Planned activity in Timor Leste for 2025 is on the rise. As Sunda Energy works towards proving up gas reserves with the drilling of the upcoming Chuditch-2 appraisal well, Finder Energy progresses its plans to develop the Jahal and Kudi Tasi oil fields and Woodside Energy once again turns its eye to options to progress development of the long-stalled Sunrise giant gas field, the future looks bright for Timor Leste. Throw in the Santos operated Bayu-Undan geological storage of CO2 project, targeting FID this year, there is much to attract further interest in this prospective region. For these current operators and those companies looking to partner in potential projects a relook at opportunities in Timor Leste, involving known fields and the untapped exploration potential across the proven petroleum systems, is gaining more attention.
Ascendience Geoscience Pty Ltd has a long involvement in Timor Leste spanning nearly 35 years. Whilst we are a new start-up, Dr Mark Lisk, our chief geologist, formally led R&D programs developing methods to mitigate trap integrity risk in the Northern Bonaparte Basin for the CSIRO, Australia’s National Science Agency, for 10 years, before joining Woodside Energy in the mid-2000s as it sought to bring the Jahal and Kuda Tasi discoveries into production as backfill for the then aging Laminaria and Corallina fields.
The issue of poor trap integrity related to Neogene fault reactivation is widely recognised as a key risk that has blighted exploration success rates across the region and continues to strongly polarise chance of success for yet to be drilled leads and prospects. A variety of methods like contemporary stress field analysis, fault orientation or modern seepage response have been employed to better manage this risk. Results showed promise, but a retrospective look-back success not exceeding 50% made it difficult to demonstrate the necessary confidence to support future exploration decisions. Dr Lisk led new research initiatives at CSIRO in the late 1990s to early 2000s to address these risks, initially using methods to identify traps that once contained oil and had been fully breached or to define the proportion of leakage in traps that still contain a live column. This work defined the extent of the problem, but pioneering structural analysis of fault patterns by team-member Dr Anthony Gartrell, calibrated using data that had been acquired on the Laminaria and Corallina oil fields, offered a solution that, for the first time, provided genuine predictive capability. Known as strain localisation, the method recognised that some trap forming faults preferentially accrue more deformation during widespread Neogene fault reactivation, and as a result become more prone to breaching. These observations highlighted a key control on the probability of trap breach, yielding a better match with the prior drilling results than other methods of the time. Despite this success the method was not widely employed and research in this area was discontinued.
In 2021 Ascendience Geoscience undertook a new regional multi-client study with the aim to extend the legacy trap integrity research conducted around Laminaria that ceased in the early 2000s. Whilst the initial CSIRO research sought to produce a predictive model to better understand the distribution of preserved oil in the Laminaria field, it also seemed to explain the repeated failures seen across the region. Drawing on these prior research outcomes, a new phase of detailed structural analysis using interpretation completed on legacy 2D and 3D seismic data, coupled with a fluid history atlas drawn from existing public domain CSIRO fluid inclusion data, was completed to produce a refined version of the earlier calibrated predictive model across the entire offshore Timor Leste region. Calibration of the model against the drilled oil fields produced a retrospective lookback success of at least 80% and 100% for all commercial oil fields. Wells with defined palaeo-oil columns or residual oil columns beneath current OWCs also yielded good adherence with the model predictions of close to 70%, much higher than that achieved using other predictive methods.
Armed with the most successful predictive model ever produced for the region, the 2021 Ascendience multi-client study includes assessment of a portfolio of more than 200 undrilled leads and prospects from across Offshore Timor Leste. Fifty of the largest undrilled opportunities were ranked by risk of trap breach, with 60% of these features, each with volume potential above the minimum economic field size for the basin and up to > 300 MMbbls for the largest lead, had either low or moderate trap breach risk. The geographical spread of these attractive leads delivered clear insights into the blocks offering the greatest potential for future success.
The fluid history atlas compiled as part of the Ascendience study revealed more regional charge access for oil, extending well away from the proven oil fairway and bringing much of the offshore region into play. Regions previously assessed as gas-prone showed proven oil potential, improving the attractiveness of many leads that are too small to be considered as viable gas development opportunities. Much of the acreage away from the current industry focus areas around the Kitan Oilfield and beyond the tightly focussed development 3D surveys acquired for the Bayu-Undan, Sunrise and Chuditch gas fields remains open acreage and is covered only by legacy 2D seismic data, mostly acquired through the 1990s. Substantial improvements in acquisition and reprocessing techniques since then offer great opportunity to apply modern methods to fully assess this attractive lead inventory of low and moderate ranked traps identified in the Ascendience study, but also to reveal new leads, prospects and previously unrecognised plays with access to a proven petroleum system.
Aside from clear application to petroleum prospectivity, the work undertaken by Ascendience Geoscience also contributes to a better understanding of leakage risk for planned CCUS projects and allows options such as bringing Sunrise to Southern Timor via sub-sea pipeline to be more effectively assessed from a geotechnical risk perspective. As an independent product, learnings from the Ascendience study offer critical data to more effectively address key risks and manage stakeholder engagement.
Success of Italian multi-national giant Eni with discovery of the modest sized, but highly lucrative Kitan oil-field in 2008 showed us that small can be beautiful in Timor Leste. The current study has evaluated a large number of undrilled opportunities with likely volumes above Minimum Economic Field Size for oil (as shown by the commercial, BHP discovered, Buffalo Oilfield) together with the expanded footprint of proven oil charge leaves plenty of running room for new exploration. 40% of these features that were ranked as having high trap integrity risk and should be avoided even where they offer substantial volume potential. Knowing the traps to avoid increases the chance of success in the remainder, where the key risk of trap integrity has been mitigated.
Exploration upside, beyond the current focus areas, has the potential to provide new players the required materiality and opportunity diversity to allow serious consideration of current farm-in opportunities or future new acreage offerings from the Timorese regulator, Autoridade Nacional do Petróleo (ANP Timor Leste). Together with our study partners from Discover Geoscience and Searcher Seismic we can offer new entrants the basis for assessing attractive acreage in Timor Leste by combining an extensive regional study and play-based assessment with the Ascendience trap integrity study to supercharge your understanding of your farm-in options.
Contact us today for more information on this game-changing technical study. The Timor Leste Trap Integrity study, priced from $USD 40,000, offers high-value insights at low cost to complement your in-house workflows. Already licenced by major companies operating in Timor Leste, this study offers the chance to more effectively screen opportunities and delivers outstanding value to address key risks. Ascendience brings unparalleled experience on Offshore Timor Leste prospectivity and in conjunction with our partner products and affiliate network we can fully assist with all aspects of sub-surface evaluation and portfolio build to ensure the study results translate into maximum value.
A copy of a project flyer can be found HERE
