ANALYSIS OF DEPOSITIONAL ENVIRONMENT AND PETROLEUM SYSTEM BASED ON INTEGRATION OF SEISMIC AND WELL DATA IN THE COASTAL OF CENTRAL SUMATRA BASIN

As one of the hydrocarbon-producing basins in Indonesia, the Central Sumatra Basin’s development had been hampered due to limited exploration and studies. This study aimed to identify depositional environments and petroleum systems through stratigraphic seismic and well studies. This study used a seismic method with Hampson Russell and Petrel software. Log data helped process seismic data with Interactive Petrophysic (IP) software and Techlog for well data processing. This research zone had five depositional sequences, most of which were formed in the depositional environment of branching channels and estuaries. There were two potential source rocks, namely in the Pematang Formation and shale layers in the upper TST-1. Based on stratigraphic sequence analysis on seismic sections, petroleum systems were identified in the Merak, Melibur, and Garib wells on the coast of the Central Sumatra Basin. Hydrocarbon reservoirs were found in the Bekasi, Bangko, and Menggala Formations and parts of the Pematang Formation; source rock was found in parts of the Menggala and Pematang Formations. The determination of reservoir layers and source rock was strengthened by the results of the analysis of wells located on seismic trajectories. Faults were useful as migration pathways for hydrocarbon fluids from source rock to reservoirs so that a petroleum system was formed in the area. This layer had immature and mature parent rocks. It was concluded that the depositional environment and the petroleum system in the wells in the area could be identified.Cekungan Sumatra Tengah merupakan salah satu cekungan penghasil hidrokarbon di Indonesia, karena keterbatasan ekplorasi dan studi, perkembangan cekungan tersebut mengalami hambatan. Penelitian ini bertujuan untuk mengidentifikasi lingkungan pengendapan dan sistem petroleum melalui studi stratigrafi seismik dan sumur. Penelitian ini menggunakan metode seismik dengan software Hampson Russell dan Petrel. Data log membantu pengolahan data seismik dengan software Interactive Petrophysic (IP) dan Techlog untuk pengolahan data sumur. Zona penelitian ini memiliki lima sekuen pengendapan yang sebagian besar terbentuk di lingkungan pengendapan alur bercabang dan estuari. Terdapat dua batuan induk potensial, yakni pada Formasi Pematang dan lapisan serpih pada TST-1 atas. Hasil analisis sekuen stratigrafi pada penampang seismik, sistem petroleum teridentifikasi pada Sumur Merak, Melibur, dan Garib di pesisir Cekungan Sumatra Tengah. Reservoar hidrokarbon terdapat di Formasi Bekasap, Bangko, Menggala, dan sebagian Formasi Pematang; batuan induk terdapat di sebagian Formasi Menggala dan Pematang. Penentuan lapisan reservoar dan batuan induk diperkuat oleh hasil analisis sumur yang terletak pada lintasan seismik. Patahan berguna sebagai jalur migrasi fluida hidrokarbon dari batuan induk hingga reservoar, sehingga terbentuk sistem petroleum pada daerah tersebut. Lapisan ini memiliki batuan induk yang belum matang dan matang. Karenanya dapat disimpulkan bahwa lingkungan pengendapan dan sistem petroleum pada sumur-sumur di daerah tersebut dapat diketahui

PRELIMINARY GEOMECHANICAL ANALYSIS ON LIMESTONES IN PPSDM GEOMINERBA CAMPUS, PADALARANG, WEST JAVA

The research location is in the PPSDM Geominerba field campus. The campus is located in Padalarang, West Java that is surrounded by the open-pit mining of limestone and marble. This limestone was formed in Oligo-Miocene of Rajamandala Formation. The research objective was to determine the condition of the slopes around the campus based on geomechanical characteristics. Based on field observations, the slope angle in the area is dominated by steep slopes. The rock hardness level is dominated by hard rock with a hardness ranging from 50-100 MPa. Rock Mass Rating shows that the area is dominated by good rocks. While the Slope Mass Rating calculation show that the maximum slope angle is between 52-75°. Level of deformation and intensive weathering process will reduce the strength of the rock in the future. Several rock fall occurrences on this research area support this assumption. Yet, some local open pit mining area activity near the toe hill of the area need to be concerned regarding the effect of the local rock fall occurrences

