SEGJ14th

Presentation information

Oral presentation

Seismic Technologies

Seismic technologies

Wed. Oct 20, 2021 1:55 PM - 3:15 PM Room 1 / Oral session (Zoom 1)

Chair:Shohei Minato

2:15 PM - 2:35 PM

[SE-04] Unlocking the potential of gas sand reservoir using seismic inversion and AVO analysis: case study in offshore North Sumatra Basin

*Dwipaningtyas Dwipaningtyas1, Amin Bunyamin1, Asri Surya Ilhami2, Rangga Perdana Putra1, Fuad Nuri1 (1. PT Pertamina Hulu Rokan (Indonesia), 2. PT Pertamina EP Cepu (Indonesia))

The offshore part of North Sumatra Basin (NSB) is considered as one of the most prolific areas for future petroleum exploration. Several fields in the northern offshore of NSB area have Carbonate Build-up reservoir or known as the Peutu Limestone. Sandstone reservoir play is also identified within Belumai Formation in the east offshore of NSB. However, despite having a great potential, Belumai Sandstone has not been explored thoroughly.
Taufiqurrahman et al (2014) mapped the Belumai Formation facies using Seismic Paleomorphology as reported in a Pertamina EP study. It was revealed that The Belumai Sandstone is a Lower Miocene with a shallow to open marine depositional environment. The Belumai Sandstone reservoir in Y Gas Field has characteristics of a sandbar deposit with excellent porosity, ranging from 15%-30%.
To assess reservoir quality and fluid content, a quantitative interpretation of seismic data was generated. The analyses were conducted based on available data in the area, including 3D seismic volume and wells data in Y Gas Field. Acoustic Impedance (AI) seismic inversion was run to deliver quality and distribution of Belumai Sandstone reservoir. In addition to this reservoir characterization, an analysis was also made to describe the fluid contained within. Considered as one of the best techniques, Amplitude Variation with Offset (AVO) was carried out to understand the fluid effect in the seismic data. It is very useful to identify the gas zone in the reservoir.
This investigation showed that the sandstone reservoir in the study area belongs to AVO Class IV, typically low impedance gas sand, which occurs when porous sand is overlained by a high-velocity unit, such as carbonate. This gas sand reservoir has successfully been mapped using this analysis. Therefore, this approach is considered suitable to successfully unlocked gas potential in the study area that is worth exploring for future discovery.

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