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Selected Papers from the 5th Annual Conference for the Development and Utilization of Deep Geothermal Energy

A special issue of Energies (ISSN 1996-1073).

Deadline for manuscript submissions: closed (31 July 2016) | Viewed by 55254

Special Issue Editors

Prof. Kewen Li

E-Mail Website
Guest Editor
School of Energy Resources, China University of Geosciences (Beijing) 29 Xueyuan Road, Beijing 100083, China
Interests: geothermal reservoir engineering; enhanced oil recovery
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Kamel Hooman

E-Mail Website
Guest Editor
Department of Process and Energy (P&E), Technische Universiteit Delft, Mekelweg 5, 2628 CD Delft, The Netherlands
Interests: melting; microchannel; carbon dioxide; acids; periodic structures; parameter design; phase change materials; cooling
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The 5th Annual Conference for the Development and Utilization of Geothermal Energy will be held in Beijing, China, on 15–17 March, 2016. The conference serves as a public forum for the exchange of ideas on the exploration, development, and use of geothermal resources for engineers, scientists, and managers in the geothermal industry. The conference will cooperate with national and international academic institutions, industry and government agencies to encourage economically and environmentally sound development and bring the innovative technology to China; and promote research, exploration and development of geothermal energy in ways compatible with the environment in China

Topics:

  • Exploration: geology, geophysics, geochemistry, heat flow studies

  • Drilling and well stimulation

  • Power generation technologies

  • Co-production from oil and gas fields

  • Enhanced Geothermal Systems (EGS)

  • Reservoir Engineering: injection, numerical simulation, empirical methods, tracers, etc.

  • Direct use: heat pumps, space heating, and cooling

Prof. Kewen Li
Assoc. Prof. Kamel Hooman
Guest Editors

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Published Papers (8 papers)

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Research

4432 KiB  
Article
Mapping the Geothermal System Using AMT and MT in the Mapamyum (QP) Field, Lake Manasarovar, Southwestern Tibet
by Lanfang He, Ling Chen, Dorji, Xiaolu Xi, Xuefeng Zhao, Rujun Chen and Hongchun Yao
Energies 2016, 9(10), 855; https://doi.org/10.3390/en9100855 - 22 Oct 2016
Cited by 24 | Viewed by 8760
Abstract
Southwestern Tibet plays a crucial role in the protection of the ecological environment and biodiversity of Southern Asia but lacks energy in terms of both power and fuel. The widely distributed geothermal resources in this region could be considered as potential alternative sources [...] Read more.
Southwestern Tibet plays a crucial role in the protection of the ecological environment and biodiversity of Southern Asia but lacks energy in terms of both power and fuel. The widely distributed geothermal resources in this region could be considered as potential alternative sources of power and heat. However, most of the known geothermal fields in Southwestern Tibet are poorly prospected and currently almost no geothermal energy is exploited. Here we present a case study mapping the Mapamyum (QP) geothermal field of Southwestern Tibet using audio magnetotellurics (AMT) and magnetotellurics (MT) methods. AMT in the frequency range 11.5–11,500 Hz was used to map the upper part of this geothermal reservoir to a depth of 1000 m, and MT in the frequency range 0.001–320 Hz was used to map the heat source, thermal fluid path, and lower part of the geothermal reservoir to a depth greater than 1000 m. Data from 1300 MT and 680 AMT stations were acquired around the geothermal field. Bostick conversion with electromagnetic array profiling (EMAP) filtering and nonlinear conjugate gradient inversion (NLCGI) was used for data inversion. The AMT and MT results presented here elucidate the geoelectric structure of the QP geothermal field, and provide a background for understanding the reservoir, the thermal fluid path, and the heat source of the geothermal system. We identified a low resistivity anomaly characterized by resistivity in the range of 1–8 Ω∙m at a depth greater than 7 km. This feature was interpreted as a potential reflection of the partially melted magma in the upper crust, which might correlate to mantle upwelling along the Karakorum fault. It is likely that the magma is the heat source of the QP geothermal system, and potentially provides new geophysical evidence to understand the occurrence of the partially melted magmas in the upper crust in Southwestern Tibet. Full article
(This article belongs to the Special Issue Selected Papers from the 5th Annual Conference for the Development and Utilization of Deep Geothermal Energy)
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Figure 1

