Bulletin of Scientific Contribution

The presence of shallow gas (Shallow Gas) in exploration wells poses significant operational risks, including kicks or blowouts during exploration activities. To mitigate these risks, it is essential to delineate subsurface data and identify areas potentially containing shallow gas. Subsurface interpretation was conducted using various datasets, including electrolysis cutting analysis, well log data (GR, RT, NEU, RHOB) from 39 wells, and gas data obtained from chromatograph-based mud logs. Well correlation was performed to identify anomalies, gas presence, and facies characteristics.

The primary stratigraphic marker surfaces indicative of shallow intervals in Field X are, from deeper to shallower, MF2, Fs-s1, s2-Fs, Fs-s3, Fs-s4, Fs-s5, and Fs-s6, with the shallow gas accumulation predominantly observed within the intervals associated with Fs-s2 and Fs-s3, at depths ranging from approximately 950 to 1300 meters below sea level (MSS). These intervals demonstrate isolated gas accumulations, primarily comprising methane (C1), with minor traces of C2, C3, C4, and C5 gases detected in the shallow zone above the marker MF2.

Gas analysis indicates a surge in total gas content within the 950-1300 MSS interval, correlating with anomalies identified from the Master Log data. This surge is attributed to limestone and coal layers, as corroborated by gas bearing reservoir mapping.

Based on the analyzed data, it can be concluded that shallow gas accumulations are localized within the 950-1300 MSS interval, specifically between the Fs-s2 and Fs-s3 markers. For subsequent drilling activities on Platform M, it is recommended to monitor and consider this depth zone to mitigate related risks effectively.

Abraham, C. U., Clement, E. B., Anietie, E. E., & Monday, U. U. (2020). Sequence stratigraphic study of X field in eastern offshore of Niger Delta, Nigeria. Journal of Geology and Mining Research, 12(2), 65. https://doi.org/10.5897/jgmr2019.0322

Al-Aziz, S. A., Al-Rowyeh, A., AL-Enezi, T., Chetri, H., & Al-Anzi, E. (2009). Sabiriyah Upper Burgan Geological Model and Reservoir Characterization. SPE Middle East Oil and Gas Show and Conference. https://doi.org/10.2118/120380-ms

Allen, G.P dan Chambers, J.L.C., 1998. Sedimentation in the modern and Miocene Mahakam Delta. Indonesian Petroleum Association, 236p.

Allen, G.P and F. Mercier. 1988. Subsurface Sedimentology of Deltaic Systems. Total Exploration Laboratory, Pessac, France: Pesa Journal, No.12, p.30-44

Allen, G.P., Laurier, D., dan Thouvenin, J.M., 1979. Etude sedimentologique du delta de la Mahakam. TOTAL Compagnie Francaise des Petroles Notes Mem., 15, 156p.

Amalia, D. (2019). APPLICATION OF DIGITAL IMAGE TECHNOLOGY FOR DETERMINING GEOMETRY, STRATIGRAPHY, AND POSITION OF CRACKS INSIDE EARTH SLOPE. International Journal of Geomate, 17(63). https://doi.org/10.21660/2019.63.25640

Asquith, G.B., 1982. Basic Well Log Analysis for Geolgists. The American Association of Petroleum Gelogists: Tulsa, Oklahoma USA

Bachtiar, A. (2018, March 5). The Tertiary Paleogeography Of The Kutai Basin And Its Unexplored Hydrocarbon Plays. Proc. Indon Petrol. Assoc., 36th Ann. Conv. https://doi.org/10.29118/ipa.0.13.g.126

Banerjee, A., & Salim, A. M. A. (2020). Seismic attribute analysis of deep-water Dangerous Grounds in the South China Sea, NW Sabah Platform region, Malaysia. Journal of Natural Gas Science and Engineering, 83, 103534. https://doi.org/10.1016/j.jngse.2020.103534

Chen, Z. (2018). Research on Constrained Sedimentary Facies Reservoir by Well-seismic Inversion. IOP Conference Series Earth and Environmental Science, 189(4), 42024. https://doi.org/10.1088/1755-1315/189/4/042024

Colke, I. R., Craig, J., & Blundell, D. J. (1999). Structural controls on the hydrocarbon and mineral deposits within the Kutai Basin, East Kalimantan. Geological Society London Special Publications, 155(1), 213. https://doi.org/10.1144/gsl.sp.1999.155.01.16

