New Major Natural Gas Discovery in North Sumatra Basin Offshore Indonesia: Mubadaba Energy’s South Andaman Find is Regionally Significant and Confirms Harbour Energy’s 2022 Discovery to the North

     Considered the world’s second-largest 2023 deepwater natural gas discovery, Abu Dhabi (UAE)-based company Mubadaba Energy announced a major natural gas discovery in December 2023. This well, the Layaran-1 Exploration well was drilled about 100km offshore Sumatra in the North Sumatra Basin. It is the first deepwater well operated by the company, drilled to a depth of 4,208 meters (13805 ft) in 1,207 meters (3959 ft) of water depth . According to Mubadaba Energy’s website:

 

 “The well encountered an extensive gas column with a thickness of over 230 meters in an Oligocene sandstone reservoir. A complete data acquisition including wireline, coring, sampling and production test (DST) were conducted. The well successfully flowed over 30mmscf/d of excellent gas quality.”

 

     Previous to this discovery there was another discovery in 2022 about 50km to the north. This well, the Timpan-1, was operated by Harbour Energy, with Mubadaba having a 40% stake. The well was drilled in a water depth of 4245 ft. From Harbour’s announcement:

 

Source: Harbour Energy

“The well was drilled to a total vertical depth of 13,818 feet subsea. The well encountered a 390 foot gas column in a high net-to-gross, fine-grained sandstone reservoir with associated permeability of 1-10 mD. A full data acquisition programme has been completed including wireline logging, 240 feet of core recovered and a drill stem test.

 

The well flowed on test at 27 mmscfd of gas and 1,884 bopd of associated 58 degrees API condensate through a 56/64 inch choke. While the well has encountered a material gas accumulation, further work will be required to establish commerciality and the full potential of this play across the licence.”

 

These wells prove that the offshore Aceh part of the North Sumatra Basin has the potential for significant gas (and gas condensate) production. Based on the size of the structure Wood MacKenzie estimates the recoverable reserves at 3.3 TCF and the gas-in-place at 6 TCF. There is a possibility of multi-TCF expansion in the broader structure. The subsurface geology of the area consists of a series of small but deep syn-rift basins (a syn-rift basin indicates that faulting and deposition are synchronous).

     While the North Sumatra Basin is one of Indonesia’s most prolific hydrocarbon-producing basins with a producing history over 100 years (first hydrocarbon production in 1885), its part offshore Aceh has been underexplored according to a 2020 paper in the IOP Conference Series Materials Science and Engineering by independent geologist Muchlis – and Chris Elders of Curtin University. Previous to these two wells there was only one economic producing field along with a number of uneconomic discoveries and unsuccessful wells.

     The structural style and stratigraphy of the greater basin are shown below. The geology and tectonic history of the basin is complex strike-slip faulting and wrench faulting (Early Eocene to Early Oligocene); rotation of fault planes with more wrenching (late Oligocene to Early Miocene); regional uplift due to reactivation of older horsts and grabens, seafloor spreading, regional unconformities with widespread erosion (Middle Miocene), and finally compression stresses (Late Miocene to Recent).

 

 

The new discovery will help the region secure needed natural gas. Indonesia aims to reach a natural gas output of 12 bcf/day by 2030.

 

References:

Mubadala Energy announces major gas discovery in South Andaman. Reuters. December 20, 2023. Mubadala Energy announces major gas discovery in South Andaman (msn.com)

Harbour plans 3 exploration, appraisal wells in Andaman II block. Petromindo.com. March 9, 2023. Investments in Oil and Gas in Indonesia; Indonesia upstream oil & gas; Harbour plan Andaman drilling; Harbour drill Andaman well; Harbour plans exploration wells - Harbour plans 3 exploration, appraisal wells in Andaman II block (petromindo.com)

Mubadala Energy announces major gas discovery in South Andaman, Indonesia. Mubadala Energy. Media Release. December 19, 2023. Mubadala Energy Announces Major Gas Discovery in South Andaman, Indonesia - Mubadala Energy

A Review of Regional Geology of the North Sumatra Basin and its Paleogene Petroleum System. Ricky A. Tampubolon, Tsania Ozza, M. Tajul Arifin, A. Syauqi Hidayatillah, Aviandito Prasetio, and Terry Furqan. Indogeo Social Enterprise. No. 37, February 2017. 66 (iagi.or.id)

Structural style of the North Sumatra basin, offshore Aceh. IOP Conference Series Materials Science and Engineering 796(1):012038. Muchlis – and Chris Elders April 2020. (PDF) Structural style of the North Sumatra basin, offshore Aceh (researchgate.net)

Mubadala Petroleum discovers gas column during offshore Indonesia exploration. World Oil. July 13, 2022. Mubadala Petroleum discovers gas column during offshore Indonesia exploration (worldoil.com)