Impact of multi-purpose aquifer utilisation on a variable-density groundwater flow system in the Gippsland Basin, Australia

Varma, Sunil; Michael, Karsten

doi:10.1007/s10040-011-0800-8

Cited by 40 publications

(32 citation statements)

References 10 publications

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“…Onshore and offshore groundwater systems connect through the subsurface, and the extent to which one influences the other depends on the geologic structure. Preferential flow paths can enhance connectivity relative to homogeneous aquifers in systems with karst conduits (Evans & Lizarralde, ; Xu et al, ), palaeochannels (Mulligan et al, ), natural faults (Varma & Michael, ), and a range of other heterogeneous geologic settings (Houben et al, ; X. Li et al, ; Michael et al, ). Knight et al () analyzed 27 coastal sites globally and found that widespread losses of offshore freshwater are associated with onshore pumping due to connections between offshore and onshore fresh groundwater reserves.…”

Section: Introductionmentioning

confidence: 99%

Offshore Pumping Impacts Onshore Groundwater Resources and Land Subsidence

Michael

2019

Geophysical Research Letters

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Freshened groundwater exists offshore along many coastlines worldwide. Pumping of these offshore resources has been proposed for more efficient oil production as well as drinking and agriculture. Although pumping can occur tens to hundreds of kilometers offshore, these activities may threaten connected onshore aquifer systems. We conducted numerical simulations of variable‐density groundwater flow and salt transport in coastal aquifers with different geologic structure subject to offshore pumping to assess potential impacts. Results show that offshore pumping can diminish both onshore groundwater availability and submarine groundwater discharge and can cause widespread land subsidence. Heterogeneity increases water resource vulnerability relative to equivalent homogeneous and layered systems and exacerbates the magnitude of land subsidence. More continuous geologic structure causes propagation of maximum subsidence farther landward. This work suggests that coastal aquifers may be vulnerable to offshore pumping activities and that these effects should be considered in feasibility assessments for offshore drilling.

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Section: Introductionmentioning

confidence: 99%

Offshore Pumping Impacts Onshore Groundwater Resources and Land Subsidence

Michael

2019

Geophysical Research Letters

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“…A specific characteristic of the Gippsland Basin is that the main regional aquifer, the Latrobe aquifer, contains groundwater resources updip and petroleum reservoirs in the deeper saline parts, with a freshwater wedge of meteoric origin extending down to 2 km depth and 20 km offshore [21]. Petroleum production since the 1970s has created a large underpressured region in the offshore Latrobe aquifer, which has also been identified as being suitable for CO 2 geological storage.…”

Section: D Simulations Of Co 2 Injection At Freshwater-seawater Intementioning

confidence: 98%

Simulating the Flow of Variable-salinity Water in Response to CO2 Injection

2014

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Subsurface injection of CO 2 creates pressure build-up in the geological formation and the formation water is displaced laterally within the storage formation and/or vertically through the top seal into overlying formations. Numerical simulations of industrialscale CO 2 injection taking into account variable-salinity water indicate that the overall potential for brine displacement resulting in significant salinization of fresh groundwater resources is low. Although the radius of pressure impacts can be on the order of 100 km, the resulting formation water flux decreases rapidly in the far-field of the injection site where the displaced volumes of saline formation water are small.

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“…Kuttan et al . () and Varma & Michael () showed that onshore the groundwater is particularly fresh in the Seaspray Depression due to meteoric recharge in the area of Latrobe outcrop. In the offshore part of the Latrobe aquifer, groundwater with salinity of around 4000 ppm (i.e.…”

Section: Gippsland Basin and Latrobe Group Overviewmentioning

confidence: 99%

“…), in the Northwest Java Basin in Indonesia (Maathuis et al . ) and the Gippsland Basin in Australia (Varma & Michael ). In these cases, the freshwater adopts a wedge shape.…”

Section: Introductionmentioning

confidence: 99%

Palaeo‐formation water evolution in the Latrobe aquifer, Gippsland Basin, south‐eastern Australia continental shelf

2014

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Offshore fresh or brackish groundwater has been observed around the globe and represents an interesting but unusual freshwater reserve. Formation waters in sedimentary basins evolve at geological time through fluid-rock interactions and water movements in aquifers. However, the mechanism and timing of freshwater displacing and mixing with pre-existing formation water offshore under the seafloor has not been investigated in many cases. The growing need for developing freshwater resources in deeper parts of sedimentary basins that have not been economic or technically feasible in the past, may potentially lead to an increasing conflict with petroleum production or injection of carbon dioxide. For being able to assess and mitigate possible impacts of fluid production or injection on groundwater flow and quality, a better understanding of the natural history of the interaction between fresh meteoric water and deep basin formation water is necessary. A low-salinity wedge of meteoric origin with less than 5000 ppm currently extends to about 20 km offshore in the confined Latrobe aquifer in the Gippsland Basin (Australia). The Latrobe aquifer is a freshwater resource in the onshore, hosts major petroleum reservoirs and has been considered for carbon dioxide storage in the offshore parts of the basin. The objective of this study is to constrain the evolution of formation water in the Latrobe aquifer by investigating the water naturally trapped in fluid inclusions during burial. The measured palaeo-salinities from onshore and offshore rock samples have a minimum of about 12 500 ppm (NaCl equivalent) and a maximum of about 50 000 ppm. Most of the salinities are in the 32 000-35 000 ppm range. There is no evidence for freshwater in fluid inclusions and the variation in palaeo-salinity across the basin is consistent with the palaeogeography of deposition of the sedimentary rocks. The current low-salinity water wedge must have started to form recently after most of the diagenetic processes that led to the trapping of water in fluid inclusions happened. The minimum homogenisation temperatures (T h ) recorded are consistent with current formation temperature. However, they are generally higher than present day suggesting that hotter temperatures were attained in the past. The T h and salinity data together suggest that the fluid inclusions record the diagenetic modification of connate water to higher salinities over a time period that was accompanied by an increase in temperature, consistent with a westward palaeo-fluid flow from the deeper part of the basin through the aquifer. Subsequent pore-water evolution from palaeo-to current day conditions is consistent with an influx of fresher and cooler meteoric water into the Latrobe Group. The meteoric recharge originates from the area of the Baragwanath anticline in the onshore part of the basin where the Latrobe Group subcrops at high elevations. . Geofluids (2015) 15, 503-526 HIGHLIGHTS • No freshwater was found in fluid inclusions in the Latrobe aquifer system • The low-salinit...

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Impact of multi-purpose aquifer utilisation on a variable-density groundwater flow system in the Gippsland Basin, Australia

Cited by 40 publications

References 10 publications

Offshore Pumping Impacts Onshore Groundwater Resources and Land Subsidence

Offshore Pumping Impacts Onshore Groundwater Resources and Land Subsidence

Simulating the Flow of Variable-salinity Water in Response to CO2 Injection

Palaeo‐formation water evolution in the Latrobe aquifer, Gippsland Basin, south‐eastern Australia continental shelf

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