Schematic of hyperbolas stacking and locating. (a) Single-sided vertical orientation coverage of the source and (b) Double-sided vertical orientation coverage of the source. The red pentagram represents the source, the inverted triangle represents the receiver, and the í µí¼ƒ represents the angle between the hyperbola and the borehole axis.

Contexts in source publication

Context 1

... in figure 6, R is the distance to the borehole axis, so Z-axis is equivalent to the borehole axis at this moment, namely, the symmetry axis. Therefore, only the hyperbolic streak artifact on the right side of the borehole axis appears in the 2D imaging profile about R-Z, forming a streak artifact extending obliquely along the Z-axis, which coincides with the stacked trace of the hyperbolas on the right side of the borehole axis in figure 9a, leading the imaging resolution of the Z-direction is worse than that of the R-direction. Because the streak artifact extends mainly along the Z-axis, the location accuracy of the source depth Z s is worse than that of the source to borehole axis distance R s . ...

Context 2

... figures 14, and 15 and Table 1, in Model 3, the imaging resolutions of the Z-direction are improved 3-24 times more than those of Table 2. The location accuracies of the two high-frequency sources are significantly improved from those of Model 2, especially for the source depth Z s , but big errors still exist in the location result of the low-frequency source compared with Model 1. Different from Models 1 and 2, although only two receivers are added above the source in Model 3, the hyperbolas of different directions and shapes are cross-stacked, as shown in figure 9b, which reserves the traces of energy smearing in figure 13 accordingly. The cross-stacked hyperbolas contribute to weakening the streak artifacts extending obliquely along the Z-axis, reducing the red areas of high energy smearing accordingly, but making the streak artifacts perpendicular to the Z-axis appear. ...