📚 Eksplorasi & Komparasi Topik Dokumen

SENSITIVITY ANALYSIS OF C7+ PSEUDO-COMPONENT ACENTRIC FACTOR ON CO? SATURATION, CO? SATURATION DISTRIBUTION, AND RECOVERY FACTOR AS A REPRESENTATION OF CO? MICROBUBBLE INFLUENCE

CO? microbubble injection is an alternative EOR strategy for sub-MMP reservoir conditions; however, commercial reservoir simulators do not yet provide a dedicated mode for this mechanism. This study extends previous work by conducting a sensitivity analysis of the acentric factor of the C7+ pseudocomponent within a three-dimensional proxy reservoir model to evaluate its influence on CO? saturation distribution and recovery factor as a representation of CO? microbubble injection, using an indirect PVT tuning approach in the tNavigator compositional simulator. A 200 × 200 × 30 Cartesian grid model representing depleted reservoir conditions was constructed, and CO? saturation matching was performed against the experimental trends of Xue et al. (2014). Five sensitivity scenarios were evaluated by reducing the C7+ acentric factor by 5%, 10%, 15%, 20%, and 25% from the base matched value. Results showed that reducing the acentric factor consistently increased average CO? saturation, improved CO? saturation distribution along the reservoir, and enhanced oil recovery as represented by the recovery factor. Quadratic polynomial correlations between the acentric factor and recovery factor were established at three injection evaluation points with R² values above 0.97, valid within the range of 0.2625 ? ? ? 0.35. These findings confirm that the acentric factor of the C7+ component is the dominant PVT parameter whose variation significantly influences CO? distribution and oil recovery in the context of CO? microbubble injection representation using the tNavigator simulator

This study evaluates the effect of Land’s Trapping Constant (C) on CO? residual trapping behavior in Field “P”, a depleted oil reservoir in the Bekasap Formation, Central Sumatra Basin, using an existing threedimensional reservoir simulation model. Continuous pure CO? injection was simulated at a rate of 1 MMSCFD for 10 years, followed by 100 years of post-injection monitoring. Sensitivity analysis was conducted by varying Land’s Trapping Constant from ???? = 1 to ???? = 7 to represent low-to-high residual trapping behavior, while ???? = 1, ???? = 3, and ???? = 6 were selected as representative scenarios for CO? plume visualization. The estimated CO? storage capacity of the reservoir model is 1.26 MtCO?, with a total injected CO? mass of 0.19 MtCO? and a storage efficiency of 15.19%, which remain identical for all sensitivity scenarios because these parameters are controlled mainly by pore volume, CO? density, injection rate, injection duration, and pressure constraint. The simulation results show that increasing Land’s Trapping Constant reduces residual trapping performance, as the Residual Trapping Index decreases from 20.71% at ???? = 1 to 5.42% at ???? = 7. In contrast, the Mobile Ratio increases from 6.40% at ???? = 1 to approximately 18.64% at ???? = 7, indicating greater mobile gas persistence at higher C values. The CO? component distribution confirms that the main sensitivity occurs in the gas phase, where residual gas decreases and mobile gas increases as C becomes larger, while CO? in the liquid phases shows smaller variation. Plume visualization further indicates that post-injection plume behavior becomes more distinguishable after 100 years, where lower C values leave a more visible residual saturation trail and provide more favorable storage behavior by reducing mobile CO?. Therefore, Land’s Trapping Constant does not control volumetric storage capacity under the evaluated scenario, but strongly influences residual trapping, mobile gas persistence, and long-term CO? storage security.

