Offshore Peninsular Malaysia is experiencing a renewed exploration focus, with industry attention shifting to play types different from those historically targeted. The Langkasuka and Penyu basins are central to this resurgence, attracting significant interest from major companies.

Langkasuka Basin: A Re-emerging Frontier

The Langkasuka basin, named after an ancient kingdom and underlying the Strait of Malacca, is a Pre-Tertiary sedimentary basin formed in the Late Triassic to Jurassic period. Petronas has demarcated three blocks within it: PM 320, PM 321, and PM 422. Early exploration in the 1970s focused on Tertiary plays, but the 1989 Singa Besar-1 discovery in the Permian prompted Petronas Carigali to look deeper into Pre-Tertiary layers. However, activity subsequently shifted to the Malay basin for three decades.

Interest has been reignited by new subsurface data. Viridien's 2023-2024 Selat Melaka 2D survey and a subsequent integrated geological study with Petronas and Malaysia Petroleum Management (MPM) provided fresh insights into Palaeozoic prospectivity. This data highlights good source rock quality, proven reservoirs, and numerous potential traps, supporting licensing and investment decisions. Petronas now analogizes the basin to Australia's Canning basin, noting similar rift-related structures and prospective Permian and older sequences.

Following the survey, a consortium of Eni, BP, PTTEP, Pertamina, and Petronas Carigali was awarded a Technical Evaluation Agreement (TEA) in February 2025. 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 (Songket-1, MG-1) 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

The Penyu basin, southwest of the Malay basin, is a relatively underexplored rifted basin with Cenozoic deposits over pre-Tertiary terranes. Past exploration focused on structural traps within Oligocene to Miocene formations, leading to discoveries like Rhu-1 and Janglau-1 on Block PM 417. Rhu-1, drilled in the early 1990s, flowed 6,050 barrels per day on test. Janglau-1, drilled in 2011, encountered 24 metres of net oil pay in Oligocene intra-rift sands and fractured pre-Tertiary sections.

However, modest oil volumes and limited reservoir development have precluded commercial development and undermined interest. Uncertainty of hydrocarbon charge is often cited as a reason for the modest success to date. Despite this, geoscientists note that deeper plays in the basin have barely been tested, presenting significant future potential.

Block PM 417 was offered in the 2020 and 2023 bid rounds, with other wells on it (Penyu-1, Merawan Batu-1) yielding no or water-bearing reservoirs. Additional blocks PM 443 and PM 445 were offered in 2023, and blocks PM 443 and PM 444 were offered in the 2025 bid round, with bid submission due by 1 April 2026. Petronas offered longer exploration terms for some blocks to reflect the lack of historical drilling, despite acquired seismic data, and aims to award the 2025 blocks by June.