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Zhang Y.-J.,Jilin University | Guo L.-L.,Jilin University | Li Z.-W.,Jilin University | Yu Z.-W.,Jilin University | And 2 more authors.
Energy | Year: 2015

Daqing City in Northern Songliao Basin (China) requires huge amounts of electric power and thermal energy for oil processing and resident support each year. We used actual geological and logging data of deep well YS-2 in Daqing oilfield to investigate electricity generation and heating potential from enhanced geothermal systems in tight rock and naturally fractured formations (3850-4500 m) using different reservoir stimulation methods. We then proposed optimized hydraulic fracturing and heat extraction strategies for each formation. Results indicate that the Yingcheng formation is suitable for the development of HDR (hot dry rock) resources in this region. Heat output in the stimulated naturally fractured formation is obviously higher than that in the tight rock formation. The development of HDR resources in the naturally fractured formation should be prioritized. In middle-low temperature (about 160 °C), tight rock formation still has great potential for heating supply, but the structure has poor capacity for electricity generation because of the low appropriate injection rate resulting from low reservoir temperature. However, when a high temperature reservoir is selected, electricity generation is feasible from tight formation by using gel-proppant hydraulic fracturing combined with horizontal well technology. © 2015 Elsevier Ltd. All rights reserved. Source

Guo L.,Jilin University | Zhang Y.,Jilin University | Xu T.,Jilin University | Jin X.,Downhole Operation Company of Daqing Oilfield
Jilin Daxue Xuebao (Diqiu Kexue Ban)/Journal of Jilin University (Earth Science Edition) | Year: 2016

To evaluate the hot dry rock (HDR) resource under different conditions in Xujiaweizi area in Daqing, based on the real logging data of one deep well we divided the existing conditions into several types. For each formation type, we proposed the corresponding fracturing strategy and created 3D fracturing model. Based on the stimulated reservoir, the hydro-thermal simulations were performed by using TOUGH2, and the extracted thermal energy was evaluated. The results indicate that Yingcheng formation is the most suitable reservoir for HDR development at present; the target formation based on feature fracture could be divided into tight and fractured formation; based on stress confinement condition, it could be subdivided to confined and unconfined formation; after 20 years operation (horizontal part length is 2000 m), the heat production from the confined and unconfined formation are 3500-5350 kJ/s and 5600-7760 kJ/s respectively, when the injection rate are 20 and 32 kg/s respectively; whereas the heat from naturally fractured formation is much higher than that from tight formation (injection rate is 30 kg/s, heat production is 17000-18500 kJ/s). Above all, the horizontal technique makes the tight formation also have the HDR resource development potential. © 2016, Jilin University Press. All right reserved. Source

In this paper, the feasibility of generating electricity from EGS (enhanced geothermal systems) by oilfield produced water circulating through reservoir stimulated by staged fracturing technology for horizontal wells is investigated based on the geological data of Xujiaweizi area, located in the Daqing Oilfield, northeast China. HDR (hot dry rock) resource potential assessment is carried out by using volumetric method. Reservoir stimulation is numerically simulated based on the geological data of well YS-1 and field fracturing experience in this region. Geometric dimensions and flow conductivity of the resulting fracture are imported into the hydro-thermal model to calculate the electricity generation potential of the proposed EGS power plant. An EGS design scheme is proposed based on the simulation results. The system is also evaluated from the economic and environmental aspects. The results indicate that HDR resource in Xujiaweizi area is of great potential for development. Through the staged fracturing technology for horizontal wells, electricity generation power of the proposed EGS project can roughly meet the commercial standard. For 20 years of continuous production, power generation from the proposed EGS power plant is economic feasible. Meanwhile, significant reductions in greenhouse gas emissions can be achieved. © 2014 Elsevier Ltd. Source

Zhang Y.-J.,Jilin University | Li Z.-W.,Jilin University | Yu Z.-W.,Jilin University | Guo L.-L.,Jilin University | And 2 more authors.
Energy and Buildings | Year: 2014

In this work, the feasibility of using enhanced geothermal system correlation techniques (hydraulic fracturing and heat extraction) to develop medium-low temperature geothermal resources for heating purposes in northeast China is investigated. A detailed experiment on field hydraulic fracturing stimulation is conducted. Combining with numerical simulation approaches, heat production potential of this system is forecasted. Field hydraulic stimulation results indicate that the matrix acidizing treatment significantly limits near wellbore friction loss. For network fracturing treatment, however, the formation of branching fractures and its enhancing effects on reservoir flow conductivity needs to be verified by production tests in the future. The geometric dimension and flow conductivity of the induced fracture are determined by numerical simulation of hydraulic fracturing process. The accuracy of the numerical model is verified through matching well head pressure curve. Parameters including production flow rate, flow impedance, production temperature, heat extraction rate and energy efficiency are determined through the simulation results of heat production forecast. The results indicate that thermal energy production from the stimulated reservoir is satisfactory for heating purpose. However, water flow impedance maintains at a relative high level during production period. © 2014 Elsevier B.V. All rights reserved. Source

Yu Z.,Jilin University | Guo L.,Jilin University | Zhang Y.,Jilin University | Xu T.,Jilin University | And 2 more authors.
Environmental Earth Sciences | Year: 2016

Ground-source heat pumps (GSHPs) have been widely applied in China in recent years. However, for heating-dominant buildings in cold regions, more heat from the ground is extracted than rejected, which leads to an annual decrease in heat source temperature and degradation of GSHP heating performance. In this study, a novel medium- to low-temperature enhanced geothermal combined with heat pump system (MLEGHP) is proposed for winter heating. Taking Shenyang city as an example, we technologically and economically investigate the applicability of this novel MLEGHP system in heating-dominated regions over a 30-year period. According to real geological data, hydraulic fracturing simulation, reservoir simulation, heating performance assessment, and economic analysis are conducted successively. Results indicate that the MLEGHP system can continuously work efficiently without performance deterioration and strengthen heating reliability during long-term operation in cold regions. Despite the high initial investment, the heat production and payback period of the system are considerable for large-scale projects. Thus, the MLEGHP system is a potential solution for the underground thermal imbalance of GSHP systems and for winter heating in cold regions. © 2016, Springer-Verlag Berlin Heidelberg. Source

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