PEMODELAN TERINTEGRASI DAN STUDI KOMPARATIF KORELASI KECEPATAN KRITIS LIQUID LOADING UNTUK OPTIMASI CONTINUOUS GAS LIFT GUNA MEMITIGASI LIQUID LOADING PADA RESERVOIR TUA DENGAN LUBANG SUMUR BERARAH

Liquid loading represents a major operational challenge in mature gas field developments, depleting well productivity as natural reservoir pressure declines. This study presents an integrated modeling approach and a comparative analysis of five critical velocity correlations, namely Turner et al., Coleman et al., Nossier et al., Li et al., and Belfroid et al., to optimize continuous gas lift (CGL) design across various deviated wellbore trajectories (0°, 15°, 30°, and 45°). The evaluation reveals that the Nossier et al. correlation establishes the highest critical velocity (vcrit) of 2.29 m/s at the surface, whereas the Li et al. correlation yields the lowest value of 0.75 m/s. Crucially, the determination of the gas lift injection rate is conducted by increasing the superficial gas velocity to exceed the critical liquid loading velocity. CGL sensitivity analysis indicates minimum injection rate requirements of 6,040–6,848 sm³/day (Li et al.), 24,082–36,830 sm³/day (Belfroid et al.), 24,843–25.721 sm³/day (Coleman et al.), 31,746–32.619 sm³/day (Turner et al.), and 38,350–39,204 sm³/day (Nossier et al.). Implementing these rates enhances the total cumulative gas production (production gain) by 1.1040%–1.2570% (Li et al.), 4.3935%–6.7320% (Belfroid et al.), 4.5315%–4.7085% (Coleman et al.), 5.7855%–5.9655% (Turner et al.), and 6.9840%–7.1640% (Nossier et al.).

OPTIMASI PRODUKSI MELALUI PEMODELAN TERINTEGRASI SUMUR ESP DAN JARINGAN FASILITAS PERMUKAAN PADA KLASTER Y DI LAPANGAN X

Many oil fields in Indonesia have entered the mature-field stage, characterized by declining reservoir pressure and increasing water production, making production optimization increasingly critical to meet national hydrocarbon targets. This paper presents a production optimization study conducted in cluster Y of Field X, an offshore production unit located in the Java Sea, consisting of 12 Electrical Submersible Pump (ESP)-lifted production wells connected through an integrated surface network comprising 5 manifolds, 2 gathering stations, and 1 flare gas system. Well performance models were constructed for all producing wells using the Inflow Performance Relationship (IPR) based on the Vogel correlation. Sensitivity analysis on tubing inner diameter was conducted to address uncertainties in actual tubing conditions, yielding a history-matched model with a coefficient of determination (R²) of 0.9986 against actual field production data. A quadrant mapping approach is introduced in this study, utilizing the ratio of actual production rate to Absolute Open Flow Potential (Q/AOFP) and ESP pump efficiency as evaluation parameters, to assess well production potential and pump performance conditions. This approach enables systematic identification of wells requiring further evaluation, prioritization of optimization candidates, and performance comparison before and after optimization. Integrated surface network simulation model was subsequently used as the basis for production network optimization. The optimization was performed using a production system simulation software, which internally employs a Mixed Integer Nonlinear Programming (MINLP) formulation solved via the BONMIN framework, with ESP operating frequency as the continuous variable and well operational status as the integer variable. The optimization was conducted subject to a maximum total ESP power consumption of 550 hp and a maximum field water handling capacity of 4,450 BPD. The optimization results demonstrate that total oil production in cluster Y of Field X increased by 26.56%, from 1,649 BOPD to 2,108 BOPD, while total water production simultaneously decreased by 10.0%, from 4,329 BPD to 3,936 BPD, without violating any established operational constraints and without requiring well intervention. These simultaneous improvements in oil and water production highlight the effectiveness of field-wide network optimization in redistributing ESP operating conditions across all wells within the integrated production system. Quadrant mapping further confirmed and quantified this improvement, demonstrating its capability to systematically evaluate well performance, identify wells requiring further attention, and capture the shift in operating conditions before and after optimization, with wells in the least favorable performance category reduced from six to two. These results demonstrate that the combination of quadrant mapping as a well performance evaluation tool and field-wide network optimization through integrated production system simulation constitutes an effective and operationally practical framework for production enhancement in mature offshore fields operating under power and water handling constraints.

