Seismic characterization of switching platform geometries and dominant carbonate producers (Miocene, Las Negras, Spain)

Abstract

The primary goals of seismic interpretation and quantification are to understand and define reservoir architecture and the distribution of petrophysical properties. Since seismic interpretation is associated with major uncertainties, outcrop analogues are used to support and improve the resulting conceptual models. In this study, the Miocene carbonates of Cerro de la Molata (Las Negras, south‐east Spain) have been selected as an outcrop analogue. The heterogeneous carbonate rocks of the Cerro de la Molata Platform were formed by a variety of carbonate‐producing factories, resulting in various platform morphologies and a wide range of physical properties. Based on textural (thin sections) and petrophysical (porosity, density, carbonate content and acoustic properties) analyses of the sediments, eleven individual facies types were determined. The data were used to produce synthetic seismic profiles of the outcrop. The profiles demonstrate that the spatial distribution of the facies and the linked petrophysical properties are of key importance in the appearance of the synthetic seismic sections. They reveal that carbonate factory and facies‐specific reflection patterns are determined by porosity contrasts, diagenetic modifications and the input of non‐carbonate sediment. The reflectors of the seismograms created with high‐frequency wavelets are coherent with the spatial distribution of the predefined facies within the depositional sequences. The synthetic seismograms resulting from convolution with lower frequency wavelets do not show these details – the major reflectors coincide with: (i) the boundary between the volcanic basement and the overlying carbonates; (ii) the platform geometries related to changes in carbonate factories, thus sequence boundaries; and (iii) diagenetic zones. Changes in seismic response related to diagenesis, switching carbonate producers and linked platform geometries are important findings that need to be considered when interpreting seismic data sets.

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.…”

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

“…The defined microfacies in the GM were vertically extrapolated to reach an equal height, thus filling the eroded zones of the upper portion of the sections. Without the extrapolation, some areas would remain unfilled and seismic artefacts could show up (Kleipool et al, 2017). This model was used during the 2D synthetic seismic modelling and allowed comparison with real seismic data (Hodgetts and Howell, 2000).…”

“…In Miocene carbonates of the Cerro de la Molata platform (SE Spain; Kleipool et al, 2017) and Barremian-Aptian carbonates from the Provence (SE France; Fournier et al, 2014) with a high-porosity domain (0% to max 50%), porosity and pore types exert a significant, first-order Acoustic impedance values were used to calculate the reflection coefficients between the individual unit interfaces. Ricker wavelet (Ricker, 1953) was used for convolution to generate a synthetic seismic profile.…”

“…Sea-level fluctuations resulted in changes in sediment composition, sedimentation rate and diagenesis, which led to variations in sonic velocities, impedance contrasts and associated hard-kick and soft-kick seismic reflections (Eberli et al, 2001(Eberli et al, , 2002. Kleipool et al (2017) proposed a conceptual model of the microfacies control on seismic reflectors within the C-factory. They noted that when coolwater carbonate factories are active, rapid microfacies shifts as a result of sea-level fluctuation are coherent with timelines and consequently with the main impedance boundaries.…”

“…The output is compared with the microfacies, rock property distribution and the general stratigraphic framework exposed in the outcrop. This comparison is used to examine the ability of seismic frequencies to resolve outcrop observations and will help to explain how much of the lithologic information ideally can be obtained from seismic data (Janson et al, 2007;Kleipool et al, 2017).…”