Seismically Constraining the Static and Dynamic Models of a Complex Fluvial System, Mangala Field, Rajasthan

Abstract

Abstract The Mangala field is located in the northern part of the onshore Barmer Basin in India. The Fatehgarh Formation is the primary reservoir, which was deposited during the rifting phase that created the Barmer Basin during the late Cretaceous to early Palaeocene period. The majority of reservoired oil is contained within the Upper FM1 member of the Fatehgarh Formation, composed of single storey and multi-storey stacked, meandering channel sands. These sands vary in thickness from 3 to 7 meters, with net-to-gross ranging from 18% to 78%. Well-based correlation of flood plain shales and fluvial sands in such a heterogeneous fluvial system poses a major challenge for reservoir characterization. These thin fluvial channel sands are not resolved in the conventional seismic data, which makes it difficult to map the lateral continuity of these sand units. Sparse-layer Inversion was performed on the 3D stack PSTM data, which resulted in a dataset with improved detectability and resolution. Results were validated using well log and production data. Amplitudes of the high resolution seismic data provided information on sand continuity and connectivity. Consequently, Colored Inversion was performed on this data which provided improved understanding of the lateral distribution of the thin FM1 channel sands.