EVALUASI PARAMETER DESAIN REKAHAN TERHADAP PRODUKTIVITAS RESERVOIR: STUDI KORELASI ANTARA SRV DAN VOLUME DRAINASE TRANSIEN TEKANAN DALAM SIMULASI RESERVOIR NON-KONVENSIONAL

Unconventional tight oil reservoirs are characterized by ultra-low permeability, making multi-stage hydraulic fracturing (MSHF) essential to achieve commercial hydrocarbon production. The effectiveness of MSHF is governed by fracture design parameters that control the extent of Stimulated Reservoir Volume (SRV). However, geometric SRV estimation does not always represent the dynamically drained reservoir volume contributing to production. Therefore, this study evaluates the influence of hydraulic fracturing design parameters on reservoir productivity and develops a correlation between geometric SRV and dynamic Drainage Volume (DV). A three-dimensional synthetic tight oil reservoir model was developed using the CMG IMEX black-oil simulator. Hydraulic fractures were represented using a single-porosity model with Local Grid Refinement (LGR). Sensitivity analyses were conducted by varying fracture stages and fracture half-length over a 20-year production period under constant-rate conditions. Dynamic DV was determined through pressure drawdown analysis during pseudo-steady-state flow. The study established an empirical relationship between DV and SRV with an R2 value of 0.8775 The techno- economic assessment also demonstrated that increasing fracture dimensions beyond the optimum design produces diminishing economic returns because of substantially higher capital expenditures (CAPEX). The highest Pre-Tax Net Present Value (NPV), amounting to USD 9,995,763.75, was obtained using a configuration of 17 fracture stages with a 500-ft fracture half-length. Increasing the fracture half-length beyond 500 ft reduced the NPV, indicating that this configuration represents the economic optimum for the evaluated reservoir.

MODEL PEMBIAYAAN KPR SYARIAH MENGGUNAKAN AKAD MURABAHAH DAN MUSYARAKAH MUTANAQISAH NISBAH PROPORSIONAL

Pembiayaan Kredit Pemilikan Rumah (KPR) syariah merupakan salah satu alternatif pembiayaan yang menerapkan prinsip syariah melalui akad jual beli maupun kemitraan. Dalam praktiknya, kemampuan nasabah dalam membayar angsuran dipengaruhi oleh fluktuasi pengh asilan sehingga diperlukan suatu model matematis yang dapat menggambarkan mekanisme pembiayaan dengan mempertimbangkan ketidakpastian tersebut. Penelitian ini bertujuan membangun model pembiayaan KPR syariah menggunakan akad Murabahah dan Musyarakah Mutanaqisah (MMQ) berbasis nisbah proporsional, membandingkan karakteristik kedua model, serta menganalisis pengaruh rata - rata pertumbuhan penghasilan dan volatilitas penghasilan terhadap hasil pembiayaan. Penghasilan nasabah dimodelkan menggunakan Geometric Brownian Motion (GBM), sedangkan analisis sensivitas dilakukan dengan metode Monte Carlo. Perbandingan imbal hasil pada pembiayaan dengan periode yang berbeda dilakukan menggunakan Holding Period Return (HPR). Hasil penelitian menunjukkan bahwa model Murabahah menghasilkan imbal hasil Bank Syariah sebesar 4,40% dan indikator kesejahteraan nasabah sebesar 34,09%, sedangkan model MMQ berbasis nisbah proporsional menghasilkan imbal hasil Bank Syariah sebesar 11,39% dan indikator kesejahteraan nasabah sebesar 53,00 %. Pada kondisi volatilitas penghasilan yang lebih tinggi ( ???? = 0 , 65 ) , model MMQ tetap mampu mengarahkan perpindahan kepemilikan rumah kepada nasabah dengan masa pembiayaan selama 187 bulan, menghasilkan imbal hasil Bank Syariah sebesar 10,92% dan indikator kesejahteraan nasabah sebesar 41,59%. Hasil analisis sensitivitas me nunjukkan bahwa peningkatan rata - rata pertumbuhan penghasilan ( ???? ) meningkatkan imbal hasil Bank Syariah dan indikator kesejahteraan nasabah, sedangkan peningkatan volatilitas penghasilan ( ???? ) meningkatkan risiko pembiayaan, memperbesar kemungkinan pembentukan utang, serta memperlambat proses perpindahan kepemilikan rumah. Secara keseluruhan, model MMQ berbasis nisbah proporsional memberikan kinerja yang lebih baik dibandingkan model Murabahah maupun KPR konvensional.

