Hemno - a Time-imaging Operator for Pegleg Multiples in 2-d and 3-d

To correctly image primary or multiple reflections in a heterogeneous earth, migration reigns supreme, although its computational cost may be nontrivial over complex geology, in 3-D, or when a “true amplitude” image is required. My earlier (Brown, 2002) technique to jointly image primaries and pegleg multiples used normal moveout (NMO), because of NMO’s speed and its amplitude predictability, in spite of its inability to account for nonflat geology. In this paper I present a new time imaging operator, “HEMNO” (Heterogeneous Earth Multiple NMO Operator), which correctly accounts for moderate subsurface structure but retains the speed and amplitude advantages of NMO. The 2-D and 3-D pegleg multiple moveout equations for two dipping planes derived by Levin and Shah (1977) and Ross et al. (1999), respectively, reduce to HEMNO in the small dip angle limit (Brown, 2003b).