Fast-Track Rock Properties From Broadband Seismic Data

Abstract

Introduction Brunei Shell Petroleum acquired 7000 km2 of broadband seismic data during 2012 and 2013, in support of its strategy to "Rejuvenate and Grow". Exploration growth is a key component of this strategic direction and the broadband data is seen as a key enabler. The new seismic data not only delivers far better structural definition but also allows for streamlined QI support to identify new prospective areas. Weeks after the final migrations are available, we delivered a full bandwidth Acoustic Impedance and a Fluid Cube for the entire 3D data space. The swift delivery of these inversion products forms a corner stone in pursuit of Brunei Shell Petroleum's exploration objectives. 1 - Regional Full Bandwidth Impedance Data Broadband seismic delivers lower frequencies in the seismic spectrum and, through application of the latest imaging techniques, also delivers higher frequency content in the migration velocities. These 2 components can be merged seamlessly, creating an acoustic impedance volume, without having the need to estimate information in the range of ~1.5 to 8 Hz. With conventional seismic this gap needs to be filled with more or less substantiated interpolations of rock properties, based on time consuming interpretation efforts. We developed a robust workflow to generate regional full bandwidth Acoustic Impedance (AI) data, that essentially relies ona) signal shaping and subsequent coloured inversion to appropriately reflect the earth's AI spectrum,b) the derivation and application of a single calibration factor to obtain band-limited AI andc) subsequent merging of this band-limited AI data with low-frequency AI data that is directly obtained from the imaging velocities. Well tests indicate the quality of the match of well log data against the final impedance volumes (Figure 1).