Geophysical Prospecting, 2020, 68, 2046–2063 doi: 10.1111/1365-2478.12980 Separation of PP- and PS-wave reflected seismic data using two-dimensional finite offset common-reflection-surface traveltime approximation Raphael Di Carlo Silva dos Santos 1,2∗ , João Carlos Ribeiro Cruz 3 and Manuel de Jesus dos Santos Costa 4 1 Universidade Federal do Pará, Programa de Pós-Graduação em Geofísica, Av. Augusto Corrêia s/n, CEP 66017–970, Guamá, Belém, Pará, Brazil, 2 Instituto de Engenharia e Geociências, Universidade Federal do Oeste do Pará, Rua Vera Paz, s/n (Unidade Tapajós), CEP 68040–255, Salé, Santarém, Pará, Brazil, 3 Instituto de Geociências, Universidade Federal do Pará, Av. Augusto Corrêia s/n, CEP 66017–970, Guamá, Belém, Pará, Brazil, and 4 Faculdade de Tecnologia e Ciências Exatas, Universidade Federal do Pará, Rua Manoel de Abreu s/n, CEP 68440–000, Multirão, Abaetetuba, Pará, Brazil Received January 2019, revision accepted May 2020 ABSTRACT Recently, the interest in PS-converted waves has increased for several applications, such as sub-basalt layer imaging, impedance estimates and amplitude-versus-offset analysis. In this study, we consider the problem of separation of PP- and PS-waves from pre-stacked multicomponent seismic data in two-dimensional isotropic medium. We aim to demonstrate that the finite-offset common-reflection-surface traveltime approximation is a good alternative for separating PP- and PS-converted waves in common-offset and common shot configurations by considering a two-dimensional isotropic medium. The five parameters of the finite-offset common-reflection-surface are firstly estimated through the inversion methodology called very fast simulated annealing, which estimates all parameters simultaneously. Next, the emergence an- gle, one of the inverted parameters, is used to build an analytical separation function of PP and PS reflection separation based on the wave polarization equations. Once the PP- and PS-converted waves were separated, the sections are stacked to increase the signal-to-noise ratio using the special curves derived from finite-offset common- reflection-surface approximation. We applied this methodology to a synthetic dataset from simple-layered to complex-structured media. The numerical results showed that the inverted parameters of the finite offset common-reflection-surface and the sepa- ration function yield good results for separating PP- and PS-converted waves in noisy common-offset and common shot gathers. Key words: PP-PS reflection separation, very fast simulated annealing, finite-offset common-reflection-surface, Seismics, Inversion. INTRODUCTION PS-waves are useful for reservoir analysis. Therefore, the sep- aration of shear waves is necessary and the methods for sep- ∗ E-mail: rssraphael@gmail.com arating PP and PS-waves are based on different filters. The stacking methods to increase the signal-to-noise ratio for dif- ferent geological environments has made continuous improve- ments. For seismic exploration, the interpretation of only P- waves is still fundamental, although S-wave information has gained importance recently. In this study, we assume the PS- waves involve the conversion of the reflected primary wave 2046 © 2020 European Association of Geoscientists & Engineers