The Experts below are selected from a list of 603 Experts worldwide ranked by ideXlab platform
Sophie Michelet - One of the best experts on this subject based on the ideXlab platform.
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fracture mapping in the soultz sous forets geothermal field using microearthquake locations
Journal of Geophysical Research, 2007Co-Authors: Sophie Michelet, Nafi M ToksozAbstract:[1] In 2003, a Massive Hydraulic Fracturing experiment was carried out at the European Geothermal Hot Dry Rock site at Soultz-sous-Forets, France. The 2 week injection of water generated a high level of microseismic activity, triggering about 90,000 microearthquakes during and after the fluid injection. Of these, 21,000 events, detected at all stations, were located individually with a grid search algorithm to characterize the extent of the seismic zones and ultimately of the fracture network. The accuracy of these initial locations was around 70 m, not sufficient to map detailed fracture patterns. A precise relocation effort was undertaken to reduce the location uncertainties using three different techniques: joint hypocenter determination (JHD), collapsing and multiplet analysis. The collapsing method was added to the JHD results to further consolidate the hypocenters. On the other hand, a multiplet analysis was performed on the initial data set for identifying microearthquakes with similar waveforms and hence relocating relatively the correlated events. The delays in traveltime were computed by wavelet analysis and the events were relocated using a grid search algorithm. We found 7463 events whose seismograms correlated with a correlation coefficient of 0.8 or higher, most of which were doublets. Multiplets are horizontal tube-like structures with lengths from a hundred to several hundred meters striking along the direction of the maximum compressive horizontal stress. We interpret these structures as the preferential paths where fluid flow is largely confined. This hypothesis is reinforced by the good correlation in depth between the events and the fluid outflows observed in the well. Therefore we believe that these relocated events highlight the zones where the permeability of the reservoir is increased.
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characterizing the mechanics of Fracturing from earthquake source parameter and multiplet analyses application to the soultz sous forets hot dry rock site
2005Co-Authors: Sophie Michelet, Nafi M ToksozAbstract:In 2000 and 2003, two Massive Hydraulic Fracturing experiments were carried out at the European Geothermal Hot Dry Rock site at Soultz-sous-Forets, France. The objective was to create a dense network of enhanced permeability fractures, which would form the heat exchanger. The injection of water in the fractured rock generated a high level of microseismic activity: around 30,000 and 90,000 micro-earthquakes were triggered during the injection of 2000 and 2003 respectively. From this around 14,000 and 9,000 events were then located to characterize the extent of the stimulated zones and hence of the fracture network. Then, the source parameters of each event, like seismic moments and stress drops, were computed automatically to characterize the mechanics of the Fracturing. We found for example that the total seismic moment released is proportional to the injected fluid volume. This suggests that the injection flow rate could be a means to control the earthquake strength released during the stimulation and perhaps also control the effectiveness of the stimulation. Finally, we performed a multiplet analysis of a subset of these data to identify microearthquakes having similar waveforms. Multiplets are considered to be microearthquakes that occur on the same fracture plane and therefore may represent either seismically activated structures and/or permeable fractures induced by Hydraulic Fracturing. We identified 350 multiplets among 1000 analyzed events. We relocated them precisely by cross-spectrum analysis and found that they belong to sub-horizontal structures, likely permeable fractures stimulated by the injection.
Nafi M Toksoz - One of the best experts on this subject based on the ideXlab platform.
