The mechanism of production increasing for the pinnate horizontal well is analyzed with the simulation technique. It is pointed out that the whole horizontal well-bore spreading widely and evenly in coal layers makes ...The mechanism of production increasing for the pinnate horizontal well is analyzed with the simulation technique. It is pointed out that the whole horizontal well-bore spreading widely and evenly in coal layers makes the stratum pressure drop evenly and fast, which increases the chance of desorption and diffusion and area controlled. This is the basic reason that the pinnate horizontal well can increase production. How such stratum parameters as permeability, Langmuir constants and adsorption time constant affect the gas production for the pinnate horizontal well is also studied with numerical simulations. Either for the vertical well or the pinnate horizontal well, bigger stratum permeability, steeper relative permeability curve, smaller residual gas saturation, higher gas content and stratum pressure are more favorable for gas production increasing. Langmuir constants decide the change of desorption quantity and influence the gas production through changing the extent of steep of isothermal adsorption curves in the pressure dropping area. The adsorption time constant only influences the time that gas production arrives at the maximum value for the vertical well, but it almost has no influence on the gas production for the pinnate horizontal well because the equivalent adsorption time constant is reduced.展开更多
Vein traits influence photosynthesis and drought resistance and are sensitive to climate change.It is unclear whether vein traits,similar to other leaf traits,have obvious regional characteristics and covariance with ...Vein traits influence photosynthesis and drought resistance and are sensitive to climate change.It is unclear whether vein traits,similar to other leaf traits,have obvious regional characteristics and covariance with other leaf traits,especially in Tibetan Plateau grasslands.We collected 66 species from 37 sites in late July of 2012 and early August of 2013 to investigate leaf vein traits and their relationships with other leaf traits in comparison with the available global database data and to elucidate vein investment of plants with different vein types.The average vein length per area(VLA)of plants in the Tibetan Plateau was within the range of the global dataset,and the relationships among vein traits and other leaf traits of alpine plants were consistent with the global models.The VLAs of parallel-veined grasses and pinnateveined forbs were significantly lower and higher than the global mean value,respectively.The leaf mass perarea and total nitrogen content of parallel-veined grasses were significantly lower and higher,respectively,than the global mean values;the opposite was observed in pinnate-veined forbs.The parallel-veined grasses exhibited almost a four-fold higher vein biomass investment(i.e.,vein mass per leaf mass)than pinnate-veined forbs in the same region.The average VLA and its relationships with other leaf traits of the alpine grassland plants on the Tibetan Plateau had no regional characteristics,suggesting a convergence in plant leaf functioning.Plants with different leaf types differ in their adaptation strategies to plateau environments,and this may relate to biomass investment into leaf veins.Our study fills the gap with regard to vein density in alpine grassland species and provides a new perspective for understanding plant physiology and ecology by calculating and comparing the proportion of vein investment among different vein types.展开更多
文摘The mechanism of production increasing for the pinnate horizontal well is analyzed with the simulation technique. It is pointed out that the whole horizontal well-bore spreading widely and evenly in coal layers makes the stratum pressure drop evenly and fast, which increases the chance of desorption and diffusion and area controlled. This is the basic reason that the pinnate horizontal well can increase production. How such stratum parameters as permeability, Langmuir constants and adsorption time constant affect the gas production for the pinnate horizontal well is also studied with numerical simulations. Either for the vertical well or the pinnate horizontal well, bigger stratum permeability, steeper relative permeability curve, smaller residual gas saturation, higher gas content and stratum pressure are more favorable for gas production increasing. Langmuir constants decide the change of desorption quantity and influence the gas production through changing the extent of steep of isothermal adsorption curves in the pressure dropping area. The adsorption time constant only influences the time that gas production arrives at the maximum value for the vertical well, but it almost has no influence on the gas production for the pinnate horizontal well because the equivalent adsorption time constant is reduced.
基金supported by the National Natural Science Foundation of China(grant numbers 41731175,31700410 and 41988101)the Strategic Priority Research Program A of the Chinese Academy of Sciences(grant number XDA20050101)。
文摘Vein traits influence photosynthesis and drought resistance and are sensitive to climate change.It is unclear whether vein traits,similar to other leaf traits,have obvious regional characteristics and covariance with other leaf traits,especially in Tibetan Plateau grasslands.We collected 66 species from 37 sites in late July of 2012 and early August of 2013 to investigate leaf vein traits and their relationships with other leaf traits in comparison with the available global database data and to elucidate vein investment of plants with different vein types.The average vein length per area(VLA)of plants in the Tibetan Plateau was within the range of the global dataset,and the relationships among vein traits and other leaf traits of alpine plants were consistent with the global models.The VLAs of parallel-veined grasses and pinnateveined forbs were significantly lower and higher than the global mean value,respectively.The leaf mass perarea and total nitrogen content of parallel-veined grasses were significantly lower and higher,respectively,than the global mean values;the opposite was observed in pinnate-veined forbs.The parallel-veined grasses exhibited almost a four-fold higher vein biomass investment(i.e.,vein mass per leaf mass)than pinnate-veined forbs in the same region.The average VLA and its relationships with other leaf traits of the alpine grassland plants on the Tibetan Plateau had no regional characteristics,suggesting a convergence in plant leaf functioning.Plants with different leaf types differ in their adaptation strategies to plateau environments,and this may relate to biomass investment into leaf veins.Our study fills the gap with regard to vein density in alpine grassland species and provides a new perspective for understanding plant physiology and ecology by calculating and comparing the proportion of vein investment among different vein types.
