scholarly journals Physical Property Characterization of the Waipapa Greywacke: An Important Geothermal Reservoir Basement Rock in New Zealand

2021 ◽  
Author(s):  
Aurelio Melia ◽  
Daniel Roy Faulkner ◽  
David Daniel McNamara
Keyword(s):  
Fluid Flow ◽  
New Zealand ◽  
Physical Property ◽  
Single Mode ◽  
Geothermal Reservoirs ◽  
Geothermal Fluids ◽  
Basement Rocks ◽  
The Matrix ◽  
Confining Pressures ◽  
Controlled Flow

Abstract Greywacke basement rocks in New Zealand host conventional geothermal reservoirs and may supply important hotter and deeper geothermal energy resources in the future. This work combines petrological analyses and physical property measurements of Waipapa greywacke, a basement unit hosting New Zealand geothermal reservoirs, in order to understand better how structurally controlled flow networks develop and channel geothermal fluids within it. Results show intact Waipapa greywacke has high tensile and triaxial compressive strengths, and low intrinsic permeability (~10-21 m2). Permeability of intact Waipapa greywacke does not increase significantly during triaxial loading to failure and is accompanied by minimal changes ultrasonic wave velocities. These data taken together suggest that microcrack development during brittle deformation is very limited. Upon failure, the permeability increases by two orders of magnitude and shows similar permeability to tests performed on synthetic, single, mode I fractures in intact Waipapa greywacke. Permeability persists in Waipapa greywacke fractures under confining pressures of at least 150 MPa. It is concluded that Waipapa greywacke rocks will not allow fluid flow through the matrix of the rock and that substantial geothermal fluid flow will only occur through macrofracture networks.

scholarly journals Physical property relationships of the Rotokawa Andesite, a significant geothermal reservoir rock in the Taupo Volcanic Zone, New Zealand

2014 ◽  
Vol 2 (1) ◽  
Author(s):  
Paul A Siratovich ◽  
Michael J Heap ◽  
Marlène C Villenueve ◽  
James W Cole ◽  
Thierry Reuschlé
Keyword(s):  
New Zealand ◽  
Physical Property ◽  
Geothermal Reservoir ◽  
Reservoir Rock ◽  
Taupo Volcanic Zone ◽  
Volcanic Zone

scholarly journals The Effect of Blue-Green Infrastructure on Habitat Connectivity and Biodiversity: A Case Study in the Ōtākaro/Avon River Catchment in Christchurch, New Zealand

2021 ◽  
Vol 13 (12) ◽  
pp. 6732
Author(s):  
Thuy Thi Nguyen ◽  
Colin Meurk ◽  
Rubianca Benavidez ◽  
Bethanna Jackson ◽  
Markus Pahlow
Keyword(s):  
New Zealand ◽  
Green Infrastructure ◽  
Natural Capital ◽  
Research Question ◽  
Urban Environments ◽  
Habitat Connectivity ◽  
Added Value ◽  
Environmental Evaluation ◽  
Representative Species ◽  
The Matrix

The natural capital components in cities (“blue-green infrastructure” BGI) are designed to address long-term sustainability and create multi-benefits for society, culture, business, and ecology. We investigated the added value of BGI through the research question “Can the implementation of blue-green infrastructure lead to an improvement of habitat connectivity and biodiversity in urban environments?” To answer this, the Biological and Environmental Evaluation Tools for Landscape Ecology (BEETLE) within the Land Utilisation and Capability Indicator (LUCI) framework was adopted and applied in Christchurch, New Zealand, for the first time. Three ecologically representative species were selected. The parameterisation was based on ecological theory and expert judgment. By implementation of BGI, the percentages of habitats of interest for kereru and paradise shelduck increased by 3.3% and 2.5%, respectively. This leads to improved habitat connectivity. We suggest several opportunities for regenerating more native patches around the catchment to achieve the recommended minimum 10% target of indigenous cover. However, BGI alone cannot return a full suite of threatened wildlife to the city without predator-fenced breeding sanctuaries and wider pest control across the matrix. The socio-eco-spatial connectivity analysed in this study was formalised in terms of four interacting dimensions.

