Energies

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4432 KiB

Open AccessArticle

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 22 | Viewed by 8310

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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6120 KiB

Open AccessArticle

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 4610

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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3321 KiB

Open AccessArticle

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 - 01 Oct 2016

Cited by 13 | Viewed by 6226

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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1829 KiB

Open AccessArticle

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 52 | Viewed by 9601

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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1182 KiB

Open AccessArticle

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 - 03 Sep 2016

Cited by 19 | Viewed by 5793

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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13233 KiB

Open AccessArticle

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 4898

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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1840 KiB

Open AccessArticle

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 9 | Viewed by 7298

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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5001 KiB

Open AccessArticle

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 4575

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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