📚 Eksplorasi & Komparasi Topik Dokumen

OPTIMALISASI HIDROGENOLISIS GLISEROL UNTUK SINTESIS BIO-PG (1,2-PROPILEN GLIKOL) MELALUI RUTE DEHIDRASI-HIDROGENASI MENGGUNAKAN KATALIS CU-NI/???? ? ????????2????3

Meningkatnya produksi biodiesel di Indonesia menyebabkan ketersediaan gliserol sebagai produk samping semakin melimpah, sementara nilai ekonominya terus mengalami penurunan. Di sisi lain, kebutuhan propilen glikol (PG) nasional masih didominasi oleh produk impor sehingga diperlukan upaya hilirisasi gliserol menjadi produk bernilai tambah. Salah satu alternatif yang menjanjikan adalah sintesis bio-propilen glikol (bio-PG) dari gliserol. Penelitian ini bertujuan untuk mengevaluasi pengaruh variasi komposisi logam Cu-Ni terhadap karakteristik fisikokimia katalis Cu-Ni/?-Al?O? serta kinerjanya dalam sintesis bio-propilen glikol. Katalis disintesis menggunakan metode impregnasi kering dengan variasi komposisi logam Cu dan Ni pada penyangga ?-Al?O?. Karakterisasi katalis dilakukan menggunakan metode X-Ray Fluorescence (XRF), X-Ray Diffraction (XRD), Brunauer-Emmett-Teller (BET), dan Scanning Electron Microscope (SEM). Reaksi hidrogenolisis dilakukan di dalam reaktor batch menggunakan larutan gliserol 20 wt% pada temperatur 180°C dan tekanan 4,5 MPa. Produk reaksi dianalisis menggunakan High Performance Liquid Chromatography (HPLC), sedangkan performa katalis dievaluasi berdasarkan konversi gliserol, selektivitas propilen glikol, dan perolehan propilen glikol. Hasil penelitian menunjukkan bahwa variasi komposisi logam Cu-Ni memberikan pengaruh terhadap karakteristik katalis dan aktivitas hidrogenolisis gliserol. Konversi gliserol tertinggi diperoleh pada katalis C sebesar 63,48%, sedangkan perolehan propilen glikol tertinggi dicapai oleh katalis B dengan konversi gliserol sebesar 43,14%, selektivitas sebesar 63,42%, dan perolehan propilen glikol sebesar 27,36%. Hasil tersebut menunjukkan bahwa perolehan propilen glikol dipengaruhi oleh keseimbangan antara konversi gliserol dan selektivitas produk, sehingga konversi yang tinggi tidak selalu menghasilkan perolehan propilen glikol yang optimum.