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fracture mapping in the soultz sous forets geothermal field using microearthquake locations
Journal of Geophysical Research, 2007Co-Authors: Sophie Michelet, Nafi M ToksozAbstract:[1] In 2003, a Massive Hydraulic Fracturing experiment was carried out at the European Geothermal Hot Dry Rock site at Soultz-sous-Forets, France. The 2 week injection of water generated a high level of microseismic activity, triggering about 90,000 microearthquakes during and after the fluid injection. Of these, 21,000 events, detected at all stations, were located individually with a grid search algorithm to characterize the extent of the seismic zones and ultimately of the fracture network. The accuracy of these initial locations was around 70 m, not sufficient to map detailed fracture patterns. A precise relocation effort was undertaken to reduce the location uncertainties using three different techniques: joint hypocenter determination (JHD), collapsing and multiplet analysis. The collapsing method was added to the JHD results to further consolidate the hypocenters. On the other hand, a multiplet analysis was performed on the initial data set for identifying microearthquakes with similar waveforms and hence relocating relatively the correlated events. The delays in traveltime were computed by wavelet analysis and the events were relocated using a grid search algorithm. We found 7463 events whose seismograms correlated with a correlation coefficient of 0.8 or higher, most of which were doublets. Multiplets are horizontal tube-like structures with lengths from a hundred to several hundred meters striking along the direction of the maximum compressive horizontal stress. We interpret these structures as the preferential paths where fluid flow is largely confined. This hypothesis is reinforced by the good correlation in depth between the events and the fluid outflows observed in the well. Therefore we believe that these relocated events highlight the zones where the permeability of the reservoir is increased.
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characterizing the mechanics of Fracturing from earthquake source parameter and multiplet analyses application to the soultz sous forets hot dry rock site
2005Co-Authors: Sophie Michelet, Nafi M ToksozAbstract:In 2000 and 2003, two Massive Hydraulic Fracturing experiments were carried out at the European Geothermal Hot Dry Rock site at Soultz-sous-Forets, France. The objective was to create a dense network of enhanced permeability fractures, which would form the heat exchanger. The injection of water in the fractured rock generated a high level of microseismic activity: around 30,000 and 90,000 micro-earthquakes were triggered during the injection of 2000 and 2003 respectively. From this around 14,000 and 9,000 events were then located to characterize the extent of the stimulated zones and hence of the fracture network. Then, the source parameters of each event, like seismic moments and stress drops, were computed automatically to characterize the mechanics of the Fracturing. We found for example that the total seismic moment released is proportional to the injected fluid volume. This suggests that the injection flow rate could be a means to control the earthquake strength released during the stimulation and perhaps also control the effectiveness of the stimulation. Finally, we performed a multiplet analysis of a subset of these data to identify microearthquakes having similar waveforms. Multiplets are considered to be microearthquakes that occur on the same fracture plane and therefore may represent either seismically activated structures and/or permeable fractures induced by Hydraulic Fracturing. We identified 350 multiplets among 1000 analyzed events. We relocated them precisely by cross-spectrum analysis and found that they belong to sub-horizontal structures, likely permeable fractures stimulated by the injection.
Liehui Zhang - One of the best experts on this subject based on the ideXlab platform.
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A semi-analytical solution for Hydraulically fractured vertical wells in tight gas reservoirs with fracture networks
International Journal of Oil Gas and Coal Technology, 2019Co-Authors: Liehui Zhang, Bin TangAbstract:Massive Hydraulic Fracturing technology is a key technology for efficient development of tight gas reservoirs. A complicated stimulated reservoir volume (SRV) is created around the wellbore and the major fracture. The fractures are essential to the recovery and performance of tight reservoirs wells. In this paper, a rectangular composite model of a tight gas reservoir was established to describe a fractured well with an SRV. The SRV is characterised by Warren-Root dual-porosity model. The solution is obtained by Green's and source functions. The well testing type curves are obtained by Stehfest's numerical inversion method. The transient gas flow regime and the sensitivity of variable parameters are analysed. Then, the transient production rate and cumulative production curves with different parameters of well-produced constant bottomhole pressure are plotted, and the corresponding parameters' sensitive analyses are done. The results show the seepage resistance was significantly decreased due to the existence of SRV. [Received: October 29, 2016; Accepted: August 10, 2017]
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pressure response and production performance for multi fractured horizontal wells with complex seepage mechanism in box shaped shale gas reservoir
Journal of Natural Gas Science and Engineering, 2016Co-Authors: Yulong Zhao, Liehui Zhang, Qi-guo Liu, Ye Xiong, Yuhui Zhou, Dan ChenAbstract:Abstract The development of shale gas reservoir has becoming tremendously thrived around the world in recent years. The horizontal well drilling, advanced completion and Massive Hydraulic Fracturing are the key technologies. How to accurately evaluate the production performance of the wells in these reservoirs, especially for multi-fractured horizontal wells, has always been the hot topic for the engineers and relevant researchers. In this paper, we presented a mathematical model to describe a horizontal well with multiple fractures in rectangular outer-boundary reservoir, which uses the Knudsen diffusion to describe the gas flow in nano-pores and also takes the slippage effect into account. By the method of point source function, Laplace transform and numerical discrete fracture methods, a semi-analytical solution of the model is obtained. Thereafter, the well test type curves and the production performance curves are plotted through Gauss elimination and Stehfest numerical inversion methods. Finally, the effects of related influential factors on well performance are also analyzed. It can be concluded that the Knudsen diffusion coefficient and slippage factor mainly affect the interporosity flow period when well producing with constant rate. When well producing with constant bottom hole pressure, the bigger the values of Knudsen diffusion coefficient and slippage factor are, the larger production rate will be. The research results summarized in this paper have significant theoretical meanings for the development, well test interpretations and production performance analysis of such unconventional gas reservoirs.
