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大家知道,页岩是横向各向同性(TI)的,而各向同性的假设会导致不正确的地下成像。在知道页岩的各向异性参数情况下,我们则可以校正地震数据中的这种各向异性效应,从而得到更准确的地下成像。为了确定地下页岩各向异性参数,我们在Wapiabi地层的陡倾海相页岩区对2个区块的野外P-波折射地震数据作了研究。第1个区块是位于加拿大艾尔伯塔省的Jumpingpound Greek,另一个区块位于加拿大艾尔伯塔省Longview的西部。地震测线分别与局部走向呈平行、垂直及45°排列。沿走向求取的两个区块的纵波首波都比垂直于走向的速度快。根据Jumpingpound Greek区的数据分析求得的各向异性参数ε=0.14±0.05,δ=0.00±0.08,而在Longview区则为ε=0.25±0.06,δ=0.00±0.06。产生ε值差异的原因是两个区块的页岩相变所致。
As you know, shales are transversely isotropic (TI), and the assumption of isotropy can lead to incorrect subsurface imaging. Knowing the anisotropy of shales, we can correct this anisotropic effect in the seismic data to get more accurate subsurface imaging. In order to determine the anisotropy parameters of the shale underground, we studied the field P-wave refraction seismic data of two blocks in the steeply shaded marine shale area of the Wapiabi formation. The first block is Jumpingpound Greek in Alberta, Canada, and the other block is in western Longview, Alberta, Canada. Seismic lines were parallel to the local trend, vertical and 45 ° arrangement. The first wave of the longitudinal waves of the two blocks along the strike is faster than the vertical. The anisotropy parameters ε = 0.14 ± 0.05 and δ = 0.00 ± 0.08 obtained from the data analysis of the Jumpingpound Greek region are ε = 0.25 ± 0.06 and δ = 0.00 ± 0.06 in the Longview region. The reason for the difference in ε values is due to the shale facies change between the two blocks.