| 1. |
- Alm, Per Gunnar, et al.
(författare)
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The use of a geological model in a cavern construction in limestone
- 2018
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Konferensbidrag (refereegranskat)abstract
- Active design is an expression that has been used fore some years now. This paper will present a case study from an excavation of two cavern constructions (80m long x 16m wide x 12m high) and access tunnels in a Bryozoan limestone in southern Sweden. By using various geophysical survey methods like for instance resistivity soundings, in combination with core drilling and geophysical well logs a geological model of the proposed construction site could be created. In this process not only the geological composition was studied but also the physical properties of the limestone was investigated. The geological model gave indication of how the final design of the caverns should be carried out to overcome problems with fault zones and ground water intrusion. During the excavation of the limestone from the cavern rooms, geological surveys were carried out to assist in the event of a redesign of the cavern constructions. The active calibration of the geological model made it possible to change and reduce the reinforcement of the rock mass. Measurements of the overburden were also taken during the excavation to monitor the setting/compaction of the limestone cover. After the cavern constructions were completed but before the final lining of the rooms, the limestone exposed at cavern walls and roof were surveyed i.e. the induration and fracturing was determined. This was done in an attempt to calibrate and validate the geological model. By active design and calibration of the geological model during the complete excavation, it has been possible to optimize both the location as well as the final cavern design. For the purpose of this article it has also been possible to reveal the actual geological explanations supporting the basic geological model.
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| 2. |
- Dahlin, Torleif, et al.
(författare)
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Use of electrical imaging in site investigations for a railway tunnel through the Hallandsås Horst, Sweden
- 1999
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Ingår i: Quarterly Journal of Engineering Geology and Hydrogeology. - 1470-9236. ; 32:2, s. 163-173
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Tidskriftsartikel (refereegranskat)abstract
- Investigations over two major tectonic zones in the Hallandsås Horst, Southern Sweden were carried out in connection with a railway tunnelling project. A combination of resistivity imaging, core drilling and geophysical logging was found to provide a good overview of the variation in rock quality and detailed information on the engineering geological characteristics and genesis of the strata. Resistivity data, acquired along parallel lines over the zones using multi-electrode equipment, were processed by means of automatic inversion software to generate sections showing the variation of resistivity with depth. Wireline core drilling at selected points gave an almost complete core recovery, which revealed major sedimentary sequences and heavily weathered crystalline rocks that were previously unknown or only partially known despite conventional core drilling and percussion drilling. Geophysical borehole logging confirms the resistivity imaging results, and would be a particularly valuable complement to core logging in cases where significant core loss occurs.
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| 3. |
- Lund, John W, et al.
(författare)
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Characteristics, development and utilization of geothermal resources - a Nordic perspective
- 2008
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Ingår i: Episodes. - 0705-3797. ; 31:1, s. 140-147
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Tidskriftsartikel (refereegranskat)abstract
- Geothermal energy is classified as a renewable energy source and it utilizes the heat generated in the earth primarily from the natural radioactive decay of isotopes of uranium, thorium and potassium. Heat is extracted from the earth to generate geothermal energy via a carrier, usually water occurring either in the liquid or steam phase. In the late 19th century and the early 20th century, the first developments of geothermal resources for power generation and household heating got underway successfully. Many of these geothermal fields are still being utilized today, proving their sustainability. Today geothermal energy is being utilized in more than 72 countries around the world and of the Nordic countries Iceland and Sweden have been in the forefront in each of their respective fields. While geothermal heat pumps are widely used for space heating in Sweden, geothermal energy covers 55% of the primary energy consumption in Iceland where it is used for space heating, power generation and industrial purposes. Future developments aim at expanding the range of viable geothermal resources by improving the capabilities to generate electricity from geothermal resources at temperatures as low as 100 C, as well as developing geothermal resources where water needs to be introduced, so-called hot dry rock resources. But the biggest expansion is expected to continue to be in the installations of geothermal heat pumps.
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| 4. |
- Rosberg, Jan-Erik, et al.
(författare)
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Well Development by Jetting Using Coiled Tubing and Simultaneous Pumping.
- 2009
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Ingår i: Ground Water. - : Wiley. - 0017-467X .- 1745-6584. ; 47:6, s. 806-815
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Tidskriftsartikel (refereegranskat)abstract
- During flow testing of a deep, 1927-m, gravel packed screen completed well, it became apparent that well development was needed to increase productivity. A hydrojetting system using coiled tubing in combination with simultaneous pumping was developed and tested and found to be successful. To verify whether the jetting improved the well, the results of a pumping test conducted before and after the jetting operation are compared. In addition, flowmeter logging and hydraulic properties obtained from pumping tests conducted during the jetting operation were also used to verify the improvements. Hydrojetting in combination with simultaneous pumping proved to be an effective cleaning method. After 100 min of pumping, around 110 m less drawdown and 15 L/s higher average flow rate were obtained compared to the values before the jetting operation. The skin factor was positive before the jetting operation and negative thereafter, thus providing additional evidence of improvements of the well. The flowmeter data also confirmed the improvements and were valuable in optimizing the jetting operation. It was also found, from the short-term pumping tests conducted during the jetting operation, that the Hantush-Jacob method for leaky confined aquifers is a valuable indicator of the well development. The combination of methods used for the well development in this case can easily be applied on other deep well projects to obtain a controlled and time-efficient well development.
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