Due to low broadside sensitivity of conventional straight DAS,distributed acoustic sensing has seldom been applied to surface seismic acquisition to receive reflected signals with the ray direction almost perpendicular to the fiber axis.As an upgrade,the helical wound cable(HWC)with enhanced broadside sensitivity makes it possible to popularize DAS in surface seismic acquisi-tion.Based on the analysis of the relationship between the relative strain of an optical fiber and its winding angle and incident angle as well as the technical difficulties and production cost of current distributed HWCs,a pilot test is performed using a distributed HWC of 2 km long with two winding angles of 30° and 60° laid in a river in Jiangsu Province.Through the comparative analysis of HWC and nearby node data as well as shot gathers and stacked sections of HWC data at different winding angles,distributed HWCs with winding angle 30°can receive seismic reflections with clear continuous wavetrain features.The underwater experiment provides technical support for seismic exploration using distributed HWCs.
维普
万方数据
