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Tuesday, 29 July 2014

Measurement standards in the geothermal industry

Historically, many of the early geothermal projects were developed in a non-systematic manner. It came with a time, that the stages and phases of a development process of geothermal resources have become more clearly defined. Even today there are differences in methodologies and techniques between different countries and agencies.
  
There are seven phases in the process of developing geothermal projects, including: preliminary survey, exploration, test drilling, project review and planning, field development, power plant construction, commissioning and operation, however this article will focus only on the two first phases, in which measurements data are the most important.
 
The Preliminary Survey Phase involves a work program to assess the already available evidence for geothermal potential within a specific area. The initial surveying involves a literature review of geological, hydrological or hot spring/thermal data, drilling data, anecdotal information from local populations, and remote sensing data from satellites, if available.
Most countries have existing databases of geological and hydrological data.  These are useful for guiding early geothermal surveying and exploration.  Information should be also gathered on legal issues, like the national, regional and local regulations that might allow or restrict access for exploration activities.
Basic information for the preliminary survey covers: the power market and possible power purchase agreements or feed in tariff, infrastructure issues (roads, water, communication, transmission), resource ownership issues, environmental and social issues, institutional and regulatory frameworks, issues related to political and financial stability and information from available literature on the resource itself.

The second phase Exploration, may start by looking at a regional level and, as more data is gleaned, focus to a more localized analysis. Exploration typically begins with gathering data from existing, nearby wells and other surface manifestations, and goes on to surface and sub-surface surveying using geological, geochemical, and geophysical methods. Surveying techniques used in this phase are following: 

    Surface studies - gathering local knowledge, locating active geothermal surface features, assessing surface geology.
    Geochemical surveying - geothermometry, electrical conductivity, pH, flow rate of fluids from active features, soil sampling.
    Geophysical surveying - gravity, electrical resistivity, magnetotelluric, temperature gradient drilling, 2D & 3D seismic sampling.

By the end of this phase, sufficient exploration data should have been collected and analyzed to select sites and targets for the first few deep exploration wells.  A preliminary estimate of the magnitude of the resource, and developing initial conceptual and numerical models should also be possible at this stage.

Geological data
In the field exploration it is very important to locate and characterize all existing geothermal features within the project area and within a relevant distance from the project area.
Geological data for the project area should be presented in the form of geological maps, structural maps, stratigraphic columns, and cross sections for the project areas.

Geochemical data
Geochemical studies focus on understanding the geothermal fluid sources and flow paths and assessing potential operational issues that will come with development, such as wellbore scaling, corrosion, and concentrations of non-condensable gases. Regional CO2 gas surveys are becoming increasingly popular, because elevated CO2 at the surface may indicate the presence of permeable faults or the extent of an active geothermal system. Fluid and gas geochemical data are presented on maps, tables, drawings, and plots for the project area. 
A good outcome of the geochemistry studies would be an indication of temperature distribution within the geothermal system, a maximum temperature range for the resource, and a fluid-mixing model.

Geophysical data
There are many types of geophysical surveys that can be carried out. They include gravity surveys, temperature gradient drilling (also referred to as heat flow surveys), electrical and electromagnetic resistivity surveys (particularly magneto-telluric (MT), but there are also several others), 2D and 3D seismic techniques. Geophysical data collection points should be presented on maps with license boundaries and cross section lines clearly labeled. Maps should be provided as geo-referenced digital files or have a grid overlain on them that allows for easy geo-referencing. Gravity data should be presented as contour maps with the appropriate reduction densities indicated. Resistivity data should be presented in a similar way, with contour maps of resistivity or conductivity at a particular elevation/depth, or isoresistivity contour maps showing the elevation of a particular resistivity or conductivity value. Seismic data requires more detailed processing and interpretation than either resistivity or gravity data. For temperature gradient drilling data should be presented graphically, with a legend listing the dates that each profile (temperature log) was made.
Each geophysical survey should be carried out soundly and the acquired data should be interpreted by an experienced operator with deep insight in the region’s tectonics and geology.

Satellite imagery
More and more data from satellite and airborne sensors are becoming readily available. Many of them can be applied to geothermal exploration, like satellite or aircraft-based infrared scans, and thermal data acquired by Thematic Mapper (TM) and Enhanced Thematic Mapper Plus (ETM+) sensors on-board Landsat-5 and Landsat-7 satellites. It may be also appropriate to develop a Geographic Information System (GIS) database of potential geothermal sites based on aerial photos and satellite data. The technique may be especially useful in difficult terrain where ground access is difficult. Relevant remote sensing data can be downloaded into GIS software for integration with data compiled from surface surveys to produce detailed maps for each project area.

