scholarly journals Lateral Percolation and Its Effect on Shale Gas Accumulation on the Basis of Complex Tectonic Background

Geofluids ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Kun Zhang ◽  
Zhenxue Jiang ◽  
Xuelian Xie ◽  
Zhiye Gao ◽  
Tianlin Liu ◽  
...  
Keyword(s):  
Shale Gas ◽  
Vertical Direction ◽  
Reverse Fault ◽  
Direction Parallel ◽  
Accumulation Pattern ◽  
Exploration Target ◽  
Fracture Development ◽  
Fault Gas ◽  
Parallel Direction ◽  
Background Gas

As a result of complex tectonic background, shale gas in China exhibits differential enrichment. Choosing a favorable exploration target accurately is a crucial problem to be solved. In this study, the tests show that there is a superior transportation pathway within shale layer. Gas in the shale layer percolates much more in the direction parallel to the plane. Therefore, the accumulation pattern of shale gas indicates a complex tectonic background. Gas in the lower part of the structure diffuses and percolates in the vertical direction into the surrounding rock. Most gas percolates towards the high part of the structure in the direction parallel to the plane. When the shale was exposed, gas percolated along the parallel direction into the air. In the case of fracture development, if there is a reverse fault, gas would be enriched in the footwall. However, if there is an unsealed fault, it would become a pathway for gas migration. The above accumulation pattern was proved in several Areas. Also, this research presented a basis of evaluation units division. According to the buried depth, fractures, and structural position, Xiuwu Basin was divided into five evaluation units and Unit A3 is the most favorable exploration target.

Fractures in continental shale reservoirs: a case study of the Upper Triassic strata in the SE Ordos Basin, Central China

2015 ◽  
Vol 153 (4) ◽  
pp. 663-680 ◽  
Author(s):  
WENLONG DING ◽  
PENG DAI ◽  
DINGWEI ZHU ◽  
YEQIAN ZHANG ◽  
JIANHUA HE ◽  
...  
Keyword(s):  
Organic Matter ◽  
Shale Gas ◽  
Mineral Content ◽  
Ordos Basin ◽  
Total Content ◽  
Upper Triassic ◽  
Thin Sections ◽  
Yanchang Formation ◽  
Fracture Development ◽  
Shale Reservoirs

AbstractFractures are important for shale-gas reservoirs with low matrix porosity because they increase the effective reservoir space and migration pathways for shale gas, thus favouring an increased volume of free gas and the adsorption of gases in shale reservoirs, and they increase the specific surface area of gas-bearing shales which improves the adsorption capacity. We discuss the characteristics and dominant factors of fracture development in a continental organic matter-rich shale reservoir bed in the Yanchang Formation based on observations and descriptions of fracture systems in outcrops, drilling cores, cast-thin sections and polished sections of black shale from the Upper Triassic Yanchang Formation in the SE Ordos Basin; detailed characteristics and parameters of fractures; analyses and tests of corresponding fracture segment samples; and the identification of fracture segments with normal logging. The results indicate that the mineral composition of the continental organic-matter-rich shale in the Yanchang Formation is clearly characterized by a low brittle mineral content and high clay mineral content relative to marine shale in the United States and China and Mesozoic continental shale in other basins. The total content of brittle minerals, such as quartz and feldspar, is c. 41%, with quartz and feldspar accounting for 22% and 19% respectively, and mainly occurring as plagioclase with small amounts of carbonate rocks. The total content of clay minerals is high at up to 52%, and mainly occurs as a mixed layer of illite-smectite (I/S) which accounts for more than 58% of the total clay mineral content. The Upper Triassic Yanchang Formation developed two groups of fracture (joint) systems: a NW–SE-trending system and near-E–W-trending system. Multiple types of fractures are observed, and they are mainly horizontal bedding seams and low-dip-angle structural fractures. Micro-fractures are primarily observed in or along organic matter bands. Shale fractures were mainly formed during Late Jurassic – late Early Cretaceous time under superimposed stress caused by regional WNW–ESE-trending horizontal compressive stress and deep burial effects. The extent of fracture development was mainly influenced by multiple factors (tectonic factors and non-tectonic factors) such as the lithology, rock mechanical properties, organic matter abundance and brittle mineral composition and content. Specifically, higher sand content has been observed to correspond to more rapid lithological changes and more extensive fracture development. In addition, higher organic matter content has been observed to correspond to greater fracture development, and higher quartz, feldspar and mixed-layer I/S contents have been observed to correspond to more extensive micro-fracture development. These results are consistent with the measured mechanical properties of the shale and silty shale, the observations of fractures in cores and thin-sections from more than 20 shale-gas drilling wells, and the registered anomalies from gas logging.

