Precious metals in high-temperature geothermal systems in New Zealand

Geothermics ◽  
2003 ◽  
Vol 32 (4-6) ◽  
pp. 619-625 ◽  
Author(s):  
Kevin L. Brown ◽  
Stuart F. Simmons
Keyword(s):  
High Temperature ◽  
New Zealand ◽  
Precious Metals ◽  
Geothermal Systems

Heat transfer estimation through a high-temperature geothermal field in New Zealand quantified by multi-channel data modelling

2021 ◽  
Author(s):  
Alberto Ardid ◽  
Rosalind Archer ◽  
David Dempsey
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
High Temperature ◽  
New Zealand ◽  
Geothermal Field ◽  
Heat Fluxes ◽  
Geothermal System ◽  
Geothermal Systems ◽  
Total Heat Flow ◽  
Sustainable Resource Management

<p>In high-temperature geothermal systems, understanding heat transfer helps conceptualize the whole system as well as estimating the resource size. To obtain the fullest picture, it is necessary to integrate different types of data, e.g., surface electromagnetic surveys, wellbore lithology, geochemistry, and temperature logs. This can be achieved through joint modelling. Here, we quantify the spatial distribution of heat transfer through the hydrothermally-altered, impermeable smectite layer that has developed atop the Wairākei-Tauhara geothermal system, New Zealand. Our approach involves first constraining 1D magnetotelluric (MT) inversion models with methylene blue analysis (MeB, an indicator of conductive smectite clay) and mapping these onto temperature and lithology data from geothermal wells. Then, one-dimensional models of heat transfer are fitted to well temperature logs to estimate heat flux variations across the field. We use our integrated method to estimate the average heat flux through the clay cap (2.2 W/m2) and total heat flow (380 ± 21 MW) of the Wairākei-Tauhara geothermal field. This approach models multiple datasets for estimating heat fluxes and could be applied in geothermal provinces around the world with implications for sustainable resource management and our understanding of magmatic systems.</p>

Precious Metals in Modern Hydrothermal Solutions and Implications for the Formation of Epithermal Ore Deposits

SEG Discovery ◽  
2008 ◽  
pp. 1-12
Author(s):  
Stuart F. Simmons ◽  
Kevin L. Brown
Keyword(s):  
New Zealand ◽  
Precious Metals ◽  
Ore Deposits ◽  
Taupo Volcanic Zone ◽  
Geothermal System ◽  
Hydrothermal Solutions ◽  
Geothermal Systems ◽  
Gold Silver ◽  
Wide Range ◽  
Time Required

ABSTRACT We determined the concentrations of gold, silver, arsenic, antimony, and mercury in deep hydrothermal solutions (~1 km depth, 200° to >300°C) from active geothermal systems in the Taupo Volcanic Zone, New Zealand, and Ladolam, Lihir Island, Papua New Guinea. The wide range of concentrations in the New Zealand systems and the stable isotope signatures at Ladolam confırm that magmas are an important source of high concentrations of gold and silver in hydrothermal solutions. The Rotokawa geothermal system in New Zealand has the highest hydrothermal fluxes of gold (~30–100 kg/yr) and silver (~5000–11,000 kg/yr), which, if they remained constant, could match the metal inventories of the largest ore deposits in the world in <50,000 years. This relatively short time span is comparable to the amount of time required to account for the known gold resource in ores at Ladolam, which has a slightly lower gold flux (~25 kg/yr). The fact that a giant gold deposit exists at Ladolam, rather than at Rotokawa, demonstrates the importance of fluid focusing and effıcient metal deposition in the formation of epithermal gold and silver ore deposits.

scholarly journals High-Temperature Properties of Needle-Like Mullite Obtained from New Zealand Kaolin

1989 ◽  
Vol 97 (1132) ◽  
pp. 1521-1524 ◽  
Author(s):  
Hiroaki KATSUKI ◽  
Akihiko KAWAHARA ◽  
Hiromichi ICHINOSE ◽  
Sachiko FURUTA ◽  
Shuji YOSHIDA
Keyword(s):  
High Temperature ◽  
New Zealand ◽  
High Temperature Properties

scholarly journals Genesis of Precious Metal Mineralization in Intrusions of Ultramafic, Alkaline Rocks and Carbonatites in the North of the Siberian Platform

Minerals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 354
Author(s):  
Anatoly M. Sazonov ◽  
Aleksei E. Romanovsky ◽  
Igor F. Gertner ◽  
Elena A. Zvyagina ◽  
Tatyana S. Krasnova ◽  
...  
Keyword(s):  
High Temperature ◽  
Siberian Platform ◽  
Precious Metal ◽  
Native Gold ◽  
Precious Metals ◽  
Ore Formation ◽  
Central Type ◽  
Alkaline Rocks ◽  
The North ◽  
Pge Mineralization

The gold and platinum-group elements (PGE) mineralization of the Guli and Kresty intrusions was formed in the process of polyphase magmatism of the central type during the Permian and Triassic age. It is suggested that native osmium and iridium crystal nuclei were formed in the mantle at earlier high-temperature events of magma generation of the mantle substratum in the interval of 765–545 Ma and were brought by meimechite melts to the area of development of magmatic bodies. The pulsating magmatism of the later phases assisted in particle enlargement. Native gold was crystallized at a temperature of 415–200 °C at the hydrothermal-metasomatic stages of the meimechite, melilite, foidolite and carbonatite magmatism. The association of minerals of precious metals with oily, resinous and asphaltene bitumen testifies to the genetic relation of the mineralization to carbonaceous metasomatism. Identifying the carbonaceous gold and platinoid ore formation associated genetically with the parental formation of ultramafic, alkaline rocks and carbonatites is suggested.

