Karl Berteussen

Effects of Pore Structure On 4D Seismic Signals In Carbonate Reservoirs

Carbonate reservoir rocks of different pore structure have quite distinct and detectable 4D seismic signatures. Using three defined pore structure types (PST), these seismic signatures are correlated with the permeability patterns of carbonate rocks. In both the high-permeability PST3 and intermediate-permeability PST2 regions, gas injection is preferred than water injection for effective 4D seismic monitoring. In the low-permeability PST1 region where lies most of the bypassed oil, both gas and water injection options result in similar 4D seismic signal magnitude. Fluid saturation changes under in-situ reservoir conditions can be better detected by offset domain 4D seismic analysis.

Is Gassmann the Best Model For Fluid Substitution In Heterogeneous Carbonates

Fluid substitution is used to predict potential changes in seismic due to production in oil reservoirs. Gassmann’s model has been successfully applied to 4D-time lapse seismic in clastic reservoirs. However, the applicability of this model in carbonates is not well understood. To evaluate alternative models, we compare Gassmann, Generalize Gassmann, and Patchy saturation models in a carbonate reservoir in the Middle East. We estimated seismic changes due to substitution of oil by water after 5 and 18 years of production. We found that Gassmann’s model generally predicts the lowest seismic variation. Therefore, a 4D-time lapse seismic would not be recommended here, according to Gassmann’s model. Generalized Gassmann’s model results corroborates that seismic response depends on porosity type. Finally, Patchy saturation model shows favourable results for a 4D-time lapse seismic in both studied scenarios. Consequently, if we are going to use 4D-time lapse seismic as a production management tool in this type of carbonate reservoirs we need more information about pore structure and saturation distribution.

Challenge and Opportunity of 4C Ocean Bottom Seismics in Shallow Water Environment

In contrast to deep-water environments, shallow water environment typical of the Arabian Gulf presents unique challenges to 4C ocean bottom cable (OBC) seismics, including strong surface waves and multiples. Acquisition of 4C OBC seismic data should consi

Time Frequency Wavenumber Analysis of Surface Waves and Signal Enhancement Using S-Transform

Highly dispersive surface waves resulting from the combination of strong lateral seafloor heterogeneities, shallow water depths and hard sea bottom severely degrade seismic reflection data quality. Considering that seismic signals are nonstationary and surface waves have various spectra over time, we proposed S-transform-based time frequency wavenumber analysis technique which allows the dynamic analysis of spectrum over time. The data is first transformed from the time-space domain to the time-wavenumber domain through one-dimensional Fourier transform over the spatial variable, then the variable-factor S-transform is applied over time. Nonstationary filtering is then designed to identify and separate surface waves in complex wavefields, based on its low frequency and low velocity properties, in the time-frequency-wavenumber (TFK) domain. Application to field data illustrates that with this technique, not only is the surface wave effectively suppressed, but also the reflective signals are enhanced, which confirm the validity of the method.