A Revisited: Facies, Diagenetic and Depositional Model of Miocene Kais Carbonate in Matoa Field, Salawati - Kepala Burung Block, Indonesia

Wahyudin, Muhammad¹, Bob Wikan H. Adibrata², Ngakan Alit Ascaria² (1) JOB Pertamina-Petrochina Salawati, Jakarta, Indonesia (2) Pertamina Upstream, PT. Pertamina (Persero), Jakarta, Indonesia

The Miocene Kais carbonates of the Salawati Basin is the one and only prolific reservoir that producing oil and gas since 1936. Thirty oil and gas fields have been discovered and had been producing of 375 MMBO and 175 BCFG through 2002. Phillips Petroleum explored Salawati Island since 1970s and discovered 9 fields. Beginning 1990s, JOB Pertamina-Trend Salawati (later Santa Fe and now PetroChina) continued exploring within the Salawati Island and discovered 6 fields, one of which is the Matoa Field. The Matoa field is located in the Salawati Island and is situated around 70 km southwest of Sorong, Papua Province.

Some new well data combined with 3D seismic data, describe this reservoir more thor­oughly. The carbonate ramp of Kais, compose of platform and reefal facies that consists of Planktonic Foraminifera wackestone, Larger Foraminifera wackestone, Coral floatstone, and Planktonic and Larger Foraminifera wackestone, are deposited as a low relief carbonate mudbank, in the restricted inner shelf-outer shelf area. These depositional models can be divided into early, middle, and last stages that correspond to the tectonic activity in the area.

Facies distribution and diagenetic succession in the Kais are strongly controlled by the depositional stages, which then controlled the porosity development in the Miocene Kais carbonates in the Matoa field.