Figure 1
<p>Simplified geologic map of the Himalayas to show the locations of the study area, the QP geothermal field, the Karakorum fault, and the Indus-Yarlung Zangbo suture zone (modified from Hu et al. [<a href="#B15-energies-09-00855" class="html-bibr">15</a>]).</p> Full article ">Figure 2
<p>Location of the QP geothermal field and field layout of AMT and MT survey. (<b>a</b>) Location of the QP geothermal field; (<b>b</b>) its geological setting; (<b>c</b>) cross section; (<b>d</b>) locations of geothermal features; (<b>e</b>) the local geological map showing field layout; and (<b>f</b>) the location of the hot springs in Tibet (modified from Wang et al. [<a href="#B17-energies-09-00855" class="html-bibr">17</a>], with permission from the authors). Line1 and Line2 show the location of the section of <a href="#energies-09-00855-f003" class="html-fig">Figure 3</a> and <a href="#energies-09-00855-f004" class="html-fig">Figure 4</a>. Numerals: (<b>1</b>) Late Holocene alluvial-proluvial fan; (<b>2</b>) Pleistocene deposits; (<b>3</b>) Lower Member of the Neocene Woma Group; (<b>4</b>) Upper Cretaceous Sangdanlin Formation; (<b>5</b>) Upper Carboniferous Lasha Formation; (<b>6</b>) Lower Carboniferous Kangtuo Formation; (<b>7</b>) Neocene monzogranite granite; (<b>8</b>) Upper Triassic mafic rocks; (<b>9</b>) Upper Triassic complex; (<b>10</b>) Quaternary sediment; (<b>11</b>) conglomerate; (<b>12</b>) sandstone; (<b>13</b>) mudstone; (<b>14</b>) shale; (<b>15</b>) siliceous rock; (<b>16</b>) complex rock; (<b>17</b>) mafic rock; (<b>18</b>) phyllite; (<b>19</b>) meta-sandstone; (<b>20</b>) metamorphic conglomerate; (<b>21</b>) mylonite; (<b>22</b>) monzogranite; (<b>23</b>) boundary of an unconformity; (<b>24</b>) reverse fault; (<b>25</b>) buried fault; and (<b>26</b>) stream or lake.</p> Full article ">Figure 3
<p>Comparison between Bostick conversion of (<b>a</b>) the XY direction, (<b>b</b>) the YX direction, and (<b>c</b>) nonlinear conjugate gradient inversion (NLCGI) results for an AMT section ((Line1 as shown in <a href="#energies-09-00855-f002" class="html-fig">Figure 2</a> and <a href="#energies-09-00855-f005" class="html-fig">Figure 5</a>). The black solid line outlines the geo-electric layers (L1 to L3). The blue dashed line shows the geothermal reservoir interpreted from the AMT results.</p> Full article ">Figure 4
<p>Conversion results from a MT section (Line2 as shown in <a href="#energies-09-00855-f002" class="html-fig">Figure 2</a> and <a href="#energies-09-00855-f005" class="html-fig">Figure 5</a>) illustrate the typical geo-electric structure of the QP geothermal field. L2 to L4 show the geo-electric layer, L2 is a low-resistivity layer mainly reflecting the reservoir (marked with the blue dashed line) which contains the brine thermal fluids (water); L3 is a resistive layer that reflects the host rock and path (has lower resistivity than the host rocks); L4 is a low resistivity layer, which the major portion reflects the heat source (marked with the black dashed line). The lower portion of L4 (marked with the green dashed line) is interpreted as partial melting.</p> Full article ">Figure 5
<p>Resistivity contour maps at elevations of (<b>a</b>) 3500 m and (<b>b</b>) 2000 m ASL. The reservoir and the thermal path of the geothermal system are outlined with the blue dashed line. Line1 and Line2 show the location of the section of <a href="#energies-09-00855-f003" class="html-fig">Figure 3</a> and <a href="#energies-09-00855-f004" class="html-fig">Figure 4</a>. The red rectangle shows the portion where three-dimensional imaging is conducted and shows in <a href="#energies-09-00855-f006" class="html-fig">Figure 6</a>.</p> Full article ">Figure 6
<p>3D resistivity imaging shows the resistivity volume with a value lower than (<b>a</b>) 15 and (<b>b</b>) 22 Ω∙m for the eastern portion of the QP geothermal field. A low-reisitivity volume with a value lower than 15 Ω∙m (<b>a</b>) reflects the heat source and upper portion of geothermal reservoir, another data volume of lower than 22 Ω∙m reflects the whole geothermal system, including the heat source, path, and the reservoir. The path has a higher resistivity of 15–22 Ω∙m than the heat source and the reservoir.</p> Full article ">Figure 7
<p>Comparison of example MT sounding curves from QP, Tibet, and the Newberry volcano, Oregon, USA. The foot figure shows the curve from Newberry volcano, the black triangles are resistivity and phase of MT <span class="html-italic">XY</span> direction, and the square are resistivity and phase of MT <span class="html-italic">YX</span> direction [<a href="#B28-energies-09-00855" class="html-bibr">28</a>]. The blue dot and red brick show the resistivity and phase of the MT <span class="html-italic">XY</span> direction of one station in QP.</p> Full article ">
6120 KiB  
Article
Polylactic Acid Improves the Rheological Properties, and Promotes the Degradation of Sodium Carboxymethyl Cellulose-Modified Alkali-Activated Cement
by Huijing Tan, Xiuhua Zheng, Chenyang Duan and Bairu Xia
Energies 2016, 9(10), 823; https://doi.org/10.3390/en9100823 - 14 Oct 2016
Cited by 6 | Viewed by 4909
Abstract
In consideration of the insolubility in water, sensitivity to heat and wide application in the oil and gas industry as a degradable additive, this paper introduces polylactic acid (PLA) to a self-degradable temporary sealing material (SDTSM) to investigate its effect on the SDTSM [...] Read more.
