Abstract

Development geologists at Caltex Pacific Indonesia have become proactive in identifying geologic situations where various engineering tools could be applied to prove up new oil in existing fields. Geologists must rethink their formation evaluation methods when considering the use of engineering techniques such as hydraulic fracturing, acid fracturing, and horizontal drilling. These techniques can not only enhance known productive formations, but can also be used to make previously unproducible zones productive.

A complete reevaluation of all logs, cores, and production data for the tight Telisa Formation at Kotabatak Field resulted in establishing new log cutoffs that would be more appropriate presuming hydraulic fracturing would be applied to the formation. This reevaluation resulted in identifying a possible 300 million barrels of oil in place which had been unrecognized in previous estimates. In a program incorporating both primary production and hydraulic fracturing, and utilizing the current Telisa recovery factor of 17 percent, over 50 million barrels of this oil may be recoverable.

Two hydraulic fracture jobs have been performed at Kotabatak to date. In both cases the incremental production increase paid for the frac jobs in about one month. These tests validated the geologist's oil identification criteria and form the basis for an upward reassessment of Telisa potential at Kotabatak and several other fields.

The techniques used in this project demonstrate the results attainable by a focused geology/engineering team in identifying new producible hydrocarbon reserves and maximizing field development while utilizing the latest technologies from both disciplines. Because this approach is used in existing fields, oil finding costs are nil and development costs are paid out quickly.