PEMODELAN LINGKUNGAN PENGENDAPAN 3D PADA RESERVOIR “C” INTERVAL FS-5 – FS-6 , LAPANGAN “CORNEA”, SUB-CEKUNGAN YAMPI SHELF, CEKUNGAN BROWSE, AUSTRALIA UTARA

Maharani Lutfi Pratiwi, Ir. Moch. Indra Novian, S.T., M.Eng., IPP.; Ir. Rahmadi Hidayat, S.T., M.Eng., Ph.D., IPP.

2026 | Skripsi | TEKNIK GEOLOGI

Eksplorasi hidrokarbon di Indonesia Timur semakin difokuskan pada reservoir batupasir berumur Kapur di batuan pra-Tersier, namun keterbatasan data bawah permukaan masih menyebabkan ketidakpastian dalam karakterisasi fasies dan distribusi reservoir. Lapangan Cornea, Sub-Cekungan Yampi Shelf, Cekungan Browse, Australia Utara dipilih sebagai analog geologi karena memiliki evolusi tektono-stratigrafi yang sebanding dengan Indonesia Timur. Penelitian ini bertujuan mengidentifikasi asosiasi fasies dan lingkungan pengendapan, menganalisis distribusi fasies, serta membangun model fasies tiga dimensi Reservoir C Formasi Heywood interval FS-5–FS-6. Penelitian menggunakan data dari 12 sumur berupa wireline log, core, sidewall core, petrografi, dan biostratigrafi (palinologi). Pemodelan fasies dilakukan menggunakan metode Truncated Gaussian Simulation (TGS) dengan Probability Map sebagai trend. Hasil penelitian mengidentifikasi lima asosiasi fasies, yaitu shoreface sand, shoreface heterolitic, lower shoreface heterolitic, offshore transition heterolitic, dan offshore mud, yang membentuk sistem pengendapan shoreface–offshore. Model tiga dimensi menunjukkan perubahan fasies dari daerah landward menuju basinward, dengan fasies berpasir berkembang pada tinggian basement dan bertransisi menjadi fasies heterolitik hingga lumpur ke arah laut yang lebih dalam. Model yang dihasilkan konsisten dengan konsep geologi Reservoir C dan dapat digunakan sebagai analog geologi untuk mendukung interpretasi reservoir batupasir berumur Kapur di Indonesia Timur.

Hydrocarbon exploration in eastern Indonesia has increasingly focused on Cretaceous sandstone reservoirs within pre-Tertiary successions. However, limited subsurface data have resulted in significant uncertainties in facies characterization and reservoir distribution. The Cornea Field, located in the Yampi Shelf Sub-basin of the Browse Basin, northwestern Australia, was selected as a geological analogue because it shares a comparable tectonostratigraphic evolution with eastern Indonesia. This study aims to identify facies associations and depositional environments, analyze facies distribution, and construct a three-dimensional facies model of Reservoir C within the FS-5–FS-6 interval of the Heywood Formation. The study utilized data from 12 wells, including wireline logs, cores, sidewall cores, petrographic analyses, and palynological data. Three-dimensional facies modeling was performed using the Truncated Gaussian Simulation (TGS) method with a Probability Map as the geological trend. The results identified five facies associations, namely shoreface sand, shoreface heterolithic, lower shoreface heterolithic, offshore transition heterolithic, and offshore mud, representing a shoreface–offshore depositional system. The three-dimensional model shows a facies transition from the southeastern landward area toward the northwestern basinward area, where sandy facies developed over basement highs gradually grade into heterolithic and muddy facies in deeper marine settings. The resulting facies model is consistent with the geological concept of Reservoir C and can be used as a geological analogue to support the interpretation of Cretaceous sandstone reservoirs in eastern Indonesia.

Kata Kunci : Reservoir C, Formasi Heywood, asosiasi fasies, Truncated Gaussian Simulation, Probability Map, shoreface–offshore, Cekungan Browse.