PEMODELAN MATEMATIKA PENYEBARAN HIV/AIDS DENGAN MODEL KOMPARTEMEN MULTI-POPULASI BERDASARKAN KELOMPOK RISIKO DI KOTA BANDUNG

HIV/AIDS merupakan salah satu permasalahan kesehatan masyarakat di Kota Bandung dengan jumlah kasus yang terus ditemukan setiap tahunnya. Penelitian ini bertujuan memformulasikan model matematika penyebaran HIV menggunakan pendekatan kompartemen ????????????????????????????, menganalisis dinamika model secara matematis, mengestimasi parameter model berdasarkan data epidemiologi Kota Bandung, serta mengevaluasi strategi pengendalian HIV melalui simulasi numerik dan analisis sensitivitas. Model yang dikembangkan mempertimbangkan faktor media awareness, transmisi vertikal, treatment saturation, serta perbedaan tingkat infektivitas pada kompartemen terinfeksi. Pendekatan multi-populasi diterapkan melalui estimasi parameter transmisi pada kelompok risiko dominan, yaitu Bumil, LSL, dan TB. Estimasi parameter dilakukan menggunakan data kasus HIV Kota Bandung periode Januari 2014 hingga Oktober 2024 dengan beberapa skenario estimasi, dan berdasarkan evaluasi kecocokan model dipilih skenario estimasi dua parameter, yaitu parameter transmisi dasar (????) dan parameter diagnosis (????), sebagai model terbaik. Hasil analisis menunjukkan adanya titik ekuilibrium bebas penyakit dan titik ekuilibrium endemik dengan nilai bilangan reproduksi dasar sebesar ????0=3,1281. Oleh karena itu, titik ekuilibrium bebas penyakit bersifat tidak stabil, sedangkan titik ekuilibrium endemik stabil asimtotik lokal, sehingga penyakit berpotensi bertahan dalam populasi. Simulasi numerik menunjukkan bahwa model mampu merepresentasikan dinamika penyebaran HIV berdasarkan data observasi, sedangkan analisis sensitivitas menunjukkan bahwa parameter laju transmisi memberikan pengaruh terbesar terhadap dinamika model. Berdasarkan hasil penelitian, strategi pengendalian HIV yang efektif meliputi percepatan deteksi dini, peningkatan akses dan keberlangsungan terapi antiretroviral (ART), pencegahan progresi menuju AIDS, serta penurunan laju transmisi melalui peningkatan media awareness dan pengurangan tingkat infektivitas individu terinfeksi. Model yang dikembangkan diharapkan dapat menjadi salah satu alat bantu dalam memahami dinamika penyebaran HIV di Kota Bandung serta mendukung perumusan kebijakan pengendalian HIV berbasis pendekatan matematis.

