scholarly journals Application of Spectral Decomposition Technique to Delineate the Evolution of Karst on Carbonate Platforms of Central Luconia, Offshore Sarawak, Malaysia

2021 ◽  
Vol 11 (24) ◽  
pp. 11627
Author(s):  
Siti Sarah Ab Rahman ◽  
Maman Hermana Husen ◽  
Grisel Jimenez Soto ◽  
Saw Bing Bing ◽  
Nur Huda M Jamin ◽  
...  
Keyword(s):  
Spectral Decomposition ◽  
Quantitative Description ◽  
Seismic Interpretation ◽  
Drilling Process ◽  
3D Seismic ◽  
Carbonate Platforms ◽  
Thin Sections ◽  
Time Frequency ◽  
Platform Margin ◽  
Central Luconia

Karstification in carbonate platforms of the Miocene age in Central Luconia province, offshore Sarawak, Malaysia, has been discussed since the onset of exploration and initial discoveries in the region, with over 200 mapped platforms to date. An extensive drilling program over the last decade confirmed the existence of karst during the drilling process where issues such as total loss circulation and bit drops were common. Karst in Central Luconia has been proposed by several authors; however, detailed quantitative description of the observed features have not yet been conducted. This study involves systematic mapping of loss circulation depths, chalkified/rubble/vuggy zones described from cores, and vugs of >2 mm in size and moldic porosity observed on thin sections of the Jintan platform. These data supplement the interpretation of karst from multiple 3D seismic attributes. Seismic interpretation of the Jintan and M1 platforms revealed an extensive dendritic pattern which is on average 70–100 m deep and 3–5 km long, and circular geobodies of 1 km in width that exist on the upper part of the platform. Spectral decomposition, also known as time-frequency analysis, was used to enhance the interpretation of karst features on seismics within a specific wavelength. In this study, a comparison of three spectral decomposition methods applied on the 3D seismic cube of the Jintan and M1 platforms was undertaken to determine the method which allowed for better delineation of the karst features. The results show that the short-time Fourier transform (STFT) method using frequencies of 46, 54, and 60 Hz delineated most of the karst features compared to the continuous wavelet transform (CWT) Morlet and CWT Ricker wavelet methods. This paper aims to discuss the dimensions, evolution and geometry of the karst features quantitatively on three selected karst horizons named “K1”, “K2”, “K3”. Interpretation revealed that the dendritic karst features were found to be most prominent on the K2 horizon which lies below a conspicuous change of the external geomorphology of the platform. Backstepping of the platform margin by 12 km is observed in both platforms. Quantitative seismic interpretation shows that the karst observed in M1 platform is approximately 70–100 m deep, and the dendritic features are around 1–2 km in length and approximately 500 m wide; whereas, in the Jintan platform the dendritic features observed are up to 5 km in length with several 1 km wide circular/sinkhole features. More than 20 dendritic features orientated SE and NS were mapped mainly in the transitional area as well as the center of both platforms. The nature of the karst morphology in Central Luconia remains controversial; however, it is proposed to be of mixing zone karst origin.

Red Sea Holocene carbonates: Windward platform margin and lagoon near Al-Wajh, northern Saudi Arabia

2021 ◽  
Vol 91 (8) ◽  
pp. 847-875
Author(s):  
D. Mark Steinhauff ◽  
Abduljaleel Abubshait ◽  
Sam J. Purkis
Keyword(s):  
Red Sea ◽  
Pore Space ◽  
Carbonate Platforms ◽  
Rift Basins ◽  
Thin Sections ◽  
Fine Grained ◽  
Platform Margin ◽  
Lagoon Sediment ◽  
Primary Porosity ◽  
Reservoir Potential

