ABSTRACT: Advanced technology imaging of the Mudi Field, East Java improvements utilizing pre-stack depth migration

Pre-Stack Depth Migration (PSDM) has significantly improved the seismic image of the Mudi Field (a Lower Miocene carbonate bank reservoir) in a structurally complex area. Original low quality seismic images of the Mudi Field created low confidence in the top reservoir interpretation and mapping that were essential to accurate reserve calculations. This reduced image quality was primarily due to complex faulting that affected seismic ray paths yielding shadow zones on the north flank of the field.

The objective of the PSDM reprocessing was to produce as accurate as possible a depth image of the Mudi field with the current 2-D seismic and then convert to time thus avoiding the artifacts induced by time migration processing. This goal was accomplished by selecting and implementing a process that iterated a detailed geological depth interpretation with dense velocity analysis, creating a new structural/velocity model for the field. The model was then applied utilizing the non-hyperbolic move out correction from PSDM processing in depth producing a significantly sharper seismic image of the field.

Results show that the depth image is well focused, with the northern flank more visible and the fault plane well defined. The new structural/velocity models produced improved migrated seismic time data and represent a more accurate geological picture of the Field when tied to the existing wells. Tangible benefits of the PSDM processing are optimum placement of future development wells and increased confidence in the interpretation, mapping and reserve estimates for the Mudi Field.

AAPG Search and Discovery Article #90913©2000 AAPG International Conference and Exhibition, Bali, Indonesia