Synthetic seismic model of a Permian biosiliceous carbonate – carbonate depositional system (Spitsbergen, Svalbard Archipelago)

Abstract

The non-unique correspondence between seismic and subsurface geology is a fundamental problem when interpreting seismic data sets. Synthetic seismic models of outcrop analogs are commonly constructed to cover the gap between the small-scale outcrop observations and low-resolution seismic data. The Permian biosiliceous carbonatecarbonate sediments on Spitsbergen are characterized by a wide variability in lithologies and microfacies determining the petrophysical properties (e.g., porosity, acoustic properties) that consequently complicate seismic interpretation. This study uses 1D and 2D synthetic seismic modelling techniques (at different resolutions) to gain an understanding of how seismic reflectors are expressed with respect to the sediment distribution, aiming to facilitate real seismic interpretation. In the study area, nine microfacies were defined that were used to produce a geological model displaying small-scale microfacies variations within a well-defined sequence stratigraphic framework. Laboratory derived petrophysical properties (Vp, ρBulk and AI) were assigned to each predefined microfacies body in the geological models in order to construct acoustic impedance models that were used to produce synthetic seismograms. The appearance of the seismic reflectors in the synthetic seismic profiles is primarily controlled by changes in mineral composition and link to spatial microfacies distributions within the depositional sequences. Differences in acoustic impedance and the origin of synthetic seismic reflections within a single microfacies type are mainly caused by porosity contrasts (varying between 5 and 20%) and diagenetic modifications such as chertification and cementation. This detailed information cannot be derived from the low-frequency seismograms (25-100 Hz) resulting in changes in seismic expression when seismic resolution diminishes. Comparison with time equivalent, real and synthetic seismic data of the Finnmark Platform reveals similarities with the synthetic seismic reflection patterns of Spitsbergen. In both areas, the pronounced seismic traces follow abrupt microfacies transitions, which are coherent with cycle boundaries and timelines.

Controlling factors of acoustic properties in continental carbonates: Implications for high-resolution seismic imaging

“…9d). It is analogous to the "destructive interfering waves" phenomena proposed by Jafarian et al (2018).…”

“…Based on the in-situ P-wave velocities and plug density measurements, synthetic seismic analyses were performed using EasyTrace TM Software (see Jafarian et al (2018) for the equations). We computed the acoustic impedance, the reflectivity coefficient (RC) and finally the 1D seismic trace (zero offset) using a convolution on the RC with an analytical Ricker wavelet.…”

“…In order to understand the stratigraphic value of seismic reflectors, several studies modelled 2D synthetic seismic sections, based on seismic-size well-exposed outcrop descriptions together with punctual ultrasonic measurements of samples (e.g., Anselmetti et al, 1997a;Jafarian et al, 2018;Janson et al, 2007;Kenter et al, 2001;Kleipool et al, 2015Kleipool et al, , 2017Stafleu and Sonnenfeld, 1994;Zeller et al, 2015). Assuming that plug-scale measurements are representative of decameter rock units, this approach is suitable for assessing the geological significance of reflectors representing large-scale geological heterogeneities within seismic resolution (size higher than 10 meters).…”

Combined controls of sedimentology and diagenesis on seismic properties in lacustrine and palustrine carbonates (Upper Miocene, Samos Island, Greece)

“…The goal of this tool is to be predictive of subsurface geology at a large scale (Anselmetti et al 1997). It is also used to create seismic models of outcrop analogues and compare them to subsurface seismic data (Zeller et al 2015;Kleipool et al 2017;Jafarian et al 2018). It is therefore of primary importance to be able to understand what controls the geological expression of seismic reflectors if one wants to use such models in an appropriate manner.…”

Distinct petroacoustic signature in heterozoan and photozoan carbonates resulting from combined depositional and diagenetic processes

“…Assessing such an impact on velocity-porosity relationships is thus a major issue for the prediction of reservoir properties from remote data such as well logs and seismics (Anselmetti and Eberli, 1999;Fournier et al, 2018;Jafarian et al, 2018;Teillet et al, 2020) and to achieve valid porosity-permeability transforms, which are of prime importance in the modelling of carbonate hydrocarbon systems. Most of the published studies dealing with velocity-porosity relationships in purely calcitic (%CaCO3 > 95 %) marine carbonate reservoirs focused on tropical photozoan shallow-water carbonates (e.g.…”