Rock Property Estimation Using Dual-Sensor Streamer Data without Well Constraint - North Sea Jurassic Case Study

Abstract

Broadband seismic data are becoming increasingly common, with many different methods of producing a broader range of frequencies. Accurately recorded broadband frequencies are of particular use for quantitative interpretation, and can give much improved seismic inversion results (Reiser et al., 2012). In this case study, dual-sensor streamer seismic data is compared with conventional seismic data over Grevling, a Jurassic oil discovery in the Central North Sea. The results of rock property estimation are compared by using an entirely seismic data-driven inversion workflow, i.e. without using any well information as input. The comparison between the two datasets demonstrates that there is highly valuable rock property information in the additional recorded frequencies of the dual-sensor seismic data, in particular the octave gain on the low frequency side at the reservoir level. The dual-sensor seismic data allows a better fluid discrimination within the reservoir and demonstrates a clear trend in the Vp/Vs data directly recorded by the seismic data. The workflow has been validated by comparing the seismic rock properties to an independently derived rock physics model and found to match closely.

Intra-Chalk Porosity Variations in Norway-Danish Central Graben: Integrated Mapping Using Broadband Elastic Attributes

“…A P-impedance volume was computed from this newly depth migrated broadband data from which the rich low frequency content allowed pre-stack inversion with confidence and reliability from 5Hz (Ozdemir, H. 2009;ten Kroode et al, 2012Reiser et al, 2012Whaley et al, 2013). Figure 2 illustrates the correlation of low P-impedance intra-chalk layers (red) with the elastic logs computed from the wells and also with the neutron porosity log.…”

Advances in broadband quantitative interpretation

“…These technologies are designed to offer a broader seismic bandwidth resulting in sharper seismic signal with significantly less side lobe artefacts (ten Kroode et al, 2013). The additional low frequencies from these solutions allow for an improved pre-stack inversion of seismic data for elastic attributes and should provide ultimately more reliable reservoir properties in 3D when combined with rock physics (Reiser et al, 2012, Whaley et al, 2013. In order to estimate these elastic properties, pre-stack or angles-stack seismic information is necessary.…”