3D Seismic Interpretation and Geological Modelling for Petroleum Reserves Estimation of I Sequence, Lower Miocene, X Field, Block Y, Malay – Tho Chu Basin, Viet Nam
Seismic attributes are widely used to enhance geological interpretation by extracting quantitative information from seismic data. They provide insights into both structural and stratigraphic features, enabling interpreters to detect subtle changes in lithology, continuity, and geometry of subsurface formations. Attributes are especially useful in improving the resolution of seismic images, helping to delineate horizons, identify fault patterns, and visualize depositional features. This study focuses on using seismic attribute analysis to clarify the distribution of sand bodies within a reservoir interval. The objective is to identify zones with favourable sand development, define their geometry and connectivity, and outline areas with high hydrocarbon reservoir potential. The interpreted I Sequence was divided into three sub-sequences, each modelled with a geological grid size of 50m×50 m and subdivided into 150 layers. The porosity model showed mean values ranging from 0.228 to 0.2484 across the main reservoir zones, while water saturation varied from 0.90659 to 0.92747. After calculating seismic attributes, the authors delineated sand bodies in the I38_upper layer located in the North–Northwest, Northeast, and smaller bodies in the South. In the I90 layer, sand bodies were identified in the North–Northeast, East, and Southeast, along with narrow, laterally restricted sands in the western part of the study area. The P2 reserve with 50% confidence for the most potential interval (I23–I38) was estimated at 86 million cubic meters after running 200 cases.