Seismic attributes and structural style of Sawan area, lower Indus basin, Pakistan (T-1487) (MFN 4286)

Abstract

The study area (Sawan Field), located in Lower Indus Basin, Pakistan, is chosen to perform attribute analysis and check their effectiveness on given seismic data. Before performing attribute analysis, both manual and digital interpretation was done for the study area. Nine horizons namely, Pirkoh Formation, Sui Upper Limestone Formation, Sui Main Limestone Formation, Upper Goru Formation, Lower Goru Formation, C Sand, Sember Formation and Chiltan Limestone Formation were marked. Time and depth contour maps were generated. Negative flower structures have been interpreted which are conforming to transtensional tectonic regime in the study area. The “C” Sand Interval of the Lower Goru Formation is acting as a reservoir, Sember Shale acts as a source and upper Goru acts as a seal in the study area. Closure was found around Sawan-01 after generation of time and depth contour map at “C” Sand level which proves that Sawan-01 was an historical producing well. Structural (faults) and Stratigraphic (reflection geometries) were studied by applying variance attribute on the seismic data. However for study purpose much useful information was gathered from selected attributes. The Sweetness attribute revealed hydrocarbon potential at “C” sand level. Variance attribute helped in recognizing and marking the faults which were difficult to be seen on the seismic section. RMS amplitude has proven to be of great importance in detecting major lithological changes. Instantaneous frequency attribute has proved useful in indicating lateral changes in lithology as well as fracture zone detection at few locations in the study area.