diagram of a gas well, and text appears: Contamination risks from conventional gas activities, The challenge – Potential incidents associated with conventional onshore gas activities e.g. spillage of drilling fluids, leakage from a storage pond, poses risk to groundwater receptors, Our response – Developed a modelling-based method for quantifying residual contamination risks, The results – Application in south east SA indicated that it is very unlikely that plausible contamination events would result in high concentrations at groundwater receptors in the vicinity of gas development]

 

OK, so over to Rebecca.

 

Dr Rebecca Doble: Thanks Sreekanth. The next couple of slides just talk about some of the work we’ve done in the Otway Basin in the south east of South Australia. And just keep in mind this is about conventional gas in this area, not CSG. So, we haven’t been looking at hydraulic fracturing as part of this research.

 

So, to better understand potential impacts of conventional gas development we developed a model to just model some contaminant transport from potential sources such as spills at the surface or from wells through the soil zone at the top and into the groundwater flow paths and towards things that we value. So bores for water, aquifer… the wetlands, and vegetation that are dependent on the groundwater for survival. We did some chemical transport modelling and looked at flow paths within the region, and potential for chemicals to be degraded and diluted as they travelled along these flow paths.

 

And this modelling indicated that it was very unlikely that any hypothetical chemical spills would result in contamination of bores and wetlands, or vegetation based on the locations of some bores, gas wells that were likely to be developed in the region. Mitigation and management of this risk is still very important but the modelling showed that it was very likely to reduce the level of concern to very low. A part in the project here also showed that there is likely to be very, very little to no impact on groundwater from water use by conventional gas industry to develop new wells in the region, just based on modelling of extracted volumes. Next slide please.

 

[Image changes to show a new slide showing a photo of a boardwalk through a grassy area, and text appears: Climate change and groundwater in gas development areas – southeast South Australia, The challenge – Climate change poses additional groundwater risks in some gas development areas – the effects of which may materialise in the coming decades when gas industry is still operating, Our response – Groundwater scenario modelling under future climates and management considering future groundwater recharge and carbon uptake, The results – Scenario modelling indicated likely reduction in recharge and groundwater lowering for all future climates, Stakeholder engagement elicited discussion around future groundwater management and broad commitment to sustainable development by all industries]

 

So, following on from this project, and also concerns, general concerns about water use by the gas industry, we identified a need for more clarity around the effects of climate change on water resources in this region in the coming decades. Despite the low water requirements of the gas industry, the gas industry is still a part of a diverse group of water stakeholders in the south east including forestry, irrigated agriculture, wine grapes, and environmental and indigenous groups. So, a key part of this project was to conduct stakeholder and community driven research. We consulted initially with stakeholders in a meeting in the region and identified a series of climate and management scenarios that were of key interest and these were modelled and these included the effects of climate change on groundwater, and also increased groundwater extraction due to agricultural expansion.

 

We used scenario modelling based on climate models approved by the intergovernmental panel on climate change for moderate to high future increases in the CO2 concentrations. These predicted a drying climate, reduced rainfall to the region, and reduced groundwater recharge. The modelled scenarios showed that there was going to be a likely decrease in groundwater levels over the next 50 years depending on the ultimate climate in the region. And we were able to communicate a range of certainty around these predictions in results by modelling over 100 different combinations of aquifer properties and climatic conditions. The lowered groundwater levels are likely to impact groundwater dependent ecosystems. So, wetlands and vegetation communities and management options needed to be explored to address this. Climate impacts on groundwater levels were found to be more widespread while increased extraction due to agriculture was more localised and there was a need to take both of these impacts into account for water planning. So, we presented the results at a stakeholder meeting and it triggered a lot of discussion around future groundwater management practices and climate resilience. It was a good opportunity for all industries and regulators to gather and be heard and everyone indicated a broad commitment to sustainable development in the region. Next slide please.