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Transient pressure analysis of fractured well in bi-zonal gas reservoirs
Journal of Hydrology, 2015Co-Authors: Yulong Zhao, Liehui Zhang, Yonghui Liu, Qi-guo LiuAbstract:For Hydraulic fractured well, how to evaluate the properties of fracture and formation are always tough jobs and it is very complex to use the conventional method to do that, especially for partially penetrating fractured well. Although the source function is a very powerful tool to analyze the transient pressure for complex structure well, the corresponding reports on gas reservoir are rare. In this paper, the continuous point source functions in anisotropic reservoirs are derived on the basis of source function theory, Laplace transform method and Duhamel principle. Application of construction method, the continuous point source functions in bi-zonal gas reservoir with closed upper and lower boundaries are obtained. Sequentially, the physical models and transient pressure solutions are developed for fully and partially penetrating fractured vertical wells in this reservoir. Type curves of dimensionless pseudo-pressure and its derivative as function of dimensionless time are plotted as well by numerical inversion algorithm, and the flow periods and sensitive factors are also analyzed. The source functions and solutions of fractured well have both theoretical and practical application in well test interpretation for such gas reservoirs, especial for the well with stimulated reservoir volume around the well in unconventional gas reservoir by Massive Hydraulic Fracturing which always can be described with the composite model.
Qi-guo Liu - One of the best experts on this subject based on the ideXlab platform.
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pressure response and production performance for multi fractured horizontal wells with complex seepage mechanism in box shaped shale gas reservoir
Journal of Natural Gas Science and Engineering, 2016Co-Authors: Yulong Zhao, Liehui Zhang, Qi-guo Liu, Ye Xiong, Yuhui Zhou, Dan ChenAbstract:Abstract The development of shale gas reservoir has becoming tremendously thrived around the world in recent years. The horizontal well drilling, advanced completion and Massive Hydraulic Fracturing are the key technologies. How to accurately evaluate the production performance of the wells in these reservoirs, especially for multi-fractured horizontal wells, has always been the hot topic for the engineers and relevant researchers. In this paper, we presented a mathematical model to describe a horizontal well with multiple fractures in rectangular outer-boundary reservoir, which uses the Knudsen diffusion to describe the gas flow in nano-pores and also takes the slippage effect into account. By the method of point source function, Laplace transform and numerical discrete fracture methods, a semi-analytical solution of the model is obtained. Thereafter, the well test type curves and the production performance curves are plotted through Gauss elimination and Stehfest numerical inversion methods. Finally, the effects of related influential factors on well performance are also analyzed. It can be concluded that the Knudsen diffusion coefficient and slippage factor mainly affect the interporosity flow period when well producing with constant rate. When well producing with constant bottom hole pressure, the bigger the values of Knudsen diffusion coefficient and slippage factor are, the larger production rate will be. The research results summarized in this paper have significant theoretical meanings for the development, well test interpretations and production performance analysis of such unconventional gas reservoirs.
