Alexander Zarkhidze

Advances In Interbed Multiples Prediction And Attenuation: Case Study From Onshore Kuwait

Multiples contamination both surface and interbed related is a problem in almost all Middle East basins. The high acoustic impedance of carbonates and anhydrites layered with clastics is the major generator of these interbed multiples. These types of multiples are known to hinder the interpretation, fracture characterization, and inversion studies; they significantly complicate both the structural and stratigraphic interpretation within the zone of interest at the Cretaceous level as well as at the frontier Jurassic and Permian sections (El-Emam et al., 2001). Previous work has demonstrated marginal success in attenuating the main interbed multiples using the 1D multiple modeling technique post-migration thorough the analysis and identification of the major multiple generators using well data (El-Emam et al., 2005).

Model‐based attenuation for scattered dispersive waves

Coherent noise in land seismic data primarily consists in source-generated surface-wave modes. The component that is traditionally considered most relevant is the so-called ground roll, consisting in surface-wave modes propagating directly from sources to receivers. In many geological situations, near-surface heterogeneities and discontinuities, as well as topography irregularities, diffract the surface waves and generate secondary events, which can heavily contaminate records. The diffracted and converted surface waves are often called scattered noise and can be a severe problem particularly in areas with shallow or outcropping hard lithological formations. Conventional noise attenuation techniques are not effective with scattering: they can usually address the tails but not the apices of the scattered events. Large source and receiver arrays can attenuate scattering but only in exchange for a compromise to signal fidelity and resolution. We present a model-based technique for the scattering attenuation, based on the estimation of surface-wave properties and on the prediction of surface waves with a complex path involving diffractions. The properties are estimated first, to produce surface-consistent volumes of the propagation properties. Then, for all gathers to filter, we integrate the contributions of all possible diffractors, building a scattering model. The estimated scattered wavefield is then subtracted from the data. The method can work in different domains and copes with aliased surface waves. The benefits of the method are demonstrated with synthetic and real data.

Model-based Coherent Noise Attenuation For Complex Dispersive Waves

The attenuation of source-generated coherent noise energy can be a challenging problem for land data where surface waves often exhibit complex behavior with multiple propagation modes, high lateral variability and relatively short wavelengths. The traditional acquisition and processing strategy for mitigation of coherent noise has combined analog spatial filtering through source and receiver arrays in the field, with multi-channel digital filtering in data processing. The field arrays act as complementary spatial anti-alias filters for data processing algorithms which have difficulty in dealing with aliased events. Limitations of the available processing procedures place constraints on the acquisition design which can potentially both limit flexibility and increase the cost of the acquisition. A new model-based approach to sourcegenerated coherent noise attenuation is presented, where the local properties of the multi-mode surface waves are estimated from the seismic data and used to generate a detailed model of surface-wave noise, spatially-variable over the survey area. The method has significant advantages with respect to the handling of aliased coherent noise energy, and robustness to spatial irregularities. The availability of effective processing tools for aliased noise attenuation can have a significant impact on required survey geometry, and on the cost of land exploration.

Survey design for high density, high productivity broadband Vibroseis point source and receiver acquisition — a case study from the UAE thrustbelt

In this paper we describe an integrated design of the acquisition parameters for a 3D seismic survey in a difficult geological and logistical environment using an ultra-high channel point receiver recording system, productivity enhancement techniques and incorporating advanced processing tools. Advances in acquisition hardware and techniques change the way seismic surveys are designed. These advances include continuous recording, faster computers that allow running more elaborate algorithms and new methods such as surface wave methods to model and subtract aliased groundroll. These new tools require different input data and different sampling. How these advances influence the design process is illustrated using a case study for a 3D survey acquired in the 3 quarter of 2011 located in the largely sand covered thrustbelt area of the United Arab Emirates. The seismic data were acquired using a high productivity technique that uses time and distance rules coupled with integrated QC rules based on active spread criteria to maximize productivity and minimize cross-talk between the individual seismic sources. The initial data from the 3D survey shows that the proposed integrated 3D survey design is adequate for coherent noise attenuation, source cross-talk removal and building a near-surface model.