Publications

The North Seram Basin is located in the northern part of the Banda Arc where the collision event of the Australia plate with the Sunda plate in the Late Tertiary resulted in structurally complex thrust belt sequence. Even though the area is currently at a mature exploration stage, accuracy and precision in the basin-wide depth conversion are difficult to achieve simultaneously mainly due to its complex geological structure with strong lateral velocity variations and the limited amount and quality of seismic data and sparse control from well data. This research performs a comprehensive and regionally extensive depth conversion analysis utilizing velocity profiles that are available in ten onshore wells and only one offshore well that penetrated the shallow section. Various depth conversion methods were applied to achieve the best depth structure maps; layer cake velocity, well velocity, and well pseudo-checkshot method. Layer cake velocity method calculated interval velocity value for each stratigraphic interval to be multiplied to isochron maps. The converted isochron maps were then stacked to generate depth structure maps. Well velocity method utilized both well markers and time interpretation across the well to calculate the velocity points and generate velocity maps. Trend surface generated from up-scaled time structure map was used as guidance to guide the velocity grid and populate the velocity variation. Pseudo-checkshot method extended the shallow offshore well velocity profile by duplicating onshore well profile for deeper section. Second and third order polynomial were then extracted to convert time to depth structure maps. Error values between well markers and depth structure map is preferred as quality control to pick the best depth conversion method. Well velocity method produced the least error between markers and structure maps, giving the best depth structure maps to be further used for basin modelling tasks and future exploration studies.