Jurnal Geosaintek, Vol. 6 No. 1 Tahun 2020. 25-32. p-ISSN: 2460-9072, e-ISSN: 2502-3659 Artikel diterima 29 Januari 2020, Revisi 09 April 2020. Online 15 April 2020 http://dx.doi.org/10.12962/j25023659.v6i1.6501 25 INTEGRATED LAMINATED SHALY SAND ANALYSIS (LSSA) AND MONTE CARLO UNCERTAINTY PROBABILISTIC APPLIED FOR THE THIN LAMINATION RESERVOIR TOWARDS SIGNIFICANT NET PAY ADDITION Frankstein Arphan 1 , Adi Gunawan 1 , Wien Lestari 2 , Widya Utama 2 1 Exploration Department, Pertamina Hulu Energi 2 Geophysical Engineering Department, Faculty of Civil, Planning and Earth Sciences, Insititut Teknologi Sepuluh Nopember e-mail : Franksteinarphan97@gmail.com Abstrak. Dalam beberapa tahun terakhir, evaluasi formasi dan analisis logging sumur telah berkembang dari pengukuran, akurasi dan penerapannya untuk menentukan kondisi bawah permukaan yang kompleks. Thin Bed Reservoir adalah salah satu analisis pemboran sumur yang kompleks dikarenakan kompleksitas kandungan tinggi mineral lempung dalam lapisan laminasi shaly-sand yang secara inheren mempengaruhi respons data log dalam bentuk nilai sinar gamma tinggi dan resistivitas rendah. Hal ini menyebabkan zona laminasi tipis sering diidentifikasi sebagai zona non-reservoir. Sementara itu, 30 - 40% cadangan sumber daya minyak berasal dari lapisan thin bed reservoir. Melihat permasalahan dalam mendapatkan parameter petrofisika thin bed reservoir, penelitian ini berfokus pada pengoptimalan potensi lapisan tipis dengan mengevaluasi kembali analisis petrofisika, menerapkan metode Laminated Shally Sand Analysis dan Monte Carlo Uncertainty untuk menghitung distribusi parameter petrofisika dan memvalidasi parameter dengan Log Image. Metode laminated Shally Sand Analysis menerapkan Thomas Steiber Plot untuk memberikan distribusi serpihan dan porositas laminasi, sedangkan saturasi air dihitung menggunakan Persamaan Waxman Smith. Dari penelitian ini, sumur SSK memiliki potensi lapisan tipis pada 2521.45 - 2543.45 ft. Laminated Shally Sand Analysis juga mampu meningkatkan ketebalan netpay dengan kisaran 40,35% berdasarkan probabilitas Monte Carlo. Kata Kunci: Laminated Shally Sand Analysis; Monte Carlo Uncertainty; Thin Bed Reservoir Abstract. In recent years, formation evaluation and well logging analysis have been evolving from its measurements, accuracy and applicability to determine tough downhole environments. Thin bed Reservoir is one of the most challenging well logging analysis due to the complexity of the high content of clay minerals in the shaly-sand lamination layer (thin bed) which inherently affects the log data response in the form of high gamma ray values and low resistivity. This causes the thin lamination zone is identified as a non-reservoir zone. Meanwhile, worldwide 30 to 40% of the oil in-place resources are confined within thin beds. Seeing the problem in the prediction of thin bed reservoirs, this research is focusing on Enhancing and developing thin bed potential by reevaluating petrophysical analysis, applying Laminated Shally Sand Analysis and Monte Carlo Uncertainty Probabilistic for calculating petrophysical parameter distribution and validating the parameter with Log Image. Laminated Shally Sand Analysis implements Thomas Steiber Plot in order to give laminated shale distribution and porosity, whereas the water saturation is calculated using Waxman Smith’s Equation. From this research, well SSK has thin bed potential at 2521.45 - 2543.45 ft. Laminated Shally Sand Analysis also capable to improve thickness of netpay with the range of 40.35% based on probabilistic delivered from Monte Carlo. Keywords: Laminated Shally Sand Analysis; Monte Carlo Uncertainty; Thin Bed Reservoir INTRODUCTION To find out the existence of petroleum, it is necessary to analyze the layer of the earth using Well logging. Well logging is the process of recording various physical, chemical, electrical, or other properties of the rock/fluid mixtures penetrated by drilling a borehole into the earth. Log data is used for qualitative and quantitative analysis and it give us information about rock formations in wells and the amount of petroleum reserves that can be obtained (Abdullatif dan Abdulraheem, 2013). brought to you by CORE View metadata, citation and similar papers at core.ac.uk provided by Center for Scientific Publication