 

[Image changes to show a new slide showing photos of a vineyard, a crop being irrigated, a forest, cattle, and a drilling rig, and text appears: Social impacts of water management in gas regions, GISERA has a strong history of researching social impacts associated with gas development, To date there has been limited work on social perspectives in the cross-over between gas development and water resource management, Initial social engagement in the south east of SA was welcomed by most stakeholders, Future direction of bringing socio-economic science into water management within gas industry regions]

 

GISERA has a fairly long history of researching socioeconomic impacts of gas development including economic assessments, community attitudes and aspirations, and maximising social benefits. And this was, this work was the first stage of crossing over between water and social perspectives, looking at concerns about water quality, impacts on groundwater quantity, and on the groundwater dependent ecosystems both now and in the future. The ongoing work indicates a future direction in water management research including multistakeholder engagement, including the gas industry and other industries in the region. It looks at co-design of research with stakeholders to target directly at what stakeholder regulator and industry needs are. This also ensures assessments are done against multiple criteria, your economic, environmental and social values of water, but also cultural values of water as well. Next slide please.

 

[Image changes to show a new slide showing the journal papers available on the subject below the text heading: Journal papers]

 

Just finishing up with a slide that indicates some of the journal publications that have come out of ten years of groundwater modelling from the GISERA project. These are publicly available. The reports coming out of GISERA are publicly available and it is just an indication that we as scientists are really committed to independent, peer-reviewed science and this is one of the ways that we get that done. So, thanks Tsuey. I think we’ll leave it there.

 

[Image changes to show a new slide showing the CSIRO logo and text: Thank you, CSIRO Land and Water, EnquiriesTeam@csiro.au]

 

Tsuey Cham: Thank you Rebecca and Sreekanth for that. I’ll jump straight into questions because we’ve got a few coming through. And while you answer the questions I’d like the audience if they can, click on the graph icon. It’s just got five quick questions for you to answer just so that we can make sure we improve on our webcast. So, the first question for Axel and Matthias is, “Can you explain what you mean by dual porosity in the Hutton Sandstone?”.

 

Dr Axel Suckow: Well, I think Matthias tried to explain that already. The Hutton Sandstone geologically is formed by fluvial sediments, which means they are old river channels, and they are clay beds that, in the historic time, in the geological time were a side of these, the river channels. So, dual porosity in this case means that the groundwater mainly flows through these old channels, whereas in the clay beds adjacent to them, the water is more or less stagnant. And as Matthias pointed out, it’s only a small fraction that actually conducts the water, conducts the groundwater. So, while the Hutton Sandstone is actually 200m thick in some places, only a few tens of metres actually conduct the water.

 

Tsuey Cham: OK, thank you. One more for you guys. Matthias you touched briefly on your new, new project, and this question goes to that. “What further research is needed to learn more about the connectivity pathways between target coal seams and aquifers in the GAB?”.

 

Dr Matthias Raiber: Yes we identified, as I said, in this previous project a few knowledge gaps and uncertainties, and in this new project we wanted to observe them further. So, that really spoke to particular spatial areas where we think we don’t have enough data yet. For example, we might want to collect additional tracer data, and we also want to conduct some airborne electromagnetic surveys. So, that’s run by a helicopter, where we want to get better insights into the upper 400m of the subsurface to identify faults and see whether they might, may form some connectivity pathways. And then finally we also want to do some geochemical modelling indicated that there is some ambiguity. So, the observations that we have had can be explained by different processes and we want to do some geochemical modelling to further determine which processes are the important ones.

 

[Image continues to show the same slide on the screen]

 

Tsuey Cham: OK. Thank you. So, one for Sreekanth and Rebecca, is there… sorry, where am I. “What’s the impact of injection of treated CSG water on the Precipice Sandstone aquifer?”. OK.

 

Dr Sreekanth Janardhanan: So, the impacts on reinjection of the pressures in the aquifer which is already about kind of atmospheric pressure. So, it’s an artesian aquifer where water level if you drill a bore, water level would normally come to the surface. The pressure will increase. So, one thing that we were interested to look at was is it actually feasible, I mean because of the high pressures you will need to inject under pressure to send more water into the unit. So, the one potential impact is rearrangement of pressure heads within the aquifer, and based on the modelling and the observations that APLNG did over a period of time they could see the pressure increases even tens of kilometres away from the injection well field, which is in fact a kind of a positive impact I would say. I mean that water flows very slowly in Precipice Sandstone, as Axel and Matthias pointed out. So, that water is going to stay there for a long time, and in future when, when deeper bores, more feasible I guess, people would access that water and use it for farming and other purposes.

