PENERAPAN ATRIBUT SEISMIK COHERENCE CUBE, VARIANCE, DAN ANT-TRACKING UNTUK KARAKTERISASI REKAHAN DAN PENENTUAN ZONA POTENSIAL HIDROKARBON DALAM RESERVOAR BASEMENT TEREKAHKAN DI LAPANGAN CASTERLY ROCK

MOHAMAD RAHMAT C, Dr. Sudarmaji, M.Si; Dr. rer. nat. Moch. Nukman, M.Sc.

2018 | Skripsi | S1 GEOFISIKA

Telah dilakukan penelitian pada basement Lapangan Casterley Rock yang terletak di Sub Cekungan Ciputat yang merupakan bagian dari Cekungan Jawa Barat Utara dengan tujuan untuk mengidentifikasi rekahan, penentuan zona potensial hidrokarbon, dan rekomendasi pengembangan lapangan ke depan. Data seismik 3D PSTM, electrical image log, dan data produksi dikombinasikan bersama dalam penelitian ini untuk mencapai tujuan tersebut. Data seismik 3D PSTM, melalui perhitungan atribut seismik coherence cube, variance volume, dan ant-tracking, digunakan untuk mengidentifikasi rekahan secara lateral di daerah penelitian. Analisis borehole image log memberikan seperangkat data orientasi rekahan pada daerah penelitian untuk memvalidasi hasil perhitungan atribut sesismik sekaligus menyediakan informasi untuk analisis kinematika regional daerah penelitian. Sementara itu, data produksi menjadi data pendukung dalam penentuan zona terekahkan yang berpotensi mengandung hidrokarbon di basement daerah penelitian. Hasil dari perhitungan atribut-atribut seismik menunjukan orientasi dominan rekahan di basement daerah penelitian berarah NNW SSE. Hal tersebut berkorelasi baik dengan orientasi dominan rekahan terbuka hasil dari analisis electrical image log yang berarah dominan NNW SSE, N S, dan NNE SSW. Sementara itu, orientasi drilling induced fractures atau DIFs dan borehole breakout yang didapatkan dari analisis electrical image log menunjukan tegasan horizontal maksimum atau SHmax yang bekerja pada daerah penelitian relatif berarah N S. Melalui serangkaian analisis yang meliputi analisis sistem petroleum basement daerah penelitian, analisis kinematika regional, dan analisis peta atribut seismik serta didukung dengan data produksi, didapatkan tiga zona terekahkan yang berpotensi mengandung hidrokarbon di basement daerah penelitian.

A research has been conducted in the basement of Casterly Rock Field located in Ciputat Sub Basin which is part of the North West Java Basin with the aim of identifying fractures, determining potential hydrocarbon zones, and recommending future field development. PSTM 3D seismic data, electrical image log, and production data are combined together in this study to achieve those goals. PSTM 3D seismic data, through the calculation of coherence cube, variance volume, and ant-tracking seismic attribute, was used to identify fractures laterally in the study area. Borehole image log analysis provided a set of fracture orientation data to validate the results of the seismic attributes calculations and gave information about regional kinematic of the study area as well. Meanwhile, the production data became supporting data to determine fractured zone in the basement that potentially containing hydrocarbons. The results of the seismic attribute calculations showed the dominant fracture orientations in the basement area, that is NNW SSE. Those orientations correlated well with the dominant orientations of open fractures identified from electrical image log, that is dominantly NNW SSE , N S, and NNE SSW. Meanwhile, the orientation of drilling induced fractures or DIFs and borehole breakouts obtained from electrical image log showed the maximum horizontal stress SHmax of the study area is working on the N S direction. Through a series of analyzes encompassing petroleum system, regional kinematics, and seismic attribute map analysis and supported by production data as well, three fractured zones that potentially containing hydrocarbon in the basement area were obtained.

Kata Kunci : Rekahan, Coherence Cube, Variance, Ant-Tracking.