ABSTRACT Analysis of Holocene sedimentary seascape is focused on the Red Sea windward Al-Wajh platform margin, its central lagoon, and nearby isolated platforms based on data that include mapped ecological facies (habitats), water depths, grain sizes, and allochem types and abundances determined from thin sections. On this basis, a depositional model applicable to Red Sea Plio-Pleistocene and other ancient icehouse carbonate platforms is presented. The model highlights favorable reservoirs in analogous ancient systems to include coral crests and columnar framework habitats with primary porosity developed in boundstone lithologies and windward platform margins to contain considerable open pore space, including cavernous openings, of which not all should be anticipated to be occluded with marine cements and sediments. Meteoric diagenesis is expected to be minor as limited freshwater is available due to extreme aridity, but may play a role during glaciation. Most habitats have potential for secondary (enhanced) porosity resulting from dissolution of aragonite skeletons, particularly mollusk shells and calcareous coral (Scleractinia) endoskeletons. Central-lagoon habitats are expected to have the least favorable reservoir potential of environments considered because they are dominated by peloids. Central-lagoon sediment differs from other published localities, having higher peloid abundances, greater peloid distribution, and little or no association with Halimeda and quartz grains. Under the likely scenario that platform-interior sediments are completely bioturbated and comprise peloid-rich, grain-dominated fabrics, with many smaller peloids (most of them likely fecal pellets) at or near 4 μm in size (i.e., mud fraction), it is possible that grain size will control pore size once the considered deposits are lithified. If so, platform-interior sediments will lithify as mudstones, wackestones, or very fine-grained grainstones, an outcome which might otherwise be unexpected given the abundance of coarse peloid grains. The Al-Wajh platform is compared with 15 Holocene analogs and found to be unique with respect to rift-margin type, restricted-marine circulation, in having a lagoon with high peloid content, and lack of karst. In further comparison with ancient reservoir analogs, two greenhouse and four icehouse, it compares favorably to icehouse platforms deposited in rift basins with respect to mineralogy of deposition, meter-scale cycle thicknesses, and general peloid content and distribution. It provides a snapshot as to how an icehouse platform might have nucleated and attached along an active rift margin; it is a broadly applicable carbonate analog for the Red Sea Plio-Pleistocene and similar icehouse, rift basins.

The analytic wavelet transform with generalized Morse wavelets to detect fluvial channels in the Bohai Bay Basin, China

Geophysics ◽  
2016 ◽  
Vol 81 (4) ◽  
pp. O1-O9 ◽  
Author(s):  
Zhiguo Wang ◽  
Jinghuai Gao ◽  
Ping Wang ◽  
Xiudi Jiang
Keyword(s):  
Wavelet Transform ◽  
Seismic Data ◽  
Spectral Decomposition ◽  
Bohai Bay ◽  
3D Seismic ◽  
Bohai Bay Basin ◽  
Significant Information ◽  
Time Frequency ◽  
Analytic Wavelet ◽  
3D Seismic Data

The Middle Miocene Minghuazhen Formation of the Bohai Bay Basin is dominated by fluvial channels and shallow-lacustrine deltaic systems. These depositional facies, along with complex postdepositional faulting, make it difficult to detect fluvial channels. As a useful seismic attribute to solve this problem in the Bohai Bay Basin, spectral decomposition of 3D seismic data can provide significant information to understand the subsurface fluvial channels. The analytic wavelet transform (AWT) is a promising approach for implementing spectral decomposition to provide a detailed time-frequency representation. In particular, by varying two parameters (beta and gamma) controlling the wavelet forms, the generalized Morse wavelets (GMWs) can be given a broad range of characteristics while remaining exactly analytic. To detect fluvial channels with thickness around and lower than the tuning thickness, we have proposed a suitable (beta = 1 and gamma = 3) pair of parameters for GMWs because such an exactly analytic Morse wavelet substantially outperforms the approximately analytic Morlet wavelet for high time localization. We have applied the AWT with a GMW (beta = 1 and gamma = 3) to 3D seismic data in the Lower Minghuazhen Formation, Bohai Bay Basin, China. The stratal slicing of spectral decomposition volumes at depositional cycle 2 of the Lower Minghuazhen Formation shows its potential for channel interpretation and the optimization of well patterns.