Palygorskite-cemented crusts (palycretes) in Southern Portugal

Soil Research ◽  
2000 ◽  
Vol 38 (1) ◽  
pp. 169 ◽  
Author(s):  
K. Stahr ◽  
J. Kühn ◽  
J. Trommler ◽  
K-H. Papenfuß ◽  
M. Zarei ◽  
...  
Keyword(s):  
Land Surface ◽  
Fine Sand ◽  
Random Orientation ◽  
Sedimentary Deposits ◽  
Early Tertiary ◽  
Basement Rocks ◽  
The Matrix ◽  
Southern Portugal ◽  
The Town ◽  
Fine Gravel

In the Oriola depression of Southern Portugal near the town of Evora, field examinations revealed the presence of Tertiary sedimentary deposits that had the consistency of duricrusts. These duricrusts, occurring close to the land surface, were examined in the field as well as in the laboratory, with the objective of establishing their composition and formation. Micromorphological examinations showed that the duricrusts were composed of clasts of fine sand to fine gravel sizes cemented together by a matrix dominated by either palygorskite or carbonate. The matrix : clasts ratio varied from about 1 : 3 when the cement was carbonate, to 3 : 1 or higher when the matrix was palygorskite. Occasionally the ratio in the latter was even higher. The clasts consisted of quartz, feldspar, and some Mg-rich metamorphic minerals. The palygorskite matrix fibres were arranged in mats within which they had parallel orientation. The mats or ‘domains’, which had a length of 15–25 □m and a width of about 40 □m, showed random orientation. In analogy to the term ‘calcrete’ the term ‘palycrete’ is used for the palygorskite duricrusts. The palycrete, of an average thickness of 0.5 m, frequently rested directly on the Hercynian basement rocks, and was covered by a recent solum. In the B horizons of the solum, the palygorskite appeared to undergo recent weathering and transformation into smectite. The duricrusts were proposed to have formed by authigenic calcite or palygorskite, which filled the interstices between clastic particles that had been deposited on Hercynian basement rocks following their peneplanation in the early Tertiary. The proposed environment of deposition and formation was that of an intermittent playa-lake in a semi-arid, seasonal climate, where strong evaporative processes had been active. Alteration and weathering of the mafic minerals contained in some of the clasts, in addition to interstitial solutions rich in Si and Mg, had created the chemical environment required for palygorskite neoformation. From the state of weathering–disintegration of the palygorskite in the soils formed on the palycrete, it is inferred that the environment for palygorskite neoformation had ceased to exist after palycrete formation.

Electrochemical Phase Diagrams for the Fe/S/H2O System under Geothermal Conditions

1985 ◽  
Vol 38 (5) ◽  
pp. 643 ◽  
Author(s):  
BG Pound ◽  
GA Wright ◽  
RM Sharp
Keyword(s):  
New Zealand ◽  
Phase Diagrams ◽  
Elevated Temperatures ◽  
Corrosion Products ◽  
Ferrous Alloys ◽  
Temperature Range ◽  
General Terms ◽  
Geothermal Fluids ◽  
Region Of Stability ◽  
Regions Of Stability

Previously published electrochemical phase (potential-pH) diagrams for the Fe/S/H2O system at elevated temperatures are assessed. It is concluded that the potential-pH equations derived by Biernat and Robins1 can be used to provide reliable diagrams over the temperature range 298-573 K. These equations were used to derive a set of diagrams relevant to geothermal fluids in general terms, so that the corrosion products of iron and ferrous alloys immersed in these fluids may be predicted. In addition, diagrams are presented for geothermal fluids in the Broadlands and Wairakei fields in New Zealand. The significant changes in the E-pH diagrams as the temperature increases over the range 298-573 K are that the region of stability for Fe(OH)3- widens and the regions of stability for FeS2 and Fe3O4 and, at higher temperatures, FeS, shrink in size.

scholarly journals Multiphase Thermal-fluid Flow through Geothermal Reservoirs

2016 ◽  
Vol 95 ◽  
pp. 22-28 ◽  
Author(s):  
Ramadan Abdelaziz ◽  
Fabio Sussumu Komori ◽  
Marcelo N.P. Carreño
Keyword(s):  
Fluid Flow ◽  
Geothermal Reservoirs ◽  
Flow Through ◽  
Thermal Fluid Flow

Petrology and geochronology of cordierite bearing assemblages from the Wanni Complex – Sri Lanka

2020 ◽  
Author(s):  
Nikolaus Lechner ◽  
Christoph Hauzenberger ◽  
Marcel Masten ◽  
Dominik Sorger ◽  
G.W.A. Rohan Fernando
Keyword(s):  
Sri Lanka ◽  
Rock Type ◽  
Granulite Facies ◽  
Granulite Facies Metamorphism ◽  
Pan African ◽  
Basement Rocks ◽  
The Matrix ◽  
The Common ◽  
Group 2 ◽  
Uht Metamorphism

