Analisis Petrofisik menggunakan data well logs di cekungan Manui, Sulawesi Tenggara

Abstract

Cekungan Manui adalah cekungan tersier yang dikategorikan sebagai cekungan sedimen dengan indikasi kandungan hidrokarbon. Penelitian ini dilakukan dengan objektif untuk mengevaluasi sifat petrofisika batuan di Cekungan Manui, lepas pantai Sulawesi Tenggara, berdasarkan data log sumuran yang ada pada Sumur Abuki-1. Sifat kuantitatif diantaranya termasuk volume lempung, porositas, dan saturasi air dilakukan menggunakan log sumuran berupa log kaliper, spontaneous potential, sinar gamma, sonic, densitas, neutron, PEF, dan resistivitas. Perhitungan petrofisika lebih lanjut dilakukan pada interval kandidat reservoir yaitu Formasi Langkawola untuk mendapatkan nilai properti statis batuan dan menentukan kandidat reservoir serta prospek. Hasil perhitungan volume lempung menunjukkan bahwa formasi Boepinang memiliki kandungan lempung yang cukup tebal yang mana bisa berfungsi sebagai lapisan tudung untuk reservoir di bawahnya yaitu Formasi Langkawola. Nilai porositas efektif Formasi Langkawola berkisar antara 3-46% dengan rata-rata 19%. Nilai saturasi air Formasi Langkawola berkisar antara 19-76% dengan nilai rata-rata 48%. Setelah pengaplikasian nilai cut-off untuk parameter volume lempung <50%, positas efektif>10%, dan Saturasi air <50%, didapatkan interval reservoir paling prospektif pada kedalaman 6485.5 – 6610 ft dengan nilai rata-rata volume lempung 19%, porositas efektif 26% dan saturasi air 39%.

The Manui Basin is a tertiary basin that is categorized as a sedimentary basin with indications of hydrocarbon. This study was conducted with the objective to evaluate the petrophysical properties of sedimentary rocks in the Manui basin, off the coast of Southeast Sulawesi, based on well log data from the Abuku-1 Well. Quantitative properties including volume of shale, porosity, and water saturation were carried out using well logs data of Caliper, Spontaneous Potential, Gamma Rays, Sonic, Density, Neutron, PEF, and Resistivity. Further petrophysical calculations were carried out at the reservoir candidate interval, the Langkawola Formation to obtain static property values and determine reservoir candidates and prospects. From the volume of shale calculation, Boepinang Formation shows a fairly thick clay content which can serve as a seal for the reservoir below, the Langkawola Formation. The effective porosity value of the Langkawola Formation ranges from 3-46% with an average of 19%. The water saturation value of this interval ranges from 19-76% with an average value of 48%. After applying the cut-off values for the parameters of volume of shale <50%, effective porosity>10%, and water saturation <50%, the most promising reservoir intervals were found at a depth of 6485.5- 6610 ft MD with an average value of 19% volume of shale, effective porosity 26%, and water saturation 39%.