References:
GeothermEx Inc., USA, and Dr. Colin Harvey: "Geothermal Practices Best Practices" (PDF download)

Authors:
Aneta Żądło
Tomasz Sasin

Tuesday, 1 July 2014

The biggest companies in the drone market and their outstanding products

The drone market is expanding very fast these days. There are many companies that are producing drones, which are being used in various sectors of the economy. Here are a few biggest companies and their most interesting products that you definitely should know about. 

1. The Boeing Company 
It is commonly known as one of the biggest producers of the passenger aircraft (Boeing Commercial Airplanes), but it has been also producing drones for military purposes (Boeing Defense, Space and Security). The Boeing Company produces a few types of drones, one of them is called Phantom Eye. The drone is powered by liquid hydrogen long endurance UAV and can fly for 96 hours. The company is also developing a solar-powered drone called the SolarEagle that will be capable of flying up to 60,000 feet for five years. This technology is very similar to Zephyr drone, which has been developed by QinetiQ. The drone is able to stay aloft for 336 hours and 22 minutes, or 14 days, without refuelling.

2. Airbus, Dessault Aviation and Alenia Aermacchi

These are three European companies that have been developing in aviation (mostly passenger aircraft). Recently, all of them decided to turn up to the drone market. If the project will come into effect it is predicted that first drones will appear in 2020. This will help Europe to become more independent of United States. 

3. Titan Aerospace 
The company now has gained notoriety due to the announcement of its acquisition by Google. It is said that Google will use these drones to provide access to their services in areas where it is not possible at the moment, as well as is planning their biggest competitor Facebook. These drones are prototypes for now, but will be powered by solar energy and able to stay high in the air for several years. 

4. General Atomics 
The company is mostly known for constructing the Predator drone. The drone is equipped with cameras and other sensors, but it has been modified and upgraded to carry and fire two AGM-114 Hellfire missiles or other munitions. The Predator has also a bigger and more powerful variant which is MQ-9 Reaper.

5. AeroVironment 
The company is known especially for its Hummingbird drone. It is a drone that mimics the look and behaviour of the hummingbird. The drone is very small, light and can hover or fly in all directions. It also carries a camera. The company is also constructing tactical military drones like RQ-11 Raven used for example to explore new territories by soldiers. 

6. Vanguard Defense Industries 
The company is mostly known for their drone called ShadowHawk. It is available in different variants (for example military, electric) and can fly day-after-day, for up to 3 hours at a time, on an accurate flight path, under computer control. 

7. Northrop Grumman 
The Northrop Grumman is also one of the biggest companies in the drone market. The X-47B is the most advanced stealth combat drone produced by this company. It can refuel itself in flight and conduct pre-programmed missions using GPS navigation. It can be equipped with sensors or weapons. 

8. Prox Dynamics AS 
The Prox Dynamics has developed the Black Hornet Nano, which is a drone that looks like a tiny helicopter. The Black Hornet Nano is equipped with a camera which gives the operator full-motion video and still images. 

9. SAIC
Science Applications International Corporation is a US company that provides government services and information technology support. They specialize in building unmanned underwater vehicles (UUV), known as underwater drones. The vehicles are able to operate underwater without a human occupant and can be used in a defense against ultra-quiet submarines. 

10. Israel Aerospace Industries 
The company is the biggest aerospace and aviation manufacturer in Israel. It is producing both military and civilian aerial systems. They are developing many types of drones such as Pioneer, RQ-5 Hunter, Heron - family of long-endurance UAV, Bird-Eye - family of mini-UAV. 

11. Draganflyer Innovations 
This company is widely known because of its product Draganflyer X6. It is a drone that is powered by battery and it’s being one of the lightest in the drone market by now. It can be equipped with a cameras and sensors, but can’t fly longer than about 20 minutes. Condor Aerial It is not a big company, but it is expanding very fast these days. It has already been offering a few types of drones like: Precepter, Talon, Phoenix, Phantom-2, SeaHawk, Scorpion and Critter, with Multi-Rotor or Fixed-Wing option.

12. Condor Aerial
It is not a big company, but it is expanding very fast these days. It has already been offering a few types of drones like: Precepter, Talon, Phoenix, Phantom-2, SeaHawk, Scorpion and Critter, with Multi-Rotor or Fixed-Wing option.

Authors:
Aneta Żądło
Jan M. Krawczyk