PENERAPAN METODE AGGREGATE COST BERBASIS MULTIPLE DECREMENT DALAM PERHITUNGAN KEWAJIBAN DAN PENDANAAN DANA PENSIUN

Program pensiun merupakan bentuk perlindungan finansial bagi karyawan setelah memasuki masa pensiun. Dalam program pensiun manfaat pasti, pemberi kerja perlu memastikan bahwa dana yang tersedia mampu memenuhi kewajiban pembayaran manfaat di masa mendatang. Perhitungan kewajiban dana pensiun menggunakan metode Aggregate Cost (AGG) berbasis model multiple decrement (MD) empat penyebab keluar, yaitu: pensiun normal, kematian, disabilitas, dan pengunduran diri. Sebagai studi kasus, digunakan data peserta aktif Perusahaan ABC per 1 Januari 2025 dengan periode proyeksi 30 tahun. Hasil perhitungan menunjukkan Normal Cost Rate (NCR) awal sebesar 13,20% yang menurun secara konsisten hingga 6,77% pada tahun ke-28. Penurunan ini disebabkan oleh akumulasi kontribusi, pertumbuhan imbal hasil investasi, dan berkurangnya jumlah peserta aktif. Proyeksi pembayaran manfaat menunjukkan pola yang relatif datar dan berfluktuasi tanpa puncak tunggal yang dominan, mencerminkan distribusi usia peserta yang merata. Analisis sensitivitas menunjukkan perubahan tingkat diskonto dan pemilihan tabel mortalitas memengaruhi pola NCR secara berpotongan antar skenario, sedangkan perubahan asumsi kenaikan gaji menghasilkan pola yang konsisten, yaitu kenaikan gaji yang lebih tinggi menghasilkan NCR yang lebih tinggi, sedangkan kenaikan gaji yang lebih rendah menghasilkan NCR yang lebih rendah.

CORE TO FIELD-SCALE NUMERICAL SIMULATION STUDY OF SP FLOODING: SENSITIVITY PARAMETER FOR OPTIMIZING THE INJECTION STRATEGY IN WAXY OIL RESERVOIR

The Ministry of Energy and Mineral Resources (ESDM) has set a production target of 1 million BOPD by 2030. However, many fields have experienced a drastic decline and have matured, making this production target challenging. The application of Chemical Enhanced Oil Recovery (EOR) in waxy oil reservoirs has the potential to support this commitment. Laboratory studies through coreflooding experiments have been conducted previously. The study results successfully demonstrated that surfactant polymer flooding can increase oil recovery by 27.47% compared to waterflooding. This study aims to predict the effectiveness of applying surfactant polymer flooding using numerical simulation with CMG-STARS at the field scale, determine the optimal injection strategy through sensitivity analysis of key injection parameters, and evaluate its streamline form. This study began with calibrating the core model with laboratory test results. The core model was then recalibrated through a connecting model. Field-scale simulations used a conceptual model with a 5-Spot well pattern. Numerical simulation results showed that the increase in oil recovery through surfactant polymer flooding decreased to 7.55%. This result is due to the level of heterogeneity at the field scale. Through the determined injection strategy, the increase in oil recovery can be optimized to 12.27%.

