Abstract

TOTAL INDONESIE has drilled numerous wells in the Mahakam Delta area of East Kalimantan, and is currently producing 210 000 BOPD from multiple pays within a deltaic sequence of Miocene age at Handil and Bekapai

A complete logging programme is run on all wells although there are differences in the logs run for exploration and development wells.

Apart from the relatively straightforward problems of correlation within the fields, the log analyst has to overcome certain awkward problems in order to define as clearly as possible the fluid contacts and reservoir parameters within the many different and laterally variable reservoirs.

For instance:

– Within the different reservoirs the contents of clay varies greatly, which can have a very large effect on the reservoir quality. Coring programmes have helped the analyst to calibrate the logs. The relationships between porosity (φ) and shaliness (Vsh), and permeability (K) and porosity (φ), have been closely studied. Permeability can be estimated in the cleaner reservoirs.

– The formation water salinity changes within the reservoirs which complicates the detection and definition of the pay zones. Fluid determination is illustrated by several examples which serve also to identify the pitfalls in log interpretation.

The experience gained in the producing fields is very usefully applied to the interpretation of exploration wells drilled in deltaic sequences elsewhere.