Brittleness evaluation of the Lower Silurian marine shale reservoirs: A case study of Longmaxi shale in Fenggang block, Southern China

2020 ◽  
pp. 1-55
Author(s):  
Yang Gu ◽  
Sheng Xu ◽  
Chao Fang ◽  
Wei Zhang ◽  
Bairen Zhang ◽  
...  
Keyword(s):  
Shale Gas ◽  
Seismic Data ◽  
Strain Energy ◽  
Southern China ◽  
Strain Energy Release ◽  
Lower Silurian ◽  
Data Inversion ◽  
Fracture Development ◽  
Longmaxi Shale ◽  
Shale Reservoirs

The brittleness of shale determines the fracturability of shale reservoir and has a great influence on the exploration and development of shale gas. Therefore, prediction of brittleness and evaluation of fracturability of shale are very important in finding favorable areas for shale gas. We used the mineral composition, rock mechanics experiment, logging evaluation, two-dimensional seismic data inversion and fracture development degree to evaluation and analysis the vertical and plane brittleness characteristics and main controlling factors of the Longmaxi shale. In addition, we established the fracturability index (FI) of shale based on the brittleness index, critical strain energy release rate and fracture toughness. The results indicate that the brittle mineral content of Longmaxi shale in Fenggang block is between 69% and 90%, shale samples are prone to brittle deformation by microscopic observation. Brittle deformation has a positive effect on the porosity and percolation ability of shale; the fractures in the upper and lower parts of Longmaxi shale are relatively developed, and the degree of core fracture development is consistent with rock brittleness. The brittleness distribution of two-dimensional seismic data inversion is in good agreement with the brittleness predicted by well logging; shale reservoirs with low fracture toughness, low critical strain energy release rate and high brittleness index have high fracturability. Therefore, the research on shale brittleness and fracturability of Lower Silurian Longmaxi shale is expected to have important guiding significance for shale gas exploration and development in Southern China.

Self-Preserving Mixing Properties of Steady Round Buoyant Turbulent Plumes in Uniform Crossflows

2006 ◽  
Vol 128 (10) ◽  
pp. 1001-1011
Author(s):  
F. J. Diez ◽  
L. P. Bernal ◽  
G. M. Faeth
Keyword(s):  
Salt Water ◽  
Velocity Ratio ◽  
Vertical Direction ◽  
The Self ◽  
Scaling Analysis ◽  
Vortex System ◽  
Direction Parallel ◽  
Mixing Properties ◽  
Source Flow ◽  
Source Fluid

The self-preserving mixing properties of steady round buoyant turbulent plumes in uniform crossflows were investigated experimentally. The experiments involved salt water sources injected into fresh water crossflows within the windowed test section of a water channel. Mean and fluctuating concentrations of source fluid were measured over cross sections of the flow using planar-laser-induced fluorescence which involved seeding the source fluid with Rhodamine 6G dye and adding small concentrations of ethanol to the crossflowing fluid in order to match the refractive indices of the source flow and the crossflow. The self-preserving penetration properties of the flow were correlated successfully based on the scaling analysis of Diez, Bernal, and Faeth (2003, ASME J. Heat Transfer, 125, pp. 1046–1057) whereas the self-preserving structure properties of the flow were correlated successfully based on the scaling analysis of Fischer et al. (1979, Mixing in Inland and Coastal Waters, Academic Press, New York, pp. 315–389); both approaches involved assumptions of no-slip convection in the cross stream (horizontal) direction (parallel to the crossflow) and a self-preserving line thermal having a conserved source specific buoyancy flux per unit length that moves in the streamwise (vertical) direction (parallel to the direction of both the initial source flow and the gravity vector). The resulting self-preserving structure consisted of two counter-rotating vortices having their axes nearly aligned with the crossflow direction that move away from the source in the streamwise (vertical) direction due to the action of buoyancy. Present measurements extended up to 202 and 620 source diameters from the source in the streamwise and cross stream directions, respectively. The onset of self-preserving behavior required that the axes of the counter-rotating vortex system be nearly aligned with the crossflow direction. This alignment, in turn, was a strong function of the source/crossflow velocity ratio, uo∕v∞. The net result was that the onset of self-preserving behavior was observed at streamwise distances of 10–20 source diameters from the source for uo∕v∞=4 (the smallest value of uo∕v∞ considered), increasing to streamwise distances of 160–170 source diameters from the source for uo∕v∞=100 (the largest value of uo∕v∞ considered). Finally, the counter-rotating vortex system was responsible for substantial increases in the rate of mixing of the source fluid with the ambient fluid compared to axisymmetric round buoyant turbulent plumes in still environments, e.g., transverse dimensions in the presence of the self-preserving counter-rotating vortex system were 2–3 times larger than the transverse dimensions of self-preserving axisymmetric plumes at similar streamwise distances from the source.

