Joint Inversion Data Gayaberat dan Aeromagnetik dalam Identifikasi Struktur Bawah Permukaan Cekungan Ajdabiya, Libya

Fatima, Avita Arin Nur (2026) Joint Inversion Data Gayaberat dan Aeromagnetik dalam Identifikasi Struktur Bawah Permukaan Cekungan Ajdabiya, Libya. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Cekungan Ajdabiya yang terletak di timur laut Cekungan Sirt, Libya, merupakan salah satu area paling prospektif untuk eksplorasi hidrokarbon namun struktur bawah permukaannya masih kurang dipahami. Penelitian ini mengimplementasikan cross-gradien joint inversion pada data gravity dan aeromegnetik menggunakan SimPEG untuk emngidentifikasi struktur bawah permukaan dan kedalman basement. Data yang digunakan meliputi 85.692 titik anomali Bouguer, data aeromagnetik dengan grid 1 km dari AMMP, dan empat data sumur berisi kedalaman firmasi sebagai constraint pemodelan. Hasil anomali Bouguer menunjukan rentang -14 hingga 16 mGal dengan trend dominan NW-SE, sedangkan peta RTP memperlihankan anomali magnetik rendah tepat diatas cekungan. Model joint inversion mengidentifikasi zona sedimen di bagian dangkal, zona kontras densitas sebagai sesar, dan keberadaan basement pada kedalaman 7.000 meter. Cross-gradient joint inversion menghasilkan model yang lebih kekontrol secara struktural dibandingkan inversi terpisah pada metode magnetik, dengan RMS Eror 0.2%, tetapi tidak berlaku untuk hasil model update densitas. Ketidak sesuaian asumsi cross gradient terduga pada zona karboant tebal yang bersifat non-magnetik, namun perbedaan respon kedua data justru memperkuat interpretasi bawah permukaan cekungan Ajdabiya.
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The Ajdabiya Basin, located in the northeastern part of the Sirt Basin, Libya, is one of the most prospective areas for hydrocarbon exploration, yet its subsurface structure remains poorly understood. This study implements a cross-gradient joint inversion of gravity and aeromagnetic data using SimPEG to identify the subsurface structure and basement depth. The data used include 85,692 Bouguer anomaly points, aeromagnetic data on a 1 km grid from AMMP, and four well datasets containing formation depths used as modeling constraints. The Bouguer anomaly results show a range of -14 to 16 mGal with a dominant NW-SE trend, while the RTP map shows a low magnetic anomaly directly above the basin. The joint inversion model identifies a shallow sedimentary zone, a density-contrast zone interpreted as a fault, and the presence of basement at a depth of 7,000 meters. The cross-gradient joint inversion produces a more structurally controlled model than separate inversion for the magnetic method, with an RMS error of 0.2%, but this does not hold for the updated density model. A mismatch in the cross-gradient assumption is identified in the thick, non-magnetic sedimentary zone; however, the differing responses of the two datasets actually strengthen the subsurface interpretation of the Ajdabiya Basin.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	joint inversion, cross-gradient, gravity, aeromagnetik, SimPEG joint inversion, cross-gradient, gravity, aeromagnetic, SimPEG
Subjects:	Q Science > QE Geology > QE601 Geology, Structural
Divisions:	Faculty of Civil, Planning, and Geo Engineering (CIVPLAN) > Geophysics Engineering > 33201-(S1) Undergraduate Thesis
Depositing User:	Avita Arin Nur Fatima
Date Deposited:	22 Jul 2026 03:56
Last Modified:	22 Jul 2026 03:56
URI:	http://repository.its.ac.id/id/eprint/136126

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