High-resolution processing for time-lapse seismic

Abstract

Time-lapse seismic technology is moving from measurement of qualitative variations to quantitative analysis of fluid saturation and pressure variations. Increasing the resolution of time-lapse seismic data relative to the reservoir body scale offers the possibility of even more accurate measurements. The resolution improvement is directly dependent on the capacity to recover the high frequency content of the seismic measurement. In this paper, we investigate a data processing methodology that provides a 4D seismic signature with an extended frequency bandwidth. We pay particular attention to the seismic data preconditioning in order to remove random noise and spatial correlated noise, such as the acquisition footprint, which can contaminate the seismic high frequency content. Using a geostatistical technique, we apply the concept of common seismic cube derived from two adjacent seismic angle stacks. The common seismic cube does not include the acquisition imprint and has an improved signal to noise ratio, especially for the high frequencies. The concept of common spectrum is used to design two symmetric matching operators in order to increase the repeatability of the high frequencies. Once the data have been preconditioned, we use an innovative technology exploiting the spatial coherence of the seismic information with predefined reflector constraints to solve a sparse reflectivity distribution. A North-Sea example shows the benefits of the new high-resolution time lapse processing workflow.