3D Reconstruction and Stress Analysis of the Free End Second Premolar Root Form Dental Implant

2016 ◽  
Vol 842 ◽  
pp. 445-450
Author(s):  
Satrio Wicaksono ◽  
Peter Lukito Ferdian ◽  
Tatacipta Dirgantara ◽  
Andi Isra Mahyuddin ◽  
Sandro Mihradi ◽  
...  
Keyword(s):  
3D Reconstruction ◽  
Dental Implant ◽  
Vertical Direction ◽  
Cone Beam ◽  
Reconstruction Method ◽  
Stress Distributions ◽  
Direction Parallel ◽  
Implant Crown ◽  
Stress Result ◽  
Modelling Process

Stress distributions that occur in the free end second premolar tooth and its root form dental implant replacement were evaluated using finite element method. In the modelling process, 3D reconstructions were performed. Instead of doing it manually, the 3D reconstruction in this paper was done using cone beam computed tomography (CBCT) scanning process. The 3D reconstruction method used in this paper, is considerably faster than the traditional manual 3D reconstruction method. In order to mimic the actual biting force, static load of 200 N was modelled in the vertical direction parallel to the long axis of the tooth which is placed on bite contact at second premolars and dental implant crown. The stress result on root form dental implant is generally higher than the stress on the natural free end second premolar tooth. The stress concentration locations on root form dental implant were also found and will be used in the future to improve the design of root form dental implant.

scholarly journals Comparing the performance of naturally ventilated and fan-ventilated greenhouses

2006 ◽  
Author(s):  
Daniel H. Willits ◽  
Meir Teitel ◽  
Josef Tanny ◽  
Mary M. Peet ◽  
Shabtai Cohen ◽  
...  
Keyword(s):  
Natural Ventilation ◽  
Evaporative Cooling ◽  
Vertical Direction ◽  
Ventilation Rate ◽  
Heat Fluxes ◽  
Climate Type ◽  
Cooling Systems ◽  
Direction Parallel ◽  
Advantages And Disadvantages ◽  
The Us

The objectives of this project were to predict the performance of naturally and fan-ventilated greenhouses as a function of climate, type of crop, evaporative cooling and greenhouse size, and to estimate the effects of the two cooling systems on yield, quality and disease development in the different crops under study. Background In the competitive field of greenhouse cultivation, growers and designers in both the US and Israel are repeatedly forced to choose between naturally ventilated (NV) and fan ventilated (FV) cooling systems as they expand their ranges in an effort to remain profitable. The known advantages and disadvantages of each system do not presently allow a clear decision. Whether essentially zero operating costs can offset the less dependable cooling of natural ventilation systems is question this report hopes to answer. Major Conclusions US It was concluded very early on that FV greenhouses without evaporative pad cooling are not competitive with NV greenhouses during hot weather. During the first year, the US team found that average air temperatures were always higher in the FV houses, compared to the NV houses, when evaporative pad cooling was not used, regardless of ventilation rate in the FV houses or the vent configuration in the NV houses. Canopy temperatures were also higher in the FV ventilated houses when three vents were used in the NV houses. A second major conclusion was that the US team found that low pressure fogging (4 atm) in NV houses does not completely offset the advantage of evaporative pad cooling in FV houses. High pressure fog (65 atm) is more effective, but considerably more expensive. Israel Experiments were done with roses in the years 2003-2005 and with tomatoes in 2005. Three modes of natural ventilation (roof, side and side + roof openings) were compared with a fan-ventilated (with evaporative cooling) house. It was shown that under common practice of fan ventilation, during summer, the ventilation rate is usually lower with NV than with FV. The microclimate under both NV and FV was not homogeneous. In both treatments there were strong gradients in temperature and humidity in the vertical direction. In addition, there were gradients that developed in horizontal planes in a direction parallel to the direction of the prevailing air velocity within the greenhouse. The gradients in the horizontal direction appear to be larger with FV than with NV. The ratio between sensible and latent heat fluxes (Bowen ratio) was found to be dependent considerably on whether NV or FV is applied. This ratio was generally negative in the naturally ventilated house (about -0.14) and positive in the fan ventilated one (about 0.19). Theoretical models based on Penman-Monteith equation were used to predict the interior air and crop temperatures and the transpiration rate with NV. Good agreement between the model and experimental results was obtained with regard to the air temperature and transpiration with side and side + roof ventilation. However, the agreement was poor with only roof ventilation. The yield (number of rose stems longer than 40 cm) was higher with FV