PENENTUAN LOKASI DAN KAPASITAS TERMINALTERMINAL BBM DI PROVINSI SULAWESI UTARA MENGGUNAKAN PEMROGRAMAN LINIER

PT X merupakan penyedia BBM utama di Indonesia dengan pangsa pasar 87% sehingga keandalannya dalam mendistribusikan BBM menjadi krusial. Salah satu terminal BBM PT X yang berlokasi di Bitung mengalami kendala operasional, ditandai dengan tingkat berth occupancy ratio jetty yang melebihi 70% serta keterbatasan kapasitas tangki yang menyebabkan stok BBM di bawah standar ideal PT X. Keterbatasan lahan di sekitar terminal tersebut menghambat upaya peningkatan kapasitas terminal. Selain itu, permasalahan terkait status kepemilikan lahan menimbulkan potensi biaya tambahan sebesar 300 miliar rupiah apabila terminal tetap digunakan. Mengingat terminal ini merupakan satu-satunya yang beroperasi di Sulawesi Utara, permasalahan ini perlu diselesaikan secara strategis. Penelitian ini bertujuan untuk merancang konfigurasi jaringan rantai pasok BBM di Sulawesi Utara yang optimal. Dengan menggunakan pendekatan pemrograman linier, dikembangkan model optimasi untuk menentukan lokasi, kapasitas, dan skema operasional terminalterminal BBM di Sulawesi Utara. Tujuan model adalah meminimasi total biaya rantai pasok selama 20 tahun yang mencakup biaya suplai, biaya backloading, biaya distribusi, biaya handling & storage¸ serta biaya investasi pembangunan terminal. Model mempertimbangkan batasan fisik, seperti kapasitas jetty, tangki, dan lahan serta batasan operasional lainnya. Hasil penelitian memperlihatkan bahwa PT X sebaiknya tetap mengoperasikan terminal eksisting di Bitung dan membangun dua terminal baru di Amurang dan Pantai RCTI. Dengan mengimplementasikan solusi tersebut, PT X memperoleh penghematan biaya dalam bentuk present value sebesar 8,98% dibandingkan kondisi eksisting. Melalui analisis sensitivitas, terbukti bahwa keputusan pembangunan terminal tetap konsisten walaupun terdapat ketidakpastian permintaan di masa depan.

SEEKING THE INFLUENCING PARAMETERS ON CO2-EOR PROJECTS THROUGH SENSITIVITY ANALYSIS USING DESIGN OF EXPERIMENT

With many of Indonesia's oil fields reaching a mature stage, Enhanced Oil Recovery (EOR) methods are critical for maximizing national hydrocarbon production. This study evaluates the potential of CO? injection in three distinct Indonesian oil fields: Field X (carbonate), Field Y (sandstone-fluvial), and Field Z (sandstone-deltaic) using the CO?PM predictive model within the EORgui software. The research aims to identify the most influential reservoir and production parameters on recovery, compare performance across different geological settings, and develop a statistical model to quantify these relationships. A Two-Level Full Factorial Design of Experiments (DoE) was conducted for each field, and the results were analyzed using Pareto Charts and residual analysis. The findings consistently show that volumetric parameters specifically Pattern Area, Porosity, and Thickness with their interactions are the most statistically significant factors controlling cumulative oil production (Np), regardless of the depositional environment. While the DoE was successful in screening and ranking these key drivers, the resulting linear regression models exhibited non-normal residuals and non-constant variance, indicating that a more advanced model, such as one developed through Response Surface Methodology (RSM), is required for precise quantitative prediction.

STRATEGI PENENTUAN PARAMETER FISKAL PADA KEEKONOMIAN CCS DI INDONESIA: STUDI KASUS INTEGRASI PENGEMBANGAN LAPANGAN MINYAK DAN GAS DENGAN KADAR CO? TINGGI

