3D seismic visualization of shelf ridges: case study from offshore northwest Java

Abstract

Detailed stratigraphic evaluation of 3D seismic data from the Miocene section of the offshore northwest Java shelf reveals the extensive presence of preserved shelf ridges. These features are deposited as long linear bodies ranging from 0.3 to 2.0 km wide, over 20 km long, and up to 17 m high. Upon closer inspection, these features appear to be asymmetric, characteristically sharp-edged and thicker on one side, gradually thinning with an irregular edge on the other side. Possible sand waves, smaller in scale, are observed superimposed upon these ridges and oriented oblique to the long axes of the ridges. Shelf ridge deposits tend to be sand prone and are observed to overlie ravinement surfaces. The ridges appear to be oriented parallel to paleo trunk valleys associated with broad structural embayments. In addition to shelf ridges, shelf ribbons, possibly less than 5 m thick and less than 100 m wide, are also imaged. * ARCO Indonesia commonly sand prone and they tend to be encased in shelf mudstone seal facies. Depending upon the degree to which sand is present in inter-ridge locations, these linear sand bodies can comprise potential stratigraphic traps.