PERANCANGAN SISTEM WASTE HEAT RECOVERY UNTUK PEMANFAATAN GAS BUANG PLTU BIOMASSA PADA PABRIK KELAPA SAWIT

Pembangkit listrik tenaga uap (PLTU) berbahan bakar biomassa pada pabrik kelapa sawit (PKS) umumnya melepaskan gas buang bertemperatur tinggi ke atmosfer tanpa pemanfaatan lebih lanjut. Pada PKS PT Arindo Trisejahtera 1 (kapasitas olah 45 ton TBS/jam) yang menjadi objek studi, gas buang dilepas pada temperatur 350°C dengan laju aliran massa 9,771 kg/s, setara dengan potensi energi termal terbuang sebesar 3.734,74 kW. Penelitian ini merancang sistem waste heat recovery (WHR) untuk mengonversi gas buang tersebut menjadi listrik tambahan melalui konfigurasi bertingkat, yaitu Steam Rankine Cycle (SRC) modifikasi sebagai topping cycle serta pemilihan siklus bottoming terbaik antara Organic Rankine Cycle (ORC) dan Kalina Cycle. Pemodelan termodinamika dilakukan pada kondisi tunak menggunakan EBSILON®Professional, estimasi biaya investasi menggunakan Aspen Process Economic Analyzer (APEA), dan pemilihan teknologi menggunakan matriks keputusan berbobot yang mempertimbangkan aspek teknis (efisiensi), ekonomi (capital cost dan levelized cost of electricity/LCOE), serta lingkungan (emisi CO? yang dihindari). Modifikasi SRC berupa penambahan air preheater dan condenser meningkatkan daya listrik dari 1.217 kW menjadi 2.096 kW dan efisiensi kogenerasi dari 77,86% menjadi 81,46%, sekaligus menurunkan temperatur gas buang menjadi 207°C sebagai sumber panas siklus bottoming. Dalam pemanfaatan gas buang sisa tersebut, Kalina Cycle menghasilkan daya 242,16 kW dengan efisiensi energi 15,26%, lebih tinggi dibandingkan ORC (178,59 kW; 11,65%), dengan potensi pengurangan emisi 1.470 dibandingkan 1.084 ton CO? per tahun. LCOE kedua siklus, yaitu Rp2.590/kWh (Kalina) dan Rp2.676/kWh (ORC), jauh lebih rendah daripada biaya pembangkitan generator diesel eksisting (Rp5.750–6.900/kWh) pada operasi PKS yang berjalan secara off-grid. Berdasarkan matriks keputusan berbobot, Kalina Cycle terpilih sebagai siklus bottoming terbaik dengan skor total 95,2 dibandingkan 86,7 untuk ORC, dan hasil ini terbukti konsisten pada empat skenario pembobotan. Secara keseluruhan, rancangan WHR bertingkat SRC–Kalina meningkatkan total pembangkitan listrik menjadi sekitar 2.338 kW tanpa konsumsi bahan bakar tambahan, sehingga berpotensi memberikan penghematan biaya energi sekaligus pengurangan emisi karbon pada operasi pabrik kelapa sawit.

ROCK TYPING BERBASIS LOG MENGGUNAKAN UNSUPERVISED MACHINE LEARNING YANG DIEVALUASI TERHADAP REFERENSI DISCRETE ROCK TYPE TURUNAN HFU DI LAPANGAN 'X'

Core-based rock typing is limited by the sparse availability of core data, whereas well logs are recorded continuously along the wellbore. This study evaluates whether unsupervised machine learning applied to well logs can reproduce a core-derived petrophysical rock type reference in the 'X' field, Central Sumatra Basin. A reference was built from 85 routine core analysis (RCAL) samples using the RQI–????z–FZI–DRT framework, and the eight original DRT classes were lumped into four hydraulic-flow-unit (HFU)-derived rock types (RT1 – RT4). Four unsupervised methods: K-Means, FCM, GMM, and MRGC, were applied to five standardized log features (GR, DT, SP, RHOB_STD, and a harmonized deep resistivity proxy, RES_DEEP) from three wells, with all core-derived variables excluded to prevent data leakage. The clusters were mapped using the Hungarian algorithm and evaluated per well and for all wells combined. GMM gave the best combined agreement (accuracy 42.35%, ARI 0.0367), but the per well results were weak (near random in the most sampled well (WS-002) and collapsed to a single rock type in WS-004) indicating that the available conventional logs only partially reproduce the HFU-derived rock types.

This research assesses the technical viability of Sulfonated di-Alkyl Ester (SAE-2), a polymeric surfactant, for chemical enhanced oil recovery (CEOR) in ultra-low salinity brine (300 ppm NaCl). Base formulation SAE-2 at 1.0 %wt reduced the interfacial tension (IFT) of high-wax crude oil from 3.386 mN/m to 0.913 mN/m. Systematic screening of alkaline agents, divalent cations, co-solvents, and co-surfactants was conducted to optimize performance. Sodium carbonate (Na?CO?) promoted in-situ soap generation and significantly lowered IFT but increased ionic sensitivity. While calcium ions (Ca²?) caused severe destabilization, magnesium ions (Mg²?) remained tolerable and contributed to IFT reduction. To overcome the stability-activity trade-off, 1.5%wt ethylene glycol butyl ether (EGBE) was incorporated as a cosolvent, maintaining clear aqueous stability for seven days at 60°C. The optimal formulation (19J) comprising 1.0 %wt SAE-2, 2.5 %wt Na?CO?, 100 ppm MgCl?, and 1.5%wt EGBE, achieved IFT of 0.04846 mN/m and formed a stable Winsor Type II microemulsion. Spontaneous imbibition tests on Berea cores yielded exceptional oil recovery of 95.61%, compared to only 50.55% for formulations containing nonylphenol ethoxylate (NPE). These findings demonstrate that Formulation 19J is highly technically feasible for reservoir-scale surfactant flooding in ultra-low salinity environments.

