Publications

The Kutai Basin is a good example of how a simple model of drilling surface and subsurface structural highs resulted in the discovery of most of the major fields. The original shallow exploration discoveries used a play concept of mapped surface anticlinal features for the selection of prospect locations. The next phase of exploration used 2D seismic to map the subsurface anticlines and drill the four way dip structures and along the anticlinal trends joining the four way dip structures. The exploration drilling resulted in the discovery of many of the major fields in a short span of time with a limited number exploration wells. The later drilling of anticlinal highs west of the Sanga Sanga trend had poor results and required a re-evaluation of the play type model. Successful drilling in the deeper water required a play type with a combination of structural and stratigraphic trapping. During the exploration and the development phase, other play types were proven but still required further evaluation. The two main play types are stratigraphic traps on the east and west flanks of the structural highs and a second play type of drilling into the overpressure zone for isolated pressure compartments. The stratigraphic traps on the east flanks were discovered in the early exploration phase in the 1970’s but could not be followed up successfully as the 2D seismic could not identify the optimum prospect locations. The isolated pressure compartment play type was proven in the drilling of a deep well below a shallower producing field. The well discovered producible gas volumes within a hard overpressure zone. Although the Kutai Basin is rated as a mature basin for exploration there are still proven play types that need to be further evaluated.