Abstract

The Offset Seismic Profiling technique (OSP) has been used successfully in the Jatibarang field of Pertamina E.P. Unit III to determine the structure of the oil producing Jatibarang volcanic formation.

The Offset Seismic Profiling technique is a natural extension of Vertical Seismic Profiling (VSP) where both up and down going reflections are recorded by a wall lock geophone in a borehole.

The simultaneous recording of both wavetrains is a major advantage over the conventional surface seismic which only records the upgoing reflections. In Offset Seismic Profiling with the source placed at non negligible offsets from the well, the objective is to delineate reflections laterally away from the well.

The Offset Seismic Profile results for the two well case study considered are shown to be superior in resolution to the available surface seismic data. The increased resolution leads to a better understanding of the volcanic formation, its structure and thickness, and thus increased confidence in the location of future development wells.