Delineasi Cekungan Waipoga Perairan Yapen Berdasarkan Pemodelan Gaya Berat dan Anomali Magnetik

Prasetya, Bima Kukuh (2022) Delineasi Cekungan Waipoga Perairan Yapen Berdasarkan Pemodelan Gaya Berat dan Anomali Magnetik. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Cekungan Waipoga merupakan Cekungan Papua Utara yang terletak di pantai utara Pulau Papua Bagian Timur dan menjadi target eksplorasi sejak 1930. Cekungan ini termasuk cekungan hybrid yang mulai terbentuk sebagai cekungan depan busur dengan dialasi kerak samudera dan selanjutnya terjadi subduksi sehingga struktur cekungan tersebut menjadi lebih kompleks. Studi menggunakan metode geofisika seperti gaya berat dan magnetik dilakukan untuk memperoleh gambaran struktur geologi area Cekungan Waipoga. Kedua metode tersebut efektif dan umum digunakan untuk memberikan informasi detail bawah permukaan, salah satunya dalam mendelineasi sub-cekungan pada tahap awal eksplorasi migas. Pemrosesan data magnetik di reduksi hingga diperoleh anomali RTP (reduce to pole). Berikutnya data magnetik yang telah direduksi dilakukan kontinuasi keatas. Sedangkan data gaya berat dimulai dari anomali udara bebas hingga anomali bouguer lengkap. Pemodelan kedepan dan inversi dilakukan pada anomali residual data gaya berat untuk menghasilkan gambaran geologi bawah permukaan, sehingga selain struktur patahan juga dapat diidentifikasi beberapa sub-cekungan pada Cekungan Waipoga sebagai salah satu indikator keberadaan hidrokarbon. Berdasarkan pemodelan kedepan diperoleh 4 lapisan sekuen yang secara berurutan dari atas kebawah yaitu Konglomerat Ansus dengan densitas 2,32 gr/cm3, Batugamping dengan densitas 2,42 gr/cm3, Formasi Makats yang terdiri dari batupasir, batulempung, dan serpih dengan densitas 2,52 gr/cm3, dan Breksi Ofiolit diduga sebagai batuan dasar dengan densitas 2,7 gr/cm3. Perbandingan hasil pemodelan kedepan terhadap model inversi menunjukkan adanya kesamaan yaitu pada bagian utara dan selatan perairan Yapen ditemukan zona sub-cekungan pada X= 622; X= 658; X= 689, dan X= 692 dengan densitas rendah pada model inversi. Terdapat kesesuaian antara pola tinggi rendah nilai anomali residual magnet dan penafsiran pola delineasi sub-cekungan dari anomali residual gaya berat. Terdapat 2 pola sub-cekungan di bagian barat, 1 pola sub-cekungan bagian tengah, dan 2 pola sub-cekungan pada bagian baratdaya perairan Yapen.
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The Waipoga Basin is the North Papua Basin which is located on the northern coast of Eastern Papua Island and has been a target of exploration since 1930. This basin is a hybrid basin which began to form as an arc-forward basin with oceanic crust overlaying it and then subduction occurred so that the structure of the basin became more complex. Studies using geophysical methods such as gravity and magnetism were carried out to obtain an overview of the geological structure of the Waipoga Basin area. Both methods are effective and commonly used to provide detailed subsurface information, one of which is delineating sub-basins in the early stages of oil and gas exploration. Magnetic data processing is reduced to obtain an RTP anomaly (reduce to pole). Next, the reduced magnetic data is continued upwards. While the gravity data starts from the free air anomaly to the complete bouguer anomaly. Forward modeling and inversion were carried out on residual anomaly of gravity data to produce a subsurface geological picture, so that apart from the fault structure, several sub-basins in the Waipoga Basin can also be identified as an indicator of the presence of hydrocarbons. Based on the forward modeling obtained 4 sequence layers from top to bottom, namely the Ansus Conglomerate with a density of 2.32 gr/cm3, Limestone with a density of 2.42 gr/cm3, the Makats Formation consisting of sandstone, claystone, and shale with a density of 2.52 gr/cm3, and Ophiolite Breccia is suspected as bedrock with a density of 2.7 gr/cm3. Comparison of forward modeling results against the inversion model shows that there are similarities in the northern and southern parts of the Yapen waters, a subbasin zone is found at X= 622; X= 658; X= 689, and X= 692 with low density in the inversion model. There is a match between the high and low pattern of residual magnetic anomaly values that are overlaid with the subbasin pattern. There are 2 sub-basin patterns in the western part, 1 sub-basin pattern in the middle part, and 2 sub-basin patterns in the southwest part of Yapen waters.

Item Type:	Thesis (Other)
Additional Information:	RSGf 538.7 Pra d-1 2022
Uncontrolled Keywords:	Waipoga Basin, Gravity, Magnetic, Modeling, Subsurface Structure, Sub-Basin.
Subjects:	Q Science > QE Geology > QE1.F557 Magnetic anomalies--Measurement.
Divisions:	Faculty of Civil, Planning, and Geo Engineering (CIVPLAN) > Geophysics Engineering > 33201-(S1) Undergraduate Thesis
Depositing User:	- Davi Wah
Date Deposited:	20 Nov 2023 08:34
Last Modified:	20 Nov 2023 08:34
URI:	http://repository.its.ac.id/id/eprint/105128

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