ANALISIS PARAMETER PEMBORAN SECARA REAL-TIME UNTUK DETEKSI DINI ANOMALI PEMBORAN DAN SISTEM PENDUKUNG KEPUTUSAN MENGGUNAKAN PENDEKATAN MACHINE LEARNING TANPA SUPERVISI DENGAN INTERPRETASI BERBASIS ATURAN

This study aims to develop a real-time drilling anomaly detection framework by combining unsupervised machine learning methods with a rule-based approach. The primary objectives are to determine the most effective and efficient machine learning model for real-time anomaly detection, develop feature engineering as model inputs, identify early signs of drilling anomalies, and validate detection results by comparing them against historical data and field reports. The case study was conducted on three wells in South Sumatra, Indonesia (Well A, Well B, and Well C) using historical drilling parameter data simulated as if it were streaming in real-time. Well A was focused on kick detection validation, Well B on lost circulation, and Well C on stuck pipe, while bit balling cases were validated using the Drilling Anomaly Index (DAI) and lithology due to the absence of specific incident records. Data pre-processing included separating data by drilling section and handling missing values, while model preparation involved tuning the Isolation Forest algorithm hyperparameters and determining the severity threshold to balance sensitivity and noise tolerance. The results indicate that the developed framework can detect anomalies earlier than conventional observations recorded in the Daily Drilling Report (DDR) or Final Well Report (FWR) and can identify early signs such as kick potential, lost circulation potential, differential sticking, and mechanical sticking. Validation using the DAI demonstrated consistent detection of abnormal drilling behaviors across the wells. Integration with a rule-based system also enhanced decision support capabilities by providing recommended actions before anomalies escalate. This study emphasizes the importance of high-quality real-time drilling parameter data for prediction accuracy and operational safety. The developed framework provides a robust platform for proactive drilling anomaly management, with potential for further development in non-rotary operations and expanded rulebased determination. Overall, the combination of feature engineering, unsupervised learning, and a rulebased system proved effective in improving safety, efficiency, and decision-making in drilling operations.

EVALUASI SKALA PORI GUM XANTHAN MENGGUNAKAN MODEL MIKROFLUIDIK UNTUK FRAKTUR HIDRAULIK: PERBANDINGAN DENGAN KARBOKSIMETIL HIDROKSIPROPIL GUAR

Polymer selection in fluid hydraulic fracturing design plays an important role in controlling mobility and minimizing formation damage, especially at high temperatures. This study presents pore-scale experimental observations of Xanthan Gum as a candidate non-Newtonian fracturing fluid with Carboxymethyl Hydroxypropyl Guar (CMHPG) used as a reference polymer. The evaluation focused on viscosity changes due to temperature changes and potential permeability disturbances using a microfluidic porous model. This study was initiated by preparing Xanthan Gum and CMHPG solutions in demineralized water, followed by rheological equalization of both solutions using a rheometer. Microfluidic experiments were carried out at temperatures of 45 oC and 70 oC with a back pressure of 10 bars to represent reservoir conditions with medium and high temperatures and to keep the polymer from evaporating easily. Initial permeability calculations and pressure changes when the polymer was injected were observed periodically to reveal the behavior of the polymer in the pore network. Then a thermal soak was carried out for 2 hours to assess the effect of temperature exposure on polymer stability and changes in flow characteristics. Mobility control and potential formation damage are characterized by calculating the resistance factor (RF) and residual resistance factor (RRF). The results of the study show that at high concentrations xanthan gum shows high RRF and RF values compared to CMHPG, reaching 10.89 and 18.95 with a decrease in permeability of up to 90.82%, while CMHPG shows relatively small RF and RRF values reaching 6.15 and 16.66 with a decrease in permeability of 83.74%. This study helps the performance of polymers that are very affected by temperature, where xanthan gum shows lower potential for formation damage at high temperatures, while CMHPG is more stable at medium temperatures.

