地震勘探中的波动方程正演模拟受计算和存储能力的限制,只能在有限空间进行,需要对其设置边界条件。常用的完全匹配层(Perfect Match Layer,PML)是一种应用广泛的边界条件,需要对边界条件设定一定的层数,层数太大时会降低正演速度和增...地震勘探中的波动方程正演模拟受计算和存储能力的限制,只能在有限空间进行,需要对其设置边界条件。常用的完全匹配层(Perfect Match Layer,PML)是一种应用广泛的边界条件,需要对边界条件设定一定的层数,层数太大时会降低正演速度和增大内存存储。因此,文中通过将PML边界条件和改进后的梯度黏弹边界(Improved Gradient Viscoelastic Layer,IGVL)结合提出一种PML-IGVL边界条件,同时,为了减少截断误差和数值频散,将PML-IGVL边界条件应用于紧致交错网格的黏滞声波方程中进行数值模拟。均匀介质和Marmousi模型中的波场数值模拟结果表明,相对于PML边界条件,PML-IGVL边界条件使用的边界厚度更小,在相同较低边界层数下,能更好地吸收反射波,同时能节省更多的存储空间,并提高正演效率,证明了PML-IGVL边界条件的有效性和优越性,是正演模拟中一种有效的边界吸收方法。展开更多
Taking low permeability cores of Daqing oilfield for example,the flow characteristics at low velocity were studied with the self-designed micro-flux measuring instrument.Considering the throat distribution and capilla...Taking low permeability cores of Daqing oilfield for example,the flow characteristics at low velocity were studied with the self-designed micro-flux measuring instrument.Considering the throat distribution and capillary model,the thickness of fluid boundary layer under different pressure gradients was calculated,and the mechanism and influencing factors of nonlinear percolation were discussed.The results show that the percolation curve of ultra-low rocks is nonlinear,and apparent permeability is not a constant which increases with pressure gradient.The absorption boundary layer decreases with the increase of pressure gradient,and changes significantly especially in low pressure gradient,which is the essence of nonlinear percolation.The absorption boundary layer is also found to be impacted by the surface property of rocks.展开更多
基金Project(2008ZX05013) supported by the National Science and Technology Project of ChinaProject(10672187) supported by the National Natural Science Foundation of China
文摘Taking low permeability cores of Daqing oilfield for example,the flow characteristics at low velocity were studied with the self-designed micro-flux measuring instrument.Considering the throat distribution and capillary model,the thickness of fluid boundary layer under different pressure gradients was calculated,and the mechanism and influencing factors of nonlinear percolation were discussed.The results show that the percolation curve of ultra-low rocks is nonlinear,and apparent permeability is not a constant which increases with pressure gradient.The absorption boundary layer decreases with the increase of pressure gradient,and changes significantly especially in low pressure gradient,which is the essence of nonlinear percolation.The absorption boundary layer is also found to be impacted by the surface property of rocks.
