Christian Strand

Simulated migration amplitude for improving amplitude estimates in seismic illumination studies

Ideally, a seismic data cube should contain amplitudes that are proportional to the reflectivity of the subsurface. However, when working with real data, the seismic amplitudes used for interpretation are highly dependent on other factors such as survey geometry, instrumentation, filtering and muting of prestack data, migration artifacts, focusing/defocusing, wave attenuation in the overburden, and several other factors. When an amplitude variation is encountered in the seismic data, determining which factor is responsible is not easy. In this paper we apply a method based on a combination of 3D seismic ray modeling and simulation of migration that is able to distinguish between some factors contributing to the amplitudes. This will reduce the risk of interpreting “false” anomalies and drilling dry wells.

Impact of Survey Design and Acquisition Technology on 3D Marine Mega-Survey Success

This paper describes how a large, 12,030km2, exploration 3D seismic survey in the Great Australian Bight was designed in order to maximize the efficiency of the survey. The entire survey area was completed within a single acquisition weather window of 7 months. Challenges for this particular survey included deep targets, very large swells, stormy weather patterns, variable ocean currents and remoteness of the survey area itself. The acquisition geometry was carefully designed to optimize the efficiency of the survey given the challenging operational constraints. The design of the acquisition parameters helped the acquisition to continue in severe swell conditions without introducing detrimental noise in the data. Unnecessary infill lines were reduced through combining active infill management with steerable streamer coverage. The required coverage was analysed using real data in the survey design stage and the achieved coverage was actively monitored during the survey

Simulated migration amplitude: modeling amplitude anomalies of PSDM in a real North Sea case

The Simulation Migration Amplitude is a ray-based, targetoriented Kirchhoff migration of synthetic data around the reflection points using the local paraxial approximation of the two-way traveltime field on the target horizon. Compared to conventional migration of synthetic data, the method is computationally efficient, making it, for example, suitable for survey planning, as the amplitude response of several configurations can be compared in a reasonable amount of time. On a real 3D case provided by PGS, the results of the method have been compared with the results from PSDM. Amplitudes from PSDM and Simulated Migration show clear similarities.