ANALYSIS OF SEQUENCE STRATIGRAPHY, LEMAT FORMATION TO GUMAI FORMATION, GN FIELD, SOUTH SUMATRA BASIN

摘要

A study of the sequence stratigraphy in GN Field, South Sumatra Basin was carried out using core data, well log data and biostratigraphy data. This study applied sequence stratigraphy concepts in GN Field to provide a detailed chronostratigraphic framework for subsurface mapping and interpretation of the sedimentation mechanisms in the area. From analysis could interpret lithology in the GN Field are consist in GN Field are non-calcite shale, calcite shale, limestone, coal, non-calcite sandstone, calcite sandstone, conglomeratic sandstone and metamorphic quartz. The defined marker have been found are as follows : Sequence Boundary type-1 (SB-1), Parasequenceset boundary-1 (PSSB-1), and Maximum Flooding Surface (MFS). The lithology from SB-1 is conglomerate sandstone, PSSB-1 is sandstone and MFS is marine shale. From this marker, sequences that have been found at GN field can be divided into two sequences namely, Sequence 1, and Sequence 2, each bounded by sequence boundaries above and below. At sequence-1, there is no system tract that could be identifies. And at sequence-2, the system tract that could be identified was Lowstand System Tract-1, Transgressive System Tract-1, Transgressive System Tract-2, and Highstand System Tract-1. In the GN Field, the depositional environment, from the Lemat to Gumai Formations showed increasing marine conditions upward in the section, and it was changing from continental to marine.