INTEGRASI PROPERTI GEOMEKANIKA DALAM OPTIMASI JARAK ANTAR KLASTER UNTUK MEMINIMALKAN EFEK STRESS SHADOW PADA SUMUR HORIZONTAL MARCELLUS SHALE

Hydraulic fracturing has become the primary stimulation technique for economically developing unconventional shale reservoirs. However, suboptimal cluster spacing can intensify stress shadow between adjacent fractures, reducing fracture conductivity and ultimately limiting hydrocarbon recovery. This study aims to quantify the influence of stress shadow on fracture conductivity, evaluate its impact on horizontal well performance through coupled geomechanics–reservoir simulation, and determine the optimum cluster spacing for a Marcellus shale reservoir. A one-dimensional Mechanical Earth Model (1D MEM) was constructed using gamma ray, bulk density, compressional sonic, and shear sonic logs acquired from the Boggess 17H vertical well. Elastic properties, including static Young's modulus and Poisson's ratio, were calculated to estimate the in-situ stress field, consisting of vertical stress, pore pressure, minimum horizontal stress, and net pressure. An analytical stress shadow model based on the Sneddon solution was subsequently employed to quantify induced stress and its effect on fracture conductivity for fracture halfheights ranging from 100 to 500 ft and cluster spacings between 0 and 500 ft. The calibrated geomechanical properties were spatially distributed into a three-dimensional reservoir model with tNavigator from RockFlowDynamics using Sequential Gaussian Simulation (SGS) and integrated with hydraulic fracture and dynamic reservoir simulations in tNavigator. Seven cluster spacing scenarios, including the base case, 15, 30, 45, 60, 75, and 90 ft, were evaluated using cumulative gas production, recovery factor, cumulative water production, gas drawdown, gas productivity index, and Estimated Ultimate Recovery (EUR). The analytical results indicate that induced stress decreases nonlinearly with increasing cluster spacing, leading to improved fracture conductivity, while the coupled simulations demonstrate that production performance is governed by the balance between stress shadow mitigation and fracture density. Among the evaluated scenarios, a cluster spacing of 45 ft yielded the highest EUR of 10.5 BSCF and representing a recovery factor of 31.85% compared with the non-hydraulic fracturing case. The proposed integrated workflow demonstrates that combining geomechanical characterization, analytical stress shadow quantification, hydraulic fracture simulation, and coupled reservoir simulation provides a technically robust framework for optimizing cluster spacing and improving completion design in unconventional shale reservoirs.

OPTIMASI PEREKAHAN HIDROLIK MELALUI SATURASI PROPPANT DAN SENSITIVITAS FLUIDA PADA BATU PASIR CLE

Hydraulic fracturing operations in low to medium permeability reservoirs are frequently overdesigned. In many cases, the injected proppant mass and fluid volume far exceed what is actually needed for optimal fracture conductivity, which ultimately leads to diminishing productivity returns. This study aims to optimize the treatment design for four CLE Sandstone wells in Field X, namely KFC 221, KFC 215, KFC 219, and KFC 220. The optimization is achieved by determining the proppant mass saturation point and evaluating the sensitivity of the fracturing fluid volume. Fracture geometries were simulated using a pseudo three dimensional model in Fracturing Propagation Software. During the simulation, the proppant mass was varied from 10 to 100 percent of the original field design. The saturation point marks the exact condition where the Fold of Increase begins to plateau. Rather than estimating this visually, the Kneedle algorithm was applied to identify the point objectively, which was then validated against a dimensionless fracture conductivity threshold of 1.6. The results indicate a clear overdesign in the initial field treatments. KFC 221 and KFC 215 reached their saturation points at just 40 percent of the original proppant mass. Meanwhile, KFC 219 and KFC 220 reached saturation at 50 percent. This reservoir behavior translates to a massive 50 to 60 percent potential reduction in proppant usage. A subsequent sensitivity analysis conducted at these saturation points showed that the clean fluid volume could also be reduced by 29.0 to 30.2 percent. Implementing these adjusted parameters significantly cuts down material waste. The drop in productivity is minimal, with the Fold of Increase only decreasing by 10.9 to 13.1 percent relative to the initial design. In conclusion, combining the Kneedle detection algorithm with Unified Fracture Design principles delivers a highly practical and objective workflow to properly size fracture treatments in mature sandstone reservoirs.