In consideration of the insolubility in water, sensitivity to heat and wide application in the oil and gas industry as a degradable additive, this paper introduces polylactic acid (PLA) to a self-degradable temporary sealing material (SDTSM) to investigate its effect on the SDTSM performance and evaluate its potential to improve the rheological properties and further promote the self-degradation of the material. The thermal degradation of PLA, the rheological properties, compressive strength, hydrated products and water absorption of SDTSMs with different PLA dosages were tested. The analysis showed that the addition of 2% PLA increased the fluidity by 13.18% and reduced the plastic viscosity by 38.04%, when compared to those of the SDTSM without PLA. PLA increased the water absorption of 200 °C-heated SDTSM and had small effect on the types but decreased the hydrate products of 85 °C-cured SDTSM, and created plenty of pores in 200 °C-heated SDTSM. PLA enhanced the self-degradation level of SDTSM by generating a large amount of pores in cement. These pores worked in two ways: one was such a large amount of pores led to a looser microstructure; the other was these pores made the water impregnate the cement more easily, and then made the dissolution of substances in the 200 °C-heated SDTSM progress faster to generate heat and to destruct the microstructure. Full article
(This article belongs to the Special Issue Selected Papers from the 5th Annual Conference for the Development and Utilization of Deep Geothermal Energy)
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Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>TGA curves for the non- and filtrate-treated PLA.</p> Full article ">Figure 2
<p>Py-GC/MS abundance-retention time curve of non-treated PLA.</p> Full article ">Figure 3
<p>Fluidity of the slurries of the control and SDTSMs with different PLA dosages.</p> Full article ">Figure 4
<p>The rheological curves of the control and SDTSMs with different PLA dosages.</p> Full article ">Figure 5
<p>The plastic viscosity of the control and SDTSMs with different PLA dosages.</p> Full article ">Figure 6
<p>Compressive strength of 85 °C-cured specimens of the control and SDTSMs with different PLA dosages.</p> Full article ">Figure 7
<p>XRD patterns of 85 °C-cured specimens of the control and SDTSMs with different PLA dosages.</p> Full article ">Figure 8
<p>Water absorption of the 200 °C-heated specimens of control and SDTSMs with different PLA dosages.</p> Full article ">Figure 9
<p>Images of the section of 200 °C-heated samples of the control and SDTSMs with different PLA dosages after immersed in water for 2 h: (<b>a</b>) the control; (<b>b</b>) 0%; (<b>c</b>) 2%; (<b>d</b>) 4%; (<b>e</b>) 6%; (<b>f</b>) 8%; (<b>g</b>) 10%.</p> Full article ">Figure 10
<p>Images of the section of the 200 °C-heated samples after being immersed in water for 24 h: (<b>a</b>) the image of the control; (<b>b</b>) 0%; (<b>c</b>) 2%; (<b>d</b>) 4%; (<b>e</b>) 6%; (<b>f</b>) 8%; (<b>g</b>) 10%.</p> Full article ">Figure 11
<p>Compressive strength of control and SDTSM with different PLA dosages after being 200 °C-heated, immersed in water for 2 h and 24 h.</p> Full article ">Figure 12
<p>SEM images of smaller magnification of the SDTSM with 2% PLA after different periods: (<b>a</b>) 85 °C-cured; (<b>b</b>) 200 °C-heated; (<b>c</b>) immersed in water for 2 h and (<b>d</b>) immersed in water for 24 h.</p> Full article ">Figure 13
<p>SEM images of greater magnification of the SDTSM with 2% PLA after different periods: (<b>a</b>) 85 °C-cured; (<b>b</b>) 200 °C-heated; (<b>c</b>) immersed in water for 2 h and (<b>d</b>) immersed in water for 24 h.</p> Full article ">
3321 KiB  
Article
Estimate of Hot Dry Rock Geothermal Resource in Daqing Oilfield, Northeast China
by Guangzheng Jiang, Yi Wang, Yizuo Shi, Chao Zhang, Xiaoyin Tang and Shengbiao Hu
Energies 2016, 9(10), 731; https://doi.org/10.3390/en9100731 - 1 Oct 2016
Cited by 13 | Viewed by 6632
Abstract
Development and utilization of deep geothermal resources, especially a hot dry rock (HDR) geothermal resource, is beneficial for both economic and environmental consideration in oilfields. This study used data from multiple sources to assess the geothermal energy resource in the Daqing Oilfield. The [...] Read more.
Development and utilization of deep geothermal resources, especially a hot dry rock (HDR) geothermal resource, is beneficial for both economic and environmental consideration in oilfields. This study used data from multiple sources to assess the geothermal energy resource in the Daqing Oilfield. The temperature logs in boreholes (both shallow water wells and deep boreholes) and the drilling stem test temperature were used to create isothermal maps in depths. Upon the temperature field and thermophysical parameters of strata, the heat content was calculated by 1 km × 1 km × 0.1 km cells. The result shows that in the southeastern part of Daqing Oilfield, the temperature can reach 150 °C at a depth of 3 km. The heat content within 3–5 km is 24.28 × 1021 J, wherein 68.2% exceeded 150 °C. If the recovery factor was given by 2% and the lower limit of temperature was set to be 150 °C, the most conservative estimate for recoverable HDR geothermal resource was 0.33 × 1021 J. The uncertainties of the estimation are mainly contributed to by the temperature extrapolation and the physical parameter selections. Full article
(This article belongs to the Special Issue Selected Papers from the 5th Annual Conference for the Development and Utilization of Deep Geothermal Energy)
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Figure 1

