Integrasi Evaluasi Petrofisika, Pore Pressure Gradient, Dan Mechanical Stratigraphy Untuk Klasifikasi Zona Kestabilan Pada Sumur “Syb” Pada Formasi Telisa Dengan Log Stress To Strength Ratio Sebagai IndikatorKestabilan Formasi

Basalamah, Muammar (2026) Integrasi Evaluasi Petrofisika, Pore Pressure Gradient, Dan Mechanical Stratigraphy Untuk Klasifikasi Zona Kestabilan Pada Sumur “Syb” Pada Formasi Telisa Dengan Log Stress To Strength Ratio Sebagai IndikatorKestabilan Formasi. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Formasi Telisa pada Cekungan Sumatra Selatan memiliki karakteristik litologi sand–shale interbedded sequence yang menyebabkan variasi sifat petrofisika, tekanan pori, dan geomekanika batuan. Kondisi tersebut dapat memengaruhi kestabilan dinding sumur, terutama pada interval reservoir yang memiliki sisipan shale. Penelitian ini dilakukan pada Sumur “SYB” dengan tujuan mengevaluasi karakteristik petrofisika, pore pressure gradient, dan mechanical stratigraphy untuk menentukan klasifikasi zona kestabilan sumur berbasis Stress to Strength Ratio (SSR). Data yang digunakan meliputi log Gamma Ray, Density, Sonic, Shear Sonic, Resistivity, serta parameter turunan berupa Vsh, porositas, saturasi air, permeabilitas, tekanan pori, tegangan in-situ, parameter elastik batuan, UCS, dan SSR. Analisis petrofisika menunjukkan bahwa interval reservoir dicirikan oleh nilai Gamma Ray relatif rendah, porositas efektif yang cukup baik, saturasi air rendah, serta resistivitas yang meningkat. Berdasarkan hasil cutoff, interval pay zone utama berada pada kedalaman 4522–4540 ft dengan net pay sebesar 13,50 ft. Namun, interval tersebut masih menunjukkan heterogenitas akibat adanya sisipan shale tipis yang dapat memengaruhi kualitas reservoir dan kestabilan mekanik. Analisis tekanan dan geomekanika menunjukkan bahwa variasi pore pressure, Shmin, Young’s Modulus, Poisson’s Ratio, dan UCS berpengaruh terhadap perubahan kestabilan batuan. Evaluasi menggunakan SSR menunjukkan bahwa interval pay zone dominan berada pada nilai 0,55–0,75 dan secara lokal mendekati 0,8–0,85, sehingga dikategorikan sebagai zona semi-stabil dengan margin keamanan terbatas. Hasil integrasi Mechanical Earth Model menunjukkan bahwa variasi SSR berkaitan dengan perubahan sifat elastik, tekanan pori, dan tegangan pada interval reservoir. Dengan demikian, interval 4522–4540 ft layak secara petrofisika sebagai pay zone, tetapi tetap memerlukan perhatian terhadap manajemen tekanan dan kestabilan sumur. SSR terbukti dapat digunakan sebagai parameter sederhana dan aplikatif untuk mengevaluasi kestabilan sumur pada Formasi Telisa
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The Telisa Formation in the South Sumatra Basin is characterized by a sand–shale interbedded sequence, which causes vertical variations in petrophysical properties, pore pressure, and rock geomechanical characteristics. These conditions may affect wellbore stability, particularly within reservoir intervals containing thin shale interbeds. This study was conducted in Well “SYB” to evaluate petrophysical characteristics, pore pressure gradient, and mechanical stratigraphy in order to classify wellbore stability zones using the Stress to Strength Ratio (SSR). The data used in this study include Gamma Ray, Density, Sonic, Shear Sonic, and Resistivity logs, as well as derived parameters such as Vsh, porosity, water saturation, permeability, pore pressure, in-situ stress, elastic rock properties, UCS, and SSR. Petrophysical analysis shows that the reservoir interval is characterized by relatively low Gamma Ray values, good effective porosity, low water saturation, and increased resistivity. Based on cutoff analysis, the main pay zone is identified at a depth interval of 4522–4540 ft, with a net pay thickness of 13.50 ft. However, this interval still shows heterogeneity due to the presence of thin shale interbeds, which may affect reservoir quality and mechanical stability. Pressure and geomechanical analyses indicate that variations in pore pressure, Shmin, Young’s Modulus, Poisson’s Ratio, and UCS influence changes in rock stability. The SSR evaluation shows that the pay zone interval is dominantly within the range of 0.55–0.75 and locally approaches 0.8–0.85, indicating a semi-stable zone with a limited safety margin. The integration of the Mechanical Earth Model shows that SSR variation is related to changes in elastic properties, pore pressure, and stress within the reservoir interval. Therefore, the interval of 4522–4540 ft is petrophysically feasible as a pay zone, but still requires attention to pressure management and wellbore stability. SSR is proven to be a simple and applicable parameter for evaluating wellbore stability in the Telisa Formation

Item Type:	Thesis (Other)
Uncontrolled Keywords:	Formasi Telisa, petrofisika, tekanan pori, geomekanika, Stress to Strength Ratio, kestabilan sumur, Telisa Formation, petrophysics, pore pressure, geomechanics, wellbore stability
Subjects:	T Technology > TA Engineering (General). Civil engineering (General) > TA749 Soil stabilization
Divisions:	Faculty of Civil, Planning, and Geo Engineering (CIVPLAN) > Geophysics Engineering > 33201-(S1) Undergraduate Thesis
Depositing User:	Muammar Basalamah
Date Deposited:	24 Jul 2026 16:08
Last Modified:	24 Jul 2026 16:08
URI:	http://repository.its.ac.id/id/eprint/137472

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