OPTIMISASI BATAS TRANSFER RUAS TRANSMISI BACKBONE DI SISTEM INTERKONEKSI SUMATERA

Peningkatan kebutuhan energi listrik di Sistem Interkoneksi Sumatera menuntut penyaluran daya yang lebih masif melalui ruas transmisi backbone. Namun, transfer daya tersebut terhambat oleh batasan operasi sistem berupa kejatuhan tegangan (New Aurduri-Peranap 500 kV), pembebanan lebih termal (Muara Enim-Gumawang 275 kV), dan instabilitas sudut rotor (Lubuk Linggau-Bangko 275 kV). Perancangan ini bertujuan mengoptimalkan batas transfer menggunakan metode Unit Commitment (UC), instalasi kompensator, penambahan pembangkit baru, serta kombinasi antara penambahan pembangkit dan UC. Berdasarkan simulasi komputasi, seluruh skenario berhasil merelaksasi batasan sistem sesuai Grid Code pada kondisi N-0 maupun N-1. Hasil analisis menunjukkan kompensator sebagai solusi paling unggul dalam menangani beban lebih termal dengan mendongkrak kapasitas batas transfer menjadi 804,10 MW. Sementara itu, kombinasi penambahan pembangkit dan UC sangat efektif mengatasi kejatuhan tegangan dengan peningkatan transfer hingga 406,62 MW, sekaligus memitigasi instabilitas sudut rotor dengan capaian 538,596 MW. Secara keseluruhan, kompensator dan kombinasi penambahan pembangkit beserta UC memberikan lonjakan Total Transfer Capability (TTC) paling optimal.

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.

DESAIN DAN IMPLEMENTASI SISTEM PENGENDALIAN UMPAN BALIK, PENGUKURAN SUHU, MANAJEMEN PENGERINGAN, DAN ANTARMUKA MANUSIA-MESIN UNTUK PLATFORM ROTASI MULTI-SUMBU BERBASIS GIMBAL DALAM MANUFAKTUR PEMBULUH DARAH TIRUAN

Tugas akhir ini membahas perancangan dan implementasi pengendalian umpan balik, pengukuran suhu, manajemen pengeringan, dan antarmuka manusiamesin pada platform rotasi multi-sumbu untuk manufaktur pembuluh darah tiruan. Sistem dirancang untuk mengatasi kelemahan metode konvensional (pencetakan manual) dan dip-coating sumbu tunggal yang rentan terhadap gaya gravitasi, sehingga memicu penggumpalan hidrogel dan ketidakseragaman ketebalan dinding. Integrasi seluruh subsistem dilakukan guna mewujudkan sistem pemantauan dan pengendalian produksi yang akurat, presisi, dan otomatis. Secara operasional, proses diawali dengan konfigurasi parameter cetakan dan durasi pengeringan melalui layar sentuh antarmuka. Saat sistem beroperasi, algoritma umpan balik mengolah data ketebalan hidrogel secara kontinu menjadi instruksi penyesuaian sudut orientasi agar aliran merata. Bersamaan dengan itu, sensor suhu membaca suhu ruang yang kemudian diperhalus melalui penyaringan sinyal digital. Data tersebut digunakan logika manajemen untuk memantau suhu sekaligus menghitung sisa waktu pengeringan. Seluruh proses ini direkam ke basis data dan ditampilkan sebagai grafik pemantauan secara real-time. Pengujian dilakukan untuk memvalidasi kinerja subsistem. Pengendalian umpan balik mencatatkan waktu respons 172.22 ± 22.36 ms yang memenuhi batas aman di bawah 500 ms agar koreksi posisi segera dieksekusi. Pada pengukuran suhu, sensor mencatat rata-rata 27.47 ± 0.11 °C dengan selisih hanya 0.07 °C dari sensor referensi. Antarmuka menyediakan platform intuitif untuk interaksi pengguna dalam pengaturan parameter dan pemantauan real-time. Secara keseluruhan, integrasi kendali, antarmuka, dan pemantauan ini menghasilkan instrumen manufaktur yang andal. Implementasi ini berhasil menuntaskan masalah koreksi cacat penggumpalan material hidrogel, mengotomatisasi siklus produksi, serta menjamin konsistensi pembuatan pembuluh darah tiruan.

