Cintia Lapilli

Imaging with complex decomposition: Numerical applications to seismic processing in difficult areas

Measured seismic wavefields have complexity that cannot be fully modeled by seismic processing, such as wave equation migration. Traditionally, a separation of data into signal and noise components is attempted, but it is difficult to isolate the noise component that cannot be modeled to be discarded. In this paper we use an alternative approach and assume that most energy in a measured wavefield is signal, and then we use variational methods to separate this signal into a simple part, which can be modeled by conventional seismic processing, and a complex part that is not amenable to investigation by these methods. In this approach, the complex part does have interpretation value and should not be discarded as noise. The simple part may be input to numerical processing such as depth migration, residual static after depth migration, and multiple attenuation, among others.

Resolution analysis for targeted illumination using two‐way wave‐equations

Recent advances in imaging prestack seismic data, in particular, more accurate migration algorithms such as reverse-time migration (RTM), have made higher-quality images possible. However, tools to understand the factors affecting the quality of the results such as illumination are not readily available. Typically, illumination and resolution studies involve ray-based methods, and although they capture the effects of lateral variations in velocities, intensity and directional information of wavefield propagation, and irregular acquisition geometries, they suffer from severe limitations in accuracy in complex regions where the high-frequency asymptotic approximation of rays might fail. Wave-equation methods generally do not generate the directional information of the wave propagation, which prevents us from using a waveequation method directly for illumination studies.

Wave equation receiver deghosting

Current solutions to receiver deghosting generally involve making complementary measurements of the wavefield or, alternatively, involve estimation of data not recorded due to ghost interference. Both solutions offer challenges in practice in that marine multimeasurement streamers are commercially available only on a limited basis and existing single-measurement deghosting methods must estimate unrecorded frequencies near the ghost notches. Here, we develop a new wave equation-based approach for single measurement deghosting that does not rely on such estimation procedures.

Imaging Beneath Complex Layering: Processing Seismic Data With Complex Decomposition And Renormalization Group

Seismic Imaging beneath complex layering is challenging and problematic. Examples of complex layering are complex shale, carbonate, basalt and salt. Both the quality of the image and wavelet fidelity of the reservoir beneath the complex layering are usually not satisfactory below complex layering, largely because of the associated multiples and elastic waves. These effects interfere with the primary reflection. The problem is more acute for seismic reservoir analysis where agreement between observed logs data and seismic is important. Apache Corporation and WesternGeco undertook a Strategic Technology Alliance Project of a modeling study to investigate old and new seismic processing methodology. The purpose is to do an in-depth analysis of assumptions and approximations in the conventional seismic processes. The study identifies which of these programs are ineffective in the presence of interference due to strong interaction in the overburden. Then we can replace these programs with the new processing programs like complex decomposition and renormalization group.