The near-surface multiple in land seismic exploration displays low-frequency linear interference in the monitoring record,and is characterized by paralleling to the first arrival multi-phase continuity after first break,which has strong energy,occupies large record space and seriously impacts the effective reflection.We take the Chepaizi area of Chunguang Oilfield as a research targets and study the genesis and characteristics of this kind of near-surface low-frequency linear interference.The results indicate that:①there are two strong impedance interfaces between the top and bottom of near-surface low-velocity layers,seismic wave propagates between the two interfaces and forms multi oscillations,which leads to relatively strong multi-phase low-frequency linear interference;②when seismic wave from deep layers propagates upgoing to the ground,low-velocity zone has low-frequency filtering effect on the effective wave,which impacts the effective reflection to some degree;③increasing shooting depth and adjusting dynamic charge size can effectively weakens the low-frequency linear interference to obtain good-quality seismic data.By field and indoor joint suppressing on near-surface multiple,high-quality seismic profiles can be achieved.
论文详情