INTERAKSI SINERGIS SISTEM ALKALI-SURFAKTAN-POLIMER DALAM KONDISI SALINITAS SANGAT RENDAH: OPTIMALISASI FORMULASI DAN MEKANISME PENINGKATAN PRODUKSI MINYAK

Alkaline–Surfactant–Polymer (ASP) flooding represents a method of Chemical Enhanced Oil Recovery (CEOR) that utilizes the synergistic interactions between alkali, surfactant, and polymer to improve oil recovery efficiency. This study evaluates the performance of ASP under ultra-low-salinity brine conditions (300 ppm) and elucidates the mechanisms that contribute to the improvement of oil recovery. Comprehensive chemical screening tests were performed, encompassing interfacial tension (IFT) measurements, aqueous stability tests (AST), phase behavior (PB) assessments, viscosity measurements, and imbibition tests on Berea sandstone cores. The optimal formulation of alkaline surfactants consisted of 2.5 %wt Na?CO? and 0.5 %wt LABS:AOS in a 1:1 ratio, resulting in an interfacial tension (IFT) of 0.28 mN/m. This formulation demonstrated remarkable aqueous stability and facilitated the formation of Winsor Type I microemulsions. Incorporation of polymer (HPAM) preserved system compatibility while elevating viscosity from 23.2 cP to 84.32 cP and decreasing the viscosity ratio from 0.974 to 0.268, thus improving sweep efficiency. Imbibition tests exhibited enhanced recovery factors in comparison to base brine injection. The enhanced oil recovery is attributed to synergistic effects, including the reduction of interfacial tension by the alkaline-surfactant system, improved sweep efficiency using polymer, and wettability alteration induced by ultra-low salinity. These conditions reduced surfactant adsorption and enhanced polymer performance, thereby facilitating the effective mobilization of residual oil.

STUDI LABORATORIUM TERHADAP KINERJA DAN SENSITIVITAS CAMPURAN SURFAKTAN ZWITTERIONIK-ANIONIK

Residual oil trapped by capillary forces remains difficult to mobilize through conventional waterflooding, necessitating the application of an Enhanced Oil Recovery method to significantly reduce the interfacial tension (IFT) between the oil and aqueous phases. This study evaluates the performance of a zwitterionicanionic surfactant mixture, consisting of Macat-AO14 (MA-AO14) as the zwitterionic surfactant and Aristonate-M (AR-M) as the anionic surfactant, with isopropyl alcohol (IPA) at a concentration of 0.1% as a co-solvent, using crude oil from Field X. The experimental evaluation consisted of three sequential stages, namely aqueous stability tests, phase behavior observations, and IFT measurements using a spinning drop tensiometer. These tests were conducted across a NaCl salinity range of 0.5% to 2.5% and total surfactant concentrations of 0.15 wt% and 0.3 wt%. The results demonstrated that the MA-AO14/AR-M formulations at 70/30 and 80/20 ratios exhibited the best aqueous stability. Notably, the 70/30 ratio successfully formed a Winsor Type III middle-phase microemulsion and achieved an ultralow minimum IFT of 8.65 × 10?³ mN/m at an optimum salinity of 1.75% NaCl. Conversely, the 80/20 ratio failed to reach the ultralow IFT order. Furthermore, increasing the total surfactant concentration to 0.3 wt% yielded no significant improvement in IFT reduction. These findings indicate that the MA-AO14/AR-M at a ratio of 70/30, with a surfactant concentration of 0.15 wt%, a salinity of 1.75% NaCl and an IPA concentration of 0.1%, represents the best performing zwitterionic-anionic surfactant formulation under the evaluated conditions.