Figure 1
<p>(<b>a</b>) The various temperature measurements on the Daqing Oilfield. Major structure zones in the Songliao basin and the structural location of the Daqing Oilfield are also shown; (<b>b</b>) stratigraphic cross-section of AA’, its location is shown in (<b>a</b>), interpreted with borehole-constrained seismic data. (Reproduced with permission from [<a href="#B22-energies-09-00731" class="html-bibr">22</a>] Ryder et al., 2003 and [<a href="#B23-energies-09-00731" class="html-bibr">23</a>] Wang et al., 2016). Formation symbols: K<sub>1</sub>h is Huoshiling, K<sub>1</sub>s is Shahezi, K<sub>1</sub>y is Yingcheng, K<sub>1</sub>d is Denglouku, K<sub>2</sub>q is Quantou, K<sub>2</sub>qn is Qingshankou, K<sub>2</sub>y is Yaojia, K<sub>2</sub>n is Nenjiang, K<sub>2</sub>s is Sifangtai, K<sub>2</sub>m is Mingshui. Tectonic units: I is North Slope, II is West Slope, III is Central Depression, IV is Southeast Uplift, V is North Uplift, VI is Southwest Uplift.</p> Full article ">Figure 2
<p>(<b>a</b>) Temperature logs from shallow water wells; (<b>b</b>) temperature logs from deep oil wells and geothermal wells, along with DST in the oil wells. Temperature logs of SK-2, W1, and W2 were newly measured in this study. W3–W6 are from Zhu [<a href="#B17-energies-09-00731" class="html-bibr">17</a>], W7 and W8 are from Zhao [<a href="#B21-energies-09-00731" class="html-bibr">21</a>], W9 and W10 are from Wu and Xie [<a href="#B15-energies-09-00731" class="html-bibr">15</a>] and Liu et al. [<a href="#B18-energies-09-00731" class="html-bibr">18</a>], and W11–W15 were extracted from oil test report.</p> Full article ">Figure 3
<p>The relationship between the temperature gradient (TG) and depth.</p> Full article ">Figure 4
<p>The temperature distribution at the different depth of 3 km (<b>a</b>), 4 km (<b>b</b>), and 5 km (<b>c</b>). The thick black lines show the isotherm of 150 °C and 200 °C.</p> Full article ">Figure 5
<p>Heat content in place with various temperature ranges in the 0.5 km thick depth intervals from 3 to 5 km. The area of the pie represents the amount of the heat content. The number in front is the heat content in 10<sup>21</sup> J, the number in the bracket is the percentage of the different temperature ranges in specific depth interval.</p> Full article ">
1829 KiB  
Article
Exploitation and Utilization of Oilfield Geothermal Resources in China
by Shejiao Wang, Jiahong Yan, Feng Li, Junwen Hu and Kewen Li
Energies 2016, 9(10), 798; https://doi.org/10.3390/en9100798 - 30 Sep 2016
Cited by 57 | Viewed by 10203
Abstract
Geothermal energy is a clean, green renewable resource, which can be utilized for power generation, heating, cooling, and could effectively replace oil, gas, and coal. In recent years, oil companies have put more efforts into exploiting and utilizing geothermal energy with advanced technologies [...] Read more.
Geothermal energy is a clean, green renewable resource, which can be utilized for power generation, heating, cooling, and could effectively replace oil, gas, and coal. In recent years, oil companies have put more efforts into exploiting and utilizing geothermal energy with advanced technologies for heat-tracing oil gathering and transportation, central heating, etc., which has not only reduced resource waste, but also improved large-scale and industrial resource utilization levels, and has achieved remarkable economic and social benefits. Based on the analysis of oilfield geothermal energy development status, resource potential, and exploitation and utilization modes, the advantages and disadvantages of harnessing oilfield geothermal resource have been discussed. Oilfield geothermal energy exploitation and utilization have advantages in resources, technical personnel, technology, and a large number of abandoned wells that could be reconstructed and utilized. Due to the high heat demand in oilfields, geothermal energy exploitation and utilization can effectively replace oil, gas, coal, and other fossil fuels, and has bright prospects. The key factors limiting oilfield geothermal energy exploitation and utilization are also pointed out in this paper, including immature technologies, lack of overall planning, lack of standards in resource assessment, and economic assessment, lack of incentive policies, etc. Full article
(This article belongs to the Special Issue Selected Papers from the 5th Annual Conference for the Development and Utilization of Deep Geothermal Energy)
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Figure 1