 

Tsuey Cham: OK, I know, we’ve reached time but there are a couple more questions so if you don’t mind just spending a couple more minutes with me to answer a couple of these questions. Now, I’m not quite sure what this question is asking but maybe you guys can help me out. It says that, “If GISERA cannot determine aquifer flow in the northern flowline around the NGP, then how did SANTOS and the New South Wales Government Department of Water give flow rates strata by strata?”. So, I’m not quite sure what that means. No, any comments? No. OK, yeah.

 

Dr Sreekanth Janardhanan: Maybe just a quick one. I guess everyone will have estimates. So, all these are estimates and they will be informed by available data and as and when more data becomes available I guess we can revise these estimates and be more certain about it.

 

Tsuey Cham: OK.

 

[Image continues to show the same slide on the screen]

 

Dr Axel Suckow: Tsuey at the beginning I tried to make clear that we were looking at deep recharge whereas there are other methods that look at shallow recharge. So, the soil science methodologies have still been applied and that are the best estimates that we have at the moment. What we presented was that the tracers that we applied, and I have to admit due to funding shortages we applied only the really cheap ones. We have another few tools in our toolbox so we could go there and do better work but the tracers that we applied failed. We would need to go into the tracer systems that we are developing here in the lab at the moment which wasn’t available to a reasonable price when we did this project.

 

Tsuey Cham: OK. Thank you. Another quick one. “A contamination risk study was done in South Australia. Was there one done in an around the NGP area?”.

 

Dr Sreekanth Janardhanan: No I think there was… there was one study that looked at I think the biodegradation of some of the chemicals and then in the monitoring project we did have a, like a particle tracking analysis to see the distances that a particle would transfer, travel, under the flow velocities in the aquifers but no there wasn’t a contamination risk assessment as such looking at the individual chemicals and their transportation within the soil and porous media, partly because it was primarily the water quantity that came first in the consultations that I think GISERA did, and we designed a project around that. And, and because there is no kind of fracking or that kind of chemicals used anyway I think we didn’t look at that at that stage.

 

Tsuey Cham: OK, thank you. Now, look I know that we’re quite over time, so just one more question, and there’s been a couple of questions around this similar theme. And I might open it to Cameron to reply and then if other presenters want to chime in feel free. There’s a couple of questions around, you know, the type of information in GISERA’s reports compared with other damning reports of the CSG industry, and then those from the industry that cherry pick from our research. So, you know, comments around that, and general comments around, you know, GISERA’s ability to be a trusted and independent source of information for, for communities. So, Cameron if you could just quickly reply because we are five minutes overdue and then I might open it to other presenters if they want to comment and then we will have to go.

 

[Image continues to show the same slide on the screen]

 

Dr Cameron Huddlestone-Holmes: Yes and thank you for that question. So, like first and foremost we’re all research scientists and we’re all working in CSIRO, the nation’s research agency. And a really important part for our career and our work is being impartial and independent with the way we do our research. That’s what drives most of us, all of us everyday about how we conduct our work. And all of the work we do goes through a peer review process and all of that kind of thing. So, ultimately we stand behind the science, the way we conduct our science. And the second thing I would say is that the type of questions that we answer are restricted to the science and the processes that we look at. So, a part of CSIRO’s mandate is, is, actually precludes us from going too far and to commenting on government policy. So, our work is very much around the science that then informs. And I think Sreekanth, when he introduced his section, talked about this very well, is that the work we do informs that kind of decision making. So, we look to understand what the impacts are and then we leave that research to speak for itself and let our policy makers and others to use it in their work. And that’s where I’d leave it there.

 

Tsuey Cham: Thanks Cameron. Did anyone else want to provide comments, and if so they need to do it quickly because we need to end fairly soon?

 

Dr Sreekanth Janardhanan: Yeah, just adding on to that, I mean I guess you mentioned “damning the CSG industry”, I mean as a researcher the way I see it is like our work answers a very particular, very specific question around water impacts. So, we quantify that, what is the x amount of water that is being lost from Pilliga Sandstone because of a particular development, and we don’t provide a qualitative statement around whether it is a good thing or a bad thing. I think that is for the decision-makers or community, or others to make based on broader amount of information they have and want to know.