Peningkatan emisi karbon dioksida (CO?) telah mendorong adopsi teknologi Carbon Capture and Storage (CCS) sebagai bagian dari strategi Net Zero Emission (NZE) pada tahun 2060. Namun, tantangan terbesar dalam implementasi CCS terletak pada aspek keekonomian dan kerangka fiskal yang belum sepenuhnya mendukung daya tarik investasi. Penelitian ini bertujuan untuk mengevaluasi dan mengoptimalkan parameter fiskal yang berpengaruh terhadap kelayakan ekonomi proyek CCS, khususnya pada kasus yang terintegrasi dengan pengembangan lapangan minyak dan gas dengan kandungan CO? tinggi. Studi kasus dilakukan pada Struktur X di wilayah lepas pantai Indonesia dengan kandungan CO? sekitar 45%. Data hasil evaluasi teknis menunjukkan kelayakan injeksi CO? melalui simulasi reservoir dan desain fasilitas permukaan yang terintegrasi. Simulasi menunjukkan bahwa reservoir mampu memproduksikan minyak dan gas dengan baik selama durasi proyek serta menyimpan CO? dalam jangka panjang dengan mekanisme residual trapping dan kumulatif injeksi sebesar 671 BSCF (34,99 juta ton CO?). Fasilitas pemrosesan dan injeksi dirancang untuk menangani pemisahan, kompresi, dan injeksi tanpa mengganggu operasi produksi hidrokarbon. Evaluasi keekonomian dilakukan berdasarkan model Production Sharing Contract (PSC) Cost Recovery yang disesuaikan dengan Peraturan Menteri ESDM No. 16 Tahun 2024 tentang kegiatan penyimpanan karbon. Pada skenario dasar, proyek menghasilkan IRR sebesar 10,66%, NPV sebesar US$ 36,02 juta, dan POT selama 15.62 tahun, yang belum memenuhi ambang kelayakan dengan asumsi MARR 15%. Hasil analisis sensitivitas terhadap delapan parameter fiskal, yaitu investment credit (IC), first tranche petroleum (FTP), contractor split (untuk minyak dan gas), CCS service fee, efisiensi capital expenditure (CAPEX), royalti, dan pajak menunjukkan bahwa parameter CCS service fee dan pajak merupakan variabel paling sensitif terhadap IRR. Strategi parameter fiskal kemudian disusun menggunakan metode DoE two-level full factorial design untuk mencari kombinasi insentif yang mampu meningkatkan IRR hingga ambang kelayakan sebesar 15%. Hasilnya menunjukkan bahwa IRR sebesar 15% dapat dicapai jika ditetapkan CCS service fee sebesar US$ 50/ton dan storage fee sebesar US$ 30/ton. Alternatif lainnya adalah kombinasi antara peningkatan contractor split, efisiensi CAPEX, dan pemberian investment credit sebesar 15%. Hasil ini menegaskan pentingnya dukungan fiskal dan fleksibilitas kontraktual dalam menarik investasi CCS, khususnya di lapangan migas yang memiliki berbagai tantangan. Penelitian ini memberikan kontribusi dalam pengembangan model evaluasi ekonomi CCS berbasis PSC serta menawarkan strategi fiskal yang aplikatif bagi pembuat kebijakan dan industri. Pendekatan ini dapat menjadi referensi dalam penyusunan insentif fiskal yang adaptif untuk mempercepat implementasi CCS di Indonesia.

IMPLEMENTASI KONTROL OPTIMUM PADA MODEL DINAMIKA PERBANKAN BERDASARKAN SISTEM PERSAMAAN DIFERENSIAL DETERMINISTIK

Bank umum menjalankan fungsinya dengan mengumpulkan dana dari nasabahnya yang disebut sebagai dana pihak ketiga (DPK) dan menyalurkannya kembali dalam bentuk kredit. Penyaluran kredit untuk memperoleh keuntungan menimbulkan risiko dalam bentuk kredit macet atau non performing loan (NPL), sehingga bank perlu mengatur strategi penyaluran kredit untuk meminimalkan kerugian akibat NPL. Model matematika berdasarkan sistem persamaan diferensial diskrit dapat digunakan untuk memodelkan interaksi antar komponen bank. Digunakan model perbankan berdasarkan tesis Aqsha (2022) dan tesis Jayadi (2024) yang memodelkan komponen DPK, kredit, dan ekuitas sebagai sistem persamaan diferensial diskrit. Dilakukan modifikasi dengan menambahkan persamaan komponen NPL dan mengubah persamaan komponen DPK, kredit, dan ekuitas. Variabel kontrol diterapkan pada model perbankan yang digunakan untuk mengontrol NPL menuju nilai yang ditargetkan. Metode numerik digunakan untuk memperoleh kontrol optimum, antara lain optimisasi spiral untuk estimasi nilai parameter model berdasarkan data laporan keuangan PT Bank Rakyat Indonesia Tbk. (Persero) pada periode Januari 2014 hingga Desember 2023, metode Runge-Kutta untuk menghitung nilai masing-masing komponen model, dan metode forward backward sweep untuk menentukan nilai kontrol optimum. Beberapa parameter model diubah untuk mensimulasikan kondisi yang tidak ideal bagi bank, dan nilai kontrol optimum dihitung berdasarkan penyesuaian. Setelah diperoleh nilai kontrol optimum, dilakukan penyesuaian untuk mengetahui efek bobot kontrol dan dilakukan analisis sensitivitas terhadap nilai maksimal variabel kontrol. Dengan pemilihan parameter awal yang tepat pada bobot kontrol dan bobot nilai target yang telah ditentukan, penggunaan variabel kontrol berhasil membawa NPL menuju nilai yang ditargetkan.

