Offshore Peninsular Malaysia is experiencing a renewed exploration focus, with industry attention shifting to the Langkasuka and Penyu basins, which offer different geological play types compared to historically exploited areas.

Langkasuka Basin: A Re-emerging Frontier

The Langkasuka basin, named after an ancient kingdom and underlying the Strait of Malacca, is gaining significant interest. Formed in the Late Triassic to Jurassic period, this Pre-Tertiary basin encompasses areas of Malaysia, Indonesia, and Thailand. Early exploration in the 1970s focused on Tertiary plays, but the 1989 Singa Besar-1 discovery in Permian layers prompted deeper investigation. However, activity shifted to the Malay basin for the next three decades. Recent new subsurface data has reignited interest in Langkasuka's largely overlooked pre-Tertiary potential.

Viridien's 2023-2024 Selat Melaka 2D seismic survey and a subsequent integrated geological study with Petronas provided fresh insights into Palaeozoic prospectivity. This data is intended to support licensing and investment decisions. Petronas now likens the Langkasuka basin to Australia's Canning basin, citing similar rift-related structures and prospective Permian and older sequences. A recent multiclient 2D survey aimed to improve seismic imaging and identify hydrocarbon traps, with factors like good source rock and proven reservoirs signaling new investment opportunities.

Following the survey, a consortium of Eni, BP, PTTEP, Pertamina, and Petronas Carigali was awarded a Technical Evaluation Agreement (TEA) for the basin in February 2025. Two blocks, PM 320 and PM 321, were offered in the 2024 bid round. Block PM 320 contains three gas discoveries (Singa Besar-1, Kebaya-1, Selendang-1) evidencing a working petroleum system. Block PM 321 has exploration wells targeting synrift plays. A second TEA was signed with Afed Texcal Energy Ventures in June 2025, underscoring Petronas's commitment to activating this frontier.

Penyu Basin: Underexplored Potential

Interest in the Penyu basin has been undermined by modest oil volumes and limited reservoir development from past discoveries. However, geoscientists note its deeper plays remain largely untested, presenting significant potential. The basin is described as a relatively underexplored rifted basin with Cenozoic deposits over pre-Tertiary terranes.

Historical exploration focused on structural traps in Oligocene to Miocene formations, leading to discoveries like Rhu-1 (drilled by Texaco in the 1990s, flowing 6050 barrels per day on test) and Janglau-1 (drilled by Lundin in 2011, encountering 24 metres of net oil pay). Despite these finds and the subsequent Ara-1 discovery in 2013, the volumes were sub-commercial, and assets were relinquished. Uncertainty regarding hydrocarbon charge is often cited as a reason for the modest success to date.

Block PM 417 was offered in the 2020 and 2023 bid rounds, with other wells on it yielding mixed results. Additional blocks, PM 443 and PM 445, were offered in 2023 with extended exploration terms. In the 2025 bid round, shallow-water blocks PM 443 and PM 444 were offered, with a bid deadline of 1 April 2026. Petronas aims to announce winners for these blocks in June and sign production sharing contracts by 30 September this year.