DESAIN DAN IMPLEMENTASI SISTEM INDOOR POSITIONING BERBASIS TIME DIFFERENCE OF ARRIVAL DENGAN ULTRA-WIDEBAND: PERANGKAT KERAS DAN INTEGRASI TOP-LEVEL

Peneliti robotika di Institut Teknologi Bandung membutuhkan informasi posisi, orientasi, kecepatan, dan percepatan drone selama pengujian di dalam ruangan, namun teknologi yang tersedia berharga sangat mahal dan GPS tidak akurat di dalam ruangan. Tugas akhir ini merancang dan mengimplementasikan indoor positioning system berbasis Time Difference of Arrival (TDoA) dengan Ultra-wideband (UWB), dengan lingkup pengerjaan berupa perangkat keras dan integrasi top-level. Perangkat keras terdiri atas sub-sistem tag dan sub-sistem anchor. Secara fungsional, tag yang dipasang pada drone memancarkan sinyal blink UWB dan mengirim data IMU setiap 40 ms, sedangkan anchor (satu master clock dan empat slave) menjadi referensi posisi dan clock melalui sinyal sinkronisasi CCP setiap 30 ms. Tag tersusun atas mikrokontroler ESP32-S3, IMU BNO055, modul UWB DWM1000, regulator daya, dan battery management system; anchor menggunakan ESP32-WROOM-32 dan DWM1000. Antarmuka antar-blok memanfaatkan SPI, I2C, sinyal UWB, serta WiFi/UDP. Integrasi top-level direalisasikan sebagai pipeline ROS2 yang menggabungkan algoritma sinkronisasi clock, perhitungan posisi TDoA, dan pengolahan data IMU menjadi keluaran end-to-end. Sistem yang terpasang di drone berdimensi 5 cm × 4 cm dengan berat total 43 gram termasuk baterai 600 mAh, sehingga memenuhi seluruh spesifikasi. Keluaran sistem berupa estimasi posisi, kecepatan dan percepatan translasi, orientasi, serta kecepatan dan percepatan angular dalam format JSON. Pipeline ROS berjalan secara real-time dengan beban komputasi 14–23%, latensi ~19 ms, dan laju pembaruan posisi ~24,7 Hz. Total biaya produksi ~Rp4,3 juta, jauh di bawah anggaran pengguna sebesar Rp10 juta, sehingga permasalahan berhasil diselesaikan.

ESTIMASI KONEKTIVITAS ANTARSUMUR PADA RESERVOAR INJEKSI AIR MENGGUNAKAN TRANSFORMASI WAVELET SILANG: PENGEMBANGAN DAN VALIDASI WAVEITB

Most of the world’s producing oil comes from mature fields where waterflooding is essential, yet identifying fluid pathways remains a challenge. Current surveillance methods face significant limitations. Full numerical reservoir simulation is labor-intensive and computationally expensive, while capacitanceresistance modeling often fails to account for dynamic, non-stationary field conditions. This study addresses these gaps by proposing a signal processing approach to evaluate dynamic interwell connectivity in waterflooded reservoirs. The study details the construction and validation of WaveITB, a desktop application built upon the cross-wavelet transform (CrWT) methodology. The study translates injection and production rate histories into a time-frequency domain using a complex Morlet wavelet. The methodology evaluates cross-wavelet coherence, quantifies phase lag to determine signal directionality, and strictly screens spurious coherence using Monte Carlo red-noise significance testing alongside cone of influence (COI) masking. The application was validated through three case studies. It successfully replicated a published benchmark, demonstrating multiscale capabilities. In a structural sensitivity test, the connectivity index for the well isolated by a sealing fault collapsed by approximately four-fifths when compared to the unhindered well in the same scenario, whereas the index remained robust across a non-sealing fault, matching simulated streamlines. When compared to a capacitance-resistance model (CRM), WaveITB identified identical flow barriers but yielded a low Spearman rank correlation of 0.316, confirming it distinctly measures dynamic signal communication rather than partitioning volumes under mass-balance constraints. The study concludes that the multiscale cross-wavelet approach is a robust, data-driven technique. WaveITB provides operators with a fast, non-stationary, and low-preparation analytical tool for continuous reservoir surveillance.