Combaz, A. dan de Matharel , M., 1978, Organic Sedimentation and Genesis of Petroleum in the Mahakam Delta, Borneo, American Association f Petroleum Geologists Bull. V. 62,p. 1684 – 1695

Drake, W. R., Hawkins, S. J., & Lapierre, S. G. (2013). The Role of Stratigraphic Architecture in Resource Distribution: An Example from the Niobrara Formation of the Denver-Julesburg Basin. Unconventional Resources Technology Conference, Denver, Colorado, 12-14 August 2013, 2465. https://doi.org/10.1190/urtec2013-257

Gastaldo, R.A dan Huc, A.Y., 1992. Sediment facies, depositional environments, and distribution of Phytoclasts in the recent Mahakam River Delta, Kalimantan, Indonesia. Palaios 7, 574-590.

Graña, D., Paparozzi, E., Mancini, S., & Tarchiani, C. (2012). Seismic driven probabilistic classification of reservoir facies for static reservoir modelling: a case history in the Barents Sea. Geophysical Prospecting, 61(3), 613. https://doi.org/10.1111/j.1365-2478.2012.01115.x

Hasan, R. A., Saberi, M. H., Riahi, M. A., & Manshad, A. K. (2023). Electro-facies classification based on core and well-log data. Journal of Petroleum Exploration and Production Technology, 13(11), 2197. https://doi.org/10.1007/s13202-023-01668-5

Keynejad, S., Sbar, M. L., & Johnson, R. A. (2020). Creating probabilistic 3D models of lithofluid facies using machine-learning algorithms. Interpretation, 8(4). https://doi.org/10.1190/int-2019-0249.1

Kompanik, G. S., HEIL, R., Al-Shammari, Z. A., & Al-Shammery, M. J. (1993). Geologic Modelling for Reservoir Simulation: Hanifa Reservoir, Berri Field, Saudi Arabia. Middle East Oil Show. https://doi.org/10.2118/25580-ms

Koning, T., Cameron, N., & Clure, J. (2021). Undiscovered Potential in the Basement Exploring in Sumatra for oil and gas in naturally fractured and weathered basement reservoirs. Berita Sedimentologi, 47(2), 67. https://doi.org/10.51835/bsed.2021.47.2.320

Mora, Stefano et. Al, 2000. Modern, Ancient Deltaic Deposits and Petroleum system of Mahakam Area. IPA 2002 Field Trip Guide Book, TOTALFINAELF E&P INDNESIE, Balikpapan

Nainggolan, T. B., Nurhasanah, U., & Setiadi, I. (2021). Depositional sequence interpretation using seismic and well data of offshore Central Sumatra Basin. IOP Conference Series Earth and Environmental Science, 944(1), 12002. https://doi.org/10.1088/1755-1315/944/1/012002

Napitupulu, V., Jannah, M., Silaen, M., & Darman, H. (2021). Hydrocarbon Columns of Oil and Gas Fields in the South Sumatra Basin. Berita Sedimentologi, 46(1), 51. https://doi.org/10.51835/bsed.2020.46.1.60

Nur, A., Hatta, M. P., Thaha, M. A., & Suriamihardja, D. A. (2020). Preliminary sediment modeling at the confluence of the Mahakam and Karang Mumus River. IOP Conference Series Earth and Environmental Science, 419(1), 12129. https://doi.org/10.1088/1755-1315/419/1/012129

Pendkar, N., Zainun, F., Parsuram, S. N., Aziz, A., Ali, M. F., & Embi, R. Bt. (2014). Sedimentology and Diagenesis of Deeper Clastic Reservoirs: Some Insights from Recent Exploration Wells in Offshore Sarawak, Malaysia. All Days. https://doi.org/10.2523/iptc-18038-ms

Syed, M. S., Khan, F. A., Farid, A., Khan, A., & Hasnain, N. S. and K. (2008). Presenting seismic stratigraphy and attribute analysis as pioneer techniques for delineation of reservoir quality sand bodies in Indus offshore, southwest Pakistan. GEO 2008. https://doi.org/10.3997/2214-4609-pdb.246.340

Yang, H., Fan, T., & Zhou, M. (2023). Study on tight reservoir law and prediction of favorable areas - Take Wangjiawan well block Wang 107 as an example. E3S Web of Conferences, 385, 3031. https://doi.org/10.1051/e3sconf/202338503031