Identifikasi Parameter Petrofisika dan Jenis Fluida Berdasarkan Sw dan Sequence Stratigraphy di Pesisir Cekungan Sumatra Tengah

Parameter petrofisika dan jenis fluida perlu diketahui pada setiap sumur di lapangan ‘X’ pesisir Cekungan Sumatra Tengah, sehingga akan memperlancar proses analisis dan eksploitasi. Tujuan penelitian ini adalah menentukan porositas, densitas, impedansi akustik dan saturasi fluida pada 3 (tiga) sumur. Metode yang digunakan adalah Metode Well Logging dan Seismik untuk menentukan porositas, densitas, impedansi akustik dan saturasi air (Sw). Berdasarkan integrasi seperangkat data log dan seismik 2D, jenis fluida dapat diidentifikasi dengan nilai Sw, sedangkan persebaran parameter porositas, densitas dan impedansi akustik dengan metode log dan Sequence Stratigraphy. Penentuan Sw pada sumur Merak-1, Garib-1 dan Melibur-1 menggunakan software Techlog dan Interactive Petrophysics (IP), dan untuk mendapatkan Sw dilakukan perhitungan Vshale, porositas, dan Rw. Hasil penelitian ini didapatkan Sw pada formasi Bekasap, Bangko dan Menggala pada sumur Merak-1 sekitar 20%, pada sumur Garib-1 antara 15%-55% sedangkan sumur Melibur-1 yaitu 20% dan jenis fluidanya gas dan minyak. Porositas di formasi Bekasap, Bangko dan Menggala antara 23,9%-27,8%, sedangkan nilai densitas antara 2,2-2,3 gr/cc dan nilai impedansi akustik antara 18863-22897 ft/s.gr/cc. Berdasarkan nilai saturasi fluida (Sw) tersebut diperoleh jenis fluida adalah gas dan minyak serta nilai parameter petrofisika tersebut di atas besarnya ada yang sama dalam satu sequence

A Success Case of Widuri Area Rejuvenation, Asri Basin, Offshore Se Sumatra Block, Indonesia

INTA/B Field is one of the most producing mature fields in Widuri Area, Asri Basin, Offshore SE Sumatera, Indonesia, therefore it is subjected to rejuvenation to enhance hydrocarbon production. INTA/B Field is distinguished from other fields from its featured anticlinal structures that have the northeast-southwest trending. This structure is heavily faulted mainly in the up-thrown south side of a major normal fault. Two structural configurations with various oil-water contact have successfully been identified within the field. The most of oil reserves are preserved in the western lobe in which Intan-1 sands. One of the most important reservoirs in this field is Talangakar (TAF) sand deposited as a meandering river system that streamed from the northwest to the southeast within the basin. Two main reservoirs, Gita-34A and Gita-34B are correlated throughout the field and interpreted as Miocene fluvio-channel sands. These two channels are thickened moderately from southwest to northeast which has descriptions as follows: fine- to-coarse grains, unconsolidated to friable, and low cementing materials.INTA/B Field has been produced for 25 years and currently undergoing a watered-out phase. Therefore, an integrated study is subjected to overcome this issue for mature field rejuvenation. The integrated study ranged from geology (e.g., depositional environment and facies analysis), geophysics (e.g., revisiting and reprocessing of seismic attributes), petrophysical calculation, and reservoir engineering (e.g., water conformance plot and volumetric calculation).This integrated study has successfully rejuvenated a mature field resulting and added a significant number in oil production with an average of 300 BPOD/well. The extended project is estimated to have a similar result to the forward pilot