ANALISIS SENSITIVITAS DAN KETIDAKPASTIAN PARAMETER YANG MEMPENGARUHI KAPASITAS PENYIMPANAN CO? PADA SALINE AQUIFER DAN DEPLETED RESERVOIR DI INDONESIA MENGGUNAKAN DESIGN OF EXPERIMENT

Global climate change, driven by rising CO? emissions, poses a serious threat to Earth's sustainability, with impacts already being felt in Indonesia through more frequent natural disasters. As a major CO? emitter, Indonesia is crucial in global climate mitigation efforts. Carbon Capture and Storage (CCS) offers a solution by capturing CO? from emission sources and storing it in geological formations such as saline aquifers and depleted reservoirs. This study aims to estimate CO? storage capacity in Indonesia’s oil and gas fields, focusing on saline aquifers and depleted reservoirs. Key geological parameters—formation area, thickness, porosity, CO? density, and depth—are analyzed using the Design of Experiments (DoE) approach, specifically Response Surface Methodology (RSM) with Central Composite Design (CCD). Data from LEMIGAS, previously used for CO? storage capacity calculations, were used for recalculations and further analysis. Results show slight variations from LEMIGAS’ original estimates, likely due to different assumptions or methods. The study finds significant CO? storage potential in Indonesia, with saline aquifers having a capacity of 572.768 gigatons and depleted reservoirs holding 7.041 gigatons across 20 basins. The analysis identifies optimal storage zones based on larger formation areas, greater thickness, and deeper depths, with formation area, thickness, and depth having the greatest impact. The interactions between parameters are key to effective CCS strategies. The study also highlights uncertainties in capacity estimates and experimental design, offering recommendations for improving data resolution and model accuracy. These findings provide valuable insights for developing CCS and CCUS strategies to support Indonesia’s emission reduction goals.

REDESAIN PERLAKUAN HYDRAULIC FRACTURING BERDASARKAN SENSITIVITAS PADA RESERVOIR KARBONAT LEPAS PANTAI BERPERMEABILITAS RENDAH

XX-16 is an offshore oil production well located in the YY Field, East Java, Indonesia, targeting the Tuban carbonate formation. The well was previously drilled and completed as a water injection well in December 2012 and was later converted into a production well through a workover in early November 2017. Post-conversion testing indicated low oil production from the Tuban Carbonate intervals. Acidizing stimulation was previously performed; however, the response was insignificant due to silica and clay minerals domination from XRD analysis. Subsequently, hydraulic fracturing was implemented as an alternative stimulation method, however still resulting low productivity index remained which largely suspected by the cause of overestimated permeability in the initial design. This study aims to address the limitations of the previous stimulation attempts by evaluating and redesigning the hydraulic fracturing treatment for XX-16. This study involves sensitivity on selecting fracturing fluid and proppant to achieve optimum performance based on the Productivity Index (PI). The permeability sensitivity is performed to make sure the design is safe and remains applicable to the permeability uncertainties. Additionally, drainage area sensitivity is also performed to indicate its influence on the productivity index on the best scenario. As a result, the redesign shows significant improvement by the Productivity Index of 0.975 and Fold of Increase (FOI) of 3.8.