3D Seismic Interpretation of the Praia Grande Impact Structure – Upper Cretaceous of Santos Basin, Offshore Brazil

2005 ◽  
Author(s):  
Gustavo Alberto Correia ◽  
Jorge Rui Corrêa de Menezes ◽  
Gilmar Vital Bueno ◽  
Edmundo Julio Jung Marques
Keyword(s):  
Upper Cretaceous ◽  
Seismic Interpretation ◽  
Impact Structure ◽  
3D Seismic

A general model for growth trajectories of linear carbonate platforms

2020 ◽  
Vol 90 (9) ◽  
pp. 1139-1155
Author(s):  
Nicolas Goudemand ◽  
Pulkit Singh ◽  
Jonathan L. Payne
Keyword(s):  
Growth Trajectories ◽  
Carbonate Platforms ◽  
Seawater Chemistry ◽  
Forward Models ◽  
Sedimentary Deposits ◽  
Sediment Production ◽  
Carbonate Sedimentation ◽  
Platform Margin ◽  
Simple Equations ◽  
Analytical Expressions

ABSTRACT A key challenge regarding development of carbonate platforms is predicting the temporal pattern of platform-margin progradation, aggradation, retrogradation, and drowning. Numerical forward models of carbonate sedimentation have been widely applied to this problem, shedding substantial light on the roles of sediment production, transport, tectonic subsidence, and eustasy on the evolution of carbonate platforms. However, forward models are typically complex and computationally expensive, preventing comprehensive exploration of parameter space. In addition, the interactions among parameters are often nonlinear, preventing the development of simple expressions relating the position of the platform margin to the governing parameters of the model. To complement the considerable insights derived from numerical forward models, this study presents analytical expressions for the temporal evolution of the position of platform margins using the simplest possible assumptions regarding sediment production and transport. These expressions provide useful null models, deviations from which can be used to identify the particular effects of biology or seawater chemistry on carbonate factories in influencing the development of these important sedimentary deposits. Application of the model to synthetic and outcrop examples demonstrates that these simple equations are useful for parameter estimation that can then be used to guide more detailed, process-based numerical forward models.

Exploring for stratigraphic traps in the Patchawarra Formation, Cooper Basin: an integrated seismic methodology

2018 ◽  
Vol 58 (2) ◽  
pp. 779
Author(s):  
Alexandra Bennett
Keyword(s):  
Complex Geometry ◽  
Imaging Techniques ◽  
South Australia ◽  
Seismic Interpretation ◽  
Seismic Survey ◽  
3D Seismic ◽  
Seismic Resolution ◽  
Seismic Reflectivity ◽  
Seismic Area ◽  
Cooper Basin

The Patchawarra Formation is characterised by Permian aged fluvial sediments. The conventional hydrocarbon play lies within fluvial sandstones, attributed to point bar deposits and splays, that are typically overlain by floodbank deposits of shales, mudstones and coals. The nature of the deposition of these sands has resulted in the discovery of stratigraphic traps across the Western Flank of the Cooper Basin, South Australia. Various seismic techniques are being used to search for and identify these traps. High seismic reflectivity of the coals with the low reflectivity of the relatively thin sands, often below seismic resolution, masks a reservoir response. These factors, combined with complex geometry of these reservoirs, prove a difficult play to image and interpret. Standard seismic interpretation has proven challenging when attempting to map fluvial sands. Active project examples within a 196 km2 3D seismic survey detail an evolving seismic interpretation methodology, which is being used to improve the delineation of potential stratigraphic traps. This involves an integration of seismic processing, package mapping, seismic attributes and imaging techniques. The integrated seismic interpretation methodology has proven to be a successful approach in the discovery of stratigraphic and structural-stratigraphic combination traps in parts of the Cooper Basin and is being used to extend the play northwards into the 3D seismic area discussed.

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