Analisis Perubahan Posisi Tiga Dimensi (3D) Platform Lepas Pantai Dengan Pemrosesan GNSS Presisi Tinggi (Studi Kasus: Platform X, Perairan Handil, Kalimantan Timur)

Christiara, Angeline Indra (2026) Analisis Perubahan Posisi Tiga Dimensi (3D) Platform Lepas Pantai Dengan Pemrosesan GNSS Presisi Tinggi (Studi Kasus: Platform X, Perairan Handil, Kalimantan Timur). Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Aktivitas pemasangan jack-up rig di sekitar offshore platform berpotensi memengaruhi kondisi tanah dasar laut dan menyebabkan perubahan posisi struktur. Oleh karena itu, penelitian ini bertujuan menganalisis perubahan posisi tiga dimensi offshore platform menggunakan data GNSS statik multi-epoch yang diolah dengan perangkat lunak GAMIT/GLOBK melalui metode static relative positioning dan double difference, mengevaluasi signifikansinya menggunakan single hypothesis test, serta memanfaatkan data waterpass leveling dan motion sensor berbasis IMU sebagai pendukung interpretasi deformasi. Data yang digunakan berupa observasi GNSS selama 11 hari pada offshore platform di Perairan Handil, Delta Mahakam, Kalimantan Timur pada tahun 2025, didukung oleh 3 stasiun CORS dan 30 stasiun IGS. Analisis dilakukan berdasarkan perubahan koordinat east, north, dan up (ΔE, ΔN, ΔU), displacement resultan tiga dimensi, serta arah pergeseran horizontal. Hasil pengolahan menunjukkan kualitas data yang baik dengan nilai post-fit NRMS sebesar 0.049–0.092 (rata-rata 0.065). Platform mengalami pergeseran horizontal yang didominasi ke arah barat daya, dengan displacement resultan tiga dimensi meningkat dari 0.017 m pada fase approaching menjadi 0.044 m pada kondisi post-RMI. Pergeseran terbesar terjadi pada komponen easting sebesar −0.038 m pada epoch 7 dan northing sebesar −0.028 m pada epoch 6, sedangkan penurunan vertikal maksimum mencapai −0.015 m pada epoch 5. Hasil single hypothesis test menunjukkan bahwa seluruh perubahan posisi tidak signifikan secara statistik pada tingkat kepercayaan 95% (T hitung = 0.126–0.758 < 1.960), sehingga pergeseran yang teramati masih berada dalam batas ketelitian pengamatan GNSS. Data IMU menunjukkan peningkatan nilai roll dan heave pada fase post-RMI, yang mengindikasikan masih adanya respons dinamis platform setelah proses preload. Hasil penelitian menunjukkan bahwa GNSS statik multi-epoch mampu mendeteksi perubahan posisi offshore platform secara presisi dalam skala sentimeter hingga milimeter serta mendukung pemantauan kestabilan struktur.
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The installation of a jack-up rig near an offshore platform has the potential to alter seabed conditions and induce structural displacement. Therefore, this study aims to analyze the three-dimensional position changes of an offshore platform using multi-epoch static GNSS observations processed with the GAMIT/GLOBK software through the static relative positioning and double-difference methods. The significance of the observed displacement was evaluated using a single hypothesis test, while waterpass leveling and Inertial Measurement Unit (IMU) data were utilized to support the interpretation of platform deformation. The dataset consisted of 11 days of static GNSS observations collected from an offshore platform in Handil Waters, Mahakam Delta, East Kalimantan, Indonesia, in 2025, supported by 3 CORS stations and 30 International GNSS Service (IGS) stations. The analysis was based on changes in east, north, and up coordinates (ΔE,ΔN,ΔU), three-dimensional resultant displacement, and horizontal displacement direction. The processing results showed good data quality, with post-fit NRMS values ranging from 0.049 to 0.092 (average 0.065). The platform exhibited predominantly southwestward horizontal displacement, with the three-dimensional resultant displacement increasing from 0.017 m during the approaching phase to 0.044 m in the post-RMI phase. The largest horizontal displacement reached −0.038 m in the easting component at Epoch 7 and −0.028 m in the northing component at Epoch 6, while the maximum vertical subsidence was −0.015 m at Epoch 5. The single hypothesis test indicated that all observed displacements were not statistically significant at the 95% confidence level (T = 0.126–0.758 < 1.960), suggesting that the detected displacements remained within the accuracy limits of the GNSS observations. The IMU data showed increased roll and heave values during the post-RMI phase, indicating that the platform continued to experience a dynamic response after the preload process. These results demonstrate that multi-epoch static GNSS is capable of detecting offshore platform displacement with centimeter- to millimeter-level precision and can effectively support structural stability monitoring. Keywords: deformation, offshore platform, multi-epoch static GNSS, GAMIT/GLOBK, jack-up rig installation, IMU.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	deformasi, offshore platform, GNSS statik multi-epoch, GAMIT/GLOBK, jack-up rig installation, IMU, deformation, offshore platform, multi-epoch static GNSS, GAMIT/GLOBK, jack-up rig installation, IMU.
Subjects:	G Geography. Anthropology. Recreation > G Geography (General) > G109.5 Global Positioning System Q Science > QE Geology > QE604 Deformation T Technology > TC Hydraulic engineering. Ocean engineering > TC1680 Offshore structures
Divisions:	Faculty of Civil, Planning, and Geo Engineering (CIVPLAN) > Geomatics Engineering > 29202-(S1) Undergraduate Thesis
Depositing User:	Angeline Indra Christiara
Date Deposited:	21 Jul 2026 09:28
Last Modified:	21 Jul 2026 09:28
URI:	http://repository.its.ac.id/id/eprint/135998

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