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Transient pressure analysis of fractured well in bi-zonal gas reservoirs
Journal of Hydrology, 2015Co-Authors: Yulong Zhao, Liehui Zhang, Yonghui Liu, Qi-guo LiuAbstract:For Hydraulic fractured well, how to evaluate the properties of fracture and formation are always tough jobs and it is very complex to use the conventional method to do that, especially for partially penetrating fractured well. Although the source function is a very powerful tool to analyze the transient pressure for complex structure well, the corresponding reports on gas reservoir are rare. In this paper, the continuous point source functions in anisotropic reservoirs are derived on the basis of source function theory, Laplace transform method and Duhamel principle. Application of construction method, the continuous point source functions in bi-zonal gas reservoir with closed upper and lower boundaries are obtained. Sequentially, the physical models and transient pressure solutions are developed for fully and partially penetrating fractured vertical wells in this reservoir. Type curves of dimensionless pseudo-pressure and its derivative as function of dimensionless time are plotted as well by numerical inversion algorithm, and the flow periods and sensitive factors are also analyzed. The source functions and solutions of fractured well have both theoretical and practical application in well test interpretation for such gas reservoirs, especial for the well with stimulated reservoir volume around the well in unconventional gas reservoir by Massive Hydraulic Fracturing which always can be described with the composite model.
Yulong Zhao - One of the best experts on this subject based on the ideXlab platform.
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pressure response and production performance for multi fractured horizontal wells with complex seepage mechanism in box shaped shale gas reservoir
Journal of Natural Gas Science and Engineering, 2016Co-Authors: Yulong Zhao, Liehui Zhang, Qi-guo Liu, Ye Xiong, Yuhui Zhou, Dan ChenAbstract:Abstract The development of shale gas reservoir has becoming tremendously thrived around the world in recent years. The horizontal well drilling, advanced completion and Massive Hydraulic Fracturing are the key technologies. How to accurately evaluate the production performance of the wells in these reservoirs, especially for multi-fractured horizontal wells, has always been the hot topic for the engineers and relevant researchers. In this paper, we presented a mathematical model to describe a horizontal well with multiple fractures in rectangular outer-boundary reservoir, which uses the Knudsen diffusion to describe the gas flow in nano-pores and also takes the slippage effect into account. By the method of point source function, Laplace transform and numerical discrete fracture methods, a semi-analytical solution of the model is obtained. Thereafter, the well test type curves and the production performance curves are plotted through Gauss elimination and Stehfest numerical inversion methods. Finally, the effects of related influential factors on well performance are also analyzed. It can be concluded that the Knudsen diffusion coefficient and slippage factor mainly affect the interporosity flow period when well producing with constant rate. When well producing with constant bottom hole pressure, the bigger the values of Knudsen diffusion coefficient and slippage factor are, the larger production rate will be. The research results summarized in this paper have significant theoretical meanings for the development, well test interpretations and production performance analysis of such unconventional gas reservoirs.
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Transient pressure analysis of fractured well in bi-zonal gas reservoirs
Journal of Hydrology, 2015Co-Authors: Yulong Zhao, Liehui Zhang, Yonghui Liu, Qi-guo LiuAbstract:For Hydraulic fractured well, how to evaluate the properties of fracture and formation are always tough jobs and it is very complex to use the conventional method to do that, especially for partially penetrating fractured well. Although the source function is a very powerful tool to analyze the transient pressure for complex structure well, the corresponding reports on gas reservoir are rare. In this paper, the continuous point source functions in anisotropic reservoirs are derived on the basis of source function theory, Laplace transform method and Duhamel principle. Application of construction method, the continuous point source functions in bi-zonal gas reservoir with closed upper and lower boundaries are obtained. Sequentially, the physical models and transient pressure solutions are developed for fully and partially penetrating fractured vertical wells in this reservoir. Type curves of dimensionless pseudo-pressure and its derivative as function of dimensionless time are plotted as well by numerical inversion algorithm, and the flow periods and sensitive factors are also analyzed. The source functions and solutions of fractured well have both theoretical and practical application in well test interpretation for such gas reservoirs, especial for the well with stimulated reservoir volume around the well in unconventional gas reservoir by Massive Hydraulic Fracturing which always can be described with the composite model.