Structural Design of 2D Piezoresistive Micro-Force Sensor

2013 ◽  
Vol 562-565 ◽  
pp. 363-368
Author(s):  
Jie Zhou ◽  
Wei Bin Rong ◽  
Li Ning Sun
Keyword(s):  
Structural Design ◽  
Vertical Direction ◽  
Force Sensor ◽  
Interaction Force ◽  
Force Detection ◽  
Target Interaction ◽  
Sensor Structure ◽  
Parallel Direction ◽  
Simulation Results ◽  
Micro Force Sensor

In order to detect the tool-substrate contact force and the tool-target interaction force during nano-manipulation process, a novel MEMS based 2D piezoresistive micro-force sensor structure was proposed. This structure can realize the 3D hardware decoupling for the X，Y and Z axis. Thus, the force detection in the vertical direction (Z axis) and parallel direction reference to base (X axis) can be done simultaneously. Theoretical analysis shows that this structure has a good structural sensitivity. The rationality and feasibility of the structure were confirmed by simulation results.

Ablation Behaviors of 3D Fine Woven Pierced Carbon/Carbon Composites

2014 ◽  
Vol 1033-1034 ◽  
pp. 864-868 ◽  
Author(s):  
Jian Yin ◽  
Hong Bo Zhang ◽  
Xiang Xiong ◽  
Hui Jin Tao
Keyword(s):  
Carbon Fiber ◽  
Vertical Direction ◽  
Fiber Bundles ◽  
Carbon Composites ◽  
Ablation Process ◽  
Arc Heater ◽  
Parallel Direction ◽  
Carbon Fiber Bundles ◽  
Scanning Electron ◽  
Better Than

The ablation behaviors of 3D fine woven pierced carbon/carbon (C/C) composites were tested on an arc heater and their ablation morphologies were observed by scanning electron microscopy (SEM). It shows that ablation of 3D fine woven pierced C/C composites tends to start at interfaces, defects and pores. Cracks mainly yield at the boundaries of carbon fiber bundles, interfaces of carbon fiber felts during the ablating processes. The ablation properties of 3D C/C composites in parallel direction are better than that in vertical direction. In addition, the work indicates that the ablation process is mainly controlled by mechanical denudation.

Self-Preserving Mixing Properties of Steady Round Buoyant Turbulent Plumes in Uniform Crossflows

2005 ◽  
Author(s):  
F. J. Diez ◽  
L. P. Bernal ◽  
G. M. Faeth
Keyword(s):  
Salt Water ◽  
Velocity Ratio ◽  
Vertical Direction ◽  
The Self ◽  
Scaling Analysis ◽  
Vortex System ◽  
Direction Parallel ◽  
Mixing Properties ◽  
Source Flow ◽  
Source Fluid

The self-preserving mixing properties of steady round buoyant turbulent plumes in uniform crossflows were investigated experimentally. The experiments involved salt water sources injected into fresh water crossflows within the windowed test section of a water channel. Mean and fluctuating concentrations of source fluid were measured over cross sections of the flow using Planar-Laser-Induced-Fluorescence (PLIF) which involved seeding the source fluid with Rhodamine 6G dye and adding small concentrations of ethanol to the crossflowing fluid in order to match the refractive indices of the source flow and the crossflow. The self-preserving penetration properties of the flow were correlated successfully based on the scaling analysis of Diez et al. (2003) whereas the self-preserving structure properties of the flow were correlated successfully based on the scaling analysis of Fischer et al. (1979); both approaches involved assumptions of no-slip convection in the cross stream (horizontal) direction (parallel to the crossflow) and a self-preserving line thermal having a conserved source specific buoyancy flux per unit length that moves in the streamwise (vertical) direction (parallel to the direction of both the initial source flow and the gravity vector). The resulting self-preserving structure consisted of two counter-rotating vortices having their axes nearly aligned with the crossflow direction that move away from the source in the streamwise (vertical) direction due to the action of buoyancy. Present measurements extended up to 202 and 620 source diameters from the source in the streamwise and cross stream directions, respectively. The onset of self-preserving behavior required that the axes of the counter-rotating vortex system be nearly aligned with the crossflow direction. This alignment, in turn, was a strong function of the source/crossflow velocity ratio, uo/v∞. The net result was that the onset of self-preserving behavior was observed at streamwise distances of 10–20 source diameters from the source for uo/v∞ = 4 (the smallest value of uo/v∞ considered), increasing to streamwise distances of 160–170 source diameters from the source for uo/v∞ = 100 (the largest value of uo/v∞ considered). Finally, the counter-rotating vortex system was responsible for substantial increases in the rate of mixing of the source fluid with the ambient fluid compared to axisymmetric round buoyant turbulent plumes in still environments, e.g., transverse dimensions in the presence of the self-preserving counter-rotating vortex system were 2–3 times larger than the transverse dimensions of self-preserving axisymmetric plumes at similar streamwise distances from the source.

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