Figure 1
<p>Distribution of petroliferous basins and heat flow in China [<a href="#B9-energies-09-00798" class="html-bibr">9</a>].</p> Full article ">Figure 2
<p>Geothermal project input and output.</p> Full article ">Figure 3
<p>Geothermal project cash flow.</p> Full article ">Figure 4
<p>Major hydrocarbon basins and geothermal resource assessment scope.</p> Full article ">
1182 KiB  
Article
Mechanism of Fiscal and Taxation Policies in the Geothermal Industry in China
by Yong Jiang, Yalin Lei, Li Li and Jianping Ge
Energies 2016, 9(9), 709; https://doi.org/10.3390/en9090709 - 3 Sep 2016
Cited by 19 | Viewed by 6069
Abstract
Geothermal energy is one of the cleanest sources of energy which is gaining importance as an alternative to hydrocarbons. Geothermal energy reserves in China are enormous and it has a huge potential for exploitation and utilization. However, the development of the geothermal industry [...] Read more.
Geothermal energy is one of the cleanest sources of energy which is gaining importance as an alternative to hydrocarbons. Geothermal energy reserves in China are enormous and it has a huge potential for exploitation and utilization. However, the development of the geothermal industry in China lags far behind other renewable energy sources because of the lack of fiscal and taxation policy support. In this paper, we adopt the system dynamics method and use the causal loop diagram to explore the development mechanism of fiscal and taxation policies in the geothermal industry. The effect of the fiscal and taxation policy on the development of the geothermal industry is analyzed. In order to promote sustainable development of the geothermal industry in China, the government should pay more attention to subsidies for the geothermal industry in the life-cycle stage of the geothermal industry. Furthermore, a plan is necessary to provide a reasonable system of fiscal and taxation policies. Full article
(This article belongs to the Special Issue Selected Papers from the 5th Annual Conference for the Development and Utilization of Deep Geothermal Energy)
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Figure 1

