## 3 Materials and Methods  
An integrated approach using multiscale data (Table 1) was utilized in this study and was crucial in order to understand the karst morphology in Jintan and M1 platforms.  
The 245 km\({}^{2}\) Jintan 3D seismic cube was acquired between 1991 and 1992 with a grid spacing of 300 m, meanwhile the M1 seismic cube was acquired between 2015 and 2016. The Jintan and M1 surveys were merged in this study for the purpose of horizon interpretation of both platforms. Four exploration wells i.e., Jintan-1, Jintan-2, Jintan-3 and M1-1, were utilized for seismic to well-tie analysis prior to horizon interpretation and also correlation between well markers and objective reflectors using available gamma ray logs (Figure 2).  
The workflow used to analyse and interpret the 3D seismic volume in conjunction with core, well log and other data is shown in Figure 3.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Materials** & **Description** & **Methodology** \\ \hline Drilling data & Final well reports of Jintan-1, Jintan-2, Jintan-3 and M1-1 wells. & Lost circulation depths recorded to preliminary identify the depth of possible karst in each platform. \\ \hline Well logs & Gamma ray logs of Jintan-1, Jintan-2, Jintan-3 and M1-1 wells. & Seismic to well-tie analysis. \\ \hline Thin Section & 32 units of Jintan-2 thin sections & Identification of pore type and cement related to dissolution \\  & 38 units of Jintan-3 thin sections & diagenesis to understand karst \\  & & morphology. \\ \hline Core data & 84 m of Jintan-2 core and 207 m of Jintan-3 core described. & The depth of chalkified and \\  & Jintan-3 core described. & rubble intervals recorded. \\ \hline
3D Seismic & Jintan \& M1 merged 3D cube & Karst horizon interpretation. \\  & seismic & Spectral decomposition \\  & & techniques application. \\ \hline \hline \end{tabular}
\end{table}
Table 1: Summary of materials and methodology analysis for this study which involved multiscale soft and hard data.  
Figure 1: The location of Jintan and M1 platforms in Central Luconia province.  
Final well reports were studied to identify lost circulation reported during drilling and provide preliminary intervals of possible karst.  
A total of 70 units of thin sections from the Jintan platform were analyzed for the identification of pore type and cement related to dissolution diagenesis relevant to understand karst morphology. In addition, cores with a total length of 291 m from Jintan-2 and Jintan-3 wells were described in detail to identify chalkified intervals as they are interpreted as karst due to intensive leaching related to mixing zone karstification [14].  
The spectral decomposition technique allows seismic trace-based attributes to be created in order to better highlight geological features. The main purpose of this technique  
Figure 3: Methodology and workflow used for the interpretation of karst geobodies from 3D seismic using spectral decomposition techniques. Geobody extraction and volumetric calculation complemented the analysis to estimate the volume of the karst geobody in the Jintan and M1 fields.  
Figure 2: (a) 3D inline section showing Jintan and M1 fields and Jintan-1 and Jintan-2 wells. Annotated are the seismic units (SU1 to SU6) as interpreted by [12] (b) 3D image of the Mega Platform structure extracted from a coherency cube displaying the Jintan and M1 fields.  
is to decompose the seismic signal into different energies corresponding to each frequency in the volume in order to create a spectrogram. By analyzing the spectrogram, it is possible to select several dominant associated frequencies corresponding to the geological target features. In combination with striatal slicing and RGB blending in PaleoScan(tm) software, this workflow can help facilitate the target detection based on the frequency imaging.