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The use of multi-wave and multi-component seismic information for reservoir prediction and characterization has been a popular research direction. The study area is located in the Orinoco heavy oil belt in Venezuela. The reservoir is a braided river delta plain deposit and the sandstone is shallowly buried and unconsolidated. Thereby, it is difficult to predict and characterize the type of reservoir effectively with seismic data of conventional P-waves. Based on multi-wave and multi-component seismic acquisition data, the study has conducted petrophysical analysis and seismic horizon calibration with converted wave (PS). Vertically, superimposed sand bodies were identified with PP wave because the PP wave has higher vertical resolution than that of PS wave. Laterally, sectional morphology and plane distribution scale of sand bodies were delineated by using the higher lateral resolution of PS wave. By combining the characteristics of PP wave and PS wave, five models for intersection and sand body superposition were summarized and the architecture units of sand bodies were divided. The seismic attribute (RMS amlpitude) boundary characteristics and continuity of the high amplitude region described by PS wave are more evident to obtain plane distribution of channel bars and braided channels. Three different seismic inversion results of seismic impedance, density and sand thickness from three different methods were compared. The average accuracy of sand body prediction with the method of PP-PS wave combined pre-stack inversion reached approximately 85% which is greater than that of the PP wave post-stack inversion and PP-PS combined post-stack inversion, with accuracy of 64% and 66% respectively. The research results showed that in the study area, the combination of multi-wave and multi-component seismic reflection information can effectively identify and predict multi-stage superimposed sand bodies with clearer vertical superposition and more accurate lateral boundary. Due to the inherent non-uniqueness of seismic information on predicting reservoir distribution, the resolution of seismic data and the difficulty of identification of the highly superimposed shallow-buried unconsolidated sandbodies, reservoir prediction uncertainty still exists. In particular, the interpretation on the sedimentary microfacies distribution and sand-body scale may only be one of the relatively reliable interpretation schemes. • Application of multi-wave and multi-component seismic data. • Description on unconsolidated sand bodies integrated well and seismic data. • PP-PS wave combined pre-stack inversion method. [ABSTRACT FROM AUTHOR]

Abstract The Eastern Venezuela Basin serves as a world-class petroliferous basin, with the sedimentary environment controlled by interactions between the Caribbean and South American plates. This complex tectonic movement could have an important impact on the unsynchronized sedimentary evolution process and heterogeneous marine transgression of different regions within the basin. Thus, it is important to clarify the impact of interactions between the fluviatic- and marine-deposits on the development of the sedimentary environment, the transition of different delta types, and sand-body distribution within this complicated tectonic movement. Based on interpretation of 3D seismic data, electrical well-logging facies and analysis of the sedimentary characteristics of the core, we were able to identify the different sedimentary association types and understand the evolutionary process of the sedimentary system within the study area. We found that the differential sedimentary process in the eastern and western Carabobo block in the Eastern Venezuela Basin was caused by differential uplift and the corresponding spatial discrepancy transgression process in the Middle and Early Miocene foreland basins in this region. The flat geomorphology in the eastern Carabobo block contributed to the obvious sea level transgression process from North to South, but the uplift in the center of the western Carabobo block continuously blocked the sea level transgression. The different transgression processes led to the different sedimentary evolution processes in the eastern and western Carabobo blocks. In the eastern Carabobo block, braided river deltas (23.3–20.43 Ma) gradually changed into meandering river deltas (20.43–15.97 Ma) and finally into tide-influenced estuaries (15.97 Ma). However, in the western subsiding Carabobo block, impacted by the uplift in the center of this area, braided river deltas (23.3–15.97 Ma) in front of the uplift (adjacent to the sea) quickly changed into tide-influenced estuaries (15.97 Ma) with the generation of meandering distributary channels. However, the relatively weak transgression impacting the area behind the uplift resulted in braided channels being retained. Along with the evolution of the sedimentary environment, the tide-related deltaic distributary channel began to change from a braided channel to a meandering one. After rebuilding the paleo-hydrodynamic field, ancient geomorphology, and combining the hydrodynamic equations, we were able to quantitatively explain why sausage-shaped mouth bars occurred in the West and isolated mouth bars occurred in the East. Differential sedimentary environment evolution in eastern and western Carabobo is related to the spatial discrepancy of transgression, which resulted in the rate of change in hydrodynamic intensity, the direction of water flow confluence, and paleo-geomorphology. Highlights • Identification of Spatial discrepancy of Miocene transgression with multi-scaled data analysis. • Recognition different kinds of sedimentary evolution process based on the seismic-log-core integration analysis. • Put out the responding channel transform pattern with rebuilding the hydrodynamic distribution. [ABSTRACT FROM AUTHOR]