Figure 1
<p>Energy consumption and carbon dioxide emissions from 1980 to 2015 in China.</p> Full article ">Figure 2
<p>System of fiscal and tax policies affecting geothermal industry.</p> Full article ">
13233 KiB  
Article
Thermodynamic Simulation on the Performance of Twin Screw Expander Applied in Geothermal Power Generation
by Yuanqu Qi and Yuefeng Yu
Energies 2016, 9(9), 694; https://doi.org/10.3390/en9090694 - 31 Aug 2016
Cited by 7 | Viewed by 5161
Abstract
A three-dimensional (3D) geometry model of twin screw expander has been developed in this paper to measure and analyze geometric parameters such as groove volume, suction port area, and leakage area, which can be described as functions of rotation angle of male rotor. [...] Read more.
A three-dimensional (3D) geometry model of twin screw expander has been developed in this paper to measure and analyze geometric parameters such as groove volume, suction port area, and leakage area, which can be described as functions of rotation angle of male rotor. Taking the suction loss, leakage loss, and real gas effect into consideration, a thermodynamic model is developed using continuity and energy conservation equation. The developed model is verified by comparing predicted results of power output and internal efficiency with experimental data. Based on the model, the relationship between mass flow rate through inlet port and leakage path with rotation angle of male rotor as well as effects of the inlet parameter and operating parameter on the performance of the expander are analyzed. Full article
(This article belongs to the Special Issue Selected Papers from the 5th Annual Conference for the Development and Utilization of Deep Geothermal Energy)
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Figure 1