<p>Based on differences in metamorphic grade and isotope model ages, the basement rocks of Sri Lanka can be subdivided from NW to SE into the Wanni Complex (WC), the Highland Complex (HC) and the Vijayan Complex (VC) (Milisenda et al. 1994). The UHT conditions of the HC were studied extensively and are well constrained whereas data from the WC and VC are less abundant. Only few recent petrological and geochemical work has been done especially along the WC–HC boundary which is still ill-defined (Kitano et al. 2018; Wanniarachchi & Akasaka 2016). Due to the common occurrence of migmatites, pyroxene bearing gneisses, and cordierite bearing metapelites/paragneisses, the WC clearly experienced granulite facies metamorphism. However, PT conditions are lower compared to the HC. In this study, U-Th-Pb monazite dating combined with a petrological study including phase equilibria modelling and thermobarometry was conducted focusing on cordierite bearing migmatic biotite gneisses located at the WC–HC boundary in the West of Sri Lanka. The HC underwent UHT metamorphism at 580-570Ma (Sajeev et al. 2010), the main metamorphic phase of the VC is dated with 580Ma. (Kröner et al., 2013). With U-Th-Pb monazite ages of around 530 Ma, the cordierite bearing assemblages from the WC are significantly younger (Wanniarachchi & Akasaka 2016). The predominantly felsic but also mafic peraluminous migmatic ortho- and paragneisses comprising the mineral assemblage cordierite + garnet + biotite + plagioclase + k-feldspar + quartz + ilmenite + magnetite + spinel + sillimanite ± orthopyroxene and contain monazite (+ zircon ± xenotime) as garnet inclusions (Group1) and in the matrix (Group2). Group1 monazite ages cluster around 575±5 Ma and 561±5 Ma whereas ages of Group 2 cluster at 550±3 and 527±3. Based on ages and textural occurrence of monazite we suggest that two thermal events at ca. 550-575 Ma and ca. 530-550 Ma are recorded in this rock type indicating a complex evolution during the late stage of the Pan-African orogeny. PT conditions range from 700–900°C and from 5–8 kbar with a decreasing north-south gradient. Further geochronological investigations are needed to relate either to the older or the younger overprint to the main metamorphic phase of the WC.</p><p>Kitano, I., Osanai, Y., Nakano, N., Adachi, T., & Fitzsimons, I. C. W. (2018). Journal of Asian Earth Sciences, 156, 122–144.</p><p>Kröner, A., Rojas-Agramonte, Y., Kehelpannala, K. V. W., Zack, T., Hegner, E., Geng, H. Y., … Barth, M. (2013). Precambrian Research, 234, 288–321. </p><p>Milisenda, C. C., Liewa, T. C., Hofmanna, A. W., & Köhler, H. (1994). Precambrian Research, 66(1–4), 95–110.</p><p>Sajeev, K., Williams, I. S., & Osanai, Y. (2010). Geology, 38(11), 971–974.</p><p>Wanniarachchi, D. N. S., & Akasaka, M. (2016). Journal of Mineralogical and Petrological Sciences, 111(5), 351–362.</p>

Low-Salinity Chase Waterfloods Improve Performance of Cr(III)-Acetate Hydrolyzed Polyacrylamide Gel in Fractured Cores

2015 ◽  
Vol 19 (02) ◽  
pp. 331-339 ◽  
Author(s):  
Bergit Brattekås ◽  
Arne Graue ◽  
Randall S. Seright
Keyword(s):  
Fluid Flow ◽  
Water Phase ◽  
Polymer Gel ◽  
Low Salinity ◽  
Gel Swelling ◽  
The Matrix ◽  
Rupture Pressure ◽  
Salinity Water ◽  
Hydrolyzed Polyacrylamide ◽  
Blocking Capacity

Summary Polymer gels are frequently applied for conformance improvement in fractured reservoirs, where fluid channeling through fractures limits the success of waterflooding. Placement of polymer gel in fractures reduces fracture conductivity, thus increasing pressure gradients across matrix blocks during chase floods. A gel-filled fracture is reopened to fluid flow if the injection pressure during chase floods exceeds the gel-rupture pressure; thus, channeling through the fractures resumes. The success of a polymer-gel treatment, therefore, depends on the rupture pressure. Salinity differences between the gel network and surrounding water phase are known causes of gel swelling (e.g., observed in recent work on preformed particle gels). Gel swelling and its effect on fluid flow have, however, been less studied in conjunction with conventional polymer gels. By use of corefloods, this work demonstrates that low-salinity water can swell conventional Cr(III)-acetate hydrolyzed polyacrylamide (HPAM) gels, thereby significantly improving gel-blocking performance after gel rupture. Formed polymer gel was placed in fractured core plugs, and chase waterfloods were performed using four different brine compositions, of which three were low-salinity brines. The fluid flow rates through the matrix and differential pressures across the matrix and fracture were measured and shown to increase with decreasing salinity in the injected water phase. In some cores, the fractures were reblocked during low-salinity waterfloods, and gel-blocking capacity was increased above the initial level. Low-salinity water subsequently flooded the matrix during chase floods, which provided additional benefits to the waterflood. The improved blocking capacity of the gel was caused by a difference in salinity between the gel and injected water phase, which induced gel swelling. The results were reproducible through several experiments, and stable for long periods of time in both sandstone and carbonate outcrop core materials. Combining polymer gel placement in fractures with low-salinity chase floods is a promising approach in integrated enhanced oil recovery (IEOR).

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