230°C Accelerometer with Digitized Output for Directional Drilling

2014 ◽  
Vol 2014 (HITEC) ◽  
pp. 000298-000304
Author(s):  
Douglas C. MacGugan ◽  
Eric C. Abbott ◽  
J. Chris Milne
Keyword(s):  
High Temperature ◽  
Oil And Gas ◽  
Elevated Temperatures ◽  
Digital Signal ◽  
Enhanced Geothermal Systems ◽  
Geothermal Systems ◽  
Directional Drilling ◽  
Orientation Measurement ◽  
Acceleration Signal ◽  
Vibrating Beams

Measurement-While-Drilling (MWD) technology for oil and gas, and geothermal directional drilling exploration is pushing into ever higher temperature environments - beyond 200°C. Orientation sensors supporting these high temperature environments need to provide highly accurate elevation and tool face measurements on the order of 0.1°. Honeywell has developed a new digital high temperature down-hole accelerometer, DHTA230, capable of providing the required accuracy at the elevated temperatures of 230°C, in the rugged MWD shock and vibration environment, with expected excellent reliability and life. The DHTA230 is designed for use in the downhole environment, but is based upon a mature Honeywell accelerometer using dual vibrating beam sensing elements. These sensing elements are configured as double-ended-tuning-forks in a push-pull orientation attached onto a pendulous proof mass. This push-pull configuration provides an acceleration signal proportional to the frequency difference of the vibrating beams, an easily captured digital signal through measurement of the two vibrating beam phases. The digitized accelerometer eliminates the need for A/D electronics in the high temperature drilling environment. The DHTA230 is 0.79” in diameter with a depth of .393” at the mount flange. The ruggedized configuration of the DHTA230 is expected to provide reliable orientation measurement in high temperature direction drilling applications up to 1000h. The DHTA230 electronics incorporate ceramic hybrids with chip and wire construction. Active die are based upon proven 300°C chips developed previously for the Enhanced Geothermal Systems OM300, fabricated using Honeywell HTSOI4 process. The electronics include power conditioning providing reliable operation using a single power supply between 7V and 15V. Dual oscillator electronic circuits provide the necessary function to drive and sense the dual vibrating beams, while providing a CMOS logic level signal of the frequency pulse train. The accelerometer provides precision output up to 15g acceleration inputs, and allows sensing of higher-g vibration levels. This paper contains information on the target application, electrical and mechanical component requirements, design, fabrication approach, and initial prototype testing. The DHTA230 is expected to enter production transition in 2015.

scholarly journals Experimental and Numerical Evaluation of Hydraulic Fracturing under High Temperature and Embedded Fractures in Large Concrete Samples

Water ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 3171
Author(s):  
Liangliang Guo ◽  
Zihong Wang ◽  
Yanjun Zhang ◽  
Zhichao Wang ◽  
Haiyang Jiang
Keyword(s):  
Numerical Simulation ◽  
High Temperature ◽  
Hydraulic Fracturing ◽  
Laboratory Test ◽  
High Temperatures ◽  
Large Scale ◽  
Hydraulic Fractures ◽  
Enhanced Geothermal Systems ◽  
Geothermal Systems ◽  
Fracture Density

In order to study the mechanism of hydraulic fracturing in enhanced geothermal systems, we analyzed the influence of high temperatures and embedded fractures on the initiation and propagation of hydraulic fractures using a laboratory test and numerical simulation. The analysis was conducted via large-scale true triaxial hydraulic fracturing tests with acoustic emission monitoring. Moreover, we discussed and established the elastic-plastic criterion of hydraulic fracturing initiation. The corresponding fracturing procedure was designed and embedded into the FLAC3D software. Then, a numerical simulation was conducted and compared with the laboratory test to verify the accuracy of the fracturing procedure. The influence of high temperatures on hydraulic fracturing presented the following features. First, multi-fractures were created, especially in the near-well region. Second, fracturing pressure, extension pressure, and fracture flow resistance became larger than those at room temperature. 3D acoustic fracturing emission results indicated that the influence of the spatial distribution pattern of embedded fractures on hydraulic fracturing direction was larger than that of triaxial stress. Furthermore, the fracturing and extension pressures decreased with the increase of embedded fracture density. For hydraulic fracturing in a high temperature reservoir, a plastic zone was generated near the borehole, and this zone increased as the injection pressure increased until the well wall failed.

Sign in / Sign up

Export Citation Format

Share Document