Figure 1
<p>The second screw expander generating unit in YangBaJing geothermal power plant.</p> Full article ">Figure 2
<p>Schematic drawing of the screw expander power generation unit.</p> Full article ">Figure 3
<p>3D geometry model and rotor profile.</p> Full article ">Figure 4
<p>Inlet area and volume curve of the screw expander.</p> Full article ">Figure 5
<p>Contact line formed between rotors.</p> Full article ">Figure 6
<p>Blowhole.</p> Full article ">Figure 7
<p>Leakage paths area.</p> Full article ">Figure 8
<p>P-V diagram of ideal and simulated work process (<span class="html-italic">P</span><sub>i</sub> = 1.3 MPa, <span class="html-italic">T</span><sub>i</sub> = 192 °C, <span class="html-italic">m</span><sub>t</sub> = 20 t/h, <span class="html-italic">P</span><sub>o</sub> = 0.19 Mpa, <span class="html-italic">n</span> = 2400 rpm).</p> Full article ">Figure 9
<p>m-θ diagram of ideal and simulated work process (<span class="html-italic">P</span><sub>i</sub> = 1.3 MPa, <span class="html-italic">T</span><sub>i</sub> = 192 °C, <span class="html-italic">m</span><sub>t</sub> = 20 t/h, <span class="html-italic">P</span><sub>o</sub> = 0.19 Mpa, <span class="html-italic">n</span> = 2400 rpm).</p> Full article ">Figure 10
<p>Simulated leakage mass over the rotation angle of the male rotor during the expansion process (<span class="html-italic">P</span><sub>i</sub> = 1.3 MPa, <span class="html-italic">T</span><sub>i</sub> = 192 °C, <span class="html-italic">m</span><sub>t</sub> = 20 t/h, <span class="html-italic">P</span><sub>o</sub> = 0.19 Mpa, <span class="html-italic">n</span> = 2400 rpm).</p> Full article ">Figure 11
<p>P-V diagram for different rotate speed (<span class="html-italic">P</span><sub>i</sub> = 1.3 MPa, <span class="html-italic">T</span><sub>i</sub> = 192 °C, <span class="html-italic">P</span><sub>o</sub> = 0.19 Mpa).</p> Full article ">Figure 12
<p>Internal efficiency and power for different rotate speed (<span class="html-italic">P</span><sub>i</sub> = 1.3 MPa, <span class="html-italic">T</span><sub>i</sub> = 192 °C, <span class="html-italic">P</span><sub>o</sub> = 0.19 Mpa).</p> Full article ">Figure 13
<p>P-V diagram for different inlet pressure (<span class="html-italic">P</span><sub>o</sub> = 0.19 Mpa, <span class="html-italic">n</span> = 2400 rpm).</p> Full article ">Figure 14
<p>Internal efficiency and power for different inlet pressure (<span class="html-italic">P</span><sub>o</sub> = 0.19 Mpa, <span class="html-italic">n</span> = 2400 rpm).</p> Full article ">
1840 KiB  
Article
Static Formation Temperature Prediction Based on Bottom Hole Temperature
by Changwei Liu, Kewen Li, Youguang Chen, Lin Jia and Dong Ma
Energies 2016, 9(8), 646; https://doi.org/10.3390/en9080646 - 17 Aug 2016
Cited by 10 | Viewed by 7660
Abstract
Static formation temperature (SFT) is required to determine the thermophysical properties and production parameters in geothermal and oil reservoirs. However, it is not easy to determine SFT by both experimental and physical methods. In this paper, a mathematical approach to predicting SFT, based [...] Read more.
Static formation temperature (SFT) is required to determine the thermophysical properties and production parameters in geothermal and oil reservoirs. However, it is not easy to determine SFT by both experimental and physical methods. In this paper, a mathematical approach to predicting SFT, based on a new model describing the relationship between bottom hole temperature (BHT) and shut-in time, has been proposed. The unknown coefficients of the model were derived from the least squares fit by the particle swarm optimization (PSO) algorithm. Additionally, the ability to predict SFT using a few BHT data points (such as the first three, four, or five points of a data set) was evaluated. The accuracy of the proposed method to predict SFT was confirmed by a deviation percentage less than ±4% and a high regression coefficient R2 (>0.98). The proposed method could be used as a practical tool to predict SFT in both geothermal and oil wells. Full article
(This article belongs to the Special Issue Selected Papers from the 5th Annual Conference for the Development and Utilization of Deep Geothermal Energy)
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Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>The relationship between bottom hole temperature (BHT) and shut-in time, when a = 100, b = −50, and c varies from 1 × 10<sup>−9</sup> to 1.</p> Full article ">Figure 2
<p>Schematic representation of the solving process of the proposed method.</p> Full article ">Figure 3
<p>Comparisons for the bottom-hole temperature (BHT) and Static formation temperature (SFT).</p> Full article ">Figure 4
<p>Comparison of the SFT estimates using the proposed method and reference SFT values. (<span class="html-italic">n</span> is the number of data points of each dataset).</p> Full article ">Figure 5
<p>SFT estimates for each method using the first three, four, five, or n points of a dataset. (e.g., DN 3 represents use of the first three points of a given dataset, (<b>a</b>) to (<b>f</b>) plotted based on the dataset 1 to 5 and 7).</p> Full article ">Figure 6
<p>SFT estimates for each method using the first three, four, or five points, or all (n) data of a set, (<b>a</b>) to (<b>f</b>) plotted based on the dataset 1 to 5 and 7.</p> Full article ">Figure 7
<p>Comparison of Theil Inequality Coefficient (TIC) values for each dataset and various estimating methods.</p> Full article ">
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Article
A Selection Method for Power Generation Plants Used for Enhanced Geothermal Systems (EGS)
by Kaiyong Hu, Jialing Zhu, Wei Zhang and Xinli Lu
Energies 2016, 9(8), 597; https://doi.org/10.3390/en9080597 - 28 Jul 2016
Cited by 6 | Viewed by 4941
Abstract
As a promising and advanced technology, enhanced geothermal systems (EGS) can be used to generate electricity using deep geothermal energy. In order to better utilize the EGS to produce electricity, power cycles’ selection maps are generated for people to choose the best system [...] Read more.
As a promising and advanced technology, enhanced geothermal systems (EGS) can be used to generate electricity using deep geothermal energy. In order to better utilize the EGS to produce electricity, power cycles’ selection maps are generated for people to choose the best system based on the geofluids’ temperature and dryness conditions. Optimizations on double-flash system (DF), flash-organic Rankine cycle system (FORC), and double-flash-organic Rankine cycle system (DFORC) are carried out, and the single-flash (SF) system is set as a reference system. The results indicate that each upgraded system (DF, FORC, and DFORC) can produce more net power output compared with the SF system and can reach a maximum net power output under a given geofluid condition. For an organic Rankine cycle (ORC) using R245fa as working fluid, the generated selection maps indicate that using the FORC system can produce more power than using other power cycles when the heat source temperature is below 170 °C. Either DF or DFORC systems could be an option if the heat source temperature is above 170 °C, but the DF system is more attractive under a relatively lower geofluid’s dryness and a higher temperature condition. Full article
(This article belongs to the Special Issue Selected Papers from the 5th Annual Conference for the Development and Utilization of Deep Geothermal Energy)
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Figure 1

