NEW EXPLORATION CONCEPT IN SALAWATI BASIN; IDENTIFICATION OF NATURALLY FRACTURED RESERVOIR USING FRACTURE PREDICTION SUPPORTED BY TRIAXIAL ROCK MECHANICS

摘要

Exploration success using current petroleum play in Salawati Basin is declining and getting more , difficult. Therefore, going forward, a new exploration concept is needed. Our latest comprehensive review and data gathering, uncovered a new petroleum play with good potential — a potential play from basement. Major tectonic movement of Sorong Fault on Salawati Island occurred in two episodes. The first one was Late Miocene related to the reactivation of Sorong Fau the fault is normally strike slip as a result of Miocene transtensional forces. The next movement was oriented west to east after the Cretaceous; approximately at transtensional time. The older fault movement is suspected as trigger for fracturing and activation in Late Miocene by the subsequent fault event. From core descriptions of Sal-K wells, the basement is Granit. Presently, the Salawati Basin is bounded to the north by Sorong Fault. Recent structures that developed in Salawati Basin are connected with Sorong Fault tectonism. These developed as associated structures of wrench tectonics. The core data show potential reservoirs not only in the Kais Formation, but also older rocks including Naturally Fractured Reservoir. The aim of this discussion is to give an insight about the possibility of fractured reservoir regarding the tectonic regime and supported by triaxial rock mechanics data from laboratory analyses. From such analyses we learn the pattern and intensity of the fractures that will emerge with geophysical analyses to produce a possible fracture map. The Klasafet and Lower Klasaman shales have been regarded as the source rock from earlier studies (Satyana, 2003). Nonetheless, it is possible that the oil have more than one source. Potential source rocks in the Salawati Basin are the Kais Formation, Sirga Formation and Kembelangan Formation (Satyana, 2003).