Figure 1
<p>Single-flash (SF) system.</p> Full article ">Figure 2
<p>Double-flash (DF) system.</p> Full article ">Figure 3
<p>Flash-organic Rankine cycle (FORC) system.</p> Full article ">Figure 4
<p>Double-flash-organic Rankine cycle (DFORC) system.</p> Full article ">Figure 5
<p>Variations of net power output of DF with flash temperature (geofluid temperature = 160 °C, steam dryness = 0.2, geofluid flow rate = 150 t/h).</p> Full article ">Figure 6
<p>Variations of net power output of FORC with evaporating temperature (geofluid temperature = 130 °C; steam dryness = 0.2; geofluid flow rate = 150 t/h).</p> Full article ">Figure 7
<p>Variations of net power output of DFORC with evaporating temperature (geofluid temperature = 180 °C, steam dryness = 0.2, geofluid flow rate = 150 t/h).</p> Full article ">Figure 8
<p>Variations of net power output of DF with geofluid temperature: (<b>a</b>) x = 0.1; (<b>b</b>) x = 0.2.</p> Full article ">Figure 9
<p>Variations of net power output of FORC with geofluid temperature: (<b>a</b>) x = 0.2; (<b>b</b>) x = 0.3.</p> Full article ">Figure 10
<p>Variations of net power output of DFORC with geofluid temperature: (<b>a</b>) x = 0.1; (<b>b</b>) x = 0.2.</p> Full article ">Figure 11
<p>Selection maps for power generation systems (DF, FORC, and DFORC) used for enhanced geothermal systems (EGS), generated based on the net power increase ratio of (<b>a</b>) 10% and (<b>b</b>) 15%, respectively.</p> Full article ">
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